import fetchPonyfill from 'fetch-ponyfill';
import Promise from 'bluebird';
import newDebug from 'debug';
import Transport from './base';

const { fetch } = fetchPonyfill(Promise);
const debug = newDebug('steem:http');

class RPCError extends Error {
  constructor(rpcError) {
    super(rpcError.message);
    this.name = 'RPCError';
    this.code = rpcError.code;
    this.data = rpcError.data;
  }
}

export function jsonRpcCall(uri, {method, id, params}) {
  const payload = {id, jsonrpc: '2.0', method, params};
  return fetch(uri, {
    body: JSON.stringify(payload),
    headers: {'User-Agent': 'steem-js/1'},
    method: 'post',
    mode: 'cors',
  }).then(res => {
    if (!res.ok) {
      throw new Error(`HTTP ${ res.status }: ${ res.statusText }`);
    }
    return res.json();
  }).then(rpcRes => {
    if (rpcRes.id !== id) {
      throw new Error(`Invalid response id: ${ rpcRes.id }`);
    }
    if (rpcRes.error) {
      throw new RPCError(rpcRes.error);
    }
    return rpcRes.result
  });
}

export default class HttpTransport extends Transport {
  send(api, data, callback) {
    debug('Steem::send', api, data);
    const id = data.id || this.id++;
    const params = [api, data.method, data.params];
    jsonRpcCall(this.options.uri, {method: 'call', id, params})
      .then(res => { callback(null, res) }, err => { callback(err) })
  }
}