/**
 * vault.ts — sole owner of vault state and chrome.storage vault keys.
 *
 * Every read/write of `peach_vault_a`, `peach_vault_b`, and `peach_settings`
 * goes through this module. No other file accesses those keys directly.
 * External callers reach vault operations via `messages.ts` — never by
 * importing from here cross-boundary (popup/content must not). Invariants
 * for the two-slot schema, unlock timing, and key/disk atomicity are in
 * Projects.md §3.2–§3.6.
 */

import { deriveKey, generateSalt } from "../crypto/argon2";
import { extractDomain } from "../shared/domain";
import {
  rootKeyToWords,
  wordsToRootKeyMaterial,
  deriveRecoveryKey,
} from "../shared/recovery-words";
import type {
  AccentColorName,
  LegacyVaultEntry,
  ManualSummonRecord,
  SavedIdentity,
  StoredVault,
  VaultEntry,
  VaultHistory,
  VaultSnapshot,
} from "../shared/types";
import { decrypt, encrypt, zeroKey } from "./aes";
import { clearAutoLock, touchAutoLock } from "./alarms";

type EntryDraft = Omit<
  VaultEntry,
  "id" | "createdAt" | "modifiedAt" | "deletedAt"
>;

// Slot-neutral storage keys (v1.4.24+). Both slots always exist; slot B
// either holds the decoy vault (when duress is configured) or random noise
// that looks identical at rest. No external indicator is stored — duress
// configuration is recorded only inside the encrypted payload of slot A.
const SLOT_A = "peach_vault_a";
const SLOT_B = "peach_vault_b";

// Legacy keys, migrated away on first access.
const LEGACY_MAIN = "peach_vault";
const LEGACY_DECOY = "peach_decoy_vault";
const LEGACY_DURESS_FLAG = "peach_duress";

// Plaintext is padded to the next multiple of this size before encryption.
// This coarsens ciphertext-length leakage into 1 KiB buckets.
const PAD_BLOCK = 1024;

let derivedKey: Uint8Array | null = null;
// 32-byte random root key, separate from the derivedKey used for vault encryption.
// The root key is wrapped (encrypted) under the recovery key derived from the
// 12-word phrase. When the user changes their password, only the wrapping changes;
// the root key and recovery words remain stable.
let rootKey: Uint8Array | null = null;
let entries: VaultEntry[] = [];
let domainIndex: Map<string, VaultEntry[]> = new Map();
let vaultMode: "real" | "decoy" = "real";
// Cached post-unlock view of whether the real vault records that duress is
// configured. Only meaningful after a real-mode unlock; for decoy-mode unlock
// this stays false because we never see slot A's plaintext.
let duressConfigured = false;

let migrationRan = false;

// ---------------------------------------------------------------------------
// Settings (persisted inside the encrypted vault store as a sidecar key)
// ---------------------------------------------------------------------------

export type DisplayFont = "cormorant-italic" | "cormorant" | "inter" | "system";
export type TextSize = "small" | "medium" | "large";

export interface VaultSettings {
  accentColor?: AccentColorName;
  theme?: "dark" | "light";
  autoLockMinutes?: number;
  clipboardClearSeconds?: number;
  lockOnClose?: boolean;
  breachMonitoring?: boolean;
  passkeyProviderEnabled?: boolean;
  trashRetentionDays?: number;
  manualSummonDomains?: Record<string, ManualSummonRecord>;
  declinedCardFingerprints?: string[];
  /**
   * Display font for headlines, brand wordmark, and narrative copy. Default
   * is "cormorant-italic" — the bold italic serif that ships as Peach's
   * voice. Non-italic options exist for users who prefer upright type.
   */
  displayFont?: DisplayFont;
  /**
   * Text size scale for body copy and entry titles. Stops at "large" by
   * design — XL clips dense screens (Vault, Health) inside the fixed
   * 330×480 popup surface.
   */
  textSize?: TextSize;
  /**
   * When true, all entrance/exit transitions and ambient animations are
   * collapsed to instant. Honoured alongside the user's OS-level
   * `prefers-reduced-motion`.
   */
  reduceMotion?: boolean;
  /**
   * User overrides for keyboard shortcuts. Keys are ShortcutAction names
   * (see src/shared/shortcuts.ts). Missing actions fall through to
   * DEFAULT_BINDINGS — `getActiveBindings(settings.shortcuts)` is the
   * canonical lookup. Storing only the deltas keeps the vault payload
   * small and lets default updates land for users who never rebind.
   */
  shortcuts?: Record<string, { key: string; ctrl?: boolean; meta?: boolean; shift?: boolean; alt?: boolean }>;
}

let settings: VaultSettings = {};

export function getSettings(): VaultSettings {
  return settings;
}

export async function ensureSettingsLoaded(): Promise<VaultSettings> {
  await loadSettings();
  return settings;
}

export async function updateSettings(patch: Partial<VaultSettings>): Promise<void> {
  await loadSettings();
  settings = { ...settings, ...patch };
  await persistSettings();
}

async function persistSettings(): Promise<void> {
  try {
    await chrome.storage.local.set({ peach_settings: settings });
  } catch (err) {
    throw mapStorageError(err);
  }
}

function mapStorageError(err: unknown): Error {
  const message = err instanceof Error ? err.message : String(err);
  if (/QUOTA_BYTES|quota/i.test(message)) {
    return new Error("STORAGE_QUOTA_EXCEEDED");
  }
  return err instanceof Error ? err : new Error(message);
}

async function loadSettings(): Promise<void> {
  const result = await chrome.storage.local.get("peach_settings");
  settings = (result as { peach_settings?: VaultSettings }).peach_settings ?? {};
}

// ---------------------------------------------------------------------------
// HIBP breach check (k-anonymity model)
// ---------------------------------------------------------------------------

export async function checkBreach(password: string): Promise<number> {
  const encoder = new TextEncoder();
  const hashBuffer = await crypto.subtle.digest("SHA-1", encoder.encode(password));
  const hashHex = Array.from(new Uint8Array(hashBuffer))
    .map((b) => b.toString(16).padStart(2, "0"))
    .join("")
    .toUpperCase();

  const prefix = hashHex.slice(0, 5);
  const suffix = hashHex.slice(5);

  try {
    const res = await fetch(`https://api.pwnedpasswords.com/range/${prefix}`);
    if (!res.ok) return 0;
    const text = await res.text();
    const match = text.split("\r\n").find((l) => l.startsWith(suffix));
    return match ? parseInt(match.split(":")[1], 10) : 0;
  } catch {
    return 0; // Network unavailable — don't block
  }
}

export async function declineCardSaveOffer(last4: string, expMonth: string, expYear: string): Promise<void> {
  const fingerprint = await cardFingerprint(last4, expMonth, expYear);
  await loadSettings();
  settings = {
    ...settings,
    declinedCardFingerprints: [...(settings.declinedCardFingerprints ?? []), fingerprint],
  };
  await persistSettings();
}

export async function isCardDeclined(last4: string, expMonth: string, expYear: string): Promise<boolean> {
  await loadSettings();
  const fingerprint = await cardFingerprint(last4, expMonth, expYear);
  return (settings.declinedCardFingerprints ?? []).includes(fingerprint);
}

async function cardFingerprint(last4: string, expMonth: string, expYear: string): Promise<string> {
  const encoder = new TextEncoder();
  const buf = await crypto.subtle.digest("SHA-1", encoder.encode(`${last4}${expMonth}${expYear}`));
  return Array.from(new Uint8Array(buf)).map(b => b.toString(16).padStart(2, "0")).join("");
}

function hex(buf: Uint8Array): string {
  return Array.from(buf)
    .map((b) => b.toString(16).padStart(2, "0"))
    .join("");
}

function unhex(s: string): Uint8Array {
  const out = new Uint8Array(s.length / 2);
  for (let i = 0; i < s.length; i += 2) {
    out[i / 2] = parseInt(s.slice(i, i + 2), 16);
  }
  return out;
}

// ---------------------------------------------------------------------------
// Root key generation and recovery word wrapping
// ---------------------------------------------------------------------------

/**
 * Generate a random 32-byte root key and wrap it (AES-256-GCM) under a key
 * derived from the recovery word material via HKDF-SHA256. The wrapped blob
 * fields are stored in slot A alongside the password-wrapped ciphertext. The
 * root key itself is kept in memory for the session so getRecoveryWords() can
 * encode it without re-deriving.
 */
async function generateAndWrapRootKey(): Promise<{
  rawRootKey: string; // hex of the plaintext root key — caller stores in rootKey
  recoverySalt: string;
  wrappedRootKey: string;
  wrappedNonce: string;
  wrappedTag: string;
}> {
  const rootKeyBytes = crypto.getRandomValues(new Uint8Array(32));

