// noinspection JSUnresolvedVariable
const {$, doAfterLoad, footer, header, nav} = window.fwdekker;


/**
 * Returns a number between `min` (inclusive) and `max` (inclusive).
 *
 * @param min the lower bound of permissible values
 * @param max the upper bound of permissible values
 */
function generateRandom(min, max) {
    return Math.floor(Math.random() * (max - min + 1) + min);
}


/**
 * An input that can be validated.
 *
 * In particular, the century, year, and day inputs of the Doomsday test.
 *
 * @property input {HTMLInputElement} the input that is validatable
 * @property titleLabel {HTMLElement} the label of which to update the text
 * @property button {HTMLButtonElement} the submission button that activates validation
 */
class ValidatableInput {
    /**
     * Constructs a new validatable input and registers event listeners.
     *
     * @param input {HTMLInputElement} the input that is validatable
     * @param titleLabel {HTMLElement} the label of which to update the text
     * @param button {HTMLButtonElement} the submission button that activates validation
     */
    constructor(input, titleLabel, button) {
        this.input = input;
        this.titleLabel = titleLabel;
        this.button = button;

        this.button.addEventListener("click", () => this.onSubmit());
        this.input.addEventListener("keydown", event => {
            if (event.key !== "Enter")
                return;

            this.onSubmit();
            event.preventDefault();
        });
    }


    /**
     * Handles the user submitting the input.
     */
    onSubmit() {
        this.input.dataset["entered"] = "true";

        if (this.isValid(this.input.value)) {
            this.showSuccess();
            this.onValidInput();
        } else {
            this.showError();
            this.selectInput();
            this.onInvalidInput();
        }
    }

    /**
     * Returns `true` if and only if the input is valid.
     *
     * This method **must** be implemented by subclasses.
     *
     * @param value {string} the value of the input to validate
     * @return {boolean} `true` if and only if the input is valid
     */
    isValid(value) {
        throw new Error("Implement this method.");
    }

    /**
     * Runs when the user submits a valid input.
     *
     * This method **must** be implemented by subclasses.
     */
    onValidInput() {
        throw new Error("Implement this method.");
    }

    /**
     * Runs when a user submits an invalid input.
     *
     * This method **must** be implemented by subclasses.
     */
    onInvalidInput() {
        throw new Error("Implement this method.");
    }


    /**
     * Resets the input, title, and error message to their initial state, and removes the value from the input.
     */
    reset() {
        this.input.value = "";
        this.input.dataset["entered"] = "false";

        this.showSuccess();
        this.updateTitle();

        this.titleLabel.classList.remove("success-message");
        this.button.classList.remove("success-box");
    }

    /**
     * Marks the input as invalid.
     */
    showError() {
        this.input.setCustomValidity("Incorrect");

        this.titleLabel.classList.remove("success-message");
        this.titleLabel.classList.add("error-message");

        this.button.classList.remove("success-box");
        this.button.classList.add("error-box");
    }

    /**
     * Marks the input as valid.
     */
    showSuccess() {
        this.input.setCustomValidity("");

        this.titleLabel.classList.remove("error-message");
        this.titleLabel.classList.add("success-message");

        this.button.classList.remove("error-box");
        this.button.classList.add("success-box");
    }

    /**
     * Updates the title label's contents.
     *
     * Does nothing by default. Implement this method to make it do something.
     */
    updateTitle() {
        // Do nothing
    }


    /**
     * Focuses the input element.
     */
    selectInput() {
        this.input.select();
    }
}

/**
 * A wrapper around a `<details>` element that persists the state in local storage.
 */
class ToggleableSection {
    /**
     * Constructs a new `ToggleableSection`.
     *
     * @param name {string} the name to identify this component with in persistent storage
     * @param details {HTMLDetailsElement} the element that can be toggled
     */
    constructor(name, details) {
        this._name = name;
        this._details = details;
        this._details.addEventListener("toggle", () => this.onToggle(this.isOpened()));

        this._loadToggle();
    }


    /**
     * Returns `true` if and only if the component is currently open.
     *
     * @return {boolean} `true` if and only if the component is currently open.
     */
    isOpened() {
        return !!this._details.open;
    }

    /**
     * Opens or closes the component.
     *
     * @param isOpened {boolean} whether to open the component
     */
    setOpened(isOpened) {
        this._details.open = isOpened;
    }

    /**
     * This method is invoked whenever the component is toggled.
     *
     * @param isOpened {boolean} the new state of the component
     */
    onToggle(isOpened) {
        this._storeToggle();
    }


