import { readFileSync } from 'node:fs';
import path from 'node:path';
import { fileURLToPath } from 'node:url';
import { RegistrySchema, type ConnectorMeta, type Registry, type RareIndexConnector } from './types.js';

const here = path.dirname(fileURLToPath(import.meta.url));
export const CONNECTORS_DIR = path.resolve(here, '../../../connectors');
export const REGISTRY_PATH = path.join(CONNECTORS_DIR, 'registry.json');

let cached: Registry | null = null;

/** Load and validate connectors/registry.json (§106). */
export function loadRegistry(force = false): Registry {
  if (cached && !force) return cached;
  const raw = JSON.parse(readFileSync(REGISTRY_PATH, 'utf8'));
  cached = RegistrySchema.parse(raw);
  const ids = new Set<string>();
  for (const c of cached.connectors) {
    if (ids.has(c.id)) throw new Error(`registry: duplicate connector id ${c.id}`);
    ids.add(c.id);
  }
  return cached;
}

export function getConnectorMeta(id: string): ConnectorMeta {
  const meta = loadRegistry().connectors.find((c) => c.id === id);
  if (!meta) throw new Error(`Unknown connector: ${id}`);
  return meta;
}

export function listConnectorMeta(filter: { enabled?: boolean; category?: string; sourceType?: string } = {}): ConnectorMeta[] {
  return loadRegistry().connectors.filter((c) => {
    if (filter.enabled !== undefined && c.enabled !== filter.enabled) return false;
    if (filter.category && !c.categories.includes(filter.category)) return false;
    if (filter.sourceType && c.sourceType !== filter.sourceType) return false;
    return true;
  });
}

/**
 * Dynamically import a connector module. Each module default-exports a factory
 * `(meta: ConnectorMeta) => RareIndexConnector`.
 */
export async function loadConnector(id: string): Promise<RareIndexConnector> {
  const meta = getConnectorMeta(id);
  const modPath = path.join(CONNECTORS_DIR, meta.module, 'index.ts');
  const mod = (await import(modPath)) as { default?: (meta: ConnectorMeta) => RareIndexConnector | Promise<RareIndexConnector>; createConnector?: (meta: ConnectorMeta) => RareIndexConnector | Promise<RareIndexConnector> };
  const factory = mod.default ?? mod.createConnector;
  if (!factory) throw new Error(`connector module ${meta.module} must default-export a factory`);
  return factory(meta);
}

/** Find connectors whose urlPatterns match a URL (scanner paste-URL, §114). */
export async function connectorsForUrl(url: string): Promise<RareIndexConnector[]> {
  const out: RareIndexConnector[] = [];
  for (const meta of listConnectorMeta({ enabled: true })) {
    if (!meta.supportsLookup) continue;
    const c = await loadConnector(meta.id);
    if (c.urlPatterns?.some((re) => re.test(url))) out.push(c);
  }
  return out;
}