  // Derive the recovery key from the BIP39 words encoding of the root key.
  const words = await rootKeyToWords(rootKeyBytes);
  const wordMaterial = await wordsToRootKeyMaterial(words);
  const recoverySalt = crypto.getRandomValues(new Uint8Array(16));
  const recoveryKey = await deriveRecoveryKey(wordMaterial, recoverySalt);

  // Wrap the root key with the recovery key using AES-256-GCM directly.
  // We hex-encode rootKeyBytes so the plaintext is always valid UTF-8.
  const nonce = crypto.getRandomValues(new Uint8Array(12));
  const encoded = new TextEncoder().encode(hex(rootKeyBytes));
  const raw = await crypto.subtle.encrypt(
    {
      name: "AES-GCM",
      iv: nonce,
      additionalData: new Uint8Array([1]).buffer as ArrayBuffer,
      tagLength: 128,
    },
    recoveryKey,
    encoded
  );
  // WebCrypto returns ciphertext || auth tag concatenated; split them.
  const rawU8 = new Uint8Array(raw);
  const ciphertext = hex(rawU8.slice(0, rawU8.length - 16));
  const tag = hex(rawU8.slice(rawU8.length - 16));

  return {
    rawRootKey: hex(rootKeyBytes),
    recoverySalt: hex(recoverySalt),
    wrappedRootKey: ciphertext,
    wrappedNonce: hex(nonce),
    wrappedTag: tag,
  };
}

/**
 * Unwrap the root key using recovery words. Called during recovery flow when
 * the user provides their 12-word phrase and a new password.
 * Exported for use by the RECOVER_WITH_WORDS message handler.
 */
export async function unwrapRootKeyForRecovery(
  wrappedRootKey: string,
  wrappedNonce: string,
  wrappedTag: string,
  recoverySaltHex: string,
  words: string[]
): Promise<void> {
  const wordMaterial = await wordsToRootKeyMaterial(words);
  const recoverySalt = unhex(recoverySaltHex);
  const recoveryKey = await deriveRecoveryKey(wordMaterial, recoverySalt);

  // Decrypt and cache the root key. The root key bytes were hex-encoded before
  // encryption so the ciphertext is valid UTF-8. We inline the AES-GCM decrypt
  // here to avoid passing a CryptoKey to the string-based encrypt/decrypt helpers.
  const combined = unhex(wrappedRootKey + wrappedNonce + wrappedTag);
  const nonceU8 = combined.slice(0, 12);
  const ciphertext = combined.slice(12, combined.length - 16);
  const storedTag = combined.slice(combined.length - 16);
  const raw = await crypto.subtle.decrypt(
    { name: "AES-GCM", iv: nonceU8, additionalData: new Uint8Array([1]).buffer as ArrayBuffer, tagLength: 128 },
    recoveryKey,
    new Uint8Array([...ciphertext, ...storedTag])
  );
  const decryptedHex = new TextDecoder().decode(raw);
  rootKey = unhex(decryptedHex);
}

/**
 * Re-wrap the cached root key under a new derived key (from the user's new
 * password). Called after password change and after recovery re-key so the
 * same recovery words continue to work with the updated password.
 */
export async function rewrapRootKeyForPassword(
  newDerivedKey: Uint8Array,
  _newSalt: Uint8Array
): Promise<void> {
  if (!rootKey) throw new Error("root key not set");
  const { nonce, ciphertext, tag } = await encrypt(
    newDerivedKey,
    hex(rootKey)
  );
  const slotA = await loadSlot(SLOT_A);
  if (!slotA) throw new Error("missing slot A");
  await writeSlot(SLOT_A, {
    ...slotA,
    recovery_wrapped_root_key: ciphertext,
    recovery_nonce: nonce,
    recovery_tag: tag,
    // recovery_salt does NOT change when password changes — the recovery
    // words always derive the same key; only the wrapping key changes.
  });
}

/**
 * Change the vault encryption to a new derived key (already derived from
 * the user's new password). Used by RECOVER_WITH_WORDS and changePassword.
 * Caller is responsible for key swap and snapshot.
 */
async function reencryptVaultForNewKey(
  newKey: Uint8Array,
  slotA: StoredVault
): Promise<void> {
  const plaintext = encodePayload(entries, duressConfigured);
  const { nonce, ciphertext, tag } = await encrypt(newKey, plaintext);
  await writeSlot(SLOT_A, {
    ...slotA,
    nonce,
    ciphertext,
    tag,
  });
}

/**
 * Full password change with an already-derived key (used after recovery).
 * Unlike changePassword(), this skips re-verification of current password
 * since recovery flow has already validated the user's identity via words.
 */
export async function changePasswordWithNewKey(
  newSalt: Uint8Array,
  newKey: Uint8Array
): Promise<void> {
  const slotA = await loadSlot(SLOT_A);
  if (!slotA) throw new Error("missing slot A");
  await reencryptVaultForNewKey(newKey, slotA);
  zeroKey(derivedKey!);
  derivedKey = newKey;
  if (!duressConfigured) {
    await writeSlot(SLOT_B, generateNoiseBlob(slotA.ciphertext.length / 2));
  }
}

// ---------------------------------------------------------------------------
// Salt generation --- exported so the RECOVER_WITH_WORDS handler can derive
// a new key after password reset without re-importing the crypto module.
// ---------------------------------------------------------------------------

export { deriveKey, generateSalt };

export async function loadSlotA(): Promise<StoredVault | null> {
  return loadSlot(SLOT_A);
}

/**
 * Re-derive the session root key from the already-derived AES key (keyA from
 * unlock) and the recovery salt stored in slot A. This is the inverse of
 * generateAndWrapRootKey() — both operations use the same HKDF with the same
 * salt and info string, so they cancel out.
 *
 * The derivedKey and rootKey are related by:
 *   derivedKey = Argon2id(password, slotA.salt)   → AES key for vault payload
 *   rootKey    = HKDF-SHA256(recovery_words, recovery_salt)  → wrapped by HKDF
 *
 * Since we only store the wrapped root key and the recovery salt, we can
 * only re-derive rootKey during an active (unlocked) session where we have
 * the derivedKey already. On lock, rootKey is zeroed.
 *
 * For pre-v2.12 vaults that have no recovery_salt, this returns null and
 * the caller must invoke migrateToRecovery() to generate the recovery escrow.
 */
async function deriveRootKeyFromDerivedKey(
  _derivedKey: Uint8Array,
  _recoverySaltHex: string
): Promise<Uint8Array | null> {
  // The root key is stored wrapped under the recovery key derived from the
  // 12-word phrase. It cannot be re-derived from derivedKey alone — that would
  // require knowing the original recovery words. The in-memory rootKey is set
  // during unlock if recovery data is present.
  // This function exists as a potential future path if we ever store an
  // additional derived-key → root-key relationship. Currently rootKey is
  // cached directly during unlock.
  return null;
}

/**
 * For vaults created before v2.12 (no recovery_salt/recovery_wrapped_root_key),
 * generate the root key, wrap it under the recovery words, and persist the
 * recovery escrow into slot A. The caller must show the recovery words to the
 * user before calling this — once called, those words are the vault's recovery
 * path. This runs once, on the first unlock of an upgraded vault.
 */
export async function migrateToRecovery(): Promise<void> {
  if (!derivedKey || vaultMode !== "real") {
    throw new Error("vault must be unlocked in real mode");
  }
  const slotA = await loadSlot(SLOT_A);
  if (!slotA) throw new Error("missing slot A");
  if (slotA.recovery_salt && slotA.recovery_wrapped_root_key) return; // already done

  const { rawRootKey, recoverySalt, wrappedRootKey, wrappedNonce, wrappedTag } =
    await generateAndWrapRootKey();

  rootKey = unhex(rawRootKey);

  const nextSlotA: StoredVault = {
    ...slotA,
    recovery_salt: recoverySalt,
    recovery_wrapped_root_key: wrappedRootKey,
    recovery_nonce: wrappedNonce,
    recovery_tag: wrappedTag,
  };
  await writeSlot(SLOT_A, nextSlotA);
}

/**
 * Returns the 12 recovery words for the current session's root key.
 * Must be called while the vault is unlocked. Throws if recovery has not
 * been set up (pre-v2.12 vault that hasn't migrated yet).
 */
export async function getRecoveryWords(): Promise<string[]> {
  if (!rootKey) {
    throw new Error("recovery not set up — vault may need migration");
  }
  return rootKeyToWords(rootKey);
}

async function loadSlot(key: string): Promise<StoredVault | null> {
  const result = await chrome.storage.local.get(key);
  return (result as Record<string, StoredVault | undefined>)[key] ?? null;
}

async function writeSlot(key: string, vault: StoredVault): Promise<void> {
  try {
    await chrome.storage.local.set({ [key]: vault });
  } catch (err) {
    throw mapStorageError(err);
  }
}

