import { describe, it } from 'node:test';
import assert from 'node:assert/strict';
import { processSessionList } from '../src/session-list.js';

/**
 * Deterministic fixture builder for processSessionList.
 * Returns already-enriched sessions (is_favorite, favorited_at, custom_name set).
 */
function makeSession(overrides = {}) {
  return {
    id: overrides.id || 'sess-1',
    engine: overrides.engine || 'codex',
    created_at: overrides.created_at || 1000,
    status: overrides.status || 'success',
    summary: overrides.summary || 'Test session',
    model: overrides.model || 'gpt-4',
    cwd: overrides.cwd || '/home/test',
    source: overrides.source || 'chat',
    custom_name: overrides.custom_name || null,
    is_favorite: overrides.is_favorite || false,
    favorited_at: overrides.favorited_at || null,
    ...overrides,
  };
}

describe('Session list pipeline (processSessionList)', () => {

  // ── Sorting ──────────────────────────────────────────────────────

  it('should place favorited sessions first, ordered by favorited_at desc', () => {
    const list = [
      makeSession({ id: 'old-fav', is_favorite: true, favorited_at: 100, created_at: 500 }),
      makeSession({ id: 'recent-fav', is_favorite: true, favorited_at: 200, created_at: 400 }),
      makeSession({ id: 'normal', is_favorite: false, created_at: 900 }),
    ];
    const result = processSessionList(list, { limit: 10 });
    assert.equal(result.sessions[0].id, 'recent-fav');
    assert.equal(result.sessions[1].id, 'old-fav');
    assert.equal(result.sessions[2].id, 'normal');
  });

  it('should apply created_at desc tie-break for equal favorited_at values', () => {
    const list = [
      makeSession({ id: 'older', is_favorite: true, favorited_at: 100, created_at: 1000 }),
      makeSession({ id: 'newer', is_favorite: true, favorited_at: 100, created_at: 2000 }),
    ];
    const result = processSessionList(list, { limit: 10 });
    // Equal favorited_at → created_at desc
    assert.equal(result.sessions[0].id, 'newer');
    assert.equal(result.sessions[1].id, 'older');
  });

  it('should order non-favorite sessions by created_at desc', () => {
    const list = [
      makeSession({ id: 'old', created_at: 100 }),
      makeSession({ id: 'mid', created_at: 200 }),
      makeSession({ id: 'new', created_at: 300 }),
    ];
    const result = processSessionList(list, { limit: 10 });
    assert.equal(result.sessions[0].id, 'new');
    assert.equal(result.sessions[1].id, 'mid');
    assert.equal(result.sessions[2].id, 'old');
  });

  it('should sort before pagination (sort covers all items, pagination slices)', () => {
    const list = [];
    // 5 favorites at timestamps favoring higher i → higher favorited_at
    for (let i = 0; i < 5; i++) {
      list.push(makeSession({ id: `fav-${i}`, is_favorite: true, favorited_at: 500 - i, created_at: 1000 + i }));
    }
    // 5 non-favorites
    for (let i = 0; i < 5; i++) {
      list.push(makeSession({ id: `normal-${i}`, created_at: 100 + i }));
    }
    // fav-0 has favorited_at=500 (highest), fav-4 has 496 (lowest among favs)
    const result = processSessionList(list, { limit: 3, offset: 0 });
    assert.equal(result.total, 10);
    assert.equal(result.sessions.length, 3);
    assert.equal(result.sessions[0].id, 'fav-0');
    assert.equal(result.sessions[1].id, 'fav-1');
    assert.equal(result.sessions[2].id, 'fav-2');
  });

  // ── Filtering ────────────────────────────────────────────────────

  it('should filter by favorite-only when opts.favorite="1"', () => {
    const list = [
      makeSession({ id: 'fav', is_favorite: true, favorited_at: 100 }),
      makeSession({ id: 'not-fav', is_favorite: false }),
    ];
    const result = processSessionList(list, { favorite: '1', limit: 10 });
    assert.equal(result.sessions.length, 1);
    assert.equal(result.sessions[0].id, 'fav');
  });

  it('should combine favorite-only with status filter', () => {
    const list = [
      makeSession({ id: 'fav-ok', is_favorite: true, favorited_at: 200, status: 'success' }),
      makeSession({ id: 'fav-err', is_favorite: true, favorited_at: 100, status: 'error' }),
      makeSession({ id: 'normal-ok', status: 'success' }),
    ];
    // Only favorited AND status=error
    const result = processSessionList(list, { favorite: '1', status: 'failed', limit: 10 });
    assert.equal(result.sessions.length, 1);
    assert.equal(result.sessions[0].id, 'fav-err');
  });

  it('should be deterministic when favorited_at and created_at both equal', () => {
    const list = [
      makeSession({ id: 'a', is_favorite: true, favorited_at: 100, created_at: 1000 }),
      makeSession({ id: 'b', is_favorite: true, favorited_at: 100, created_at: 1000 }),
    ];
    // When both are equal, sort is stable (preserves original order)
    const result = processSessionList(list, { limit: 10 });
    assert.equal(result.sessions[0].id, 'a');
    assert.equal(result.sessions[1].id, 'b');
  });

  it('should combine favorite-only with query and status filter (composition test)', () => {
    const list = [
      // Favorited, matches query, has error status
      makeSession({ id: 'match-all', is_favorite: true, favorited_at: 300, status: 'error', summary: 'OAuth fix', custom_name: null }),
      // Favorited, does NOT match query
      makeSession({ id: 'fav-no-query', is_favorite: true, favorited_at: 200, status: 'error', summary: 'Other thing' }),
      // Favorited, matches query but wrong status
      makeSession({ id: 'fav-ok-status', is_favorite: true, favorited_at: 100, status: 'success', summary: 'OAuth callback' }),
      // Not favorited, matches query and status
      makeSession({ id: 'not-fav', is_favorite: false, status: 'error', summary: 'OAuth failure' }),
    ];
    // Only favorited + query matching "OAuth" + status failed
    const result = processSessionList(list, { favorite: '1', query: 'OAuth', status: 'failed', limit: 10 });
    assert.equal(result.sessions.length, 1);
    assert.equal(result.sessions[0].id, 'match-all');
  });

  // ── Edge cases ───────────────────────────────────────────────────

  it('should return empty array for empty input', () => {
    const result = processSessionList([], { limit: 10 });
    assert.deepEqual(result, { sessions: [], total: 0 });
  });

  it('should respect limit and offset', () => {
    const list = [];
    for (let i = 0; i < 20; i++) {
      list.push(makeSession({ id: `s-${i}`, created_at: 2000 - i }));
    }
    // s-0 has created_at=2000 (highest → first after sort desc)
    const page1 = processSessionList(list, { limit: 5, offset: 0 });
    assert.equal(page1.sessions.length, 5);
    assert.equal(page1.sessions[0].id, 's-0');
    assert.equal(page1.total, 20);

    const page2 = processSessionList(list, { limit: 5, offset: 5 });
    assert.equal(page2.sessions.length, 5);
    assert.equal(page2.sessions[0].id, 's-5');
  });

  it('should cap limit at 200', () => {
    const list = Array.from({ length: 300 }, (_, i) =>
      makeSession({ id: `s-${i}`, created_at: 300 - i })
    );
    const result = processSessionList(list, { limit: 999 });
    assert.equal(result.sessions.length, 200);
    assert.equal(result.total, 300);
  });
});