import { readFileSync } from 'node:fs';
import { parse } from 'yaml';

interface Endpoint {
  method: string;
  path: string;
  summary: string;
  tag: string;
}

function extractEndpoints(specPath: string): Endpoint[] {
  const spec = parse(readFileSync(specPath, 'utf-8'));
  const endpoints: Endpoint[] = [];

  for (const [path, methods] of Object.entries(spec.paths as Record<string, Record<string, unknown>>)) {
    for (const [method, details] of Object.entries(methods)) {
      if (['get', 'post', 'put', 'delete', 'patch'].includes(method)) {
        const op = details as { summary?: string; tags?: string[] };
        endpoints.push({
          method: method.toUpperCase(),
          path,
          summary: op.summary ?? '',
          tag: op.tags?.[0] ?? 'Untagged',
        });
      }
    }
  }

  return endpoints.sort((a, b) => a.path.localeCompare(b.path) || a.method.localeCompare(b.method));
}

function endpointKey(e: Endpoint): string {
  return `${e.method} ${e.path}`;
}

const specPath = new URL('../openapi.yaml', import.meta.url).pathname;
const manifestPath = new URL('../endpoint-manifest.json', import.meta.url).pathname;

const current = extractEndpoints(specPath);

let manifest: Endpoint[];
try {
  manifest = JSON.parse(readFileSync(manifestPath, 'utf-8'));
} catch {
  console.error('Error: endpoint-manifest.json not found. Run `npm run extract-endpoints > endpoint-manifest.json` first.');
  process.exit(1);
}

const manifestKeys = new Set(manifest.map(endpointKey));
const currentKeys = new Set(current.map(endpointKey));

const added = current.filter((e) => !manifestKeys.has(endpointKey(e)));
const removed = manifest.filter((e) => !currentKeys.has(endpointKey(e)));

if (added.length === 0 && removed.length === 0) {
  console.log(`No endpoint drift detected. ${current.length} endpoints match the manifest.`);
  process.exit(0);
}

console.log('Endpoint drift detected!\n');

if (added.length > 0) {
  console.log(`New endpoints (${added.length}):`);
  for (const e of added) {
    console.log(`  + ${e.method} ${e.path} — ${e.summary} [${e.tag}]`);
  }
  console.log();
}

if (removed.length > 0) {
  console.log(`Removed endpoints (${removed.length}):`);
  for (const e of removed) {
    console.log(`  - ${e.method} ${e.path} — ${e.summary} [${e.tag}]`);
  }
  console.log();
}

console.log('Update endpoint-manifest.json: npm run extract-endpoints > endpoint-manifest.json');
process.exit(1);