import { fetchCache } from './fetch-cache'
import { getRequestCacheKey } from './get-request-cache-key'
import { handleOptions } from './handle-options'
import { fetchRequest } from './fetch-request'
import { resolveRequest } from './resolve-request'
import { globalResHeaders } from './global-res-headers'

addEventListener('fetch', (event) => {
  event.respondWith(handleFetchEvent(event))
})

/**
 * @param {*} event
 */
async function handleFetchEvent(event) {
  const gatewayStartTime = Date.now()
  let gatewayTimespan
  let res

  function recordTimespans() {
    const now = Date.now()
    gatewayTimespan = now - gatewayStartTime
  }

  try {
    const { request } = event
    const { method } = request

    if (method === 'OPTIONS') {
      return handleOptions(request)
    }

    const url = new URL(request.url)

    if (url.search.length < 0 || url.pathname === '/' || url.pathname === '') {
      return new Response(null, {
        status: 400,

        statusText: 'bad request'
      })
    }

    const { originReq } = await resolveRequest(event, request)

    try {
      const cacheKey = await getRequestCacheKey(originReq)
      const originRes = await fetchCache({
        event,
        cacheKey,
        fetch: () => fetchRequest(event, { originReq })
      })

      res = new Response(originRes.body, originRes)
      recordTimespans()

      res.headers.set('x-proxy-response-time', `${gatewayTimespan}ms`)

      return res
    } catch (err) {
      console.error(err)
      recordTimespans()

      res = new Response(
        JSON.stringify({
          error: err.message,
          type: err.type,
          code: err.code
        }),
        { status: 500, headers: globalResHeaders }
      )

      return res
    }
  } catch (err) {
    console.error(err)

    if (err.response) {
      // TODO: make sure this response also has CORS globalResHeaders
      return err.response
    } else {
      return new Response(
        JSON.stringify({
          error: err.message,
          type: err.type,
          code: err.code
        }),
        {
          status: 500,
          headers: globalResHeaders
        }
      )
    }
  }
}