import { readFileSync } from 'node:fs';
import { fileURLToPath } from 'node:url';

import Fastify, { type FastifyInstance, type FastifyServerOptions } from 'fastify';
import multipart from '@fastify/multipart';
import secureSession from '@fastify/secure-session';

import type { AppConfig } from './config.js';
import { registerErrorHandler } from './error-handler.js';
import { ensureUploadDir, removeFile } from './lib/storage.js';
import { createUploadSessionStore } from './lib/upload-sessions.js';
import { createOidcClient, type OidcClient } from './oidc.js';
import { authRoutes } from './routes/auth.js';
import { chunkedUploadRoutes } from './routes/upload-chunked.js';
import { healthRoutes } from './routes/health.js';
import { uploadRoutes } from './routes/upload.js';

const INDEX_HTML = readFileSync(
  fileURLToPath(new URL('../public/index.html', import.meta.url)),
  'utf8',
);

const SESSION_COOKIE_NAME = 'mediadrop_session';

export interface BuildAppOptions {
  /** Passer `false` pour couper les logs (utile en test). */
  logger?: FastifyServerOptions['logger'];
  /** Façade OIDC injectée (test). Par défaut : découverte réelle de l'issuer. */
  oidcClient?: OidcClient;
}

/**
 * Construit l'instance Fastify : session chiffrée, façade OIDC, plugins, dossier
 * de dépôt, gestionnaire d'erreurs, page (`GET /`) et routes (`/auth/*`,
 * `/health`, `/upload`). Exportée pour les tests.
 */
export async function buildApp(
  config: AppConfig,
  options: BuildAppOptions = {},
): Promise<FastifyInstance> {
  const oidcClient = options.oidcClient ?? (await createOidcClient(config));

  const app = Fastify({
    logger: options.logger ?? { level: config.logLevel },
    // Uploads pouvant durer longtemps (fichiers de plusieurs Go) : pas de
    // timeout serveur imposé. Régler les timeouts sur le reverse proxy.
    requestTimeout: 0,
    connectionTimeout: 0,
  });

  const uploadSessions = createUploadSessionStore((session) => {
    void removeFile(session.partPath);
  });

  app.decorate('appConfig', config);
  app.decorate('oidcClient', oidcClient);
  app.decorate('uploadSessions', uploadSessions);
  app.addHook('onClose', () => {
    uploadSessions.stop();
  });

  // Corps brut (flux) pour les morceaux d'upload fragmenté ; écrit en streaming.
  app.addContentTypeParser('application/octet-stream', (_request, payload, taskDone) => {
    taskDone(null, payload);
  });

  await app.register(secureSession, {
    key: config.session.key,
    cookieName: SESSION_COOKIE_NAME,
    cookie: {
      path: '/',
      httpOnly: true,
      sameSite: 'lax',
      secure: config.publicUrl.startsWith('https://'),
      maxAge: config.session.maxAgeSeconds,
    },
  });

  await app.register(multipart, {
    throwFileSizeLimit: true,
    limits: {
      files: 1,
      fileSize: config.maxFileSizeBytes,
    },
  });

  for (const target of config.targets) {
    await ensureUploadDir(target.dir);
  }
  registerErrorHandler(app);

  app.get('/', (_request, reply): void => {
    reply.type('text/html; charset=utf-8').send(INDEX_HTML);
  });

  await app.register(authRoutes);
  await app.register(healthRoutes);
  await app.register(uploadRoutes);
  await app.register(chunkedUploadRoutes);

  return app;
}