"use strict";

/**
 * @callback anp_loader_default_callback
 * @returns {void}
 */

/**
 * @callback anp_loader_execute_callback
 * @param {...(any|null)} [parameters] 
 * @returns {any|null}
 */

/**
 * @class
 * @constructor
 * @param {!(Object.<string, any|null>|Array.<any|null>)} inputs 
 * @returns {void}
 * @access public
 */
export const AnPLoader = (function(){

    /**
     * @constructs AnPLoader
     * @param {!(Object.<string, any|null>|Array.<any|null>)} inputs 
     * @param {!anp_loader_default_callback} callback 
     * @returns {void}
     * @access private
     */
    const AnPLoader = function(inputs, callback){

        /** @type {AnPLoader} */
        const self = this;

        /**
         * @returns {void}
         * @access private
         */
        const constructor = () => {

            /** @type {number} */
            let i = 0;
            /** @type {anp_loader_default_callback} */
            const end = () => {
                ++ i == 2 && AnPLoader.execute(callback);
            };

            AnPLoader.styles_loader(AnPLoader.get_list_strings(AnPLoader.get_value(["style", "styles"], inputs)), end);
            AnPLoader.scripts_loader(AnPLoader.get_list_strings(AnPLoader.get_value(["script", "scripts"], inputs)), end);

        };

        constructor();

    };

    /** @type {string} */
    AnPLoader.DOMAIN = /^[^\:]+\:\/{2}[^\/]+\.([lg]ocal|anprm(\.[lg]ocal)?)\/?/i.test(window.location.href) ? "local" : "k3y.pw";

    /**
     * @param {?any} item 
     * @returns {boolean}
     * @access public
     * @static
     */
    AnPLoader.is_string = item => typeof item == "string";

    /**
     * @param {?any} item 
     * @returns {boolean}
     * @access public
     * @static
     */
    AnPLoader.is_key = item => item && AnPLoader.is_string(item) && /^[a-z0-9_]+$/i.test(item);

    /**
     * @param {?any} item 
     * @returns {boolean}
     * @access public
     * @static
     */
    AnPLoader.is_array = item => item instanceof Array;

    /**
     * @param {?any} item 
     * @returns {boolean}
     * @access public
     * @static
     */
    AnPLoader.is_dictionary = item => item && item.constructor == Object;

    /**
     * @param {?any} item 
     * @returns {boolean}
     * @access public
     * @static
     */
    AnPLoader.is_function = item => typeof item == "function";

    /**
     * @param {?any} item 
     * @returns {Array.<any|null>}
     * @access public
     * @static
     */
    AnPLoader.get_array = item => AnPLoader.is_array(item) ? item : [item];

    /**
     * @param {!(string|Array.<string>)} keys 
     * @returns {Array.<string>}
     * @access public
     * @static
     */
    AnPLoader.get_keys = keys => AnPLoader.get_array(keys).filter((key, i, array) => AnPLoader.is_key(key) && array.indexOf(key) == i);

    /**
     * @param {!(string|Array.<string>)} keys 
     * @param {!(Object.<string, any|null>|Array.<any|null>)} inputs 
     * @param {?any} [_default = null] 
     * @returns {any|null|undefined}
     * @access public
     * @static
     */
    AnPLoader.get_value = (keys, inputs, _default = null) => {
        if(AnPLoader.is_array(inputs)){
            for(let i = 0, l = inputs.length; i < l; i ++){

                /** @type {any|null|undefined} */
                const value = AnPLoader.get_value(keys, inputs[i], undefined)

                if(value !== undefined)
                    return value;

            };
        }else if(AnPLoader.is_dictionary(inputs)){
            for(let i = 0, l = (keys = AnPLoader.get_keys(keys)).length; i < l; i ++)
                if(inputs[keys[i]] !== undefined)
                    return inputs[keys[i]];
        };
        return _default;
    };