/**
 * One-shot migration from the pre-A-2 schema (peach_vault + peach_decoy_vault
 * + peach_duress flag) to the slot-neutral schema (peach_vault_a +
 * peach_vault_b). Runs at most once per session; safe to call repeatedly.
 */
async function ensureMigrated(): Promise<void> {
  if (migrationRan) return;
  migrationRan = true;

  const keys = [LEGACY_MAIN, LEGACY_DECOY, LEGACY_DURESS_FLAG, SLOT_A, SLOT_B];
  const raw = await chrome.storage.local.get(keys);
  const slotAExists = raw[SLOT_A] !== undefined;
  const slotBExists = raw[SLOT_B] !== undefined;
  const legacyMain = raw[LEGACY_MAIN] as StoredVault | undefined;
  const legacyDecoy = raw[LEGACY_DECOY] as StoredVault | undefined;

  // Fresh install with nothing in storage — nothing to do; createVault() sets up both slots.
  if (!slotAExists && !legacyMain) return;

  // Already migrated.
  if (slotAExists && slotBExists && !legacyMain && !legacyDecoy) return;

  if (legacyMain && !slotAExists) {
    await writeSlot(SLOT_A, legacyMain);
  }

  // If slot B isn't set, populate it: use legacy decoy when present, else noise.
  if (!slotBExists) {
    const target = (legacyMain ?? raw[SLOT_A]) as StoredVault | undefined;
    if (legacyDecoy) {
      await writeSlot(SLOT_B, legacyDecoy);
    } else if (target) {
      await writeSlot(SLOT_B, generateNoiseBlob(target.ciphertext.length / 2));
    }
  }

  const toRemove: string[] = [];
  if (legacyMain) toRemove.push(LEGACY_MAIN);
  if (legacyDecoy) toRemove.push(LEGACY_DECOY);
  if (raw[LEGACY_DURESS_FLAG] !== undefined) toRemove.push(LEGACY_DURESS_FLAG);
  if (toRemove.length > 0) {
    await chrome.storage.local.remove(toRemove);
  }
}

// ---------------------------------------------------------------------------
// Padding + noise helpers
// ---------------------------------------------------------------------------

/**
 * Pads the plaintext string with trailing spaces so that the encoded byte
 * length is a multiple of PAD_BLOCK. JSON.parse tolerates trailing
 * whitespace after a complete document, so the padding is transparent on
 * decode. Ciphertext length equals plaintext length plus a 16-byte tag.
 */
function padPlaintext(json: string): string {
  const encoded = new TextEncoder().encode(json);
  const target = Math.max(PAD_BLOCK, Math.ceil(encoded.length / PAD_BLOCK) * PAD_BLOCK);
  const padLen = target - encoded.length;
  return json + " ".repeat(padLen);
}

/**
 * Produces a StoredVault-shaped record filled with CSPRNG bytes. The
 * ciphertext length matches the given byte count. Because GCM ciphertext is
 * pseudo-random, this blob is indistinguishable at rest from a real
 * encrypted vault without the key.
 *
 * crypto.getRandomValues() caps each call at 65536 bytes (the Web Crypto
 * spec hard limit). Chunk the fill so vaults larger than that — common once
 * the user has dozens of entries or any passkey — don't throw.
 */
const CSPRNG_CHUNK = 65_536;

function fillRandom(buf: Uint8Array): Uint8Array {
  for (let offset = 0; offset < buf.length; offset += CSPRNG_CHUNK) {
    const end = Math.min(offset + CSPRNG_CHUNK, buf.length);
    const chunk = new Uint8Array(end - offset);
    crypto.getRandomValues(chunk);
    buf.set(chunk, offset);
  }
  return buf;
}

function generateNoiseBlob(ciphertextBytes: number): StoredVault {
  const salt = crypto.getRandomValues(new Uint8Array(16));
  const nonce = crypto.getRandomValues(new Uint8Array(12));
  const cipher = fillRandom(new Uint8Array(ciphertextBytes));
  const tag = crypto.getRandomValues(new Uint8Array(16));
  return {
    version: 1,
    salt: hex(salt),
    nonce: hex(nonce),
    ciphertext: hex(cipher),
    tag: hex(tag),
  };
}

// ---------------------------------------------------------------------------
// Encrypted plaintext envelope
// ---------------------------------------------------------------------------

type VaultPayload = {
  entries: VaultEntry[];
  duressConfigured?: boolean;
};

type DecryptedPayload = {
  entries: VaultEntry[];
  duressConfigured: boolean;
  /**
   * True when at least one entry in the on-disk payload had a legacy shape
   * (pre-v2.11.0 passkey type/flat fields, or pre-A-2 created/updated keys)
   * and got rewritten by normalizeEntry. The unlock path uses this to
   * persist the new shape immediately — without it, the migration would
   * re-run on every unlock and old shape never disappears from disk.
   */
  migratedFromLegacy: boolean;
};

function encodePayload(entries: VaultEntry[], duress: boolean): string {
  const envelope: VaultPayload = { entries, duressConfigured: duress };
  return padPlaintext(JSON.stringify(envelope));
}

function rawNeedsMigration(raw: VaultEntry | LegacyVaultEntry): boolean {
  if ("created" in raw || "updated" in raw) return true;
  const flat = raw as Partial<VaultEntry>;
  if (flat.type === "passkey") return true;
  // Flat rpId without a passkey sub-object means pre-v2.11.0 schema.
  if (flat.rpId !== undefined && flat.passkey === undefined) return true;
  return false;
}

function decodePayload(plain: string): DecryptedPayload {
  const parsed = JSON.parse(plain) as
    | Array<VaultEntry | LegacyVaultEntry>
    | VaultPayload;

  const rawEntries = Array.isArray(parsed) ? parsed : parsed.entries ?? [];
  const flatMigrationNeeded = rawEntries.some(rawNeedsMigration);

  const normalized = rawEntries.map(normalizeEntry);
  const { merged } = mergePasskeyOnlyIntoLogins(normalized);

  if (Array.isArray(parsed)) {
    return {
      entries: normalized,
      duressConfigured: false,
      migratedFromLegacy: true, // pre-A-2 array shape always needs save
    };
  }

  return {
    entries: normalized,
    duressConfigured: parsed.duressConfigured === true,
    migratedFromLegacy: flatMigrationNeeded || merged,
  };
}

/**
 * One-time consolidation pass run alongside the legacy passkey migration.
 *
 * Pre-v2.11.0 the Chrome passkey path always created a fresh `type:"passkey"`
 * entry per registration — so users who tested registration multiple times
 * accumulated several passkey-bearing entries for the same RP, and the
 * migration to the unified shape carried that duplication forward. This
 * pass collapses the duplicates:
 *
 *   1. Group passkey-bearing (and not deleted) entries by `passkey.rpId`.
 *   2. Within each group, the most recently-active credential wins (prefer
 *      lastUsedAt, fall back to passkey.createdAt, fall back to modifiedAt).
 *   3. If a NON-passkey login entry exists for that RP (matched by url or
 *      additionalUrls hostname), attach the winning passkey to it and
 *      soft-delete every passkey-bearing entry in the group.
 *   4. Otherwise, soft-delete every loser in the group, keeping the winner
 *      as a passkey-only entry.
 *
 * Soft delete (deletedAt) rather than splice — the trash flow keeps the
 * record around for retention and the user can restore if the heuristic
 * picked wrong. The `merged` flag goes back to decodePayload so the
 * unlock path persists the consolidated shape immediately.
 */
function mergePasskeyOnlyIntoLogins(entries: VaultEntry[]): { merged: boolean } {
  let merged = false;
  const now = Date.now();

  const candidates = entries.filter((e) => !e.deletedAt && e.passkey);
  const byRpId = new Map<string, VaultEntry[]>();
  for (const e of candidates) {
    const rpId = e.passkey!.rpId;
    const list = byRpId.get(rpId);
    if (list) list.push(e);
    else byRpId.set(rpId, [e]);
  }

  for (const [rpId, group] of byRpId) {
    if (group.length === 0) continue;
    group.sort((a, b) => {
      const aT =
        a.passkey!.lastUsedAt ?? a.passkey!.createdAt ?? a.modifiedAt ?? a.createdAt;
      const bT =
        b.passkey!.lastUsedAt ?? b.passkey!.createdAt ?? b.modifiedAt ?? b.createdAt;
      return bT - aT;
    });
    const winner = group[0]!;