    /**
     * Persists the state of this component.
     *
     * @private
     */
    _storeToggle() {
        localStorage.setItem(`/tools/doomsday//toggle-${this._name}`, "" + this.isOpened());
    }

    /**
     * Reads the state of this component from persistent storage and applies it.
     *
     * @private
     */
    _loadToggle() {
        const target = localStorage.getItem(`/tools/doomsday//toggle-${this._name}`);
        if (target === null) {
            this.setOpened(true);
            this._storeToggle();
            return;
        }

        this.setOpened(target === "true");
    }
}

/**
 * A wrapper around the good ol' `Date` class that provides a bunch of useful Doomsday-specific methods.
 *
 * @property {Date} the underlying date
 */
class DoomsdayDate {
    /**
     * Wraps a `DoomsdayDate` around the given date.
     *
     * @param date {Date} the date to be wrapped
     */
    constructor(date) {
        this.date = date;
    }


    /**
     * Returns the number of this `DoomsdayDate`'s century.
     *
     * @return {number} the number of this `DoomsdayDate`'s century
     */
    getCentury() {
        return Math.floor(this.date.getFullYear() / 100);
    }

    /**
     * Returns the day of the week of the anchor of this `DoomsdayDate`'s century.
     *
     * @return {string} the day of the week of the anchor of this `DoomsdayDate`'s century
     */
    getCenturyAnchorString() {
        const centuryAnchorNumber = (5 * (this.getCentury() % 4)) % 7 + 2;
        return DoomsdayDate.dayNumberToString(centuryAnchorNumber);
    };

    /**
     * Returns the day of the week of the anchor day of this `DoomsdayDate`'s year.
     *
     * @return {string} the day of the week of the anchor day of this `DoomsdayDate`'s year
     */
    getYearAnchorString() {
        const anchorDate = new Date(this.date);
        anchorDate.setDate(4); // 4th
        anchorDate.setMonth(3); // April
        return DoomsdayDate.dayNumberToString(anchorDate.getDay());
    };

    /**
     * Returns the day of the week of this `DoomsdayDate`.
     *
     * @return {string} the day of the week of this `DoomsdayDate`
     */
    getWeekdayString() {
        return DoomsdayDate.dayNumberToString(this.date.getDay());
    };


    /**
     * Returns the name of the day given its 0-based index, where 0 is `Sunday`.
     *
     * @param dayNumber {number} the number of the day, as returned by `Date`'s `#getDay` function.
     * @return {string} the name of the day given its 0-based index, where 0 is `Sunday`
     */
    static dayNumberToString(dayNumber) {
        switch (dayNumber % 7) {
            case 0:
                return "Sunday";
            case 1:
                return "Monday";
            case 2:
                return "Tuesday";
            case 3:
                return "Wednesday";
            case 4:
                return "Thursday";
            case 5:
                return "Friday";
            case 6:
                return "Saturday";
        }
    };

    /**
     * Returns the day of the week corresponding to the given string.
     *
     * This is a convenience method for interpreting (incomplete) user inputs.
     *
     * @param dayString {string} the day of the week to expand
     * @return {string} the day of the week corresponding to the given string
     */
    static expandDayString(dayString) {
        dayString = dayString.toLowerCase();
        if (dayString.startsWith("m"))
            return "Monday";
        else if (dayString.startsWith("tu"))
            return "Tuesday";
        else if (dayString.startsWith("w"))
            return "Wednesday";
        else if (dayString.startsWith("th"))
            return "Thursday";
        else if (dayString.startsWith("f"))
            return "Friday";
        else if (dayString.startsWith("sa"))
            return "Saturday";
        else if (dayString.startsWith("su"))
            return "Sunday";
        else
            return undefined;
    }

    /**
     * Returns a random date in the range `0001-01-01` (inclusive) to `9999-12-31` (inclusive), wrapped inside a
     * `DoomsdayDate` object.
     *
     * @return {DoomsdayDate} a random date
     */
    static random() {
        // TODO Give custom dates to this method
        const minDate = new Date("0001-01-01").getTime() / 86400000;
        const maxDate = new Date("9999-12-31").getTime() / 86400000;
        return new DoomsdayDate(new Date(generateRandom(minDate, maxDate) * 86400000));
    }
}


doAfterLoad(() => {
    // Initialize template
    $("#nav").appendChild(nav("/Tools/Doomsday/"));
    $("#header").appendChild(header({
        title: "Doomsday",
        description: `
            Test your mastery of \
            <a href="https://en.wikipedia.org/wiki/Doomsday_rule">&#9099; Conway's Doomsday rule</a>
        `
    }));
    $("#footer").appendChild(footer({
        vcsURL: "https://git.fwdekker.com/FWDekker/doomsday/",
        version: "v%%VERSION_NUMBER%%"
    }));
    $("main").classList.remove("hidden");


