'use strict';

// Load modules

const Assert = require('assert');
const Crypto = require('crypto');
const Path = require('path');

const DeepEqual = require('./deep-equal');
const Escape = require('./escape');
const Types = require('./types');


// Declare internals

const internals = {
    needsProtoHack: new Set([Types.set, Types.map, Types.weakSet, Types.weakMap])
};


// Deep object or array comparison

exports.deepEqual = DeepEqual;


// Clone object or array

exports.clone = function (obj, options = {}, _seen = null) {

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

        return obj;
    }

    const seen = _seen || new Map();

    const lookup = seen.get(obj);
    if (lookup) {
        return lookup;
    }

    const baseProto = Types.getInternalProto(obj);
    let newObj;

    switch (baseProto) {
        case Types.buffer:
            return Buffer.from(obj);

        case Types.date:
            return new Date(obj.getTime());

        case Types.regex:
            return new RegExp(obj);

        case Types.array:
            newObj = [];
            break;

        default:
            if (options.prototype !== false) {              // Defaults to true
                const proto = Object.getPrototypeOf(obj);
                if (proto &&
                    proto.isImmutable) {

                    return obj;
                }

                if (internals.needsProtoHack.has(baseProto)) {
                    newObj = new proto.constructor();
                    if (proto !== baseProto) {
                        Object.setPrototypeOf(newObj, proto);
                    }
                }
                else {
                    newObj = Object.create(proto);
                }
            }
            else if (internals.needsProtoHack.has(baseProto)) {
                newObj = new baseProto.constructor();
            }
            else {
                newObj = {};
            }
    }

    seen.set(obj, newObj);                                  // Set seen, since obj could recurse

    if (baseProto === Types.set) {
        for (const value of obj) {
            newObj.add(exports.clone(value, options, seen));
        }
    }
    else if (baseProto === Types.map) {
        for (const [key, value] of obj) {
            newObj.set(key, exports.clone(value, options, seen));
        }
    }

    const keys = internals.keys(obj, options);
    for (let i = 0; i < keys.length; ++i) {
        const key = keys[i];

        if (baseProto === Types.array &&
            key === 'length') {

            continue;
        }

        const descriptor = Object.getOwnPropertyDescriptor(obj, key);
        if (descriptor &&
            (descriptor.get ||
                descriptor.set)) {

            Object.defineProperty(newObj, key, descriptor);
        }
        else {
            Object.defineProperty(newObj, key, {
                enumerable: descriptor ? descriptor.enumerable : true,
                writable: true,
                configurable: true,
                value: exports.clone(obj[key], options, seen)
            });
        }
    }

    if (baseProto === Types.array) {
        newObj.length = obj.length;
    }

    return newObj;
};


internals.keys = function (obj, options = {}) {

    return options.symbols ? Reflect.ownKeys(obj) : Object.getOwnPropertyNames(obj);
};


// Merge all the properties of source into target, source wins in conflict, and by default null and undefined from source are applied

exports.merge = function (target, source, isNullOverride = true, isMergeArrays = true) {

    exports.assert(target && typeof target === 'object', 'Invalid target value: must be an object');
    exports.assert(source === null || source === undefined || typeof source === 'object', 'Invalid source value: must be null, undefined, or an object');

    if (!source) {
        return target;
    }

    if (Array.isArray(source)) {
        exports.assert(Array.isArray(target), 'Cannot merge array onto an object');
        if (!isMergeArrays) {
            target.length = 0;                                                          // Must not change target assignment
        }

        for (let i = 0; i < source.length; ++i) {
            target.push(exports.clone(source[i]));
        }

        return target;
    }

    const keys = internals.keys(source);
    for (let i = 0; i < keys.length; ++i) {
        const key = keys[i];
        if (key === '__proto__' ||
            !Object.prototype.propertyIsEnumerable.call(source, key)) {

            continue;
        }

        const value = source[key];
        if (value &&
            typeof value === 'object') {

            if (!target[key] ||
                typeof target[key] !== 'object' ||
                (Array.isArray(target[key]) !== Array.isArray(value)) ||
                value instanceof Date ||
                Buffer.isBuffer(value) ||
                value instanceof RegExp) {

                target[key] = exports.clone(value);
            }
            else {
                exports.merge(target[key], value, isNullOverride, isMergeArrays);
            }
        }
        else {
            if (value !== null &&
                value !== undefined) {                              // Explicit to preserve empty strings

                target[key] = value;
            }
            else if (isNullOverride) {
                target[key] = value;
            }
        }
    }

    return target;
};


