ethers.js/src.ts/providers/etherscan-provider.ts

import { checkTransactionResponse, Provider, TransactionRequest } from './provider';
import { Networkish } from './networks';

import { hexlify, hexStripZeros } from '../utils/bytes';
import { defineReadOnly } from '../utils/properties';
import { fetchJson } from '../utils/web';

import * as errors from '../utils/errors';

// The transaction has already been sanitized by the calls in Provider
function getTransactionString(transaction: TransactionRequest): string {
    var result = [];
    for (var key in transaction) {
        if (transaction[key] == null) { continue; }
        var value = hexlify(transaction[key]);
        if ({ gasLimit: true, gasPrice: true, nonce: true, value: true }[key]) {
            value = hexStripZeros(value);
        }
        result.push(key + '=' + value);
    }
    return result.join('&');
}

function getResult(result) {
    // getLogs, getHistory have weird success responses
    if (result.status == 0 && (result.message === 'No records found' || result.message === 'No transactions found')) {
        return result.result;
    }

    if (result.status != 1 || result.message != 'OK') {
        // @TODO: not any
        var error: any = new Error('invalid response');
        error.result = JSON.stringify(result);
        throw error;
    }

    return result.result;
}

function getJsonResult(result) {
    if (result.jsonrpc != '2.0') {
        // @TODO: not any
        let error: any = new Error('invalid response');
        error.result = JSON.stringify(result);
        throw error;
    }

    if (result.error) {
        // @TODO: not any
        let error: any = new Error(result.error.message || 'unknown error');
        if (result.error.code) { error.code = result.error.code; }
        if (result.error.data) { error.data = result.error.data; }
        throw error;
    }

    return result.result;
}

// The blockTag was normalized as a string by the Provider pre-perform operations
function checkLogTag(blockTag: string): number | "latest" {
    if (blockTag === 'pending') { throw new Error('pending not supported'); }
    if (blockTag === 'latest') { return blockTag; }

    return parseInt(blockTag.substring(2), 16);
}


export class EtherscanProvider extends Provider{
    readonly baseUrl: string;
    readonly apiKey: string;
    constructor(network?: Networkish, apiKey?: string) {
        super(network);
        errors.checkNew(this, EtherscanProvider);

        let name = 'invalid';
        if (this.network) { name = this.network.name; }

        let baseUrl = null;
        switch(name) {
            case 'homestead':
                baseUrl = 'https://api.etherscan.io';
                break;
            case 'ropsten':
                baseUrl = 'https://api-ropsten.etherscan.io';
                break;
            case 'rinkeby':
                baseUrl = 'https://api-rinkeby.etherscan.io';
                break;
            case 'kovan':
                baseUrl = 'https://api-kovan.etherscan.io';
                break;
            default:
                throw new Error('unsupported network');
        }

        defineReadOnly(this, 'baseUrl', baseUrl);
        defineReadOnly(this, 'apiKey', apiKey);
    }


    perform(method: string, params: any) {
        //if (!params) { params = {}; }

        var url = this.baseUrl;

        let apiKey = '';
        if (this.apiKey) { apiKey += '&apikey=' + this.apiKey; }

        switch (method) {
            case 'getBlockNumber':
                url += '/api?module=proxy&action=eth_blockNumber' + apiKey;
            return fetchJson(url, null, getJsonResult);

            case 'getGasPrice':
                url += '/api?module=proxy&action=eth_gasPrice' + apiKey;
                return fetchJson(url, null, getJsonResult);

            case 'getBalance':
                // Returns base-10 result
                url += '/api?module=account&action=balance&address=' + params.address;
                url += '&tag=' + params.blockTag + apiKey;
                return fetchJson(url, null, getResult);

            case 'getTransactionCount':
                url += '/api?module=proxy&action=eth_getTransactionCount&address=' + params.address;
                url += '&tag=' + params.blockTag + apiKey;
                return fetchJson(url, null, getJsonResult);


            case 'getCode':
                url += '/api?module=proxy&action=eth_getCode&address=' + params.address;
                url += '&tag=' + params.blockTag + apiKey;
                return fetchJson(url, null, getJsonResult);

            case 'getStorageAt':
                url += '/api?module=proxy&action=eth_getStorageAt&address=' + params.address;
                url += '&position=' + params.position;
                url += '&tag=' + params.blockTag + apiKey;
                return fetchJson(url, null, getJsonResult);


            case 'sendTransaction':
                url += '/api?module=proxy&action=eth_sendRawTransaction&hex=' + params.signedTransaction;
                url += apiKey;
                return fetchJson(url, null, getJsonResult);