    /**
     * @param {!(string|Array.<any|null>)} items 
     * @returns {Array.<any>}
     * @access public
     * @static
     */
    AnPLoader.get_list_strings = items => {
        if(items){
            if(AnPLoader.is_string(items))
                return [items];
            if(AnPLoader.is_array(items))
                return items.filter(item => AnPLoader.is_string(item) || AnPLoader.is_array(item)).map(item => AnPLoader.is_array(item) ? AnPLoader.get_list_strings(item) : item);
        };
        return [];
    };

    /**
     * @param {!anp_loader_execute_callback} callback 
     * @param {...(any|null)} parameters 
     * @returns {any|null}
     * @access public
     * @static
     */
    AnPLoader.execute = (callback, ...parameters) => {
        return AnPLoader.is_function(callback) ? callback(...parameters) : null;
    };

    /**
     * @param {!Array.<Array.<string>>} scripts 
     * @param {?anp_loader_default_callback} [callback = null] 
     * @param {!number} [i = 0] 
     * @returns {void}
     * @access public
     * @static
     */
    AnPLoader.scripts_loader = (scripts, callback = null, i = 0) => {
        if(i == scripts.length){
            AnPLoader.execute(callback);
            return;
        };

        /** @type {number} */
        let loaded = 0;
        /** @type {number} */
        const l = scripts[i].length, 
              /** @type {anp_loader_default_callback} */
              end = () => {
                  ++ loaded == l && AnPLoader.scripts_loader(scripts, callback, i + 1);
              }, 
              /** @type {HTMLHeadElement} */
              head = document.querySelector("head");

        AnPLoader.get_array(scripts[i]).forEach(script => {
            if(AnPLoader.is_string(script)){

                /** @type {HTMLScriptElement} */
                const item = head.appendChild(document.createElement("script"));

                ["load", "error"].forEach(key => {
                    item.addEventListener(key, event => {
                        end();
                    });
                });

                item.setAttribute("data-type", "text/javascript;charset=utf-8");
                item.setAttribute("data-language", script.slice(-8).toLowerCase() == ".ecma.js" ? "ECMAScript 2015" : "JavaScript 1.8.5");
                item.setAttribute("src", script);
                item.setAttribute("data-crossorigin", "anonymous");
                item.setAttribute("charset", "utf-8");

            }else 
                end();
        });

    };

    /**
     * @param {!Array.<Array.<string>>} styles 
     * @param {?anp_loader_default_callback} [callback = null] 
     * @param {!number} [i = 0] 
     * @returns {void}
     * @access public
     * @static
     */
    AnPLoader.styles_loader = (styles, callback = null, i = 0) => {
        if(i == styles.length){
            AnPLoader.execute(callback);
            return;
        };

        /** @type {number} */
        let loaded = 0;
        /** @type {number} */
        const l = styles[i].length, 
              /** @type {anp_loader_default_callback} */
              end = () => {
                  ++ loaded == l && AnPLoader.styles_loader(styles, callback, i + 1);
              }, 
              /** @type {HTMLHeadElement} */
              head = document.querySelector("head");

        AnPLoader.get_array(styles[i]).forEach(style => {
            if(AnPLoader.is_string(style)){

                /** @type {HTMLScriptElement} */
                const item = head.appendChild(document.createElement("link")), 
                      /** @type {boolean} */
                      is_sass = style.slice(-5).toLowerCase() == ".scss";

                ["load", "error"].forEach(key => {
                    item.addEventListener(key, event => {
                        end();
                    });
                });

                item.setAttribute("type", "text/css;charset=utf-8");
                item.setAttribute("data-language", (is_sass ? "SASS/" : "") + "CSS3");
                item.setAttribute("rel", "stylesheet");
                if(is_sass){

                    /** @type {string} */
                    const css_file = style.substring(0, style.length - 5) + ".css";

                    item.setAttribute("href", css_file);
                    item.setAttribute("data-scss", style);
                    item.setAttribute("data-css-map", css_file + ".map");

                }else 
                    item.setAttribute("href", style);
                item.setAttribute("data-crossorigin", "anonymous");
                item.setAttribute("charset", "utf-8");

            }else 
                end();
        });

    };

    return AnPLoader;
})();