// Apply options to a copy of the defaults

exports.applyToDefaults = function (defaults, options, isNullOverride = false) {

    exports.assert(defaults && typeof defaults === 'object', 'Invalid defaults value: must be an object');
    exports.assert(!options || options === true || typeof options === 'object', 'Invalid options value: must be true, falsy or an object');

    if (!options) {                                                 // If no options, return null
        return null;
    }

    const copy = exports.clone(defaults);

    if (options === true) {                                         // If options is set to true, use defaults
        return copy;
    }

    return exports.merge(copy, options, isNullOverride, false);
};


// Clone an object except for the listed keys which are shallow copied

exports.cloneWithShallow = function (source, keys, options) {

    if (!source ||
        typeof source !== 'object') {

        return source;
    }

    const storage = internals.store(source, keys);    // Move shallow copy items to storage
    const copy = exports.clone(source, options);      // Deep copy the rest
    internals.restore(copy, source, storage);         // Shallow copy the stored items and restore
    return copy;
};


internals.store = function (source, keys) {

    const storage = new Map();
    for (let i = 0; i < keys.length; ++i) {
        const key = keys[i];
        const value = exports.reach(source, key);
        if (typeof value === 'object' ||
            typeof value === 'function') {

            storage.set(key, value);
            internals.reachSet(source, key, undefined);
        }
    }

    return storage;
};


internals.restore = function (copy, source, storage) {

    for (const [key, value] of storage) {
        internals.reachSet(copy, key, value);
        internals.reachSet(source, key, value);
    }
};


internals.reachSet = function (obj, key, value) {

    const path = Array.isArray(key) ? key : key.split('.');
    let ref = obj;
    for (let i = 0; i < path.length; ++i) {
        const segment = path[i];
        if (i + 1 === path.length) {
            ref[segment] = value;
        }

        ref = ref[segment];
    }
};


// Apply options to defaults except for the listed keys which are shallow copied from option without merging

exports.applyToDefaultsWithShallow = function (defaults, options, keys) {

    exports.assert(defaults && typeof defaults === 'object', 'Invalid defaults value: must be an object');
    exports.assert(!options || options === true || typeof options === 'object', 'Invalid options value: must be true, falsy or an object');
    exports.assert(keys && Array.isArray(keys), 'Invalid keys');

    if (!options) {                                                 // If no options, return null
        return null;
    }

    const copy = exports.cloneWithShallow(defaults, keys);

    if (options === true) {                                         // If options is set to true, use defaults
        return copy;
    }

    const storage = internals.store(options, keys);     // Move shallow copy items to storage
    exports.merge(copy, options, false, false);         // Deep copy the rest
    internals.restore(copy, options, storage);          // Shallow copy the stored items and restore
    return copy;
};


// Find the common unique items in two arrays

exports.intersect = function (array1, array2, justFirst = false) {

    if (!array1 ||
        !array2) {

        return (justFirst ? null : []);
    }

    const common = [];
    const hash = (Array.isArray(array1) ? new Set(array1) : array1);
    const found = new Set();
    for (const value of array2) {
        if (internals.has(hash, value) &&
            !found.has(value)) {

            if (justFirst) {
                return value;
            }

            common.push(value);
            found.add(value);
        }
    }

    return (justFirst ? null : common);
};


internals.has = function (ref, key) {

    if (typeof ref.has === 'function') {
        return ref.has(key);
    }

    return ref[key] !== undefined;
};


// Test if the reference contains the values

exports.contain = function (ref, values, options = {}) {        // options: { deep, once, only, part, symbols }

