const { ApplicationV2, HandlebarsApplicationMixin } = foundry.applications.api;

export class SessionTrackerApp extends HandlebarsApplicationMixin(ApplicationV2) {
    static instance;

    constructor(options = {}) {
        super(options);
    }

    static DEFAULT_OPTIONS = {
        id: "session-tracker-app",
        tag: "aside",
        classes: ["session-tracker"],
        window: {
            frame: false,
            positioned: true,
        },
        position: {
            width: "auto",
            height: "auto",
        },
        actions: {
            increment: SessionTrackerApp.#onIncrement,
            decrement: SessionTrackerApp.#onDecrement,
        }
    };

    static PARTS = {
        content: {
            template: "modules/fvtt-session-tracker/templates/session-tracker.hbs",
        },
    };

    static initialize() {
        this.instance = new SessionTrackerApp();
        if (!game.settings.get("fvtt-session-tracker", "showTracker")) return;
        const pos = game.settings.get("fvtt-session-tracker", "position");
        this.instance.render(true, { position: pos });
    }

    async _prepareContext(options) {
        return {
            sessionNumber: game.settings.get("fvtt-session-tracker", "sessionCount"),
            scale: game.settings.get("fvtt-session-tracker", "scale"),
            isGM: game.user.isGM
        };
    }

    static async #onIncrement(event, target) {
        if (!game.user.isGM) return;
        const current = game.settings.get("fvtt-session-tracker", "sessionCount");
        await game.settings.set("fvtt-session-tracker", "sessionCount", current + 1);
    }

    static async #onDecrement(event, target) {
        if (!game.user.isGM) return;
        const current = game.settings.get("fvtt-session-tracker", "sessionCount");
        if (current <= 1) return;
        await game.settings.set("fvtt-session-tracker", "sessionCount", current - 1);
    }

    // Drag and drop support for positioning
    _onRender(context, options) {
        if (!game.user.isGM) return;

        const dragHandle = this.element;
        let isDragging = false;
        let startX, startY, startLeft, startTop;

        dragHandle.addEventListener('mousedown', (e) => {
            if (e.button !== 0) return; // Only left click
            isDragging = true;
            startX = e.clientX;
            startY = e.clientY;
            const rect = this.element.getBoundingClientRect();
            startLeft = rect.left;
            startTop = rect.top;

            this.element.style.cursor = 'grabbing';
        });

        window.addEventListener('mousemove', (e) => {
            if (!isDragging) return;
            const dx = e.clientX - startX;
            const dy = e.clientY - startY;

            const newLeft = startLeft + dx;
            const newTop = startTop + dy;

            this.element.style.left = `${newLeft}px`;
            this.element.style.top = `${newTop}px`;
        });

        window.addEventListener('mouseup', () => {
            if (!isDragging) return;
            isDragging = false;
            this.element.style.cursor = 'move';

            // Save position
            const rect = this.element.getBoundingClientRect();
            const pos = {
                top: rect.top,
                left: rect.left
            };

            // Update the application's position state
            this.position.top = pos.top;
            this.position.left = pos.left;

            // Save to settings for persistence across sessions
            game.settings.set("fvtt-session-tracker", "position", pos);
        });
    }
}