var hasMap = typeof Map === 'function' && Map.prototype;
var mapSizeDescriptor = Object.getOwnPropertyDescriptor && hasMap ? Object.getOwnPropertyDescriptor(Map.prototype, 'size') : null;
var mapSize = hasMap && mapSizeDescriptor && typeof mapSizeDescriptor.get === 'function' ? mapSizeDescriptor.get : null;
var mapForEach = hasMap && Map.prototype.forEach;
var hasSet = typeof Set === 'function' && Set.prototype;
var setSizeDescriptor = Object.getOwnPropertyDescriptor && hasSet ? Object.getOwnPropertyDescriptor(Set.prototype, 'size') : null;
var setSize = hasSet && setSizeDescriptor && typeof setSizeDescriptor.get === 'function' ? setSizeDescriptor.get : null;
var setForEach = hasSet && Set.prototype.forEach;
var booleanValueOf = Boolean.prototype.valueOf;
var objectToString = Object.prototype.toString;

var inspectCustom = require('./util.inspect').custom;
var inspectSymbol = (inspectCustom && isSymbol(inspectCustom)) ? inspectCustom : null;

module.exports = function inspect_ (obj, opts, depth, seen) {
    if (typeof obj === 'undefined') {
        return 'undefined';
    }
    if (obj === null) {
        return 'null';
    }
    if (typeof obj === 'boolean') {
        return obj ? 'true' : 'false';
    }
    if (typeof obj === 'string') {
        return inspectString(obj);
    }
    if (typeof obj === 'number') {
      if (obj === 0) {
        return Infinity / obj > 0 ? '0' : '-0';
      }
      return String(obj);
    }

    if (!opts) opts = {};

    var maxDepth = typeof opts.depth === 'undefined' ? 5 : opts.depth;
    if (typeof depth === 'undefined') depth = 0;
    if (depth >= maxDepth && maxDepth > 0 && typeof obj === 'object') {
        return '[Object]';
    }

    if (typeof seen === 'undefined') seen = [];
    else if (indexOf(seen, obj) >= 0) {
        return '[Circular]';
    }

    function inspect (value, from) {
        if (from) {
            seen = seen.slice();
            seen.push(from);
        }
        return inspect_(value, opts, depth + 1, seen);
    }

    if (typeof obj === 'function') {
        var name = nameOf(obj);
        return '[Function' + (name ? ': ' + name : '') + ']';
    }
    if (isSymbol(obj)) {
        var symString = Symbol.prototype.toString.call(obj);
        return typeof obj === 'object' ? markBoxed(symString) : symString;
    }
    if (isElement(obj)) {
        var s = '<' + String(obj.nodeName).toLowerCase();
        var attrs = obj.attributes || [];
        for (var i = 0; i < attrs.length; i++) {
            s += ' ' + attrs[i].name + '="' + quote(attrs[i].value) + '"';
        }
        s += '>';
        if (obj.childNodes && obj.childNodes.length) s += '...';
        s += '</' + String(obj.nodeName).toLowerCase() + '>';
        return s;
    }
    if (isArray(obj)) {
        if (obj.length === 0) return '[]';
        return '[ ' + arrObjKeys(obj, inspect).join(', ') + ' ]';
    }
    if (isError(obj)) {
        var parts = arrObjKeys(obj, inspect);
        if (parts.length === 0) return '[' + String(obj) + ']';
        return '{ [' + String(obj) + '] ' + parts.join(', ') + ' }';
    }
    if (typeof obj === 'object') {
        if (inspectSymbol && typeof obj[inspectSymbol] === 'function') {
            return obj[inspectSymbol]();
        } else if (typeof obj.inspect === 'function') {
            return obj.inspect();
        }
    }
    if (isMap(obj)) {
        var parts = [];
        mapForEach.call(obj, function (value, key) {
            parts.push(inspect(key, obj) + ' => ' + inspect(value, obj));
        });
        return collectionOf('Map', mapSize.call(obj), parts);
    }
    if (isSet(obj)) {
        var parts = [];
        setForEach.call(obj, function (value ) {
            parts.push(inspect(value, obj));
        });
        return collectionOf('Set', setSize.call(obj), parts);
    }
    if (isNumber(obj)) {
        return markBoxed(inspect(Number(obj)));
    }
    if (isBoolean(obj)) {
        return markBoxed(booleanValueOf.call(obj));
    }
    if (isString(obj)) {
        return markBoxed(inspect(String(obj)));
    }
    if (!isDate(obj) && !isRegExp(obj)) {
        var xs = arrObjKeys(obj, inspect);
        if (xs.length === 0) return '{}';
        return '{ ' + xs.join(', ') + ' }';
    }
    return String(obj);
};

