/*
    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 utils.js
 * @authors:
 *   Marek Kotewicz <marek@ethdev.com>
 * @date 2015
 */

if (process.env.NODE_ENV !== 'build') {
    var BigNumber = require('bignumber.js'); // jshint ignore:line
}

var unitMap = {
    'wei':      '1',
    'kwei':     '1000',
    'ada':      '1000',
    'mwei':     '1000000',
    'babbage':  '1000000',
    'gwei':     '1000000000',
    'shannon':  '1000000000',
    'szabo':    '1000000000000',
    'finney':   '1000000000000000',
    'ether':    '1000000000000000000',
    'kether':   '1000000000000000000000',
    'grand':    '1000000000000000000000',
    'einstein': '1000000000000000000000',
    'mether':   '1000000000000000000000000',
    'gether':   '1000000000000000000000000000',
    'tether':   '1000000000000000000000000000000'
};


/// Finds first index of array element matching pattern
/// @param array
/// @param callback pattern
/// @returns index of element
var findIndex = function (array, callback) {
    var end = false;
    var i = 0;
    for (; i < array.length && !end; i++) {
        end = callback(array[i]);
    }
    return end ? i - 1 : -1;
};

/// @returns ascii string representation of hex value prefixed with 0x
var toAscii = function(hex) {
// Find termination
    var str = "";
    var i = 0, l = hex.length;
    if (hex.substring(0, 2) === '0x') {
        i = 2;
    }
    for (; i < l; i+=2) {
        var code = parseInt(hex.substr(i, 2), 16);
        if (code === 0) {
            break;
        }

        str += String.fromCharCode(code);
    }

    return str;
};
    
var toHexNative = function(str) {
    var hex = "";
    for(var i = 0; i < str.length; i++) {
        var n = str.charCodeAt(i).toString(16);
        hex += n.length < 2 ? '0' + n : n;
    }

    return hex;
};

/// @returns hex representation (prefixed by 0x) of ascii string
var fromAscii = function(str, pad) {
    pad = pad === undefined ? 0 : pad;
    var hex = toHexNative(str);
    while (hex.length < pad*2)
        hex += "00";
    return "0x" + hex;
};

/// @returns display name for function/event eg. multiply(uint256) -> multiply
var extractDisplayName = function (name) {
    var length = name.indexOf('('); 
    return length !== -1 ? name.substr(0, length) : name;
};

/// @returns overloaded part of function/event name
var extractTypeName = function (name) {
    /// TODO: make it invulnerable
    var length = name.indexOf('(');
    return length !== -1 ? name.substr(length + 1, name.length - 1 - (length + 1)).replace(' ', '') : "";
};

/// Filters all function from input abi
/// @returns abi array with filtered objects of type 'function'
var filterFunctions = function (json) {
    return json.filter(function (current) {
        return current.type === 'function'; 
    }); 
};

/// Filters all events form input abi
/// @returns abi array with filtered objects of type 'event'
var filterEvents = function (json) {
    return json.filter(function (current) {
        return current.type === 'event';
    });
};

var toDecimal = function (val) {

    // pass it through is its already a number
    if(typeof val === 'number' || (typeof val === 'string' && val.indexOf('0x') === -1))
        return val;

    // remove 0x and place 0, if it's required
    val = val.length > 2 ? val.substring(2) : "0";
    return new BigNumber(val, 16).toNumber();
};

var fromDecimal = function (val) {
    return "0x" + (new BigNumber(val).toString(16));
};


var toHex = function (val) {
    return '0x' + toBigNumber(val).toString(16);
};

/**
 * Returns value of unit in Wei
 *
 * @method getValueOfUnit
 * @param {String} unit the unit to convert to, default ether
 * @returns {BigNumber} value of the unit (in Wei)
 * @throws error if the unit is not correct:w
 */
var getValueOfUnit = function (unit) {
    unit = unit ? unit.toLowerCase() : 'ether';
    var unitValue = unitMap[unit];
    if (unitValue === undefined) {
        throw new Error('This unit doesn\'t exists, please use the one of the following units' + JSON.stringify(unitMap, null, 2));
    }
    return new BigNumber(unitValue, 10);
};

/**
 * Takes a number of wei and converts it to any other ether unit.
 *
 * Possible units are:
 * - kwei/ada
 * - mwei/babbage
 * - gwei/shannon
 * - szabo
 * - finney
 * - ether
 * - kether/grand/einstein
 * - mether
 * - gether
 * - tether
 *
 * @method fromWei
 * @param {Number|String} number can be a number, number string or a HEX of a decimal
 * @param {String} unit the unit to convert to, default ether
 * @return {String|Object} When given a BigNumber object it returns one as well, otherwise a number
*/
var fromWei = function(number, unit) {
    return toBigNumber(number).dividedBy(getValueOfUnit(unit)).toString(10);
};

/**
 * Takes a number of a unit and converts it to wei.
 *
 * Possible units are:
 * - kwei/ada
 * - mwei/babbage
 * - gwei/shannon
 * - szabo
 * - finney
 * - ether
 * - kether/grand/einstein
 * - mether
 * - gether
 * - tether
 *
 * @method toWei
 * @param {Number|String|BigNumber} number can be a number, number string or a HEX of a decimal
 * @param {String} unit the unit to convert from, default ether
 * @return {String|Object} When given a BigNumber object it returns one as well, otherwise a number
*/
var toWei = function(number, unit) {
    return toBigNumber(number).times(getValueOfUnit(unit)).toString(10);
};

/**
 * Takes an input and transforms it into an bignumber
 *
 * @method toBigNumber
 * @param {Number|String|BigNumber} a number, string, HEX string or BigNumber
 * @return {Object} BigNumber
*/
var toBigNumber = function(number) {
    number = number || 0;
    if (isBigNumber(number))
        return number;

    if (isString(number) && number.indexOf('0x') === 0)
        return new BigNumber(number, 16);
      
    return new BigNumber(number.toString(10), 10);
};

/**
 * Checks if the given string has proper length
 *
 * @method isAddress
 * @param {String} address the given HEX adress
 * @return {Boolean}
*/
var isAddress = function(address) {
    return ((address.indexOf('0x') === 0 && address.length === 42) ||
            (address.indexOf('0x') === -1 && address.length === 40));
};

/**
 * Returns true if object is BigNumber, otherwise false
 *
 * @method isBigNumber
 * @param {Object}
 * @return {Boolean} 
 */
var isBigNumber = function (object) {
    return object instanceof BigNumber ||
        (object && object.constructor && object.constructor.name === 'BigNumber');
};

/**
 * Returns true if object is string, otherwise false
 * 
 * @method isString
 * @param {Object}
 * @return {Boolean}
 */
var isString = function (object) {
    return typeof object === 'string';
};

module.exports = {
    findIndex: findIndex,
    toHex: toHex,
    toDecimal: toDecimal,
    fromDecimal: fromDecimal,
    toAscii: toAscii,
    fromAscii: fromAscii,
    extractDisplayName: extractDisplayName,
    extractTypeName: extractTypeName,
    filterFunctions: filterFunctions,
    filterEvents: filterEvents,
    toWei: toWei,
    fromWei: fromWei,
    toBigNumber: toBigNumber,
    isBigNumber: isBigNumber,
    isAddress: isAddress
};