ethminer/lib/web3/filter.js

/*
    This file is part of ethereum.js.

    ethereum.js is free software: you can redistribute it and/or modify
    it under the terms of the GNU Lesser General Public License as published by
    the Free Software Foundation, either version 3 of the License, or
    (at your option) any later version.

    ethereum.js is distributed in the hope that it will be useful,
    but WITHOUT ANY WARRANTY; without even the implied warranty of
    MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
    GNU Lesser General Public License for more details.

    You should have received a copy of the GNU Lesser General Public License
    along with ethereum.js.  If not, see <http://www.gnu.org/licenses/>.
*/
/** @file filter.js
 * @authors:
 *   Jeffrey Wilcke <jeff@ethdev.com>
 *   Marek Kotewicz <marek@ethdev.com>
 *   Marian Oancea <marian@ethdev.com>
 *   Fabian Vogelsteller <fabian@ethdev.com>
 *   Gav Wood <g@ethdev.com>
 * @date 2014
 */

var RequestManager = require('./requestmanager');
var formatters = require('./formatters');
var utils = require('../utils/utils');

/**
* Converts a given topic to a hex string, but also allows null values.
*
* @param {Mixed} value
* @return {String}
*/
var toTopic = function(value){

    if(value === null || typeof value === 'undefined')
        return null;

    value = String(value);

    if(value.indexOf('0x') === 0)
        return value;
    else
        return utils.fromAscii(value);
};

/// This method should be called on options object, to verify deprecated properties && lazy load dynamic ones
/// @param should be string or object
/// @returns options string or object
var getOptions = function (options) {

    if (utils.isString(options)) {
        return options;
    } 

    options = options || {};

    // make sure topics, get converted to hex
    options.topics = options.topics || [];
    options.topics = options.topics.map(function(topic){
        return (utils.isArray(topic)) ? topic.map(toTopic) : toTopic(topic);
    });

    // lazy load
    return {
        topics: options.topics,
        to: options.to,
        address: options.address,
        fromBlock: formatters.inputBlockNumberFormatter(options.fromBlock),
        toBlock: formatters.inputBlockNumberFormatter(options.toBlock) 
    }; 
};

var Filter = function (options, methods, formatter) {
    var implementation = {};
    methods.forEach(function (method) {
        method.attachToObject(implementation);
    });
    this.options = getOptions(options);
    this.implementation = implementation;
    this.callbacks = [];
    this.formatter = formatter;
    this.filterId = this.implementation.newFilter(this.options);
};

Filter.prototype.watch = function (callback) {
    this.callbacks.push(callback);
    var self = this;

    var onMessage = function (error, messages) {
        if (error) {
            return self.callbacks.forEach(function (callback) {
                callback(error);
            });
        }

        messages.forEach(function (message) {
            message = self.formatter ? self.formatter(message) : message;
            self.callbacks.forEach(function (callback) {
                callback(null, message);
            });
        });
    };

    // call getFilterLogs on start
    if (!utils.isString(this.options)) {
        this.get(function (err, messages) {
            // don't send all the responses to all the watches again... just to this one
            if (err) {
                callback(err);
            }

            messages.forEach(function (message) {
                callback(null, message);
            });
        });
    }

    RequestManager.getInstance().startPolling({
        method: this.implementation.poll.call,
        params: [this.filterId],
    }, this.filterId, onMessage, this.stopWatching.bind(this));
};

Filter.prototype.stopWatching = function () {
    RequestManager.getInstance().stopPolling(this.filterId);
    this.implementation.uninstallFilter(this.filterId);
    this.callbacks = [];
};

Filter.prototype.get = function (callback) {
    var self = this;
    if (utils.isFunction(callback)) {
        this.implementation.getLogs(this.filterId, function(err, res){
            if (err) {
                callback(err);
            } else {
                callback(null, res.map(function (log) {
                    return self.formatter ? self.formatter(log) : log;
                }));
            }
        });
    } else {
        var logs = this.implementation.getLogs(this.filterId);
        return logs.map(function (log) {
            return self.formatter ? self.formatter(log) : log;
        });
    }
};

module.exports = Filter;