webu/lib/webu/method.js

IrChain JavaScript API, middleware to talk to a irchain node over RPC

/*
    This file is part of webu.js.

    webu.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.

    webu.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 webu.js.  If not, see <http://www.gnu.org/licenses/>.
*/
/**
 * @file method.js
 * @author Marek Kotewicz <marek@ethdev.com>
 * @date 2015
 */

var utils = require('../utils/utils');
var errors = require('./errors');

var Method = function(options) {
    this.name = options.name;
    this.call = options.call;
    this.params = options.params || 0;
    this.inputFormatter = options.inputFormatter;
    this.outputFormatter = options.outputFormatter;
    this.requestManager = null;
};

Method.prototype.setRequestManager = function(rm) {
    this.requestManager = rm;
};

/**
 * Should be used to determine name of the jsonrpc method based on arguments
 *
 * @method getCall
 * @param {Array} arguments
 * @return {String} name of jsonrpc method
 * @param args
 */
Method.prototype.getCall = function(args) {
    return utils.isFunction(this.call) ? this.call(args) : this.call;
};

/**
 * Should be used to extract callback from array of arguments. Modifies input param
 *
 * @method extractCallback
 * @param {Array} arguments
 * @return {Function|Null} callback, if exists
 * @param args
 */
Method.prototype.extractCallback = function(args) {
    if (utils.isFunction(args[args.length - 1])) {
        return args.pop(); // modify the args array!
    }
};

/**
 * Should be called to check if the number of arguments is correct
 *
 * @method validateArgs
 * @param {Array} arguments
 * @throws {Error} if it is not
 * @param args
 */
Method.prototype.validateArgs = function(args) {
    if (args.length !== this.params) {
        throw errors.InvalidNumberOfRPCParams();
    }
};

/**
 * Should be called to format input args of method
 *
 * @method formatInput
 * @return {Array}
 * @param args
 */
Method.prototype.formatInput = function(args) {
    if (!this.inputFormatter) {
        return args;
    }

    return this.inputFormatter.map(function(formatter, index) {
        return formatter ? formatter(args[index]) : args[index];
    });
};

/**
 * Should be called to format output(result) of method
 *
 * @method formatOutput
 * @return {Object}
 * @param result
 */
Method.prototype.formatOutput = function(result) {
    return this.outputFormatter && result ? this.outputFormatter(result) : result;
};

/**
 * Should create payload from given input args
 *
 * @method toPayload
 * @param {Array} args
 * @return {Object}
 */
Method.prototype.toPayload = function(args) {
    var call = this.getCall(args);
    var callback = this.extractCallback(args);
    var params = this.formatInput(args);
    this.validateArgs(params);

    return {
        method  : call,
        params  : params,
        callback: callback,
    };
};

Method.prototype.attachToObject = function(obj) {
    var func = this.buildCall();
    func.call = this.call;
    var name = this.name.split('.');
    if (name.length > 1) {
        obj[name[0]] = obj[name[0]] || {};
        obj[name[0]][name[1]] = func;
    } else {
        obj[name[0]] = func;
    }
};

Method.prototype.buildCall = function() {
    var method = this;
    var send = function() {
        var payload = method.toPayload(Array.prototype.slice.call(arguments));
        if (payload.callback) {
            return method.requestManager.sendAsync(
                payload,
                function(err, result) {
                    payload.callback(err, method.formatOutput(result));
                });
        }
        return method.formatOutput(method.requestManager.send(payload));
    };
    send.request = this.request.bind(this);
    return send;
};

/**
 * Should be called to create pure JSONRPC request which can be used in batch request
 *
 * @method request
 * @param {...} arguments
 * @return {Object} jsonrpc request
 */
Method.prototype.request = function() {
    var payload = this.toPayload(Array.prototype.slice.call(arguments));
    payload.format = this.formatOutput.bind(this);
    return payload;
};

module.exports = Method;