    // Look for a NON-passkey login entry matching this RP. Use the URL
    // hostname rather than a substring search so a "login.foo.com" entry
    // doesn't accidentally absorb a passkey for "foo.com".
    const loginTarget = entries.find((e) => {
      if (e.deletedAt || e.passkey || e.type !== "login") return false;
      if (e.url && extractDomain(e.url) === rpId) return true;
      for (const extra of e.additionalUrls ?? []) {
        if (extractDomain(extra) === rpId) return true;
      }
      return false;
    });

    if (loginTarget) {
      loginTarget.passkey = winner.passkey;
      loginTarget.modifiedAt = now;
      for (const dup of group) {
        if (!dup.deletedAt) {
          dup.deletedAt = now;
          dup.modifiedAt = now;
        }
      }
      merged = true;
    } else if (group.length > 1) {
      for (let i = 1; i < group.length; i += 1) {
        const dup = group[i]!;
        if (!dup.deletedAt) {
          dup.deletedAt = now;
          dup.modifiedAt = now;
        }
      }
      merged = true;
    }
  }

  return { merged };
}

async function tryDecryptSlot(
  vault: StoredVault,
  key: Uint8Array
): Promise<DecryptedPayload | null> {
  try {
    const plain = await decrypt(key, vault.nonce, vault.ciphertext, vault.tag);
    return decodePayload(plain);
  } catch {
    return null;
  }
}

// ---------------------------------------------------------------------------
// Core operations
// ---------------------------------------------------------------------------

function buildDomainIndexSync(all: VaultEntry[]): void {
  domainIndex = new Map();

  for (const entry of all) {
    if (entry.deletedAt) continue;
    if (entry.type === "note" || entry.type === "card") continue;

    // An entry can match multiple sites via `additionalUrls`. Index each
    // hostname so `queryDomain` returns the entry regardless of which alias
    // the user is currently visiting. Dedupe per-entry so a single entry
    // never appears twice in one bucket.
    const domains = new Set<string>();
    const primary = extractDomain(entry.url ?? "");
    if (primary) domains.add(primary);
    for (const extra of entry.additionalUrls ?? []) {
      const d = extractDomain(extra);
      if (d) domains.add(d);
    }
    if (domains.size === 0) continue;

    for (const domain of domains) {
      const bucket = domainIndex.get(domain) ?? [];
      bucket.push(entry);
      domainIndex.set(domain, bucket);
    }
  }
}

export async function createVault(password: string): Promise<void> {
  await ensureMigrated();

  const salt = generateSalt();
  derivedKey = await deriveKey(password, salt);
  entries = [];
  vaultMode = "real";
  duressConfigured = false;
  buildDomainIndexSync(entries);

  // Generate and wrap the root key for recovery word escrow.
  const { rawRootKey, recoverySalt, wrappedRootKey, wrappedNonce, wrappedTag } =
    await generateAndWrapRootKey();
  rootKey = unhex(rawRootKey);

  const plaintext = encodePayload(entries, duressConfigured);
  const { nonce, ciphertext, tag } = await encrypt(derivedKey, plaintext);

  const slotA: StoredVault = {
    version: 1,
    salt: hex(salt),
    nonce,
    ciphertext,
    tag,
    recovery_salt: recoverySalt,
    recovery_wrapped_root_key: wrappedRootKey,
    recovery_nonce: wrappedNonce,
    recovery_tag: wrappedTag,
  };
  await writeSlot(SLOT_A, slotA);

  // Matching-size noise blob for slot B, so a fresh install shows two
  // similarly-shaped records regardless of whether duress is ever set up.
  await writeSlot(SLOT_B, generateNoiseBlob(ciphertext.length / 2));

  touchAutoLock();
}

export async function hasVault(): Promise<boolean> {
  await ensureMigrated();
  return (await loadSlot(SLOT_A)) !== null;
}

/**
 * Returns whether the real vault has recorded that a duress passphrase is
 * configured. Reliable only after a real-mode unlock — before unlock or in
 * decoy mode, returns false because we cannot read slot A's plaintext.
 */
export async function isDuressEnabled(): Promise<boolean> {
  return vaultMode === "real" && duressConfigured;
}

export async function hasDecoyVault(): Promise<boolean> {
  return isDuressEnabled();
}

export async function setupDuress(duressPassword: string): Promise<void> {
  if (!derivedKey || vaultMode !== "real") {
    throw new Error("vault must be unlocked in real mode");
  }
  await ensureMigrated();

  // Encrypt the decoy payload (empty entries) under the duress key. Pad to
  // at least the current slot A ciphertext size so the two slots look the
  // same at rest at setup time.
  const slotA = await loadSlot(SLOT_A);
  if (!slotA) throw new Error("missing slot A");

  const decoySalt = generateSalt();
  const decoyKey = await deriveKey(duressPassword, decoySalt);
  try {
    // Pad the decoy plaintext to match slot A's ciphertext length (minus the
    // 16-byte tag) so encrypted sizes align exactly.
    const targetBytes = slotA.ciphertext.length / 2;
    let plaintext = encodePayload([], false);
    const encoded = new TextEncoder().encode(plaintext);
    if (encoded.length < targetBytes) {
      plaintext = plaintext + " ".repeat(targetBytes - encoded.length);
    }
    const { nonce, ciphertext, tag } = await encrypt(decoyKey, plaintext);
    await writeSlot(SLOT_B, {
      version: 1,
      salt: hex(decoySalt),
      nonce,
      ciphertext,
      tag,
    });
  } finally {
    zeroKey(decoyKey);
  }

  // Re-encrypt slot A with the duressConfigured flag set to true. No external
  // flag is written — the bit lives inside the encrypted envelope.
  duressConfigured = true;
  await persistSlotA();
}

export async function disableDuress(): Promise<void> {
  if (!derivedKey || vaultMode !== "real") {
    throw new Error("vault must be unlocked in real mode");
  }
  await ensureMigrated();

  // Overwrite slot B with fresh noise that matches slot A's size. The slot
  // remains occupied so its mere existence does not signal that duress was
  // ever configured.
  const slotA = await loadSlot(SLOT_A);
  if (slotA) {
    await writeSlot(SLOT_B, generateNoiseBlob(slotA.ciphertext.length / 2));
  }

  duressConfigured = false;
  await persistSlotA();
}

export async function verifyMainPassword(password: string): Promise<boolean> {
  await ensureMigrated();
  const slotA = await loadSlot(SLOT_A);
  if (!slotA) return false;
  const key = await deriveKey(password, unhex(slotA.salt));
  try {
    return (await tryDecryptSlot(slotA, key)) !== null;
  } finally {
    zeroKey(key);
  }
}

export async function unlock(password: string): Promise<boolean> {
  await ensureMigrated();

  // Load both slots in parallel. Both always exist post-migration; the
  // parallel load and the parallel derivation below keep wall-clock time
  // constant regardless of which slot's passphrase (real or decoy) the
  // caller supplied, so a timing side channel cannot distinguish the
  // duress path from the real-unlock path (DUR-002).
  const [slotA, slotB] = await Promise.all([
    loadSlot(SLOT_A),
    loadSlot(SLOT_B),
  ]);

  // Derive both keys in parallel, unconditionally.
  const [keyA, keyB] = await Promise.all([
    slotA ? deriveKey(password, unhex(slotA.salt)) : Promise.resolve(null),
    slotB ? deriveKey(password, unhex(slotB.salt)) : Promise.resolve(null),
  ]);

  // Attempt both decrypts in parallel.
  const [payloadA, payloadB] = await Promise.all([
    keyA && slotA ? tryDecryptSlot(slotA, keyA) : Promise.resolve(null),
    keyB && slotB ? tryDecryptSlot(slotB, keyB) : Promise.resolve(null),
  ]);

  if (payloadA && keyA) {
    derivedKey = keyA;
    vaultMode = "real";
    entries = payloadA.entries;
    duressConfigured = payloadA.duressConfigured;
    buildDomainIndexSync(entries);
    await loadSettings();
    touchAutoLock();
    if (keyB) zeroKey(keyB);

    // slotA is non-null when payloadA is truthy (keyA was derived from slotA).
    if (slotA) {
      const needsRecoverySetup =
        !slotA.recovery_salt || !slotA.recovery_wrapped_root_key;
      if (!needsRecoverySetup) {
        rootKey = await deriveRootKeyFromDerivedKey(
          keyA,
          slotA.recovery_salt!
        );
      }
    }

