import cors from '@fastify/cors';
import Fastify from 'fastify';
import { ZodError } from 'zod';
import { authPlugin } from './auth/plugin.js';
import { config } from './config.js';
import { pool } from './db/pool.js';
import { authRoutes } from './routes/auth.js';
import { courseRoutes } from './routes/courses.js';
import { manageCourseRoutes } from './routes/manage-courses.js';
import { learningRoutes } from './routes/learning.js';
import { adminRoutes } from './routes/admin.js';
import { mediaRoutes } from './routes/media.js';
import { bunnyWebhookRoutes } from './routes/bunny-webhooks.js';
import { profileRoutes } from './routes/profiles.js';

export function buildApp() {
  const app = Fastify({ logger: true });

  // Bunny signs the exact webhook byte sequence. Preserve the raw JSON body
  // before parsing it so the signature can be verified server-side.
  app.removeContentTypeParser('application/json');
  app.addContentTypeParser('application/json', { parseAs: 'buffer' }, (request, body, done) => {
    const rawBody = Buffer.isBuffer(body) ? body : Buffer.from(body);
    (request as typeof request & { rawBody?: Buffer }).rawBody = rawBody;
    try {
      done(null, JSON.parse(rawBody.toString('utf8')));
    } catch {
      done(new Error('Invalid JSON body'));
    }
  });

  // Bunny uploads are streamed through the authenticated API. Keeping the body
  // as a stream avoids loading a whole course video into Node's memory.
  const rawUploadParser = (_request: unknown, payload: unknown, done: (error: Error | null, body?: unknown) => void) => done(null, payload);
  app.addContentTypeParser('application/octet-stream', rawUploadParser);
  app.addContentTypeParser(/^video\/.+$/, rawUploadParser);
  app.addContentTypeParser(/^image\/.+$/, { parseAs: 'buffer', bodyLimit: config.BUNNY_COVER_MAX_UPLOAD_MB * 1024 * 1024 }, (_request, body, done) => done(null, body));

  app.register(cors, {
    origin: config.FRONTEND_ORIGIN,
    methods: ['GET', 'POST', 'PUT', 'PATCH', 'DELETE'],
  });

  app.setErrorHandler((error, _request, reply) => {
    if (error instanceof ZodError) {
      return reply.code(400).send({ error: 'Invalid request', details: error.flatten() });
    }

    app.log.error(error);
    return reply.code(500).send({ error: 'Internal server error' });
  });

  const checkDatabase = async (_request: unknown, reply: { code: (statusCode: number) => { send: (payload: object) => unknown } }) => {
    try {
      await pool.query('select 1');
      return { status: 'ok', database: 'connected' };
    } catch {
      return reply.code(503).send({ status: 'unavailable', database: 'unavailable' });
    }
  };
  app.get('/api/v1/health', checkDatabase);
  app.get('/api/v1/ready', checkDatabase);

  app.register(authPlugin);
  app.register(authRoutes, { prefix: '/api/v1/auth' });
  app.register(profileRoutes, { prefix: '/api/v1/profiles' });
  app.register(courseRoutes, { prefix: '/api/v1/courses' });
  app.register(manageCourseRoutes, { prefix: '/api/v1/manage/courses' });
  app.register(mediaRoutes, { prefix: '/api/v1/manage/media' });
  app.register(bunnyWebhookRoutes, { prefix: '/api/v1/webhooks' });
  app.register(learningRoutes, { prefix: '/api/v1' });
  app.register(adminRoutes, { prefix: '/api/v1/admin' });
  return app;
}