import { deriveKey, generateSalt } from "../crypto/argon2";
import { extractDomain } from "../shared/domain";
import type {
  AccentColorName,
  LegacyVaultEntry,
  StoredVault,
  VaultEntry,
} 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;
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 interface VaultSettings {
  accentColor?: AccentColorName;
  theme?: "dark" | "light";
  autoLockMinutes?: number;
  clipboardClearSeconds?: number;
  lockOnClose?: boolean;
  breachMonitoring?: boolean;
  passkeyProviderEnabled?: boolean;
  trashRetentionDays?: number;
}

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
  }
}

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;
}

// ---------------------------------------------------------------------------
// Storage schema migration
// ---------------------------------------------------------------------------

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.
 */
function generateNoiseBlob(ciphertextBytes: number): StoredVault {
  const salt = crypto.getRandomValues(new Uint8Array(16));
  const nonce = crypto.getRandomValues(new Uint8Array(12));
  const cipher = crypto.getRandomValues(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;
};

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

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

  if (Array.isArray(parsed)) {
    // Pre-A-2 plaintext: bare array of entries, no duress flag.
    return {
      entries: parsed.map(normalizeEntry),
      duressConfigured: false,
    };
  }

  return {
    entries: (parsed.entries ?? []).map(normalizeEntry),
    duressConfigured: parsed.duressConfigured === true,
  };
}

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 === "passkey") continue;

    const domain = extractDomain(entry.url ?? "");
    if (!domain) continue;

    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);

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

  const slotA: StoredVault = {
    version: 1,
    salt: hex(salt),
    nonce,
    ciphertext,
    tag,
  };
  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);
    // If the payload came from the pre-envelope (legacy) shape, rewrite
    // it immediately so the next save uses the new format.
    if (hasLegacyShape(payloadA.entries)) {
      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;
  }

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

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

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

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 the CJK phrase restore path 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();
  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 type = entry.type ?? "login";
  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;

  if (type === "login" && typeof entry.password !== "string") {
    return null;
  }
  if (
    type === "passkey" &&
    (typeof entry.rpId !== "string" ||
      typeof entry.credentialId !== "string" ||
      !entry.privateKeyJwk)
  ) {
    return null;
  }

  return {
    ...entry,
    id,
    title,
    type,
    createdAt,
    modifiedAt,
  };
}

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,
  };

  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];
  entries[idx] = {
    ...current,
    ...sanitizeEntryPatch(patch),
    modifiedAt: Date.now(),
  };

  // sanitizeEntryPatch maps an empty password to `undefined`. For login
  // entries that would silently produce a passwordless record — roll back
  // the merge and refuse.
  if (entries[idx].type === "login" && !entries[idx].password) {
    entries[idx] = current;
    throw new Error("password is required for login entries");
  }

  await persistEntries();

  // Fire-and-forget breach check when password changes (if monitoring enabled and entry is a login)
  if ("password" in patch && settings.breachMonitoring !== false && entries[idx].type === "login" && entries[idx].password) {
    const password = entries[idx].password!;
    checkBreach(password).then(async (count) => {
      const i = entries.findIndex((e) => e.id === id);
      if (i !== -1) {
        entries[i] = { ...entries[i], breach: count > 0 ? count : undefined, 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(): Promise<StoredVault> {
  if (!derivedKey) throw new Error("vault locked");

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

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

  const nextSlotA: StoredVault = {
    ...slotA,
    nonce,
    ciphertext,
    tag,
  };
  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(): Promise<void> {
  if (!derivedKey) throw new Error("vault locked");

  if (vaultMode === "decoy") {
    await persistSlotB();
  } else {
    const freshSlotA = await persistSlotA();
    // Save a snapshot of the real vault after every successful write.
    // Failures are silently swallowed — snapshots must never interrupt saves.
    const activeCount = entries.filter((e) => !e.deletedAt).length;
    void takeSnapshot(freshSlotA, activeCount);
  }
  buildDomainIndexSync(entries);
}