    /*
        string -> string(s)
        array -> item(s)
        object -> key(s)
        object -> object (key:value)
    */

    let valuePairs = null;
    if (typeof ref === 'object' &&
        typeof values === 'object' &&
        !Array.isArray(ref) &&
        !Array.isArray(values)) {

        valuePairs = values;
        const symbols = Object.getOwnPropertySymbols(values).filter(Object.prototype.propertyIsEnumerable.bind(values));
        values = [...Object.keys(values), ...symbols];
    }
    else {
        values = [].concat(values);
    }

    exports.assert(typeof ref === 'string' || typeof ref === 'object', 'Reference must be string or an object');
    exports.assert(values.length, 'Values array cannot be empty');

    let compare;
    let compareFlags;
    if (options.deep) {
        compare = exports.deepEqual;

        const hasOnly = options.only !== undefined;
        const hasPart = options.part !== undefined;

        compareFlags = {
            prototype: hasOnly ? options.only : hasPart ? !options.part : false,
            part: hasOnly ? !options.only : hasPart ? options.part : false
        };
    }
    else {
        compare = (a, b) => a === b;
    }

    let misses = false;
    const matches = new Array(values.length);
    for (let i = 0; i < matches.length; ++i) {
        matches[i] = 0;
    }

    if (typeof ref === 'string') {
        let pattern = '(';
        for (let i = 0; i < values.length; ++i) {
            const value = values[i];
            exports.assert(typeof value === 'string', 'Cannot compare string reference to non-string value');
            pattern += (i ? '|' : '') + exports.escapeRegex(value);
        }

        const regex = new RegExp(pattern + ')', 'g');
        const leftovers = ref.replace(regex, ($0, $1) => {

            const index = values.indexOf($1);
            ++matches[index];
            return '';          // Remove from string
        });

        misses = !!leftovers;
    }
    else if (Array.isArray(ref)) {
        const onlyOnce = !!(options.only && options.once);
        if (onlyOnce && ref.length !== values.length) {
            return false;
        }

        for (let i = 0; i < ref.length; ++i) {
            let matched = false;
            for (let j = 0; j < values.length && matched === false; ++j) {
                if (!onlyOnce || matches[j] === 0) {
                    matched = compare(values[j], ref[i], compareFlags) && j;
                }
            }

            if (matched !== false) {
                ++matches[matched];
            }
            else {
                misses = true;
            }
        }
    }
    else {
        const keys = internals.keys(ref, options);
        for (let i = 0; i < keys.length; ++i) {
            const key = keys[i];
            const pos = values.indexOf(key);
            if (pos !== -1) {
                if (valuePairs &&
                    !compare(valuePairs[key], ref[key], compareFlags)) {

                    return false;
                }

                ++matches[pos];
            }
            else {
                misses = true;
            }
        }
    }

    if (options.only) {
        if (misses || !options.once) {
            return !misses;
        }
    }

    let result = false;
    for (let i = 0; i < matches.length; ++i) {
        result = result || !!matches[i];
        if ((options.once && matches[i] > 1) ||
            (!options.part && !matches[i])) {

            return false;
        }
    }

    return result;
};


// Flatten array

exports.flatten = function (array, target) {

    const result = target || [];

    for (let i = 0; i < array.length; ++i) {
        if (Array.isArray(array[i])) {
            exports.flatten(array[i], result);
        }
        else {
            result.push(array[i]);
        }
    }

    return result;
};


