import { types, flow } from 'mobx-state-tree';

const MetricsService = types
  .model('MetricsService', {
    isCollectingMetrics: types.optional(types.boolean, true),
  })
  .volatile(self => ({
    env: {} as Env,
    ctx: {} as ExecutionContext,
  }))
  .actions(self => ({
    setEnv(env: Env) {
      self.env = env;
    },
    setCtx(ctx: ExecutionContext) {
      self.ctx = ctx;
    },
    handleMetricsRequest: flow(function* (request: Request) {
      const url = new URL(request.url);
      let proxyUrl = '';
      if (self.env.METRICS_HOST) {
        proxyUrl = new URL(`${self.env.METRICS_HOST}${url.pathname}${url.search}`).toString();
      }

      if (proxyUrl) {
        try {
          const response = yield fetch(proxyUrl, {
            method: request.method,
            headers: request.headers,
            body: ['GET', 'HEAD'].includes(request.method) ? null : request.body,
            redirect: 'follow',
          });

          return response;
        } catch (error) {
          console.error('Failed to proxy metrics request:', error);
          return new Response('metrics misconfigured', { status: 200 });
        }
      } else {
        const event = {
          method: request.method,
          headers: request.headers,
          body: ['GET', 'HEAD'].includes(request.method) ? null : request.body,
        };
        if (self.env?.KV_STORAGE?.put) {
          self.env.KV_STORAGE.put(`metrics_events::${crypto.randomUUID()}`, JSON.stringify(event));
        } else {
          console.log('Detected metrics misconfiguration...not storing');
        }
      }
    }),
  }));

export default MetricsService;