/**
 * codex-types.ts — shared shapes for the Peach Codex.
 *
 * The Codex is a printed A4 PDF that encodes the user's encrypted vault as
 * Aztec barcodes. Recovery words are never included in the PDF — they live
 * on paper separately by design. See peach_codex_v2.md + peach_codex_addendum.md
 * for the full design doc.
 *
 * These types are the contract between four execution boundaries:
 *  - service worker (`src/background/codex-handlers.ts`)
 *  - popup library (`src/popup/codex/*`)
 *  - popup views (`src/popup/views/CodexGenerateView.tsx`, `CodexRestoreView.tsx`)
 *  - tests (`src/popup/codex/*.test.ts`)
 *
 * Bump `version` (and `ChunkEnvelope.v`) only on breaking changes to the
 * on-paper format. A v2 Codex must always be decodable by future Peach
 * versions.
 */

import type { VaultEntry } from "./types";

/** Payload that the Codex encodes. Compressed, chunked, erasure-coded, then printed. */
export interface CodexPayload {
  /** Format version. Increment on breaking changes. */
  version: 2;
  /** 12-char alphanumeric: `PX-XXXX-XXXX`. Identifies a vault across Codex prints. */
  verifyCode: string;
  /** Base64url-encoded JSON `{ a: slotA, b: slotB|null }` — both encrypted vault slots. */
  vaultBlob: string;
  /** Vault last-modified unix timestamp (ms). Used to compare against on-device vault on restore. */
  timestamp: number;
  /** Visible entry count for user confirmation at restore time. */
  entryCount: number;
  /** First 32 chars (128 bits) of SHA-256(vaultBlob), uppercase hex. Verifies reconstruction integrity. AUD-004: was 16 chars; legacy Codexes still verify. */
  vaultFingerprint: string;
  /** When this Codex PDF was generated. Printed in the footer. */
  generatedAt: number;
}

/**
 * One Aztec barcode's contents. Each envelope is a JSON-encoded chunk of the
 * compressed payload plus a per-chunk integrity hash.
 *
 * Field names are intentionally single letters to keep the encoded JSON
 * compact — every byte saved shrinks the printed page count.
 */
export interface ChunkEnvelope {
  /** Envelope format version. Increment on breaking changes. */
  v: 2;
  /** First 12 chars of `verifyCode` ("PX-XXXX-XXXX"). Lets the scanner reject foreign Codexes. */
  c: string;
  /** Chunk index, 0-based. */
  i: number;
  /** Total chunk count (data + parity). */
  t: number;
  /** True if this is a Reed-Solomon parity shard. */
  p: boolean;
  /** Chunk data, base64url-encoded. */
  d: string;
  /** First 32 chars (128 bits) of SHA-256(rawChunkBytes), hex. Catches per-chunk corruption with ≤2^-128 collision odds. AUD-004: was 16 chars; legacy Codexes still verify. */
  h: string;
}

/** Bookkeeping returned alongside the generated PDF. */
export interface CodexManifest {
  verifyCode: string;
  totalChunks: number;
  dataChunks: number;
  parityChunks: number;
  pageCount: number;
  entryCount: number;
  vaultFingerprint: string;
  generatedAt: number;
}

/** Dependencies the generator needs from the service worker. */
export interface CodexDeps {
  getSlotA: () => Promise<string | null>;
  getSlotB: () => Promise<string | null>;
  getLastModified: () => Promise<string | null>;
  getAllEntries: () => Promise<VaultEntry[]>;
  getVerifyCode: () => Promise<string>;
  isVaultUnlocked: () => boolean;
}

/**
 * Progress reporter for the generator. Called at named milestones; for the
 * Aztec step `current`/`total` advance per code so the UI can render a bar.
 */
export type CodexProgress = (
  step: "compress" | "erasure" | "aztec" | "verify" | "pdf",
  current?: number,
  total?: number,
) => void;

/** Payload sent from the popup to the SW to perform the actual vault restoration. */
export interface CodexRestorePayload {
  vaultBlob: string;
  timestamp: number;
  verifyCode: string;
  vaultFingerprint: string;
  entryCount: number;
  masterPassphrase: string;
}

/** Vault data the SW exposes to the popup so it can build a CodexPayload. */
export interface CodexVaultSnapshot {
  slotA: string | null;
  slotB: string | null;
  lastModified: string | null;
  entryCount: number;
  recoveryWords: string[] | null;
  verifyCode: string;
  vaultUnlocked: boolean;
}

/**
 * Every Codex error is loud and named. The `code` field is a stable identifier
 * for log analysis; the human-readable message lives in `.message`.
 */
export class CodexError extends Error {
  constructor(
    public code: CodexErrorCode,
    message: string,
  ) {
    super(message);
    this.name = "CodexError";
  }
}

export type CodexErrorCode =
  | "VAULT_LOCKED"
  | "VAULT_EMPTY"
  | "COMPRESSION_ROUNDTRIP_FAILED"
  | "ERASURE_CODING_VERIFICATION_FAILED"
  | "ERASURE_CODING_CONTENT_MISMATCH"
  | "AZTEC_GENERATION_FAILED"
  | "AZTEC_ROUNDTRIP_FAILED"
  | "AZTEC_CONTENT_MISMATCH"
  | "INSUFFICIENT_CHUNKS"
  | "RECONSTRUCTION_SIMULATION_FAILED"
  | "RECONSTRUCTION_VERIFY_CODE_MISMATCH"
  | "RECONSTRUCTION_FINGERPRINT_MISMATCH"
  | "RECONSTRUCTION_COUNT_MISMATCH"
  | "PDF_GENERATION_FAILED"
  | "RS_LIBRARY_FAILED"
  | "PRO_REQUIRED"
  | "WRONG_PASSPHRASE"
  | "INVALID_VAULT_BLOB"
  | "RESTORE_FAILED";

// ── Constants — shared across generation and restoration ─────────────────────

/**
 * Bytes of binary data per chunk. Each chunk becomes one Aztec code.
 *
 * 3200 bytes base64url-encodes to ~4267 chars; combined with the JSON envelope
 * overhead (~100 chars) the printed text is ~4367 chars — well under the
 * bwip-js limit of 4999 chars at eclevel=25. DO NOT increase without re-running
 * a bwip-js capacity test for the densest envelope.
 *
 * Sized to drive a typical vault down to ~6 A4 pages instead of ~24. Old
 * Codexes printed with a smaller chunk size still restore — the erasure
 * decoder derives shard size from the scanned chunks, not from this constant.
 */
export const CHUNK_SIZE = 3200;

/**
 * Number of parity shards. With 2 parity shards, the Codex survives the loss
 * of any 2 chunks (torn corner, coffee stain over one code, etc.) without
 * data loss. Raising this beyond 2 grows the page count meaningfully.
 */
export const PARITY_SHARDS = 2;

/** Aztec error-correction percentage. 25% balances barcode density vs. resilience. */
export const AZTEC_ECC_PERCENT = 25;

/** PDF layout: 6 columns × 6 rows = 36 codes per A4 page. */
export const CODES_PER_ROW = 6;
export const CODES_PER_COL = 6;
export const CODES_PER_PAGE = CODES_PER_ROW * CODES_PER_COL;

/** Stable storage keys for Codex bookkeeping. */
export const STORAGE_KEY_VERIFY_CODE = "peach_codex_verify_code";
export const STORAGE_KEY_LAST_GENERATED = "peach_codex_last_generated";
export const STORAGE_KEY_LAST_RESTORED = "peach_last_restored_at";