'use strict';

var Provider = require('./provider.js');

var utils = (function() {
    var convert = require('ethers-utils/convert.js');
    return {
        defineProperty: require('ethers-utils/properties.js').defineProperty,

        hexlify: convert.hexlify,
    };
})();

function getTransactionString(transaction) {
    var result = [];
    for (var key in transaction) {
        if (transaction[key] == null) { continue; }
        result.push(key + '=' + utils.hexlify(transaction[key]));
    }
    return result.join('&');
}

function EtherscanProvider(testnet, apiKey) {
    Provider.call(this, testnet);

    utils.defineProperty(this, 'apiKey', apiKey || null);
}
Provider.inherits(EtherscanProvider);

utils.defineProperty(EtherscanProvider.prototype, '_call', function() {
});

utils.defineProperty(EtherscanProvider.prototype, '_callProxy', function() {
});

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

    if (result.status != 1 || result.message != 'OK') {
        var error = new Error('invalid response');
        error.result = JSON.stringify(result);
        throw error;
    }

    return result.result;
}

function getJsonResult(result) {
    if (result.jsonrpc != '2.0') {
        var error = new Error('invalid response');
        error.result = JSON.stringify(result);
        throw error;
    }

    if (result.error) {
        var error = 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;
}

function checkLogTag(blockTag) {
    if (blockTag === 'pending') { throw new Error('pending not supported'); }
    if (blockTag === 'latest') { return blockTag; }

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

utils.defineProperty(EtherscanProvider.prototype, 'perform', function(method, params) {
    if (!params) { params = {}; }

    var url = this.testnet ? 'https://testnet.etherscan.io': 'https://api.etherscan.io';

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

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

        case 'getGasPrice':
            url += '/api?module=proxy&action=eth_gasPrice' + apiKey;
            return Provider.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 Provider.fetchJSON(url, null, getResult);

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

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

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

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

        default:
            break;
    }

    return Promise.reject(new Error('not implemented - ' + method));
});

module.exports = EtherscanProvider;;