// Convert an object key chain string ('a.b.c') to reference (object[a][b][c])

exports.reach = function (obj, chain, options) {

    if (chain === false ||
        chain === null ||
        chain === undefined) {

        return obj;
    }

    options = options || {};
    if (typeof options === 'string') {
        options = { separator: options };
    }

    const isChainArray = Array.isArray(chain);

    exports.assert(!isChainArray || !options.separator, 'Separator option no valid for array-based chain');

    const path = isChainArray ? chain : chain.split(options.separator || '.');
    let ref = obj;
    for (let i = 0; i < path.length; ++i) {
        let key = path[i];

        if (Array.isArray(ref)) {
            const number = Number(key);

            if (Number.isInteger(number) && number < 0) {
                key = ref.length + number;
            }
        }

        if (!ref ||
            !((typeof ref === 'object' || typeof ref === 'function') && key in ref) ||
            (typeof ref !== 'object' && options.functions === false)) {         // Only object and function can have properties

            exports.assert(!options.strict || i + 1 === path.length, 'Missing segment', key, 'in reach path ', chain);
            exports.assert(typeof ref === 'object' || options.functions === true || typeof ref !== 'function', 'Invalid segment', key, 'in reach path ', chain);
            ref = options.default;
            break;
        }

        ref = ref[key];
    }

    return ref;
};


exports.reachTemplate = function (obj, template, options) {

    return template.replace(/{([^}]+)}/g, ($0, chain) => {

        const value = exports.reach(obj, chain, options);
        return (value === undefined || value === null ? '' : value);
    });
};


exports.assert = function (condition, ...args) {

    if (condition) {
        return;
    }

    if (args.length === 1 && args[0] instanceof Error) {
        throw args[0];
    }

    const msgs = args
        .filter((arg) => arg !== '')
        .map((arg) => {

            return typeof arg === 'string' ? arg : arg instanceof Error ? arg.message : exports.stringify(arg);
        });

    throw new Assert.AssertionError({
        message: msgs.join(' ') || 'Unknown error',
        actual: false,
        expected: true,
        operator: '==',
        stackStartFunction: exports.assert
    });
};


exports.Bench = class {

    constructor() {

        this.ts = 0;
        this.reset();
    }

    reset() {

        this.ts = exports.Bench.now();
    }

    elapsed() {

        return exports.Bench.now() - this.ts;
    }

    static now() {

        const ts = process.hrtime();
        return (ts[0] * 1e3) + (ts[1] / 1e6);
    }
};


// Escape string for Regex construction

exports.escapeRegex = function (string) {

    // Escape ^$.*+-?=!:|\/()[]{},
    return string.replace(/[\^\$\.\*\+\-\?\=\!\:\|\\\/\(\)\[\]\{\}\,]/g, '\\$&');
};


// Escape attribute value for use in HTTP header

exports.escapeHeaderAttribute = function (attribute) {

    // Allowed value characters: !#$%&'()*+,-./:;<=>?@[]^_`{|}~ and space, a-z, A-Z, 0-9, \, "

    exports.assert(/^[ \w\!#\$%&'\(\)\*\+,\-\.\/\:;<\=>\?@\[\]\^`\{\|\}~\"\\]*$/.test(attribute), 'Bad attribute value (' + attribute + ')');

    return attribute.replace(/\\/g, '\\\\').replace(/\"/g, '\\"');                             // Escape quotes and slash
};


exports.escapeHtml = function (string) {

    return Escape.escapeHtml(string);
};


exports.escapeJson = function (string) {

    return Escape.escapeJson(string);
};


exports.once = function (method) {

    if (method._hoekOnce) {
        return method;
    }

    let once = false;
    const wrapped = function (...args) {

        if (!once) {
            once = true;
            method(...args);
        }
    };

    wrapped._hoekOnce = true;
    return wrapped;
};


exports.ignore = function () { };


exports.uniqueFilename = function (path, extension) {

    if (extension) {
        extension = extension[0] !== '.' ? '.' + extension : extension;
    }
    else {
        extension = '';
    }

    path = Path.resolve(path);
    const name = [Date.now(), process.pid, Crypto.randomBytes(8).toString('hex')].join('-') + extension;
    return Path.join(path, name);
};


exports.stringify = function (...args) {

    try {
        return JSON.stringify.apply(null, args);
    }
    catch (err) {
        return '[Cannot display object: ' + err.message + ']';
    }
};


exports.wait = function (timeout) {

    return new Promise((resolve) => setTimeout(resolve, timeout));
};


exports.block = function () {

    return new Promise(exports.ignore);
};