function sanitizeEntryDraft(entry: EntryDraft): EntryDraft {
  const title = entry.title.trim();
  const type = entry.type ?? "login";

  if (!title) throw new Error("title is required");
  if (type === "login" && !entry.password?.trim()) {
    throw new Error("password is required");
  }
  if (type === "passkey") {
    if (
      !entry.rpId?.trim() ||
      !entry.rpName?.trim() ||
      !entry.credentialId?.trim() ||
      !entry.publicKeyCose?.trim() ||
      !entry.privateKeyJwk ||
      !entry.userHandle?.trim() ||
      !entry.userName?.trim() ||
      !entry.userDisplayName?.trim() ||
      (entry.algorithm !== -7 && entry.algorithm !== -8)
    ) {
      throw new Error("invalid passkey entry");
    }
  }

  return {
    type,
    title,
    username: type === "login" ? entry.username?.trim() ?? "" : undefined,
    password: type === "login" ? entry.password : undefined,
    url: type === "login" ? entry.url?.trim() ?? "" : undefined,
    totp: type === "login" ? entry.totp?.trim() || undefined : undefined,
    notes: type === "passkey" ? undefined : entry.notes?.trim() || undefined,
    breach: type === "login" ? entry.breach : undefined,
    canary: type === "login" ? entry.canary : undefined,
    rpId: type === "passkey" ? entry.rpId?.trim() : undefined,
    rpName: type === "passkey" ? entry.rpName?.trim() : undefined,
    credentialId: type === "passkey" ? entry.credentialId?.trim() : undefined,
    publicKeyCose: type === "passkey" ? entry.publicKeyCose?.trim() : undefined,
    privateKeyJwk: type === "passkey" ? entry.privateKeyJwk : undefined,
    userHandle: type === "passkey" ? entry.userHandle?.trim() : undefined,
    userName: type === "passkey" ? entry.userName?.trim() : undefined,
    userDisplayName: type === "passkey" ? entry.userDisplayName?.trim() : undefined,
    algorithm: type === "passkey" ? entry.algorithm : undefined,
    signCount: type === "passkey" ? entry.signCount ?? 0 : undefined,
    aaguid: type === "passkey" ? entry.aaguid?.trim() : undefined,
    backupEligible: type === "passkey" ? entry.backupEligible === true : undefined,
    backupState: type === "passkey" ? entry.backupState === true : undefined,
    lastUsedAt: type === "passkey" ? entry.lastUsedAt : 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 ("username" in patch) {
    nextPatch.username = patch.username?.trim() ?? "";
  }

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

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

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

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

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

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

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

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

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

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

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

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

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

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

  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;

  return {
    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,
    rpId: "rpId" in entry ? entry.rpId : undefined,
    rpName: "rpName" in entry ? entry.rpName : undefined,
    credentialId: "credentialId" in entry ? entry.credentialId : undefined,
    publicKeyCose: "publicKeyCose" in entry ? entry.publicKeyCose : undefined,
    privateKeyJwk: "privateKeyJwk" in entry ? entry.privateKeyJwk : undefined,
    userHandle: "userHandle" in entry ? entry.userHandle : undefined,
    userName: "userName" in entry ? entry.userName : undefined,
    userDisplayName: "userDisplayName" in entry ? entry.userDisplayName : undefined,
    algorithm: "algorithm" in entry ? entry.algorithm : undefined,
    signCount: "signCount" in entry ? entry.signCount : undefined,
    aaguid: "aaguid" in entry ? entry.aaguid : undefined,
    backupEligible: "backupEligible" in entry ? entry.backupEligible : undefined,
    backupState: "backupState" in entry ? entry.backupState : undefined,
    lastUsedAt: "lastUsedAt" in entry ? entry.lastUsedAt : undefined,
    createdAt,
    modifiedAt,
    deletedAt: entry.deletedAt,
    tags: "tags" in entry ? entry.tags : undefined,
  };
}

function hasLegacyShape(parsed: VaultEntry[]): boolean {
  return parsed.some(
    (entry) => "created" in entry || "updated" in entry
  );
}

