#!/usr/bin/env node
/**
 * Generate a synthetic npm-workspaces TypeScript monorepo for fallow performance testing.
 *
 * Usage:
 *   node gen-monorepo.cjs --out <dir> --workspaces N --files-per-workspace M [--git] [--dupes]
 *
 * Defaults: --workspaces 80 --files-per-workspace 300 (≈24,000 files)
 *
 * Each workspace gets:
 *   - A package.json with deps that activate ~10 fallow plugins (react, eslint, vitest, ...)
 *   - A tsconfig.json
 *   - M source files with realistic export counts and cross-imports
 *
 * The repo as a whole gets:
 *   - A root package.json declaring all workspaces
 *   - A root tsconfig.base.json
 *   - Optional: `git init` + initial commit (when --git is passed)
 *   - Optional: each workspace gets one large duplicated file (when --dupes is passed)
 */

const fs = require('node:fs');
const path = require('node:path');
const { execSync } = require('node:child_process');

// ─── Args ────────────────────────────────────────────────────────────────────

const args = parseArgs(process.argv.slice(2));
const OUT = path.resolve(args.out || './synthetic-monorepo');
const WORKSPACES = parseInt(args.workspaces || '80', 10);
const FILES_PER_WS = parseInt(args['files-per-workspace'] || '300', 10);
const WITH_GIT = args.git === true;
const WITH_DUPES = args.dupes === true;
const EXTRA_COMMITS = parseInt(args.commits || '0', 10);
// `--heavy`: turn on barrel files + cross-workspace imports + heterogeneous plugin deps.
// Designed to stress fallow's analyze + plugins stages the way real-world monorepos do.
const HEAVY = args.heavy === true;
// `--config-files`: per-workspace, write extra fallow-relevant config files (jest, eslint,
// tailwind, project.json, *.config.ts variants). Designed to stress fallow's plugins stage,
// which globs every config pattern against every discovered file and reads matches from disk.
const WITH_CONFIG_FILES = args['config-files'] === true;

// 80-line block copy-pasted into every workspace -> guaranteed clones for the dupes scanner.
const DUPLICATED_BLOCK = Array.from({ length: 80 }, (_, n) => `const k${n} = ${n} * 7 + ${n};`).join('\n') + '\n';

// 5 different plugin profiles to rotate through workspaces in --heavy mode.
// Each profile activates a distinct set of fallow plugins.
const PLUGIN_PROFILES = [
  // 0: React + Storybook + Vitest
  {
    deps: { react: '^18.0.0', 'react-dom': '^18.0.0' },
    devDeps: { typescript: '^5.0.0', vitest: '^1.0.0', '@storybook/react': '^7.0.0', tailwindcss: '^3.0.0', eslint: '^8.0.0' },
  },
  // 1: Angular
  {
    deps: { '@angular/core': '^17.0.0', '@angular/common': '^17.0.0', '@angular/router': '^17.0.0', rxjs: '^7.0.0' },
    devDeps: { typescript: '^5.0.0', '@angular/cli': '^17.0.0', karma: '^6.0.0', jasmine: '^5.0.0', '@storybook/angular': '^7.0.0' },
  },
  // 2: Vue + Vite
  {
    deps: { vue: '^3.0.0', 'vue-router': '^4.0.0', pinia: '^2.0.0' },
    devDeps: { typescript: '^5.0.0', vite: '^5.0.0', vitest: '^1.0.0', '@vitejs/plugin-vue': '^5.0.0', cypress: '^13.0.0' },
  },
  // 3: SvelteKit + Playwright
  {
    deps: { svelte: '^4.0.0', '@sveltejs/kit': '^2.0.0' },
    devDeps: { typescript: '^5.0.0', vite: '^5.0.0', vitest: '^1.0.0', playwright: '^1.0.0', '@playwright/test': '^1.0.0' },
  },
  // 4: Next.js + Jest + GraphQL
  {
    deps: { next: '^14.0.0', react: '^18.0.0', 'react-dom': '^18.0.0', graphql: '^16.0.0' },
    devDeps: { typescript: '^5.0.0', jest: '^29.0.0', '@graphql-codegen/cli': '^5.0.0', sentry: '^7.0.0', prettier: '^3.0.0' },
  },
];

console.error(`Generating: ${OUT}`);
console.error(`  workspaces=${WORKSPACES} files/ws=${FILES_PER_WS} (~${WORKSPACES * FILES_PER_WS} files)`);
console.error(`  git=${WITH_GIT} commits=${EXTRA_COMMITS} dupes=${WITH_DUPES}`);

