// Top-level application container
export default (Toolkit,_package)=>class App extends Toolkit.Component {

    // Instance fields
    #components; // Registered Toolkit.Components
    #locale;     // Current display text dictionary
    #locales;    // Registered display text dictionaries
    #title;      // Application title



    ///////////////////////// Initialization Methods //////////////////////////

    static {
        _package.App = {
            localize: (a,c)=>a.#localize(c),
            onCreate: (a,c)=>a.#onCreate(c),
            onDelete: (a,c)=>a.#onDelete(c)
        };
    }

    constructor(overrides) {
        super(null, _package.override(overrides, { className: "tk-app" }));

        this.#components = new Set();
        this.#locale     = null;
        this.#locales    = new Map();
        this.#title      = null;
    }



    /////////////////////////////// Properties ////////////////////////////////

    // Display text dictionary
    get locale() { return this.#locale?.get("id"); }
    set locale(value) {

        // Unset the locale
        if (value == null) {
            if (this.#locale == null)
                return;
            this.#locale = null;
        }

        // Change to a different locale
        else {
            value = value == null ? null : String(value);
            if (this.#locale?.get("id") == value)
                return; // Same locale specified
            if (!this.#locales.has(value))
                throw new RangeError("No locale with ID " + value);
            this.#locale = this.#locales.get(value);
        }

        // Update all display text
        this.#localize();
    }

    // Display title
    get title() { return this.#title; }
    set title(value) {
        if (value != null && !(value instanceof RegExp))
            value = String(value);
        this.#title = value;
        this.#onLocalize();
    }



    ///////////////////////////// Public Methods //////////////////////////////

    // Register translation text
    addLocale(data) {

        // Error checking
        if (!(data instanceof Object))
            throw new TypeError("Data must be an object.");

        // Working variables
        let locale  = new Map();
        let objects = [ [null,data] ];

        // Process all objects
        while (objects.length != 0) {
            let object = objects.shift();
            let prefix = object[0] ? object[0] + "." : "";

            // Process all members of the object
            for (let entry of Object.entries(object[1])) {
                let key   = prefix + entry[0];
                let value = entry[1];

                // Add the new object to he queue
                if (value instanceof Object) {
                    objects.push([ key, entry[1] ]);
                    continue;
                }

                // Error checking
                if (typeof(value) != "string")
                    throw new TypeError("Non-string value encountered: "+key);

                // Register the localization value
                locale.set(key, new RegExp(value));
            }

        }

        // Validate "id"
        let id = locale.get("id");
        if (id == null)
            throw new Error("Locale does not contain \"id\" member.");

        // Register the locale
        this.#locales.set(id.source, locale);
        return id;
    }

    // Resolve the value of some display text
    translate(text, comp = null) {

        // Error checking
        if (comp != null) {
            if (!(comp instanceof Toolkit.Component))
                throw new TypeError("Component must be a Toolkit.Component.");
            if (comp != this && comp.app != this)
                throw new RangeError("Compoment must belong to this App.");
        }

        // Nothing to resolve
        if (text == null)
            return null;

        // Input validation
        if (!(text instanceof RegExp))
            text = String(text);

        // Working variables
        let locale = this.#locale;
        let ret    = [ text ];

        // Process all substitutions
        for (let x = 0; x < ret.length; x++) {
            let part = ret[x];

            // Do not perform substitutions
            if (!(part instanceof RegExp))
                continue;

            // Working variables
            part = part.source;

            // Locate the close of the innermost substitution
            let close = part.indexOf("}}");
            if (close == -1) {
                if (part.indexOf("{{") != -1)
                    throw new Error("Found {{ without matching }}.");
                ret[x] = part;
                continue;
            }

            // Locate the opening of the innermost substitution
            let open = part.substring(0, close).lastIndexOf("{{");
            if (open == -1)
                throw new Error("Found }} without matching {{.");

            // Working variables
            let after  = part.substring(close + 2);
            let before = part.substring(0, open);
            let key    = part.substring(open + 2, close).trim();
            let value  = comp?.getSubstitution(key) ?? locale?.get(key) ??
                "{{\u00d7" + key.toUpperCase() + "\u00d7}}";
            let within = value instanceof RegExp ? value.source : value;

            // Compose the replacement text
            part = before + within + after;
            if (value instanceof RegExp)
                ret[x--] = new RegExp(part);
            else ret[x] = part;
        }

        return ret.join("");
    }



    ///////////////////////////// Event Handlers //////////////////////////////

    // Component created
    #onCreate(comp) {
        this.#components.add(comp);
    }

    // Component deleted
    #onDelete(comp) {
        this.#components.delete(comp);
    }

    // Configure display text
    #onLocalize() {
        document.title = this.translate(this.#title, this) ?? "";
    }



    ///////////////////////////// Package Methods /////////////////////////////

    // Update the display text for one or all components
    #localize(comp = null) {
        for (comp of (comp == null ? this.#components : [comp]))
            _package.Component.onLocalize(comp);
    }

};