    // Initialize quiz
    let quizDate;

    const centuryDetails = new class extends ToggleableSection {
        onToggle(isOpened) {
            super.onToggle(isOpened);
            if (isOpened) centuryInput.selectInput();
            centuryInput.updateTitle();
        }
    }("century", $("#century-details"));
    const yearDetails = new class extends ToggleableSection {
        onToggle(isOpened) {
            super.onToggle(isOpened);
            if (isOpened) yearInput.selectInput();
            yearInput.updateTitle();
        }
    }("year", $("#year-details"));

    const centuryInput = new class extends ValidatableInput {
        isValid(value) {
            console.log("# Validate century");
            console.log(`Input:    ${value}`);
            console.log(`Expanded: ${DoomsdayDate.expandDayString(value)}`);
            console.log(`Expected: ${quizDate.getCenturyAnchorString()}`);
            return DoomsdayDate.expandDayString(value) === quizDate.getCenturyAnchorString();
        }

        onValidInput() {
            this.input.value = DoomsdayDate.expandDayString(this.input.value);
            if (yearDetails.isOpened())
                yearInput.selectInput();
            else
                dayInput.selectInput();
        }

        onInvalidInput() {
            // Do nothing
        }

        updateTitle() {
            if (centuryDetails.isOpened())
                this.titleLabel.innerText = `Anchor day of century starting in ${quizDate.getCentury() * 100}?`;
            else
                this.titleLabel.innerText = `Century`;
        }
    }($("#century-input"), $("#century-title-label"), $("#century-submit"));
    const yearInput = new class extends ValidatableInput {
        isValid(value) {
            console.log("# Validate year");
            console.log(`Input:    ${value}`);
            console.log(`Expanded: ${DoomsdayDate.expandDayString(value)}`);
            console.log(`Expected: ${quizDate.getYearAnchorString()}`);
            return DoomsdayDate.expandDayString(value) === quizDate.getYearAnchorString();
        }

        onValidInput() {
            this.input.value = DoomsdayDate.expandDayString(this.input.value);
            dayInput.selectInput();
        }

        onInvalidInput() {
            // Do nothing
        }

        updateTitle() {
            if (yearDetails.isOpened())
                this.titleLabel.innerText = `Doomsday of year ${quizDate.date.getFullYear()}?`;
            else
                this.titleLabel.innerText = `Year`;
        }
    }($("#year-input"), $("#year-title-label"), $("#year-submit"));
    const dayInput = new class extends ValidatableInput {
        isValid(value) {
            console.log("# Validate day");
            console.log(`Input:    ${value}`);
            console.log(`Expanded: ${DoomsdayDate.expandDayString(value)}`);
            console.log(`Expected: ${quizDate.getWeekdayString()}`);
            return DoomsdayDate.expandDayString(value) === quizDate.getWeekdayString();
        }

        onValidInput() {
            this.input.value = DoomsdayDate.expandDayString(this.input.value);
            resetButton.focus();
        }

        onInvalidInput() {
            // Do nothing
        }

        updateTitle() {
            this.titleLabel.innerText = `Weekday of ${quizDate.date.toISOString().substr(0, 10)}?`;
        }
    }($("#day-input"), $("#day-title-label"), $("#day-submit"));

    const resetButton = $("#reset-button");
    resetButton.addEventListener("click", () => {
        console.log(" ");
        console.log(" ");
        reloadQuiz();
    });


    /**
     * Generates a new date for the quiz and resets the inputs to reflect this.
     */
    function reloadQuiz() {
        quizDate = DoomsdayDate.random();
        console.log("# Reset");
        console.log(`New date:  ${quizDate.date.toISOString().substr(0, 10)}`);
        console.log(`Century#:  ${quizDate.getCentury()}`);
        console.log(`Century:   ${quizDate.getCenturyAnchorString()}`);
        console.log(`Year:      ${quizDate.getYearAnchorString()}`);
        console.log(`Day:       ${quizDate.getWeekdayString()}`);

        centuryInput.reset();
        yearInput.reset();
        dayInput.reset();
        if (centuryDetails.isOpened())
            centuryInput.selectInput();
        else if (yearDetails.isOpened())
            yearInput.selectInput();
        else
            dayInput.selectInput();
    }

    // Let the fun begin
    reloadQuiz();
});