import { randomBytes } from 'node:crypto';
import { createServer, type Server } from 'node:http';
import log from 'electron-log';
import type { HostApiContext } from './context';
import type { HostApiRequest } from './route-utils';
import {
  parseRawJsonBody,
  requireJsonContentType,
  sendJsonResponse,
  setCorsHeaders,
} from './route-utils';

const DEFAULT_HOST_API_PORT = 13210;

type StartHostApiServerOptions = {
  ctx: HostApiContext;
  dispatchRequest: (request: HostApiRequest) => Promise<unknown | null>;
  fallbackRequest?: (request: HostApiRequest) => Promise<unknown>;
  port?: number;
};

let hostApiToken = '';

export function getHostApiPort(): number {
  const raw = process.env['ZN_AI_HOST_API_PORT'];
  const parsed = raw ? Number.parseInt(raw, 10) : NaN;
  return Number.isFinite(parsed) && parsed > 0 ? parsed : DEFAULT_HOST_API_PORT;
}

export function getHostApiToken(): string {
  return hostApiToken;
}

export function getHostApiBase(): string {
  return `http://127.0.0.1:${getHostApiPort()}`;
}

export function startHostApiServer(options: StartHostApiServerOptions): Server {
  const port = options.port ?? getHostApiPort();
  hostApiToken = randomBytes(32).toString('hex');

  const server = createServer(async (req, res) => {
    try {
      const requestUrl = new URL(req.url || '/', `http://127.0.0.1:${port}`);
      setCorsHeaders(res, req.headers.origin);

      if (req.method === 'OPTIONS') {
        res.statusCode = 204;
        res.end();
        return;
      }

      const bearerHeader = req.headers.authorization || '';
      const bearerToken = bearerHeader.startsWith('Bearer ')
        ? bearerHeader.slice('Bearer '.length)
        : '';
      const token = (
        req.headers['x-host-api-token']
        || requestUrl.searchParams.get('token')
        || bearerToken
      );

      if (token !== hostApiToken) {
        sendJsonResponse(res, 401, {
          success: false,
          ok: false,
          error: 'Unauthorized',
        });
        return;
      }

      if (requestUrl.pathname === '/api/events' && req.method === 'GET') {
        res.writeHead(200, {
          'Content-Type': 'text/event-stream; charset=utf-8',
          'Cache-Control': 'no-cache, no-transform',
          Connection: 'keep-alive',
        });
        res.write(': connected\n\n');
        options.ctx.eventBus.addSseClient(res);
        res.write(`event: gateway:status\ndata: ${JSON.stringify(options.ctx.gatewayManager.getStatus())}\n\n`);
        return;
      }

      if (!requireJsonContentType(req)) {
        sendJsonResponse(res, 415, {
          success: false,
          ok: false,
          error: 'Content-Type must be application/json',
        });
        return;
      }

      const body = req.method && ['POST', 'PUT', 'PATCH', 'DELETE'].includes(req.method)
        ? await parseRawJsonBody<unknown>(req)
        : null;

      const forwardedHeaders: Record<string, string> = {};
      Object.entries(req.headers).forEach(([key, value]) => {
        if (typeof value === 'string') {
          forwardedHeaders[key] = value;
        }
      });
      delete forwardedHeaders['x-host-api-token'];

      const request: HostApiRequest = {
        path: `${requestUrl.pathname}${requestUrl.search}`,
        method: req.method,
        headers: forwardedHeaders,
        body,
      };

      const localResult = await options.dispatchRequest(request);
      const response = localResult ?? (
        options.fallbackRequest
          ? await options.fallbackRequest(request)
          : null
      );

      if (response == null) {
        sendJsonResponse(res, 404, {
          success: false,
          ok: false,
          error: `No route for ${req.method} ${requestUrl.pathname}`,
        });
        return;
      }

      const result = response as {
        status?: number;
        data?: unknown;
        json?: unknown;
        success?: boolean;
        ok?: boolean;
        error?: string;
        text?: string;
      };

      sendJsonResponse(res, result.status ?? 200, response);
    } catch (error) {
      sendJsonResponse(res, 500, {
        success: false,
        ok: false,
        error: error instanceof Error ? error.message : String(error),
      });
    }
  });

  server.on('error', (error) => {
    log.error('Host API server failed:', error);
  });

  server.on('close', () => {
    hostApiToken = '';
  });

  server.listen(port, '127.0.0.1');
  return server;
}