'use strict';

var hexTable = (function () {

var array = new Array(256);
for (var i = 0; i < 256; ++i) {
    array[i] = '%' + ((i < 16 ? '0' : '') + i.toString(16)).toUpperCase();
}

return array;

}());

exports.arrayToObject = function (source, options) {

var obj = options.plainObjects ? Object.create(null) : {};
for (var i = 0; i < source.length; ++i) {
    if (typeof source[i] !== 'undefined') {
        obj[i] = source[i];
    }
}

return obj;

};

exports.merge = function (target, source, options) {

if (!source) {
    return target;
}

if (typeof source !== 'object') {
    if (Array.isArray(target)) {
        target.push(source);
    } else if (typeof target === 'object') {
        target[source] = true;
    } else {
        return [target, source];
    }

    return target;
}

if (typeof target !== 'object') {
    return [target].concat(source);
}

var mergeTarget = target;
if (Array.isArray(target) && !Array.isArray(source)) {
    mergeTarget = exports.arrayToObject(target, options);
}

return Object.keys(source).reduce(function (acc, key) {
    var value = source[key];

    if (Object.prototype.hasOwnProperty.call(acc, key)) {
        acc[key] = exports.merge(acc[key], value, options);
    } else {
        acc[key] = value;
    }
    return acc;
}, mergeTarget);

};

exports.decode = function (str) {

try {
    return decodeURIComponent(str.replace(/\+/g, ' '));
} catch (e) {
    return str;
}

};

exports.encode = function (str) {

// This code was originally written by Brian White (mscdex) for the io.js core querystring library.
// It has been adapted here for stricter adherence to RFC 3986
if (str.length === 0) {
    return str;
}

var string = typeof str === 'string' ? str : String(str);

var out = '';
for (var i = 0; i < string.length; ++i) {
    var c = string.charCodeAt(i);

    if (
        c === 0x2D || // -
        c === 0x2E || // .
        c === 0x5F || // _
        c === 0x7E || // ~
        (c >= 0x30 && c <= 0x39) || // 0-9
        (c >= 0x41 && c <= 0x5A) || // a-z
        (c >= 0x61 && c <= 0x7A) // A-Z
    ) {
        out += string.charAt(i);
        continue;
    }

    if (c < 0x80) {
        out = out + hexTable[c];
        continue;
    }

    if (c < 0x800) {
        out = out + (hexTable[0xC0 | (c >> 6)] + hexTable[0x80 | (c & 0x3F)]);
        continue;
    }

    if (c < 0xD800 || c >= 0xE000) {
        out = out + (hexTable[0xE0 | (c >> 12)] + hexTable[0x80 | ((c >> 6) & 0x3F)] + hexTable[0x80 | (c & 0x3F)]);
        continue;
    }

    i += 1;
    c = 0x10000 + (((c & 0x3FF) << 10) | (string.charCodeAt(i) & 0x3FF));
    out += hexTable[0xF0 | (c >> 18)] + hexTable[0x80 | ((c >> 12) & 0x3F)] + hexTable[0x80 | ((c >> 6) & 0x3F)] + hexTable[0x80 | (c & 0x3F)];
}

return out;

};

exports.compact = function (obj, references) {

if (typeof obj !== 'object' || obj === null) {
    return obj;
}

var refs = references || [];
var lookup = refs.indexOf(obj);
if (lookup !== -1) {
    return refs[lookup];
}

refs.push(obj);

if (Array.isArray(obj)) {
    var compacted = [];

    for (var i = 0; i < obj.length; ++i) {
        if (obj[i] && typeof obj[i] === 'object') {
            compacted.push(exports.compact(obj[i], refs));
        } else if (typeof obj[i] !== 'undefined') {
            compacted.push(obj[i]);
        }
    }

    return compacted;
}

var keys = Object.keys(obj);
for (var j = 0; j < keys.length; ++j) {
    var key = keys[j];
    obj[key] = exports.compact(obj[key], refs);
}

return obj;

};

exports.isRegExp = function (obj) {

return Object.prototype.toString.call(obj) === '[object RegExp]';

};

exports.isBuffer = function (obj) {

if (obj === null || typeof obj === 'undefined') {
    return false;
}

return !!(obj.constructor && obj.constructor.isBuffer && obj.constructor.isBuffer(obj));

};