// ─── Generate ────────────────────────────────────────────────────────────────

if (fs.existsSync(OUT)) {
  fs.rmSync(OUT, { recursive: true, force: true });
}
fs.mkdirSync(OUT, { recursive: true });

writeRoot();
for (let w = 0; w < WORKSPACES; w++) {
  writeWorkspace(w);
}
if (WITH_GIT) initGit();

console.error('Done.');

// ─── Templates ───────────────────────────────────────────────────────────────

function writeRoot() {
  const pkg = {
    name: 'synthetic-monorepo',
    private: true,
    workspaces: Array.from({ length: WORKSPACES }, (_, w) => `packages/ws-${w}`),
  };
  fs.writeFileSync(path.join(OUT, 'package.json'), JSON.stringify(pkg, null, 2) + '\n');
  fs.writeFileSync(
    path.join(OUT, 'tsconfig.base.json'),
    JSON.stringify(
      {
        compilerOptions: {
          target: 'ES2022',
          module: 'ESNext',
          moduleResolution: 'bundler',
          strict: true,
          esModuleInterop: true,
          skipLibCheck: true,
        },
      },
      null,
      2,
    ) + '\n',
  );
  // Root tsconfig.json that references all workspaces (silences fallow's broken-chain warning)
  fs.writeFileSync(
    path.join(OUT, 'tsconfig.json'),
    JSON.stringify({ extends: './tsconfig.base.json', files: [] }, null, 2) + '\n',
  );
  fs.writeFileSync(path.join(OUT, '.gitignore'), 'node_modules/\n.fallow/\n');
}

function writeWorkspace(w) {
  const wsDir = path.join(OUT, 'packages', `ws-${w}`);
  fs.mkdirSync(path.join(wsDir, 'src'), { recursive: true });

  // In --heavy mode rotate through plugin profiles so workspaces are heterogeneous.
  // Otherwise use a fixed React-ish profile (small, quick, predictable).
  const profile = HEAVY ? PLUGIN_PROFILES[w % PLUGIN_PROFILES.length] : PLUGIN_PROFILES[0];
  const pkg = {
    name: `@synthetic/ws-${w}`,
    version: '0.0.0',
    main: 'src/index.ts',
    dependencies: profile.deps,
    devDependencies: { ...profile.devDeps, husky: '^9.0.0', 'lint-staged': '^15.0.0' },
  };
  fs.writeFileSync(path.join(wsDir, 'package.json'), JSON.stringify(pkg, null, 2) + '\n');
  fs.writeFileSync(
    path.join(wsDir, 'tsconfig.json'),
    JSON.stringify({ extends: '../../tsconfig.base.json', include: ['src/**/*'] }, null, 2) + '\n',
  );

  for (let i = 0; i < FILES_PER_WS; i++) {
    const filePath = path.join(wsDir, 'src', `mod-${i}.ts`);
    fs.writeFileSync(filePath, makeModule(w, i));
  }

  // index.ts: re-export everything (a real barrel file).
  // In --heavy mode this re-exports ALL FILES_PER_WS modules; otherwise just the first 10.
  const reexportCount = HEAVY ? FILES_PER_WS : Math.min(10, FILES_PER_WS);
  const reexports = Array.from({ length: reexportCount }, (_, i) => `export * from './mod-${i}';`).join('\n');
  fs.writeFileSync(path.join(wsDir, 'src', 'index.ts'), reexports + '\n');

  // --heavy: also write a deeply-nested barrel that re-exports the barrel,
  // creating a re-export chain that fallow has to walk.
  if (HEAVY) {
    fs.writeFileSync(path.join(wsDir, 'src', 'barrel-1.ts'), `export * from './index';\n`);
    fs.writeFileSync(path.join(wsDir, 'src', 'barrel-2.ts'), `export * from './barrel-1';\n`);
    fs.writeFileSync(path.join(wsDir, 'src', 'barrel-3.ts'), `export * from './barrel-2';\n`);
  }

  // Optional duplicated block (one large copy-pasted file per workspace)
  if (WITH_DUPES) {
    fs.writeFileSync(path.join(wsDir, 'src', 'duplicated-block.ts'), DUPLICATED_BLOCK);
  }