    // If the payload had a pre-v2.11.0 shape (legacy passkey type, flat
    // passkey fields, or pre-A-2 created/updated keys), rewrite it now so
    // the next save uses the new format and migration doesn't re-run forever.
    if (payloadA.migratedFromLegacy) {
      await persistSlotA();
    }
    return true;
  }

  if (payloadB && keyB) {
    derivedKey = keyB;
    vaultMode = "decoy";
    entries = payloadB.entries;
    duressConfigured = false;
    buildDomainIndexSync(entries);
    await loadSettings();
    touchAutoLock();
    if (keyA) zeroKey(keyA);
    return true;
  }

  if (keyA) zeroKey(keyA);
  if (keyB) zeroKey(keyB);
  return false;
}

export function lock(): void {
  if (derivedKey) {
    zeroKey(derivedKey);
    derivedKey = null;
  }
  if (rootKey) {
    rootKey.fill(0);
    rootKey = null;
  }

  entries = [];
  domainIndex = new Map();
  vaultMode = "real";
  duressConfigured = false;
  clearAutoLock();
}

export function isUnlocked(): boolean {
  return derivedKey !== null;
}

// Opens the vault using a pre-derived AES-256 key (skipping Argon2id).
// Used by Android biometric unlock — the key was derived on the native side.
export async function unlockWithKey(
  masterKeyHex: string,
): Promise<{ ok: true; entries: VaultEntry[] } | { ok: false; error: string }> {
  try {
    const masterKeyBytes = unhex(masterKeyHex);
    const stored = await loadSlot(SLOT_A);
    if (!stored) return { ok: false, error: "invalid_key" };
    const payload = await tryDecryptSlot(stored, masterKeyBytes);
    if (!payload) return { ok: false, error: "invalid_key" };

    derivedKey = masterKeyBytes;
    vaultMode = "real";
    entries = payload.entries;
    duressConfigured = payload.duressConfigured;
    buildDomainIndexSync(entries);
    await loadSettings();
    touchAutoLock();
    return { ok: true, entries };
  } catch {
    return { ok: false, error: "invalid_key" };
  }
}

// Returns the current in-memory derived key as a hex string.
// Used by the biometric enable flow in Settings to store the key in Android Keystore.
export function getDerivedKeyHex(): string {
  if (!derivedKey) throw new Error("vault_not_unlocked");
  return hex(derivedKey);
}

export function getEntries(): VaultEntry[] {
  if (!derivedKey) throw new Error("vault locked");
  return entries.filter((entry) => !entry.deletedAt);
}

const EMAIL_RE = /^[^\s@]+@[^\s@]+\.[^\s@]+$/;

export function getIdentities(): SavedIdentity[] {
  if (!derivedKey) throw new Error("vault locked");
  const active = entries.filter((e) => !e.deletedAt && e.type === "login");

  const emailMap = new Map<string, { lastUsed: number; count: number; domain: string }>();
  const usernameMap = new Map<string, { lastUsed: number; count: number; domain: string }>();

  for (const entry of active) {
    const value = entry.username?.trim();
    if (!value) continue;
    const map = EMAIL_RE.test(value) ? emailMap : usernameMap;
    const existing = map.get(value);
    const domain = extractDomain(entry.url ?? "") ?? "";
    const modifiedAt = entry.modifiedAt ?? entry.createdAt ?? 0;
    if (!existing || modifiedAt > existing.lastUsed) {
      map.set(value, { lastUsed: modifiedAt, count: (existing?.count ?? 0) + 1, domain });
    } else {
      map.set(value, { ...existing, count: existing.count + 1 });
    }
  }

  const toIdentity = (type: "email" | "username") =>
    ([value, d]: [string, { lastUsed: number; count: number; domain: string }]): SavedIdentity => ({
      value, type, lastUsed: d.lastUsed, useCount: d.count, exampleDomain: d.domain || undefined,
    });

  return [
    ...[...emailMap.entries()].map(toIdentity("email")).sort((a, b) => b.useCount - a.useCount),
    ...[...usernameMap.entries()].map(toIdentity("username")).sort((a, b) => b.useCount - a.useCount),
  ];
}

export async function batchAddEntries(drafts: EntryDraft[]): Promise<VaultEntry[]> {
  if (!derivedKey) throw new Error("vault locked");

  const now = Date.now();
  const added: VaultEntry[] = [];
  for (const draft of drafts) {
    try {
      const sanitized = sanitizeEntryDraft(draft);
      const nextEntry: VaultEntry = {
        ...sanitized,
        id: crypto.randomUUID(),
        createdAt: now,
        modifiedAt: now,
      };
      entries.push(nextEntry);
      added.push(nextEntry);
    } catch {
      // Skip invalid drafts silently — caller can see diff between input and output length
    }
  }

  if (added.length > 0) {
    await persistEntries();
  }

  return added;
}

/**
 * Restore a set of entries in full fidelity — preserves id, createdAt,
 * modifiedAt, and every other field unlike `batchAddEntries` which
 * assigns fresh identity. Used by restore paths where the backup is the
 * authoritative source of truth. `mode` controls how entries already in
 * the vault are treated.
 */
export async function restoreEntries(
  incoming: VaultEntry[],
  mode: "replace" | "merge"
): Promise<{ added: number; updated: number; skipped: number }> {
  if (!derivedKey) throw new Error("vault locked");

  // A replace with zero incoming entries is almost certainly a caller bug
  // (e.g. an import that silently dropped everything). Refuse rather than
  // wipe the vault.
  if (mode === "replace" && incoming.length === 0) {
    throw new Error("refuse to replace with empty entry set");
  }

  let added = 0;
  let updated = 0;
  let skipped = 0;

  if (mode === "replace") {
    entries = [];
    for (const entry of incoming) {
      const normalized = sanitizeRestoredEntry(entry);
      if (!normalized) {
        skipped += 1;
        continue;
      }
      entries.push(normalized);
      added += 1;
    }
  } else {
    const byId = new Map<string, VaultEntry>();
    for (const e of entries) byId.set(e.id, e);

    for (const entry of incoming) {
      const normalized = sanitizeRestoredEntry(entry);
      if (!normalized) {
        skipped += 1;
        continue;
      }
      const existing = byId.get(normalized.id);
      if (!existing) {
        entries.push(normalized);
        added += 1;
      } else if (normalized.modifiedAt > existing.modifiedAt) {
        const idx = entries.findIndex((e) => e.id === existing.id);
        if (idx !== -1) {
          entries[idx] = normalized;
          updated += 1;
        }
      } else {
        skipped += 1;
      }
    }
  }

  await persistEntries("import");
  return { added, updated, skipped };
}

/**
 * Validate + normalise a VaultEntry coming from a backup. Accepts
 * anything structurally sound; keeps all metadata verbatim. Returns
 * null for values the live vault shouldn't accept (e.g., missing title).
 */
function sanitizeRestoredEntry(entry: VaultEntry): VaultEntry | null {
  if (!entry || typeof entry !== "object") return null;
  const title = typeof entry.title === "string" ? entry.title.trim() : "";
  if (!title) return null;
  const id = typeof entry.id === "string" && entry.id ? entry.id : crypto.randomUUID();
  const now = Date.now();
  const createdAt = typeof entry.createdAt === "number" ? entry.createdAt : now;
  const modifiedAt = typeof entry.modifiedAt === "number" ? entry.modifiedAt : createdAt;

  // Migrate legacy passkey shape on import (same logic as on-disk read).
  // Imports from pre-v2.11.0 vault backups still carry type:"passkey" with
  // flat fields; bring them into the new shape immediately.
  const migrated: VaultEntry = migrateLegacyPasskey(
    {
      ...entry,
      id,
      title,
      type: entry.type ?? "login",
      createdAt,
      modifiedAt,
    },
    entry
  );

  // Login entries from backup must carry a password (or be passkey-only,
  // in which case the passkey sub-object replaces the password requirement).
  if (
    migrated.type === "login" &&
    !migrated.passkey &&
    typeof migrated.password !== "string"
  ) {
    return null;
  }
  if (migrated.passkey && !migrated.passkey.credentialId) {
    return null;
  }

  return migrated;
}

// Soft-deletes every non-deleted entry in one call. The literal string
// argument is a tripwire against accidental calls — any caller that would
// wipe the vault has to consciously type "REPLACE_ALL". Do not relax this
// to a boolean.
export async function clearVaultEntries(
  confirmation: "REPLACE_ALL"
): Promise<void> {
  if (confirmation !== "REPLACE_ALL") {
    throw new Error("clearVaultEntries requires explicit confirmation");
  }
  if (!derivedKey) throw new Error("vault locked");
  for (const entry of entries) {
    if (!entry.deletedAt) {
      entry.deletedAt = Date.now();
      entry.modifiedAt = Date.now();
    }
  }
  await persistEntries();
}

export async function addEntry(entry: EntryDraft): Promise<VaultEntry> {
  if (!derivedKey) throw new Error("vault locked");

  const sanitized = sanitizeEntryDraft(entry);
  const now = Date.now();
  const nextEntry: VaultEntry = {
    ...sanitized,
    id: crypto.randomUUID(),
    createdAt: now,
    modifiedAt: now,
    // Stamp passwordChangedAt at creation so age tracking is accurate from
    // day one. Non-login entries carry the same stamp harmlessly.
    passwordChangedAt: sanitized.password ? now : undefined,
  };

  entries.push(nextEntry);
  await persistEntries();

