import { afterEach, beforeEach, describe, expect, it } from 'bun:test';
import { mkdir, mkdtemp, readFile, readdir, rm, writeFile } from 'node:fs/promises';
import { tmpdir } from 'node:os';
import { join } from 'node:path';
import { handleModuleVersion } from './module-version';

let dir: string;

const MANIFEST = (kind: string | null) =>
  [
    'celilo_contract: "1.0"',
    'id: lunacycle',
    'name: LunaCycle',
    'version: 1.0.1   # keep this comment',
    ...(kind ? ['version_source:', `  kind: ${kind}`] : []),
    'description: an app',
  ].join('\n');

async function seed(kind: string | null, changesets: Record<string, string> = {}) {
  await writeFile(join(dir, 'manifest.yml'), MANIFEST(kind));
  await mkdir(join(dir, '.changeset'), { recursive: true });
  await writeFile(join(dir, '.changeset', 'README.md'), '# Changesets\n');
  for (const [name, body] of Object.entries(changesets)) {
    await writeFile(join(dir, '.changeset', name), body);
  }
}

beforeEach(async () => {
  dir = await mkdtemp(join(tmpdir(), 'celilo-modver-'));
});
afterEach(async () => {
  await rm(dir, { recursive: true, force: true });
});

describe('handleModuleVersion (changeset kind)', () => {
  it('bumps the manifest version, writes CHANGELOG, consumes changesets', async () => {
    await seed('changeset', {
      'a.md': '---\n"lunacycle": minor\n---\n\nAdded tasks view.\n',
      'b.md': '---\n"lunacycle": patch\n---\n\nFixed a typo.\n',
    });

    const res = await handleModuleVersion([dir], {});
    expect(res.success).toBe(true);

    const manifest = await readFile(join(dir, 'manifest.yml'), 'utf-8');
    expect(manifest).toContain('version: 1.1.0'); // max(minor,patch) = minor
    expect(manifest).toContain('# keep this comment'); // comment preserved? (line replaced, but others intact)
    expect(manifest).toContain('kind: changeset');

    const changelog = await readFile(join(dir, 'CHANGELOG.md'), 'utf-8');
    expect(changelog).toContain('# lunacycle');
    expect(changelog).toContain('## 1.1.0');
    expect(changelog).toContain('### Minor Changes');
    expect(changelog).toContain('- Added tasks view.');

    const remaining = (await readdir(join(dir, '.changeset'))).filter((f) => f !== 'README.md');
    expect(remaining).toEqual([]); // both consumed
  });

  it('prepends newest-on-top to an existing CHANGELOG', async () => {
    await seed('changeset', { 'a.md': '---\nlunacycle: patch\n---\nfix\n' });
    await writeFile(
      join(dir, 'CHANGELOG.md'),
      '# lunacycle\n\n## 1.0.1\n\n### Patch Changes\n\n- old\n',
    );

    await handleModuleVersion([dir], {});
    const changelog = await readFile(join(dir, 'CHANGELOG.md'), 'utf-8');
    expect(changelog.indexOf('## 1.0.2')).toBeLessThan(changelog.indexOf('## 1.0.1'));
    expect(changelog.split('# lunacycle').length).toBe(2); // header not duplicated
  });

  it('is a clean no-op when no changeset targets the module', async () => {
    await seed('changeset', { 'a.md': '---\nnigredo: minor\n---\nother app\n' });
    const res = await handleModuleVersion([dir], {});
    expect(res.success).toBe(true);
    const manifest = await readFile(join(dir, 'manifest.yml'), 'utf-8');
    expect(manifest).toContain('version: 1.0.1'); // unchanged
    // the non-targeting changeset is left in place
    expect((await readdir(join(dir, '.changeset'))).includes('a.md')).toBe(true);
  });

  it('is a clean no-op with no changesets at all', async () => {
    await seed('changeset', {});
    const res = await handleModuleVersion([dir], {});
    expect(res.success).toBe(true);
    expect(await readFile(join(dir, 'manifest.yml'), 'utf-8')).toContain('version: 1.0.1');
  });

  it('fails loudly on a malformed changeset', async () => {
    await seed('changeset', { 'bad.md': 'no frontmatter here' });
    const res = await handleModuleVersion([dir], {});
    expect(res.success).toBe(false);
  });
});

describe('handleModuleVersion (other kinds)', () => {
  it('recipe kind is a no-op', async () => {
    await seed('recipe', { 'a.md': '---\nlunacycle: minor\n---\nx\n' });
    const res = await handleModuleVersion([dir], {});
    expect(res.success).toBe(true);
    expect(await readFile(join(dir, 'manifest.yml'), 'utf-8')).toContain('version: 1.0.1');
  });

  it('absent version_source defaults to recipe (no-op)', async () => {
    await seed(null, { 'a.md': '---\nlunacycle: minor\n---\nx\n' });
    const res = await handleModuleVersion([dir], {});
    expect(res.success).toBe(true);
    expect(await readFile(join(dir, 'manifest.yml'), 'utf-8')).toContain('version: 1.0.1');
  });

  it('pin kind is a not-yet-implemented notice (no change)', async () => {
    await seed('pin', {});
    const res = await handleModuleVersion([dir], {});
    expect(res.success).toBe(true);
    expect(res.success && res.message).toContain('pin');
  });
});