function quote (s) {
    return String(s).replace(/"/g, '&quot;');
}

function isArray (obj) { return toStr(obj) === '[object Array]' }
function isDate (obj) { return toStr(obj) === '[object Date]' }
function isRegExp (obj) { return toStr(obj) === '[object RegExp]' }
function isError (obj) { return toStr(obj) === '[object Error]' }
function isSymbol (obj) { return toStr(obj) === '[object Symbol]' }
function isString (obj) { return toStr(obj) === '[object String]' }
function isNumber (obj) { return toStr(obj) === '[object Number]' }
function isBoolean (obj) { return toStr(obj) === '[object Boolean]' }

var hasOwn = Object.prototype.hasOwnProperty || function (key) { return key in this; };
function has (obj, key) {
    return hasOwn.call(obj, key);
}

function toStr (obj) {
    return objectToString.call(obj);
}

function nameOf (f) {
    if (f.name) return f.name;
    var m = String(f).match(/^function\s*([\w$]+)/);
    if (m) return m[1];
}

function indexOf (xs, x) {
    if (xs.indexOf) return xs.indexOf(x);
    for (var i = 0, l = xs.length; i < l; i++) {
        if (xs[i] === x) return i;
    }
    return -1;
}

function isMap (x) {
    if (!mapSize) {
        return false;
    }
    try {
        mapSize.call(x);
        try {
            setSize.call(x);
        } catch (s) {
            return true;
        }
        return x instanceof Map; // core-js workaround, pre-v2.5.0
    } catch (e) {}
    return false;
}

function isSet (x) {
    if (!setSize) {
        return false;
    }
    try {
        setSize.call(x);
        try {
            mapSize.call(x);
        } catch (m) {
            return true;
        }
        return x instanceof Set; // core-js workaround, pre-v2.5.0
    } catch (e) {}
    return false;
}

function isElement (x) {
    if (!x || typeof x !== 'object') return false;
    if (typeof HTMLElement !== 'undefined' && x instanceof HTMLElement) {
        return true;
    }
    return typeof x.nodeName === 'string'
        && typeof x.getAttribute === 'function'
    ;
}

function inspectString (str) {
    var s = str.replace(/(['\\])/g, '\\$1').replace(/[\x00-\x1f]/g, lowbyte);
    return "'" + s + "'";
}

function lowbyte (c) {
    var n = c.charCodeAt(0);
    var x = { 8: 'b', 9: 't', 10: 'n', 12: 'f', 13: 'r' }[n];
    if (x) return '\\' + x;
    return '\\x' + (n < 0x10 ? '0' : '') + n.toString(16);
}

function markBoxed (str) {
    return 'Object(' + str + ')';
}

function collectionOf (type, size, entries) {
    return type + ' (' + size + ') {' + entries.join(', ') + '}';
}

function arrObjKeys (obj, inspect) {
    var isArr = isArray(obj);
    var xs = [];
    if (isArr) {
        xs.length = obj.length;
        for (var i = 0; i < obj.length; i++) {
            xs[i] = has(obj, i) ? inspect(obj[i], obj) : '';
        }
    }
    for (var key in obj) {
        if (!has(obj, key)) continue;
        if (isArr && String(Number(key)) === key && key < obj.length) continue;
        if (/[^\w$]/.test(key)) {
            xs.push(inspect(key, obj) + ': ' + inspect(obj[key], obj));
        } else {
            xs.push(key + ': ' + inspect(obj[key], obj));
        }
    }
    return xs;
}
