/**
 * The class provides overreaching options for building the website.
 */
class PageBuilder {
    #cssClasses;
    #functions;
    #delayedFunctions;
    #repeatingFunctions;
    #functionNames;
    #cssElementIdentifiers;

    constructor() {
        this.#cssClasses = document.createElement("style");
        this.#functions = document.createElement("script");
        this.#functionNames = [];
        this.#cssElementIdentifiers = [];
        this.#delayedFunctions = [];
        this.#repeatingFunctions = {};
    }

    /**
     * Registers a function to be added later in a script tag in the head of the document.
     * @param {string} name 
     * @param {func} fun 
     */
    registerFunction(name, fun) {
        if (!this.#functionNames.includes(name)) {
            this.#functions.innerText += `const ${name} = ${fun};`;
            this.#functionNames.push(name);
        }
    }

    /**
     * @experimental Attention is adviced, registration mechanism doesn't work yet
     * @param {string} name The name the interval will be tied to
     * @param {Function} fun the function that is supposed to be executed repeatedly
     * @param {number} interval the time in ms between executions
     */
    registerRepeatingFunction(name, fun, interval) {
        if (!Object.keys(this.#repeatingFunctions).includes(name)) {
            this.#repeatingFunctions[name] = {
                name: name,
                fun: fun,
                interval: interval
            };
        }
    }

    /**
     * Adds the styling rules to the element identifiers into the style tag.
     * An elementDefinition can only be used once, repeated use will be ignored.
     * @param {string} elementDefinition The element identifier
     * @param {Map<string, string>} styleRuleMap The Styling rules/values
     */
    registerStyling(elementDefinition, styleRuleMap) {
        if (!this.#cssElementIdentifiers.includes(elementDefinition)) {
            this.#cssClasses.innerText += `${elementDefinition
                } {${Object.keys(styleRuleMap)
                    .map(e => e + ": " + styleRuleMap[e] + "; ")
                    .join(" ")
                }} `
            this.#cssElementIdentifiers.push(elementDefinition)
        }
    }

    /**
     * Adds into the (head) document. 
     * - script tag
     * - function tag
     * - sets and registers repeatedly executed functions
     * - sets (timeout and) functions that are supposed to be executed after load
     */
    generate() {
        let head = document.querySelector("head");
        head.appendChild(this.#functions)
        head.appendChild(this.#cssClasses)

        /* set repeating functions  */
        let repeatedFun = Object.values(this.#repeatingFunctions)
            .reduce((a, c, i, arr) => Object.assign(a, {
                [c.name]: setInterval(c.fun, c.interval)
            }), {});

        /* set timeouts for funcitons executed after load */
        for (let i = 0; i < this.#delayedFunctions.length; i++) {
            let func = this.#delayedFunctions[i];
            if (func.repeat) {
                setTimeout(setInterval(func.func, func.interval), func.dl, func.args);
            } else {
                setTimeout(func.func, func.dl, func.args);
            }
        }
        console.log(this.#functionNames);
    }

    /**
     * Registeres a function to be executed after page-load
     * @param {Function} func the function that will be executed
     * @param {number} delay the time in ms the execution is delayed after load
     * @param {string} name if provided the function will be registered as well
     * @param {Array<any>} args arguments for the function
     * @param {boolean} repeat defines if the function is supposed to be repeated as well
     * @param {number} interval if the function is supposed to repeat, this defines the interval of repetition
     */
    executeAfterLoad(func, delay = 1000, name = '', args = [], repeat = false, interval = 5000) {
        if (name !== '') {
            this.registerFunction(name, func);
        }
        this.#delayedFunctions.push({ dl: delay, func: func, args: args, repeat: repeat, interval: interval });
    }

    /**
     * 
     * @param {number} relaunchSeconds timeinterval for page to reload (changes)
     */
    inDev(relaunchSeconds = 20) {
        let head = document.querySelector("head");
        let meta = document.createElement("meta");
        meta.setAttribute("http-equiv", "refresh");
        meta.setAttribute("content", `${relaunchSeconds}`);

        head.insertAdjacentElement("beforeend", meta);
        this.#functions.innerText = `
            let ts = new Date();
            console.log("Refreshed at: ", ts.getHours()+':'+ts.getMinutes()+':'+ts.getSeconds(), "Intervall ${relaunchSeconds}s");
            `;
    }
}

const Page = new PageBuilder();