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

function entryDupeKey(e: VaultEntry): string {
  if (e.type === "note") return `note|${e.title.toLowerCase()}`;
  if (e.type === "passkey") return `passkey|${(e.rpId ?? "").toLowerCase()}|${(e.userName ?? "").toLowerCase()}`;
  return `login|${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 snapshot system — last 6 encrypted states, used for self-recovery
// ---------------------------------------------------------------------------

const SNAPSHOT_KEY = "peach_vault_snapshots";
const MAX_SNAPSHOTS = 6;

interface VaultSnapshot {
  timestamp: number;
  entryCount: number;
  slot: StoredVault;
}

/** Public summary (no sensitive data) returned to the popup. */
export interface SnapshotSummary {
  index: number;
  timestamp: number;
  entryCount: number;
}

async function takeSnapshot(
  slot: StoredVault,
  entryCount: number
): Promise<void> {
  try {
    const raw = await chrome.storage.local.get(SNAPSHOT_KEY);
    const existing: VaultSnapshot[] = (raw as Record<string, VaultSnapshot[]>)[SNAPSHOT_KEY] ?? [];
    const next: VaultSnapshot[] = [
      { timestamp: Date.now(), entryCount, slot },
      ...existing,
    ].slice(0, MAX_SNAPSHOTS);
    await chrome.storage.local.set({ [SNAPSHOT_KEY]: next });
  } catch {
    // Non-fatal — snapshot failure must never interrupt vault saves
  }
}

export async function listSnapshots(): Promise<SnapshotSummary[]> {
  const raw = await chrome.storage.local.get(SNAPSHOT_KEY);
  const snapshots: VaultSnapshot[] = (raw as Record<string, VaultSnapshot[]>)[SNAPSHOT_KEY] ?? [];
  return snapshots.map((s, i) => ({
    index: i,
    timestamp: s.timestamp,
    entryCount: s.entryCount,
  }));
}

/**
 * Restore a snapshot by index. The password must decrypt that snapshot
 * (i.e., the same master password used when the snapshot was taken).
 * On success the vault is unlocked in-memory with the restored entries
 * — no re-login required.
 */
export async function restoreFromSnapshot(
  index: number,
  password: string
): Promise<boolean> {
  const raw = await chrome.storage.local.get(SNAPSHOT_KEY);
  const snapshots: VaultSnapshot[] = (raw as Record<string, VaultSnapshot[]>)[SNAPSHOT_KEY] ?? [];
  const snapshot = snapshots[index];
  if (!snapshot) return false;

  // Verify the password decrypts this snapshot
  const key = await deriveKey(password, unhex(snapshot.slot.salt));
  const payload = await tryDecryptSlot(snapshot.slot, key);
  if (!payload) {
    zeroKey(key);
    return false;
  }

  // Write the snapshot back to slot A. Regenerate noise for slot B.
  await writeSlot(SLOT_A, snapshot.slot);
  await writeSlot(SLOT_B, generateNoiseBlob(snapshot.slot.ciphertext.length / 2));

  // Swap in-memory state to the restored vault — caller gets immediate access
  if (derivedKey) zeroKey(derivedKey);
  derivedKey = key;
  entries = payload.entries;
  duressConfigured = payload.duressConfigured;
  vaultMode = "real";
  buildDomainIndexSync(entries);
  await loadSettings();
  touchAutoLock();

  return 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,
  };
  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;

  // Snapshot now that in-memory key and disk are consistent. Pass the
  // slot content we just wrote rather than re-reading from storage so the
  // snapshot is immune to any microtask-coalesced read-after-write race.
  const activeCount = entries.filter((e) => !e.deletedAt).length;
  void takeSnapshot(freshSlotA, activeCount);

  // 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;
}