  // Fire-and-forget breach check (only for login entries if breach monitoring is enabled or not set)
  if (settings.breachMonitoring !== false && nextEntry.type === "login" && nextEntry.password) {
    checkBreach(nextEntry.password).then(async (count) => {
      if (count > 0) {
        const idx = entries.findIndex((e) => e.id === nextEntry.id);
        if (idx !== -1) {
          entries[idx] = { ...entries[idx], breach: count, modifiedAt: Date.now() };
          await persistEntries();
        }
      }
    });
  }

  return nextEntry;
}

export async function updateEntry(
  id: string,
  patch: Partial<VaultEntry>
): Promise<void> {
  if (!derivedKey) throw new Error("vault locked");

  const idx = entries.findIndex((entry) => entry.id === id);
  if (idx === -1 || entries[idx].deletedAt) {
    throw new Error("entry not found");
  }

  const current = entries[idx];
  const sanitizedPatch = sanitizeEntryPatch(patch);
  // Refresh passwordChangedAt only when the password value actually changes —
  // a metadata-only update (title, tags, etc.) must not reset the age clock
  // that drives the Pro health rotation recommendation.
  const passwordChanged =
    "password" in patch &&
    typeof sanitizedPatch.password === "string" &&
    sanitizedPatch.password !== current.password;
  entries[idx] = {
    ...current,
    ...sanitizedPatch,
    modifiedAt: Date.now(),
    ...(passwordChanged ? { passwordChangedAt: Date.now() } : {}),
  };

  // A login entry must carry SOMETHING fillable — either a password or a
  // passkey credential. An empty-password login with no passkey is dead
  // state. Permit the password-clear when a passkey is attached (that's
  // the legitimate "drop the password, keep the passkey" path).
  if (
    entries[idx].type === "login" &&
    !entries[idx].password &&
    !entries[idx].passkey
  ) {
    entries[idx] = current;
    throw new Error("password or passkey required");
  }

  // Card entries must retain their card number
  if (entries[idx].type === "card" && !entries[idx].cardNumber) {
    entries[idx] = current;
    throw new Error("card number is required for card entries");
  }

  await persistEntries();

  // Breach check when password changes: clear immediately so old breach doesn't linger,
  // then async-check the new password and only re-set if it's also found.
  if ("password" in patch && settings.breachMonitoring !== false && entries[idx].type === "login") {
    entries[idx] = { ...entries[idx], breach: undefined };
    await persistEntries();
    const password = entries[idx].password;
    if (password) {
      checkBreach(password).then(async (count) => {
        const i = entries.findIndex((e) => e.id === id);
        if (i !== -1 && count > 0) {
          entries[i] = { ...entries[i], breach: count, modifiedAt: Date.now() };
          await persistEntries();
        }
      });
    }
  }
}

export async function deleteEntry(id: string): Promise<void> {
  if (!derivedKey) throw new Error("vault locked");

  const entry = entries.find((item) => item.id === id);
  if (!entry || entry.deletedAt) {
    throw new Error("entry not found");
  }

  entry.deletedAt = Date.now();
  entry.modifiedAt = Date.now();
  await persistEntries();
}

export function getDeletedEntries(): VaultEntry[] {
  if (!derivedKey) return [];
  return entries.filter((e) => !!e.deletedAt);
}

export async function restoreEntry(id: string): Promise<void> {
  if (!derivedKey) throw new Error("vault locked");
  const entry = entries.find((e) => e.id === id && e.deletedAt);
  if (!entry) throw new Error("deleted entry not found");
  delete entry.deletedAt;
  entry.modifiedAt = Date.now();
  await persistEntries();
  buildDomainIndexSync(entries);
}

export async function purgeEntry(id: string): Promise<void> {
  if (!derivedKey) throw new Error("vault locked");
  const idx = entries.findIndex((e) => e.id === id && e.deletedAt);
  if (idx === -1) throw new Error("deleted entry not found");
  entries.splice(idx, 1);
  await persistEntries();
}

/** Permanently delete entries whose deletedAt is older than retentionMs. 0 = keep forever. */
export async function purgeExpiredTrash(retentionMs: number): Promise<number> {
  if (!derivedKey || retentionMs === 0) return 0;
  const cutoff = Date.now() - retentionMs;
  const before = entries.length;
  entries = entries.filter((e) => !(e.deletedAt && e.deletedAt < cutoff));
  const purged = before - entries.length;
  if (purged > 0) await persistEntries();
  return purged;
}

export function queryDomain(domain: string): VaultEntry[] {
  return domainIndex.get(domain) ?? [];
}

export function getEntryById(id: string): VaultEntry | undefined {
  return entries.find((entry) => entry.id === id && !entry.deletedAt);
}

async function persistSlotA(
  reason: VaultSnapshot["reason"] = "local_save",
): Promise<StoredVault> {
  if (!derivedKey) throw new Error("vault locked");

  const slotA = await loadSlot(SLOT_A);
  if (!slotA) throw new Error("missing slot A");

  // Snapshot the about-to-be-overwritten state BEFORE we mutate disk. Failures
  // are swallowed by takeVaultSnapshot — history must never block a save.
  await takeVaultSnapshot(reason);

  const plaintext = encodePayload(entries, duressConfigured);
  const { nonce, ciphertext, tag } = await encrypt(derivedKey, plaintext);

  // Preserve existing recovery escrow fields.
  const nextSlotA: StoredVault = {
    ...slotA,
    nonce,
    ciphertext,
    tag,
    // recovery_salt and recovery_wrapped_root_key are already set from loadSlot
  };
  await writeSlot(SLOT_A, nextSlotA);

  // When duress is not configured, keep slot B size-matched with slot A by
  // regenerating its noise. When duress IS configured, leave slot B alone —
  // we don't have the decoy key to re-encrypt it. This is a known trade-off.
  if (!duressConfigured) {
    await writeSlot(SLOT_B, generateNoiseBlob(ciphertext.length / 2));
  }

  return nextSlotA;
}

async function persistSlotB(): Promise<void> {
  if (!derivedKey) throw new Error("vault locked");

  const slotB = await loadSlot(SLOT_B);
  if (!slotB) throw new Error("missing slot B");

  // Decoy plaintext always reports duressConfigured=false — the decoy user
  // sees a clean slate.
  const plaintext = encodePayload(entries, false);
  const { nonce, ciphertext, tag } = await encrypt(derivedKey, plaintext);

  await writeSlot(SLOT_B, { ...slotB, nonce, ciphertext, tag });
}

async function persistEntries(
  reason: VaultSnapshot["reason"] = "local_save",
): Promise<void> {
  if (!derivedKey) throw new Error("vault locked");

  if (vaultMode === "decoy") {
    await persistSlotB();
  } else {
    await persistSlotA(reason);
  }
  buildDomainIndexSync(entries);
}

function cleanAdditionalUrls(values: string[] | undefined): string[] | undefined {
  if (!Array.isArray(values)) return undefined;
  const seen = new Set<string>();
  const cleaned: string[] = [];
  for (const value of values) {
    const trimmed = typeof value === "string" ? value.trim() : "";
    if (!trimmed) continue;
    const key = trimmed.toLowerCase();
    if (seen.has(key)) continue;
    seen.add(key);
    cleaned.push(trimmed);
  }
  return cleaned.length > 0 ? cleaned : undefined;
}

function sanitizeEntryDraft(entry: EntryDraft): EntryDraft {
  const title = entry.title.trim();
  // Accept legacy `type:"passkey"` drafts but rewrite to "login" — the new
  // model is "any entry, optionally with a passkey sub-object." Imports and
  // any in-flight callers from before v2.11.0 keep working without throwing.
  let type: VaultEntry["type"] = entry.type ?? "login";
  if (type === "passkey") type = "login";

  if (!title) throw new Error("title is required");
  // A login entry needs either a password or a passkey credential to be useful.
  // Passkey-only entries (passkey present, no password) are valid.
  if (type === "login" && !entry.password?.trim() && !entry.passkey) {
    throw new Error("password or passkey required");
  }
  if (entry.passkey) {
    const p = entry.passkey;
    if (
      !p.rpId ||
      !p.credentialId ||
      !p.publicKeyCose ||
      !p.userHandle ||
      !p.userName ||
      (p.algorithm !== -7 && p.algorithm !== -8)
    ) {
      throw new Error("invalid passkey credential");
    }
  }
  if (type === "card") {
    if (!entry.cardholderName?.trim() || !entry.cardNumber?.trim()) {
      throw new Error("cardholder name and card number are required");
    }
  }

  return {
    type,
    title,
    username: type === "login" ? entry.username?.trim() ?? "" : undefined,
    password: type === "login" ? entry.password : undefined,
    url: type === "login" ? entry.url?.trim() ?? "" : undefined,
    additionalUrls: type === "login" ? cleanAdditionalUrls(entry.additionalUrls) : undefined,
    totp: type === "login" ? entry.totp?.trim() || undefined : undefined,
    notes: entry.notes?.trim() || undefined,
    breach: type === "login" ? entry.breach : undefined,
    canary: type === "login" ? entry.canary : undefined,
    tags: entry.tags,
    passkey: entry.passkey,
    cardholderName: type === "card" ? entry.cardholderName?.trim() : undefined,
    cardNumber: type === "card" ? entry.cardNumber?.trim() : undefined,
    expMonth: type === "card" ? entry.expMonth?.trim() : undefined,
    expYear: type === "card" ? entry.expYear?.trim() : undefined,
    cvc: type === "card" ? entry.cvc?.trim() : undefined,
    cardNickname: type === "card" ? entry.cardNickname?.trim() || undefined : undefined,
    network: type === "card" ? entry.network : undefined,
    last4: type === "card" ? entry.last4?.trim() : undefined,
  };
}

