#!/usr/bin/env node
/**
 * Generate a Markdown changelog from two OpenAPI specs using the api-compat-diff tool.
 *
 * Usage:
 *   node scripts/api-compat-changelog.mjs <oldSpec> <newSpec> [--title "Release X"] [--fail-on-breaking]
 *
 * Output is written to stdout.
 */
import { execFileSync } from 'child_process';
import process from 'process';
import path from 'path';

function panic(message) {
  console.error(`[api-compat-changelog] ${message}`);
  process.exit(1);
}

function parseArgs(argv) {
  const args = argv.slice(2);
  if (args.length < 2) {
    panic('Usage: node scripts/api-compat-changelog.mjs <oldSpec> <newSpec> [--title "Release X"] [--fail-on-breaking]');
  }

  const opts = {
    oldSpec: args[0],
    newSpec: args[1],
    title: 'API Compatibility Report',
    failOnBreaking: false,
  };

  for (let i = 2; i < args.length; i += 1) {
    const arg = args[i];
    if (arg === '--title' && args[i + 1]) {
      opts.title = args[i + 1];
      i += 1;
    } else if (arg === '--fail-on-breaking') {
      opts.failOnBreaking = true;
    }
  }

  return opts;
}

function runCompatDiff(oldSpec, newSpec) {
  const output = execFileSync(
    'node',
    ['scripts/api-compat-diff.mjs', oldSpec, newSpec, '--output', 'json'],
    { encoding: 'utf8' }
  );
  return JSON.parse(output);
}

function formatList(items, symbol) {
  if (!items || items.length === 0) {
    return `${symbol} None`;
  }
  return items.map((item) => `${symbol} ${item}`).join('\n');
}

function renderMarkdown(title, diff, oldSpec, newSpec) {
  return [
    `# ${title}`,
    '',
    `- Old spec: \`${path.relative(process.cwd(), oldSpec)}\``,
    `- New spec: \`${path.relative(process.cwd(), newSpec)}\``,
    '',
    '## Summary',
    `- Additive operations: ${diff.additive.operations.length}`,
    `- Breaking operations: ${diff.breaking.operations.length}`,
    `- Additive responses: ${diff.additive.responses.length}`,
    `- Breaking responses: ${diff.breaking.responses.length}`,
    '',
    '## Additive',
    '### Operations',
    formatList(diff.additive.operations, '-'),
    '',
    '### Responses',
    formatList(diff.additive.responses, '-'),
    '',
    '## Breaking',
    '### Operations',
    formatList(diff.breaking.operations, '-'),
    '',
    '### Responses',
    formatList(diff.breaking.responses, '-'),
    '',
  ].join('\n');
}

function main() {
  const opts = parseArgs(process.argv);
  const diff = runCompatDiff(opts.oldSpec, opts.newSpec);
  const markdown = renderMarkdown(opts.title, diff, opts.oldSpec, opts.newSpec);
  console.log(markdown);

  if (opts.failOnBreaking && (diff.breaking.operations.length > 0 || diff.breaking.responses.length > 0)) {
    process.exit(2);
  }
}

if (import.meta.url === `file://${process.argv[1]}`) {
  main();
}