const corsHeaders = {
  "Access-Control-Allow-Origin": "*",
  "Access-Control-Allow-Methods": "GET,HEAD,POST,OPTIONS",
  "Access-Control-Max-Age": "86400",
}
function handleOptions(request) {
  // Make sure the necessary headers are present
  // for this to be a valid pre-flight request
  let headers = request.headers;
  if (
    headers.get("Origin") !== null &&
    headers.get("Access-Control-Request-Method") !== null &&
    headers.get("Access-Control-Request-Headers") !== null
  ){
    // Handle CORS pre-flight request.
    // If you want to check or reject the requested method + headers
    // you can do that here.
    let respHeaders = {
      ...corsHeaders,
    // Allow all future content Request headers to go back to browser
    // such as Authorization (Bearer) or X-Client-Name-Version
      "Access-Control-Allow-Headers": request.headers.get("Access-Control-Request-Headers"),
    }

    return new Response(null, {
      headers: respHeaders,
    })
  }
  else {
    // Handle standard OPTIONS request.
    // If you want to allow other HTTP Methods, you can do that here.
    return new Response(null, {
      headers: {
        Allow: "GET, HEAD, POST, OPTIONS",
      },
    })
  }
}

addEventListener('fetch', event => {
  if (event.request.method === "OPTIONS") {
      // Handle CORS preflight requests
      event.respondWith(handleOptions(event.request))
    }
    else if(
      event.request.method === "GET" ||
      event.request.method === "HEAD" ||
      event.request.method === "POST"
    ){event.respondWith(handleRequest(event.request))}
  
});

addEventListener('scheduled', event => {
  event.waitUntil(handleCron());
});

const pairs = [
  {
    pair: 'BTCUSD',
    value: 'XXBTZUSD',
    kvName: 'btc'
  },
  {
    pair: 'ETHUSD',
    value: 'XETHZUSD',
    kvName: 'eth'
  },
  {
    pair: 'BCHUSD',
    value: 'BCHUSD',
    kvName: 'bch'
  },
  {
    pair: 'XMRUSD',
    value: 'XXMRZUSD',
    kvName: 'xmr'
  },
  {
    kvName: 'grin'
  }
];

async function handleRequest(request) {
  const obj = {};
  const data = await KV.get('info', 'json');
  return new Response(JSON.stringify(data), {
    status: 200,
    headers: {
      'Content-Type': 'application/json',
      'Access-Control-Allow-Origin': '*'
    }
  });
}


function handleCron() {
  return new Promise(async (resolve, reject) => {
    const obj = {};

    for (let i = 0; i < (pairs.length); i++) {
      if (i == 4){
        const resa = await fetch('https://api-grin.blockscan.com/v1/api?module=stats&action=grinprice');
        const dataa = await resa.json();
        obj["grin"] = dataa.result["grinusd"];
        break;
      }
      const pair = pairs[i];
      const res = await fetch('https://api.kraken.com/0/public/Ticker?pair=' + pair.pair);
      const data = await res.json();

      const ticker = data.result[pair.value];
      obj[pair.kvName] = ticker.a[0];
    }
        datas = ["bitcoin-cash","bitcoin-sv","monero"];
    for (let **0; i<4;i++){
      if (i==3){
        const resd = await fetch('https://api.whatsonchain.com/v1/bsv/main/exchangerate');
        const datad = await resd.json();
        obj["bsv"] = datad["rate"]; 
        break;
      }
      const resb = await fetch('https://api.blockchair.com/'+datas[i]+'/stats');
      const datab = await resb.json();
      obj[datas[i]+"fee"] = datab.data["suggested_transaction_fee_per_byte_sat"];
      obj[datas[i]+"median"] = datab.data["median_transaction_fee_usd_24h"];
    }

    await KV.put('info', JSON.stringify(obj));
      
    resolve();
  })
}