// T-001: BIP39 word-list integrity
//
// Why this test exists: a single transcription error in recovery-word-list.ts
// silently shifts every subsequent word index and renders affected recovery
// phrases permanently unrestorable. There is no runtime error — the wrong word
// just maps to a valid (but different) root-key prefix, which decrypts a
// completely different vault. No test previously guarded this.

import { describe, expect, it } from "vitest";
import { WORD_LIST } from "../../shared/recovery-word-list";

describe("T-001: BIP39 word-list integrity", () => {
  // T-001a: exact length is load-bearing — 2048 words = 2^11 indices per word,
  // which is what the BIP39 bit-packing arithmetic in recovery-words.ts assumes.
  it("T-001a: list has exactly 2048 words", () => {
    expect(WORD_LIST).toHaveLength(2048);
  });

  // T-001b: a duplicate word at position N collapses two indices to one,
  // making N different root keys produce identical phrases (silent collision).
  it("T-001b: no duplicates — Set.size === 2048", () => {
    expect(new Set(WORD_LIST).size).toBe(2048);
  });

  // T-001c: BIP39 requires lowercase ASCII 3–8 letters. A word with an accent,
  // uppercase letter, or number breaks the WORD_LIST.indexOf() lookup in
  // wordsToRootKeyMaterial and returns -1 → "unknown word" error on restore.
  it("T-001c: every word is lowercase ASCII only (3–8 letters)", () => {
    const badWords: string[] = [];
    for (const word of WORD_LIST) {
      if (!/^[a-z]{3,8}$/.test(word)) {
        badWords.push(word);
      }
    }
    expect(badWords).toEqual([]);
  });

  // T-001d: canonical BIP39 position anchors.
  // Verified against the official BIP39 English wordlist
  // (https://github.com/trezor/python-mnemonic/blob/master/src/mnemonic/wordlist/english.txt).
  // A transposition, insertion, or deletion anywhere in the list shifts all
  // subsequent positions and is caught by one of these four anchors.
  it("T-001d: canonical BIP39 spot-checks", () => {
    expect(WORD_LIST[0]).toBe("abandon");    // first word
    expect(WORD_LIST[1]).toBe("ability");    // second word
    expect(WORD_LIST[2047]).toBe("zoo");     // last word
    expect(WORD_LIST[585]).toBe("empty");    // mid-list anchor
  });

  // T-001e: the list must be in strict alphabetical order.
  // An out-of-order word would pass T-001b (no duplicates) but would break
  // any tooling or human verification that cross-references by position.
  it("T-001e: list is in canonical alphabetical order", () => {
    const sorted = [...WORD_LIST].sort((a, b) => a.localeCompare(b));
    expect(WORD_LIST).toEqual(sorted);
  });
});