  // --config-files: write a realistic spread of fallow-relevant config files.
  // Each is small (empty object / no-op export), but the *count* matters for
  // the plugins stage: every config has to be globbed and read.
  if (WITH_CONFIG_FILES) {
    fs.writeFileSync(path.join(wsDir, '.eslintrc.json'), '{}\n');
    fs.writeFileSync(path.join(wsDir, '.prettierrc'), '{}\n');
    fs.writeFileSync(path.join(wsDir, 'tsconfig.spec.json'), '{}\n');
    fs.writeFileSync(path.join(wsDir, 'tsconfig.lib.json'), '{}\n');
    fs.writeFileSync(path.join(wsDir, 'jest.config.ts'), 'export default {};\n');
    fs.writeFileSync(path.join(wsDir, 'vitest.config.ts'), 'export default {};\n');
    fs.writeFileSync(path.join(wsDir, 'tailwind.config.ts'), 'export default {};\n');
    fs.writeFileSync(path.join(wsDir, 'webpack.config.ts'), 'export default {};\n');
    fs.writeFileSync(path.join(wsDir, 'project.json'), '{"name":"ws"}\n');
    fs.writeFileSync(path.join(wsDir, '.babelrc'), '{}\n');
  }
}

function makeModule(w, i) {
  const importTarget = (i + 1) % FILES_PER_WS;

  // --heavy: cross-workspace import pulling from the next workspace's barrel.
  // Forces fallow's resolver and the analyze stage to walk across workspace boundaries.
  const crossWsImport = HEAVY
    ? `import { value0 as crossWs } from '@synthetic/ws-${(w + 1) % WORKSPACES}';\n`
    : '';
  // --heavy: import from the local barrel-3 so fallow has a re-export chain to resolve.
  const barrelImport = HEAVY ? `import { value1 as fromBarrel } from './barrel-3';\n` : '';
  // --heavy: extra exports + a type, an enum, and a re-export to widen the analyze surface.
  const extraExports = HEAVY
    ? `
export type T${i} = { id: number; tag: string; meta: Record<string, unknown> };
export enum E${i} { A = '${w}-${i}-a', B = '${w}-${i}-b', C = '${w}-${i}-c' }
export interface I${i} { fn(x: T${i}): T${i}; }
export { value0 as alias${i} } from './mod-${(i + 2) % FILES_PER_WS}';
export const arr${i} = [1, 2, 3].map((x) => x + ${i});
`
    : '';

  return `${crossWsImport}${barrelImport}import { value0 as upstream } from './mod-${importTarget}';

export const value0 = upstream + ${i}${HEAVY ? ' + (typeof crossWs === "number" ? crossWs : 0) + (typeof fromBarrel === "number" ? fromBarrel : 0)' : ''};
export const value1 = ${i} * 2;
export const value2 = '${w}-${i}';
export function fn0(x: number): number { return x + ${i}; }
export class Cls0 { id = ${i}; method(): string { return 'm-${i}'; } }${extraExports}`;
}

// ─── Helpers ─────────────────────────────────────────────────────────────────

function initGit() {
  console.error('Initializing git...');
  execSync('git init -q', { cwd: OUT });
  execSync('git config user.email "synthetic@example.com"', { cwd: OUT });
  execSync('git config user.name "Synthetic User"', { cwd: OUT });
  execSync('git add .', { cwd: OUT });
  execSync('git commit -q -m "initial commit"', { cwd: OUT });

  if (EXTRA_COMMITS > 0) {
    console.error(`Adding ${EXTRA_COMMITS} extra commits (touching one file each)...`);
    // Touch one random module per commit so churn data is realistic, not all on one file.
    for (let c = 0; c < EXTRA_COMMITS; c++) {
      const w = c % WORKSPACES;
      const i = c % FILES_PER_WS;
      const filePath = path.join(OUT, 'packages', `ws-${w}`, 'src', `mod-${i}.ts`);
      // Append a no-op comment line. Each commit modifies a different file when possible.
      fs.appendFileSync(filePath, `// commit ${c}\n`);
      execSync(`git add ${filePath}`, { cwd: OUT });
      execSync(`git commit -q -m "commit ${c}"`, { cwd: OUT });
    }
  }
}

function parseArgs(argv) {
  const out = {};
  for (let i = 0; i < argv.length; i++) {
    const a = argv[i];
    if (!a.startsWith('--')) continue;
    const key = a.slice(2);
    const next = argv[i + 1];
    if (next === undefined || next.startsWith('--')) {
      out[key] = true;
    } else {
      out[key] = next;
      i++;
    }
  }
  return out;
}