import Fastify, { type FastifyInstance } from 'fastify';
import cors from '@fastify/cors';
import compress from '@fastify/compress';
import etag from '@fastify/etag';
import rateLimit from '@fastify/rate-limit';
import { randomUUID } from 'node:crypto';
import { getSql } from '@rareindex/database';
import { authPlugin, rateKeyFor, rateLimitFor } from './plugins/auth.js';
import { v1Routes } from './routes/v1.js';
import { internalRoutes } from './routes/internal.js';
import { problem } from './lib/envelope.js';

export interface BuildOptions {
  logger?: boolean;
}

export async function buildApp(opts: BuildOptions = {}): Promise<FastifyInstance> {
  const app = Fastify({
    logger: opts.logger === false ? false : { level: process.env.LOG_LEVEL ?? 'info', redact: ['req.headers.authorization'] },
    genReqId: (req) => (req.headers['x-request-id'] as string | undefined) ?? randomUUID(),
    trustProxy: true,
  });

  await app.register(cors, { origin: true, methods: ['GET', 'HEAD', 'OPTIONS'], exposedHeaders: ['x-request-id', 'x-ratelimit-limit', 'x-ratelimit-remaining', 'x-ratelimit-reset'] });
  await app.register(compress, { global: true, encodings: ['gzip', 'br', 'deflate'] });
  await app.register(etag);
  await app.register(authPlugin);
  await app.register(rateLimit, {
    global: true,
    max: (req) => rateLimitFor(req),
    timeWindow: '1 minute',
    keyGenerator: (req) => rateKeyFor(req),
    errorResponseBuilder: (req, ctx) => ({
      statusCode: 429,
      type: 'https://www.rareindex.io/api-docs#errors',
      title: 'Rate limit exceeded',
      status: 429,
      detail: `Limit ${ctx.max} requests per ${ctx.after}. Retry after ${ctx.ttl} ms.`,
      instance: req.url,
      request_id: req.id,
    }),
  });

  app.addHook('onSend', async (req, reply, payload) => {
    reply.header('x-request-id', req.id);
    return payload;
  });

  app.setErrorHandler((err: Error & { statusCode?: number; status?: number; title?: string; detail?: string }, req, reply) => {
    const status = err.statusCode ?? err.status ?? 500;
    if (status >= 500) req.log.error({ err }, 'unhandled api error');
    const title = status >= 500 ? 'Internal error' : (err.title ?? err.message);
    const detail = status >= 500 ? 'The request could not be completed.' : (err.detail ?? err.message);
    return problem(reply, status, title, detail);
  });
  app.setNotFoundHandler((req, reply) => problem(reply, 404, 'Not found', `No route for ${req.method} ${req.url}`));

  app.get('/healthz', async (_req, reply) => {
    try {
      await getSql()`select 1`;
      return { ok: true, service: 'rareindex-api', time: new Date().toISOString() };
    } catch (err) {
      return reply.code(503).send({ ok: false, service: 'rareindex-api', error: err instanceof Error ? err.message : String(err) });
    }
  });
  app.get('/', async () => ({ name: 'RareIndex Public API', docs: 'https://www.rareindex.io/api-docs', openapi: '/v1/openapi.json' }));

  await app.register(v1Routes);
  await app.register(internalRoutes);
  return app;
}