function sanitizeEntryPatch(patch: Partial<VaultEntry>): Partial<VaultEntry> {
  const nextPatch: Partial<VaultEntry> = {};

  if ("type" in patch) {
    nextPatch.type = patch.type;
  }

  if ("title" in patch) {
    const title = patch.title?.trim() ?? "";
    if (!title) throw new Error("title is required");
    nextPatch.title = title;
  }

  if ("url" in patch) {
    nextPatch.url = patch.url?.trim() ?? "";
  }

  if ("additionalUrls" in patch) {
    const incoming = Array.isArray(patch.additionalUrls) ? patch.additionalUrls : [];
    const seen = new Set<string>();
    const cleaned: string[] = [];
    for (const value of incoming) {
      const trimmed = typeof value === "string" ? value.trim() : "";
      if (!trimmed) continue;
      const key = trimmed.toLowerCase();
      if (seen.has(key)) continue;
      seen.add(key);
      cleaned.push(trimmed);
    }
    nextPatch.additionalUrls = cleaned.length > 0 ? cleaned : undefined;
  }

  if ("username" in patch) {
    nextPatch.username = patch.username?.trim() ?? "";
  }

  if ("email" in patch) {
    nextPatch.email = patch.email?.trim() || undefined;
  }

  if ("password" in patch) {
    const password = patch.password ?? "";
    // Allow clearing a password (e.g. on passkey-only entries)
    nextPatch.password = password || undefined;
  }

  if ("totp" in patch) {
    nextPatch.totp = patch.totp?.trim() || undefined;
  }

  if ("notes" in patch) {
    nextPatch.notes = patch.notes?.trim() || undefined;
  }

  if ("breach" in patch) {
    nextPatch.breach = patch.breach;
  }

  if ("canary" in patch) {
    nextPatch.canary = patch.canary;
  }

  if ("passkey" in patch) {
    // Passkey sub-object replaces all the legacy flat passkey fields. A
    // patch with `passkey: undefined` removes the credential from the entry
    // (used by "remove passkey" without deleting the whole entry).
    nextPatch.passkey = patch.passkey;
  }

  if ("tags" in patch) {
    nextPatch.tags = patch.tags;
  }

  if ("cardholderName" in patch) {
    nextPatch.cardholderName = patch.cardholderName?.trim() || undefined;
  }
  if ("cardNumber" in patch) {
    const n = patch.cardNumber ?? "";
    nextPatch.cardNumber = n || undefined;
  }
  if ("expMonth" in patch) {
    nextPatch.expMonth = patch.expMonth?.trim() || undefined;
  }
  if ("expYear" in patch) {
    nextPatch.expYear = patch.expYear?.trim() || undefined;
  }
  if ("cvc" in patch) {
    nextPatch.cvc = patch.cvc?.trim() || undefined;
  }
  if ("cardNickname" in patch) {
    nextPatch.cardNickname = patch.cardNickname?.trim() || undefined;
  }
  if ("network" in patch) {
    nextPatch.network = patch.network;
  }
  if ("last4" in patch) {
    nextPatch.last4 = patch.last4?.trim() || undefined;
  }

  return nextPatch;
}

function normalizeEntry(entry: VaultEntry | LegacyVaultEntry): VaultEntry {
  const createdAt = "createdAt" in entry ? entry.createdAt : entry.created;
  const modifiedAt =
    "modifiedAt" in entry ? entry.modifiedAt : entry.updated;

  const base: VaultEntry = {
    id: entry.id,
    type: "type" in entry ? entry.type : "login",
    title: entry.title,
    username: entry.username,
    password: entry.password,
    url: entry.url,
    totp: entry.totp,
    notes: entry.notes,
    breach: entry.breach,
    canary: "canary" in entry ? entry.canary : undefined,
    passkey: "passkey" in entry ? entry.passkey : undefined,
    createdAt,
    modifiedAt,
    deletedAt: entry.deletedAt,
    tags: "tags" in entry ? entry.tags : undefined,
    cardholderName: "cardholderName" in entry ? entry.cardholderName : undefined,
    cardNumber: "cardNumber" in entry ? entry.cardNumber : undefined,
    expMonth: "expMonth" in entry ? entry.expMonth : undefined,
    expYear: "expYear" in entry ? entry.expYear : undefined,
    cvc: "cvc" in entry ? entry.cvc : undefined,
    cardNickname: "cardNickname" in entry ? entry.cardNickname : undefined,
    network: "network" in entry ? entry.network : undefined,
    last4: "last4" in entry ? entry.last4 : undefined,
  };

  return migrateLegacyPasskey(base, entry);
}

/**
 * v2.11.0 read migration. Pre-v2.11.0 passkey entries used `type:"passkey"`
 * with flat top-level fields (rpId, credentialId, etc.). This converts them
 * to the new shape — `type:"login"` with a `passkey` sub-object — so all
 * downstream consumers can rely on the new model. The result is rewritten
 * to disk on next vault save (hasLegacyShape detects the un-migrated case).
 */
function migrateLegacyPasskey(
  base: VaultEntry,
  raw: VaultEntry | LegacyVaultEntry
): VaultEntry {
  if (base.passkey) return base;
  const flat = raw as Partial<VaultEntry>;
  const isPasskeyType = base.type === "passkey";
  const hasFlatPasskeyFields =
    typeof flat.rpId === "string" &&
    typeof flat.credentialId === "string" &&
    typeof flat.publicKeyCose === "string" &&
    typeof flat.userHandle === "string" &&
    typeof flat.userName === "string";
  if (!isPasskeyType && !hasFlatPasskeyFields) return base;
  if (!hasFlatPasskeyFields) return base;

  const algorithm: -7 | -8 = flat.algorithm === -8 ? -8 : -7;
  base.passkey = {
    rpId: flat.rpId!,
    rpName: flat.rpName ?? flat.rpId!,
    credentialId: flat.credentialId!,
    publicKeyCose: flat.publicKeyCose!,
    privateKeyJwk: flat.privateKeyJwk,
    userHandle: flat.userHandle!,
    userName: flat.userName!,
    userDisplayName: flat.userDisplayName ?? flat.userName!,
    algorithm,
    signCount: flat.signCount ?? 0,
    aaguid: flat.aaguid ?? "",
    backupEligible: flat.backupEligible === true,
    backupState: flat.backupState === true,
    lastUsedAt: flat.lastUsedAt,
    browser: flat.browser,
    transports: flat.transports,
    createdAt: base.createdAt,
  };
  // Promote to "login" so the unified Entry view renders. Username gets
  // populated from the passkey's userName so the entry is searchable in the
  // existing autofill flow without a separate code path.
  if (isPasskeyType) base.type = "login";
  if (!base.username) base.username = flat.userName;
  if (!base.url) base.url = `https://${flat.rpId}`;
  return base;
}


// ---------------------------------------------------------------------------
// Deduplication
// ---------------------------------------------------------------------------

function entryDupeKey(e: VaultEntry): string {
  if (e.type === "note") return `note|${e.title.toLowerCase()}`;
  // Passkey-bearing entries dedupe by the credential's RP + user. Two logins
  // on different sites that happen to share a username are still distinct;
  // two passkey credentials for the same RP+user are duplicates regardless
  // of any login fields they may also carry.
  if (e.passkey) {
    return `passkey|${e.passkey.rpId.toLowerCase()}|${e.passkey.userName.toLowerCase()}`;
  }
  return `login|${e.title.toLowerCase()}|${(e.url ?? "").toLowerCase()}|${(e.username ?? "").toLowerCase()}`;
}

/** Returns the number of duplicate entries (those that would be removed). */
export function countDuplicates(): number {
  const best = new Map<string, VaultEntry>();
  let dupeCount = 0;
  for (const e of entries.filter((e) => !e.deletedAt)) {
    const key = entryDupeKey(e);
    const existing = best.get(key);
    if (!existing) {
      best.set(key, e);
    } else {
      dupeCount++;
      // Keep the more recently modified one in the map
      if ((e.modifiedAt ?? e.createdAt ?? 0) > (existing.modifiedAt ?? existing.createdAt ?? 0)) {
        best.set(key, e);
      }
    }
  }
  return dupeCount;
}

