#!/usr/bin/env node
// @ts-nocheck

import fs from 'node:fs';
import os from 'node:os';
import path from 'node:path';
import { fileURLToPath } from 'node:url';

const __dirname = path.dirname(fileURLToPath(import.meta.url));

function usage() {
  console.error(
    [
      'Usage: purge-copilot-history-quarantine.mjs [options]',
      '',
      'Options:',
      '  --quarantine-dir <path>     Override quarantine root directory.',
      '  --before <iso>              Purge runs created before or at this timestamp.',
      '  --keep-latest <n>           Keep the newest <n> run directories. Default: 1',
      '  --execute                   Perform purge. Default is dry-run.',
      '  --help                      Show this help text.',
    ].join('\n'),
  );
}

function parseArgs(argv) {
  const options = {
    quarantineDir: path.join(
      os.homedir(),
      '.copilot-resources-state',
      'quarantine',
      'copilot-history-cleanup',
    ),
    before: '',
    keepLatest: 1,
    execute: false,
  };

  for (let index = 0; index < argv.length; index += 1) {
    const arg = argv[index];
    if (arg === '--help' || arg === '-h') {
      usage();
      process.exit(0);
    }
    if (arg === '--quarantine-dir') {
      options.quarantineDir = path.resolve(argv[index + 1] ?? options.quarantineDir);
      index += 1;
      continue;
    }
    if (arg === '--before') {
      options.before = argv[index + 1] ?? '';
      index += 1;
      continue;
    }
    if (arg === '--keep-latest') {
      options.keepLatest = Number.parseInt(argv[index + 1] ?? '1', 10);
      index += 1;
      continue;
    }
    if (arg === '--execute') {
      options.execute = true;
      continue;
    }

    throw new Error(`Unknown argument: ${arg}`);
  }

  if (!Number.isInteger(options.keepLatest) || options.keepLatest < 0) {
    throw new Error(`Invalid --keep-latest value: ${options.keepLatest}`);
  }

  return options;
}

function safeStat(filePath) {
  try {
    return fs.statSync(filePath);
  } catch {
    return null;
  }
}

function listRuns(rootDir) {
  if (!fs.existsSync(rootDir)) {
    return [];
  }

  return fs.readdirSync(rootDir, { withFileTypes: true })
    .filter((entry) => entry.isDirectory())
    .map((entry) => {
      const runPath = path.join(rootDir, entry.name);
      const stat = safeStat(runPath);
      return stat ? { path: runPath, mtimeMs: stat.mtimeMs } : null;
    })
    .filter(Boolean)
    .sort((left, right) => right.mtimeMs - left.mtimeMs);
}

function formatBytes(bytes) {
  const units = ['B', 'KB', 'MB', 'GB', 'TB'];
  let value = Number(bytes) || 0;
  let unitIndex = 0;
  while (value >= 1024 && unitIndex < units.length - 1) {
    value /= 1024;
    unitIndex += 1;
  }
  return `${value.toFixed(unitIndex === 0 ? 0 : 2)} ${units[unitIndex]}`;
}

function measureSize(filePath) {
  const stat = safeStat(filePath);
  if (!stat) {
    return 0;
  }
  if (stat.isFile()) {
    return stat.size;
  }
  if (!stat.isDirectory()) {
    return 0;
  }

  let total = 0;
  for (const entry of fs.readdirSync(filePath, { withFileTypes: true })) {
    const childPath = path.join(filePath, entry.name);
    if (entry.isDirectory()) {
      total += measureSize(childPath);
    } else if (entry.isFile()) {
      total += safeStat(childPath)?.size ?? 0;
    }
  }
  return total;
}

function writeSummary(rootDir, execute, beforeIso, keepLatest, results, totalBytes) {
  const summaryPath = path.join(rootDir, 'purge-summary.md');
  const lines = [
    '# Copilot History Quarantine Purge Summary',
    '',
    `- Generated: ${new Date().toISOString()}`,
    `- Mode: ${execute ? 'execute' : 'dry-run'}`,
    `- Before: ${beforeIso || '(none)'}`,
    `- Keep latest: ${keepLatest}`,
    `- Runs considered: ${results.length}`,
    `- Runs purged: ${results.filter((entry) => entry.status === 'purged').length}`,
    `- Runs skipped: ${results.filter((entry) => entry.status === 'skipped').length}`,
    `- Runs failed: ${results.filter((entry) => entry.status === 'failed').length}`,
    `- Estimated bytes affected: ${formatBytes(totalBytes)}`,
    '',
    '## Results',
    '',
  ];

  if (results.length === 0) {
    lines.push('- None');
  } else {
    for (const result of results) {
      const sizeText = result.bytes > 0 ? ` (${formatBytes(result.bytes)})` : '';
      lines.push(`- [${result.status}] ${result.path}${sizeText}`);
      if (result.message) {
        lines.push(`  - ${result.message}`);
      }
    }
  }

  fs.writeFileSync(summaryPath, `${lines.join('\n')}\n`, 'utf8');
  return summaryPath;
}

export function runPurge(rawOptions) {
  const options = {
    ...rawOptions,
    quarantineDir: path.resolve(rawOptions.quarantineDir),
  };
  const beforeMs = options.before ? Date.parse(options.before) : Number.POSITIVE_INFINITY;
  if (Number.isNaN(beforeMs)) {
    throw new Error(`Invalid --before timestamp: ${options.before}`);
  }

  const runs = listRuns(options.quarantineDir);
  const protectedRuns = new Set(runs.slice(0, options.keepLatest).map((run) => run.path));
  const results = [];
  let totalBytes = 0;

  for (const run of runs) {
    const bytes = measureSize(run.path);
    totalBytes += bytes;

    if (protectedRuns.has(run.path)) {
      results.push({ status: 'skipped', path: run.path, bytes, message: 'Protected by keep-latest.' });
      continue;
    }
    if (run.mtimeMs > beforeMs) {
      results.push({ status: 'skipped', path: run.path, bytes, message: 'Newer than cutoff.' });
      continue;
    }
    if (!options.execute) {
      results.push({ status: 'skipped', path: run.path, bytes, message: 'Dry-run: no changes were applied.' });
      continue;
    }

    try {
      fs.rmSync(run.path, { recursive: true, force: true });
      results.push({ status: 'purged', path: run.path, bytes, message: '' });
    } catch (error) {
      results.push({ status: 'failed', path: run.path, bytes, message: error?.message || String(error) });
    }
  }

  const summaryPath = writeSummary(
    options.quarantineDir,
    options.execute,
    options.before,
    options.keepLatest,
    results,
    totalBytes,
  );

  return {
    quarantineDir: options.quarantineDir,
    considered: results.length,
    purged: results.filter((entry) => entry.status === 'purged').length,
    failed: results.filter((entry) => entry.status === 'failed').length,
    summaryPath,
  };
}

function main() {
  const options = parseArgs(process.argv.slice(2));
  const result = runPurge(options);

  console.log('Copilot history quarantine purge complete.');
  console.log(`Quarantine directory: ${result.quarantineDir}`);
  console.log(`Runs considered: ${result.considered}`);
  console.log(`Runs purged: ${result.purged}`);
  console.log(`Runs failed: ${result.failed}`);
  console.log(`Summary: ${result.summaryPath}`);
}

const isMainModule = process.argv[1] && path.resolve(process.argv[1]) === fileURLToPath(import.meta.url);
if (isMainModule) {
  main();
}