            case 'getBlock':
                if (params.blockTag) {
                    url += '/api?module=proxy&action=eth_getBlockByNumber&tag=' + params.blockTag;
                    url += '&boolean=false';
                    url += apiKey;
                    return fetchJson(url, null, getJsonResult);
                }
                throw new Error('getBlock by blockHash not implmeneted');

            case 'getTransaction':
                url += '/api?module=proxy&action=eth_getTransactionByHash&txhash=' + params.transactionHash;
                url += apiKey;
                return fetchJson(url, null, getJsonResult);

            case 'getTransactionReceipt':
                url += '/api?module=proxy&action=eth_getTransactionReceipt&txhash=' + params.transactionHash;
                url += apiKey;
                return fetchJson(url, null, getJsonResult);


            case 'call':
                var transaction = getTransactionString(params.transaction);
                if (transaction) { transaction = '&' + transaction; }
                url += '/api?module=proxy&action=eth_call' + transaction;
                url += apiKey;
                return fetchJson(url, null, getJsonResult);

            case 'estimateGas':
                var transaction = getTransactionString(params.transaction);
                if (transaction) { transaction = '&' + transaction; }
                url += '/api?module=proxy&action=eth_estimateGas&' + transaction;
                url += apiKey;
                return fetchJson(url, null, getJsonResult);

            case 'getLogs':
                url += '/api?module=logs&action=getLogs';
                try {
                    if (params.filter.fromBlock) {
                        url += '&fromBlock=' + checkLogTag(params.filter.fromBlock);
                    }

                    if (params.filter.toBlock) {
                        url += '&toBlock=' + checkLogTag(params.filter.toBlock);
                    }

                    if (params.filter.address) {
                        url += '&address=' + params.filter.address;
                    }

                    // @TODO: We can handle slightly more complicated logs using the logs API
                    if (params.filter.topics && params.filter.topics.length > 0) {
                        if (params.filter.topics.length > 1) {
                            throw new Error('unsupported topic format');
                        }
                        var topic0 = params.filter.topics[0];
                        if (typeof(topic0) !== 'string' || topic0.length !== 66) {
                            throw new Error('unsupported topic0 format');
                        }
                        url += '&topic0=' + topic0;
                    }
                } catch (error) {
                    return Promise.reject(error);
                }

                url += apiKey;

                var self = this;
                return fetchJson(url, null, getResult).then(function(logs) {
                    var txs = {};

                    var seq = Promise.resolve();
                    logs.forEach(function(log) {
                        seq = seq.then(function() {
                            if (log.blockHash != null) { return null; }
                            log.blockHash = txs[log.transactionHash];
                            if (log.blockHash == null) {
                                return self.getTransaction(log.transactionHash).then(function(tx) {
                                    txs[log.transactionHash] = tx.blockHash;
                                    log.blockHash = tx.blockHash;
                                });
                            }
                            return null;
                        });
                    });

                    return seq.then(function() {
                        return logs;
                    });
                });

            case 'getEtherPrice':
                if (this.network.name !== 'homestead') { return Promise.resolve(0.0); }
                url += '/api?module=stats&action=ethprice';
                url += apiKey;
                return fetchJson(url, null, getResult).then(function(result) {
                    return parseFloat(result.ethusd);
                });

            default:
                break;
         }

        return super.perform(method, params);
    }

    getHistory(addressOrName, startBlock, endBlock) {

        var url = this.baseUrl;

        var apiKey = '';
        if (this.apiKey) { apiKey += '&apikey=' + this.apiKey; }

        if (startBlock == null) { startBlock = 0; }
        if (endBlock == null) { endBlock = 99999999; }

        return this.resolveName(addressOrName).then(function(address) {
            url += '/api?module=account&action=txlist&address=' + address;
            url += '&startblock=' + startBlock;
            url += '&endblock=' + endBlock;
            url += '&sort=asc' + apiKey;

            return fetchJson(url, null, getResult).then(function(result) {
                var output = [];
                result.forEach(function(tx) {
                    ['contractAddress', 'to'].forEach(function(key) {
                        if (tx[key] == '') { delete tx[key]; }
                    });
                    if (tx.creates == null && tx.contractAddress != null) {
                        tx.creates = tx.contractAddress;
                    }
                    var item = checkTransactionResponse(tx);
                    if (tx.timeStamp) { item.timestamp = parseInt(tx.timeStamp); }
                    output.push(item);
                });
                return output;
            });
        });
    }
}