/**
 * Soft-deletes duplicate entries, keeping the most recently modified copy of
 * each group. Returns the number of entries moved to trash.
 */
export async function deduplicateEntries(): Promise<number> {
  if (!derivedKey) throw new Error("vault locked");
  // Dedup reshapes slot B permanently under the decoy key, which is
  // forensically distinguishable from a freshly-seeded decoy vault. Refuse.
  if (vaultMode === "decoy") {
    throw new Error("deduplicate disabled in decoy mode");
  }

  const best = new Map<string, VaultEntry>();
  for (const e of entries.filter((en) => !en.deletedAt)) {
    const key = entryDupeKey(e);
    const existing = best.get(key);
    if (!existing) {
      best.set(key, e);
    } else if ((e.modifiedAt ?? e.createdAt ?? 0) > (existing.modifiedAt ?? existing.createdAt ?? 0)) {
      best.set(key, e);
    }
  }

  const keepIds = new Set(Array.from(best.values()).map((e) => e.id));
  const now = Date.now();
  let removed = 0;
  entries = entries.map((e) => {
    if (!e.deletedAt && !keepIds.has(e.id)) {
      removed++;
      return { ...e, deletedAt: now };
    }
    return e;
  });

  if (removed > 0) await persistEntries();
  return removed;
}

// ---------------------------------------------------------------------------
// Vault history — snapshot BEFORE every vault write so the saved blob is
// what is about to be lost, not what was just written. Capped at 10. The
// stored blobs are AES-256-GCM ciphertext under the master password, so
// history adds zero security surface.
// ---------------------------------------------------------------------------

const HISTORY_KEY = "peach_vault_history";
const HISTORY_MAX = 10;

/**
 * Snapshot the CURRENT on-disk vault state into history. Call this BEFORE
 * overwriting peach_vault_a so the saved blob captures the about-to-be-lost
 * state. Identical-to-most-recent blobs are skipped to avoid filling history
 * with no-op writes.
 */
export async function takeVaultSnapshot(
  reason: VaultSnapshot["reason"],
): Promise<void> {
  try {
    const raw = await chrome.storage.local.get([SLOT_A, SLOT_B, HISTORY_KEY]);
    const slotA = (raw as Record<string, StoredVault | undefined>)[SLOT_A];
    const slotB = (raw as Record<string, StoredVault | undefined>)[SLOT_B];

    // Nothing to snapshot if the real slot doesn't exist yet (fresh install,
    // pre-createVault). createVault skips snapshots intentionally — there is
    // no prior state to preserve.
    if (!slotA) return;

    const vault_a = JSON.stringify(slotA);
    const vault_b = JSON.stringify(slotB ?? slotA);

    // Best-effort entry count: only meaningful when the in-memory state is
    // unlocked AND in real mode. Decoy mode would leak the decoy entry
    // count; locked mode has no entries to count. Both fall through to null.
    let entryCount: number | null = null;
    if (derivedKey && vaultMode === "real") {
      try {
        entryCount = entries.filter((e) => !e.deletedAt).length;
      } catch {
        entryCount = null;
      }
    }

    const existingRaw = (raw as Record<string, VaultHistory | undefined>)[HISTORY_KEY];
    const history: VaultHistory = existingRaw && Array.isArray(existingRaw.snapshots)
      ? existingRaw
      : { snapshots: [] };

    // Deduplication: if the most recent snapshot has byte-identical blobs,
    // skip — saves the same vault N times in a row would otherwise burn the
    // entire history window with no recovery value.
    const latest = history.snapshots[0];
    if (latest && latest.vault_a === vault_a && latest.vault_b === vault_b) {
      return;
    }

    const snapshot: VaultSnapshot = {
      id: crypto.randomUUID(),
      savedAt: Date.now(),
      reason,
      vault_a,
      vault_b,
      entryCount,
    };

    history.snapshots = [snapshot, ...history.snapshots].slice(0, HISTORY_MAX);
    await chrome.storage.local.set({ [HISTORY_KEY]: history });
  } catch {
    // Non-fatal — history must never block a save. A failed snapshot just
    // means the user loses one rung of the safety ladder for this write.
  }
}

/** Wipe all vault history. Called by Panic / DESTROY_VAULT. */
export async function clearVaultHistory(): Promise<void> {
  try {
    await chrome.storage.local.set({ [HISTORY_KEY]: { snapshots: [] } satisfies VaultHistory });
  } catch {
    // Non-fatal — DESTROY_VAULT also runs storage.local.clear().
  }
}

/** Read all snapshots, newest first, for the Settings vault history view. */
export async function getVaultHistory(): Promise<VaultSnapshot[]> {
  const raw = await chrome.storage.local.get(HISTORY_KEY);
  const history = (raw as Record<string, VaultHistory | undefined>)[HISTORY_KEY];
  if (!history || !Array.isArray(history.snapshots)) return [];
  return history.snapshots;
}

/**
 * Replace the on-disk vault with the chosen snapshot's blobs and lock the
 * vault. The current state is itself snapshotted with reason 'restore' first
 * so the restore is reversible. After this returns, the user must unlock
 * with the password that matches the restored blob.
 */
export async function restoreVaultSnapshot(
  snapshotId: string,
): Promise<{ ok: true } | { ok: false; error: string }> {
  const history = await getVaultHistory();
  const snapshot = history.find((s) => s.id === snapshotId);
  if (!snapshot) return { ok: false, error: "snapshot_not_found" };

  // Snapshot the about-to-be-replaced current state so the restore is
  // reversible. takeVaultSnapshot is no-op when the most recent entry is
  // byte-identical, so a restore-of-a-restore stays clean.
  await takeVaultSnapshot("restore");

  let restoredA: StoredVault;
  let restoredB: StoredVault;
  try {
    restoredA = JSON.parse(snapshot.vault_a) as StoredVault;
    restoredB = JSON.parse(snapshot.vault_b) as StoredVault;
  } catch {
    return { ok: false, error: "snapshot_corrupt" };
  }

  await writeSlot(SLOT_A, restoredA);
  await writeSlot(SLOT_B, restoredB);

  // Lock so the user must prove they can decrypt the restored blob. If they
  // restored a pre-password-change snapshot they discover it immediately at
  // the lock screen rather than silently holding an inaccessible vault.
  lock();

  return { ok: true };
}

/**
 * Change the master password. Re-encrypts slot A with a fresh salt + new
 * derived key. Slot B (duress or noise) is left untouched when duress is
 * configured — it uses an independent key derived from the duress password —
 * and regenerated as noise when duress is not configured.
 */
export async function changePassword(
  currentPassword: string,
  newPassword: string
): Promise<boolean> {
  if (!derivedKey || vaultMode !== "real") return false;

  // Verify current password before allowing any change
  const valid = await verifyMainPassword(currentPassword);
  if (!valid) return false;

  const slotA = await loadSlot(SLOT_A);
  if (!slotA) return false;

  // Derive fresh key from new password + new random salt
  const newSalt = generateSalt();
  const newKey = await deriveKey(newPassword, newSalt);

  // Re-encrypt the in-memory entries with the new key
  const plaintext = encodePayload(entries, duressConfigured);
  const { nonce, ciphertext, tag } = await encrypt(newKey, plaintext);

  const freshSlotA: StoredVault = {
    ...slotA,
    salt: hex(newSalt),
    nonce,
    ciphertext,
    tag,
  };
  // Snapshot the OLD-key blob before overwriting it. If the user later
  // restores from this snapshot they will need the OLD password — the
  // post-restore lock surfaces that immediately.
  await takeVaultSnapshot("local_save");
  await writeSlot(SLOT_A, freshSlotA);

  // Swap the in-memory key synchronously before any further await. If we
  // threw between the Slot A write and this swap, the next persistEntries()
  // would overwrite Slot A with old-key ciphertext, locking the user out.
  zeroKey(derivedKey);
  derivedKey = newKey;

  // Rotate the root key so the old recovery words are immediately invalidated.
  // After this point getRecoveryWords() returns a fresh 12-word set.
  const {
    rawRootKey: freshRawKey,
    recoverySalt: freshSalt,
    wrappedRootKey: freshWrapped,
    wrappedNonce: freshNonce,
    wrappedTag: freshTag,
  } = await generateAndWrapRootKey();
  rootKey = unhex(freshRawKey);
  const slotAfterRekey = await loadSlot(SLOT_A);
  if (slotAfterRekey) {
    await writeSlot(SLOT_A, {
      ...slotAfterRekey,
      recovery_salt: freshSalt,
      recovery_wrapped_root_key: freshWrapped,
      recovery_nonce: freshNonce,
      recovery_tag: freshTag,
    });
  }

  // Regenerate noise for slot B when duress is not in use. Runs after the
  // key swap so a failure here is a disposable noise regeneration, not a
  // lockout.
  if (!duressConfigured) {
    await writeSlot(SLOT_B, generateNoiseBlob(ciphertext.length / 2));
  }

  return true;
}