import { test } from 'node:test';
import assert from 'node:assert/strict';
import { fetchDiff } from '../src/lib/review.js';

function giteaStub() {
  const calls = [];
  return {
    calls,
    getPrDiff: (o, r, i) => { calls.push(['pr', o, r, i]); return Promise.resolve('PRDIFF'); },
    getCommitDiff: (o, r, sha) => { calls.push(['commit', o, r, sha]); return Promise.resolve('HEADDIFF'); },
    getCompareDiff: (o, r, before, after) => { calls.push(['compare', o, r, before, after]); return Promise.resolve('RANGEDIFF'); }
  };
}

const HEAD = 'a'.repeat(40);
const BEFORE = 'b'.repeat(40);

test('PR jobs use the PR diff', async () => {
  const g = giteaStub();
  const out = await fetchDiff({ gitea: g, job: { owner: 'o', repo: 'r', prIndex: 5, sha: HEAD, before: null } });
  assert.equal(out, 'PRDIFF');
  assert.deepEqual(g.calls, [['pr', 'o', 'r', 5]]);
});

test('push uses ONE compare diff over the full before...after range', async () => {
  const g = giteaStub();
  const out = await fetchDiff({
    gitea: g,
    job: {
      owner: 'o', repo: 'r', prIndex: null, sha: HEAD, before: BEFORE,
      // 25 commits in the payload: must NOT fall back to per-commit slicing
      commitShas: Array.from({ length: 25 }, (_, i) => String(i).padStart(40, '0'))
    }
  });
  assert.equal(out, 'RANGEDIFF');
  assert.deepEqual(g.calls, [['compare', 'o', 'r', BEFORE, HEAD]]);
});

test('new-branch push (before = zero sha) falls back to head commit diff', async () => {
  const g = giteaStub();
  const out = await fetchDiff({
    gitea: g,
    job: { owner: 'o', repo: 'r', prIndex: null, sha: HEAD, before: '0'.repeat(40), commitShas: [HEAD] }
  });
  assert.equal(out, 'HEADDIFF');
  assert.deepEqual(g.calls, [['commit', 'o', 'r', HEAD]]);
});

test('missing before also falls back to head commit diff', async () => {
  const g = giteaStub();
  const out = await fetchDiff({
    gitea: g,
    job: { owner: 'o', repo: 'r', prIndex: null, sha: HEAD, before: null, commitShas: [HEAD] }
  });
  assert.equal(out, 'HEADDIFF');
  assert.deepEqual(g.calls, [['commit', 'o', 'r', HEAD]]);
});

test('compare failure propagates (no silent placeholder diff)', async () => {
  const g = giteaStub();
  g.getCompareDiff = () => Promise.reject(new Error('boom 500'));
  await assert.rejects(
    () => fetchDiff({ gitea: g, job: { owner: 'o', repo: 'r', prIndex: null, sha: HEAD, before: BEFORE } }),
    /boom 500/
  );
});

// ---- fallback chain (compare 404: force-push, rebase-then-push, or the web
// ---- compare route ignoring token auth on private repos) ----

function nf(path) {
  const e = new Error(`gitea GET ${path} -> 404: Not found.`);
  e.status = 404;
  return e;
}

test('compare 404 falls back to default-branch compare', async () => {
  const g = giteaStub();
  const real = g.getCompareDiff;
  g.getCompareDiff = (o, r, before, after) => before === BEFORE
    ? Promise.reject(nf(`/o/r/compare/${before}...${after}.diff`))
    : real(o, r, before, after);
  const out = await fetchDiff({
    gitea: g,
    job: { owner: 'o', repo: 'r', prIndex: null, sha: HEAD, before: BEFORE, defaultBranch: 'main' }
  });
  assert.equal(out, 'RANGEDIFF');
  assert.deepEqual(g.calls.at(-1), ['compare', 'o', 'r', 'main', HEAD]);
});

test('compare 404 without defaultBranch on the job looks it up via getRepo', async () => {
  const g = giteaStub();
  const real = g.getCompareDiff;
  g.getCompareDiff = (o, r, before, after) => before === BEFORE
    ? Promise.reject(nf(`/o/r/compare/${before}...${after}.diff`))
    : real(o, r, before, after);
  g.getRepo = () => Promise.resolve({ default_branch: 'develop' });
  const out = await fetchDiff({
    gitea: g,
    job: { owner: 'o', repo: 'r', prIndex: null, sha: HEAD, before: BEFORE }
  });
  assert.equal(out, 'RANGEDIFF');
  assert.deepEqual(g.calls.at(-1), ['compare', 'o', 'r', 'develop', HEAD]);
});

test('both compares 404 -> API commit list -> concatenated per-commit diffs', async () => {
  const g = giteaStub();
  const C1 = 'c'.repeat(40), C2 = 'd'.repeat(40);
  g.getCompareDiff = (o, r, before, after) =>
    Promise.reject(nf(`/o/r/compare/${before}...${after}.diff`));
  g.compare = (o, r, before, after) => {
    g.calls.push(['apicompare', o, r, before, after]);
    return Promise.resolve({ total_commits: 2, commits: [{ sha: C1 }, { sha: C2 }] });
  };
  g.getCommitDiff = (o, r, sha) => {
    g.calls.push(['commit', o, r, sha]);
    return Promise.resolve(`DIFF(${sha.slice(0, 1)})`);
  };
  const out = await fetchDiff({
    gitea: g,
    job: { owner: 'o', repo: 'r', prIndex: null, sha: HEAD, before: BEFORE, defaultBranch: 'main' }
  });
  assert.equal(out, 'DIFF(c)\nDIFF(d)');
  assert.deepEqual(g.calls.filter(c => c[0] === 'commit'), [['commit', 'o', 'r', C1], ['commit', 'o', 'r', C2]]);
});

test('API compare 404 too -> per-commit diffs from the webhook commitShas', async () => {
  const g = giteaStub();
  const C1 = 'c'.repeat(40);
  g.getCompareDiff = (o, r, before, after) =>
    Promise.reject(nf(`/o/r/compare/${before}...${after}.diff`));
  g.compare = (o, r, before, after) =>
    Promise.reject(nf(`/api/v1/repos/o/r/compare/${before}...${after}`));
  g.getCommitDiff = (o, r, sha) => {
    g.calls.push(['commit', o, r, sha]);
    return Promise.resolve(`DIFF(${sha.slice(0, 1)})`);
  };
  const out = await fetchDiff({
    gitea: g,
    job: {
      owner: 'o', repo: 'r', prIndex: null, sha: HEAD, before: BEFORE,
      defaultBranch: 'main', commitShas: [C1, HEAD]
    }
  });
  assert.equal(out, 'DIFF(c)\nDIFF(a)');
});

test('per-commit fallback stops fetching past maxBytes (review truncates after)', async () => {
  const g = giteaStub();
  const shas = ['c'.repeat(40), 'd'.repeat(40), 'e'.repeat(40)];
  g.getCompareDiff = () => Promise.reject(nf('/o/r/compare/x...y.diff'));
  g.compare = () => Promise.resolve({ commits: shas.map(sha => ({ sha })) });
  const fetched = [];
  g.getCommitDiff = (o, r, sha) => { fetched.push(sha); return Promise.resolve('x'.repeat(10)); };
  const out = await fetchDiff({
    gitea: g,
    job: { owner: 'o', repo: 'r', prIndex: null, sha: HEAD, before: BEFORE, defaultBranch: 'main' },
    maxBytes: 15
  });
  // first two diffs exceed the cap (20 > 15) -> third commit never fetched
  assert.equal(fetched.length, 2);
  assert.equal(out, 'x'.repeat(10) + '\n' + 'x'.repeat(10));
});

test('every source 404 -> throws listing every URL tried (then fail-open)', async () => {
  const g = giteaStub();
  g.getCompareDiff = (o, r, before, after) =>
    Promise.reject(nf(`/o/r/compare/${before}...${after}.diff`));
  g.compare = (o, r, before, after) =>
    Promise.reject(nf(`/api/v1/repos/o/r/compare/${before}...${after}`));
  g.getCommitDiff = (o, r, sha) =>
    Promise.reject(nf(`/api/v1/repos/o/r/git/commits/${sha}.diff`));
  await assert.rejects(
    () => fetchDiff({
      gitea: g,
      job: { owner: 'o', repo: 'r', prIndex: null, sha: HEAD, before: BEFORE, defaultBranch: 'main' }
    }),
    (e) => {
      assert.match(e.message, /^all diff sources failed: /);
      assert.match(e.message, new RegExp(`compare/${BEFORE}\\.\\.\\.${HEAD}\\.diff`));
      assert.match(e.message, new RegExp(`compare/main\\.\\.\\.${HEAD}\\.diff`));
      assert.match(e.message, new RegExp(`api/v1/repos/o/r/compare/${BEFORE}`));
      assert.match(e.message, new RegExp(`git/commits/${HEAD}\\.diff`));
      return true;
    }
  );
});

test('PR diff 404 falls back to the head commit diff', async () => {
  const g = giteaStub();
  g.getPrDiff = (o, r, i) => Promise.reject(nf(`/api/v1/repos/o/r/pulls/${i}.diff`));
  const out = await fetchDiff({ gitea: g, job: { owner: 'o', repo: 'r', prIndex: 7, sha: HEAD, before: null } });
  assert.equal(out, 'HEADDIFF');
  assert.deepEqual(g.calls, [['commit', 'o', 'r', HEAD]]);
});

test('empty compare body is treated as a miss, not a reviewable diff', async () => {
  const g = giteaStub();
  g.getCompareDiff = (o, r, before) => before === BEFORE ? Promise.resolve('') : Promise.resolve('RANGEDIFF');
  const out = await fetchDiff({
    gitea: g,
    job: { owner: 'o', repo: 'r', prIndex: null, sha: HEAD, before: BEFORE, defaultBranch: 'main' }
  });
  assert.equal(out, 'RANGEDIFF');
});