const inputConfig = {
    clickRadius: 10, // Radius to be considered a click (pixels). If farther, turns into a drag
    clickTiming: 500, // Timing window to be considered a click (ms). If longer, turns into a drag
    dClickTiming: 500, // Timing window to be considered a double click (ms).
};

/**
 * Mouse input processing
 */
// Base object generator functions
function _context_coords() {
    return {
        dragging: {
            left: null,
            middle: null,
            right: null,
        },

        prev: {
            x: 0,
            y: 0,
        },

        pos: {
            x: 0,
            y: 0,
        },
    };
}
function _mouse_observers() {
    return {
        // Simple click handlers
        onclick: new Observer(),
        // Double click handlers (will still trigger simple click handler as well)
        ondclick: new Observer(),
        // Drag handler
        ondragstart: new Observer(),
        ondrag: new Observer(),
        ondragend: new Observer(),
        // Paint handler (like drag handler, but with no delay); will trigger during clicks too
        onpaintstart: new Observer(),
        onpaint: new Observer(),
        onpaintend: new Observer(),
    };
}

function _context_observers() {
    return {
        onmousemove: new Observer(),
        left: _mouse_observers(),
        middle: _mouse_observers(),
        right: _mouse_observers(),
    };
}

const mouse = {
    buttons: {
        right: null,
        left: null,
        middle: null,
    },

    // Mouse Actions in Window Coordinates
    window: _context_coords(),

    // Mouse Actions in Canvas Coordinates
    canvas: _context_coords(),

    // Mouse Actions in World Coordinates
    world: _context_coords(),

    listen: {
        window: _context_observers(),
        canvas: _context_observers(),
        world: _context_observers(),
    },
};

function _mouse_state_snapshot() {
    return {
        buttons: window.structuredClone(mouse.buttons),
        window: window.structuredClone(mouse.window),
        canvas: window.structuredClone(mouse.canvas),
        world: window.structuredClone(mouse.world),
    };
}

const _double_click_timeout = {};
const _drag_start_timeout = {};

window.onmousedown = (evn) => {
    const time = new Date();

    // Processes for a named button
    const onhold = (key) => () => {
        if (_double_click_timeout[key]) {
            // ondclick event
            ['window', 'canvas', 'world'].forEach((ctx) =>
                mouse.listen[ctx][key].ondclick.emit({
                    buttonId: evn.button,
                    x: mouse[ctx].pos.x,
                    y: mouse[ctx].pos.y,
                    timestamp: new Date(),
                })
            );
        } else {
            // Start timer
            _double_click_timeout[key] = setTimeout(
                () => delete _double_click_timeout[key],
                inputConfig.dClickTiming
            );
        }

        // Set drag start timeout
        _drag_start_timeout[key] = setTimeout(() => {
            ['window', 'canvas', 'world'].forEach((ctx) => {
                mouse.listen[ctx][key].ondragstart.emit({
                    buttonId: evn.button,
                    x: mouse[ctx].pos.x,
                    y: mouse[ctx].pos.y,
                    timestamp: new Date(),
                });
                if (mouse[ctx].dragging[key])
                    mouse[ctx].dragging[key].drag = true;

                delete _drag_start_timeout[key];
            });
        }, inputConfig.clickTiming);

        ['window', 'canvas', 'world'].forEach((ctx) => {
            mouse.buttons[key] = time;
            mouse[ctx].dragging[key] = {};
            Object.assign(mouse[ctx].dragging[key], mouse[ctx].pos);

            // onpaintstart event
            mouse.listen[ctx][key].onpaintstart.emit({
                buttonId: evn.button,
                x: mouse[ctx].pos.x,
                y: mouse[ctx].pos.y,
                timestamp: new Date(),
            });
        });
    };

    // Runs the correct handler
    const buttons = [onhold('left'), onhold('middle'), onhold('right')];

    buttons[evn.button] && buttons[evn.button]();
};

window.onmouseup = (evn) => {
    const time = new Date();

    // Processes for a named button
    const onrelease = (key) => () => {
        ['window', 'canvas', 'world'].forEach((ctx) => {
            const start = {
                x: mouse[ctx].dragging[key].x,
                y: mouse[ctx].dragging[key].y,
            };

            // onclick event
            const dx = mouse[ctx].pos.x - start.x;
            const dy = mouse[ctx].pos.y - start.y;

            if (
                time.getTime() - mouse.buttons[key].getTime() <
                    inputConfig.clickTiming &&
                dx * dx + dy * dy <
                    inputConfig.clickRadius * inputConfig.clickRadius
            )
                mouse.listen[ctx][key].onclick.emit({
                    buttonId: evn.button,
                    x: mouse[ctx].pos.x,
                    y: mouse[ctx].pos.y,
                    timestamp: new Date(),
                });

            // onpaintend event
            mouse.listen[ctx][key].onpaintend.emit({
                buttonId: evn.button,
                x: mouse[ctx].pos.x,
                y: mouse[ctx].pos.y,
                timestamp: new Date(),
            });

            // ondragend event
            if (mouse[ctx].dragging[key].drag)
                mouse.listen[ctx][key].ondragend.emit({
                    buttonId: evn.button,
                    x: mouse[ctx].pos.x,
                    y: mouse[ctx].pos.y,
                    timestamp: new Date(),
                });

            mouse[ctx].dragging[key] = null;
        });

        if (_drag_start_timeout[key] !== undefined) {
            clearTimeout(_drag_start_timeout[key]);
            delete _drag_start_timeout[key];
        }
        mouse.buttons[key] = null;
    };

    // Runs the correct handler
    const buttons = [
        onrelease('left'),
        onrelease('middle'),
        onrelease('right'),
    ];

    buttons[evn.button] && buttons[evn.button]();
};

window.onmousemove = (evn) => {
    // Set Window Coordinates
    Object.assign(mouse.window.prev, mouse.window.pos);
    mouse.window.pos = { x: evn.clientX, y: evn.clientY };

    // Set Canvas Coordinates (using overlay canvas as reference)
    if (evn.target.id === 'overlayCanvas') {
        Object.assign(mouse.canvas.prev, mouse.canvas.pos);
        mouse.canvas.pos = { x: evn.layerX, y: evn.layerY };
    }

    // Set World Coordinates (For now the same as canvas coords; Will be useful with infinite canvas)
    if (evn.target.id === 'overlayCanvas') {
        Object.assign(mouse.world.prev, mouse.world.pos);
        mouse.world.pos = { x: evn.layerX, y: evn.layerY };
    }

    ['window', 'canvas', 'world'].forEach((ctx) => {
        mouse.listen[ctx].onmousemove.emit({
            px: mouse[ctx].prev.x,
            py: mouse[ctx].prev.y,
            x: mouse[ctx].pos.x,
            y: mouse[ctx].pos.y,
            timestamp: new Date(),
        });
        ['left', 'middle', 'right'].forEach((key) => {
            // ondrag event
            if (mouse[ctx].dragging[key] && mouse[ctx].dragging[key].drag)
                mouse.listen[ctx][key].ondrag.emit({
                    px: mouse[ctx].prev.x,
                    py: mouse[ctx].prev.y,
                    x: mouse[ctx].pos.x,
                    y: mouse[ctx].pos.y,
                    timestamp: new Date(),
                });

            // onpaint event
            if (mouse[ctx].dragging[key])
                mouse.listen[ctx][key].onpaint.emit({
                    px: mouse[ctx].prev.x,
                    py: mouse[ctx].prev.y,
                    x: mouse[ctx].pos.x,
                    y: mouse[ctx].pos.y,
                    timestamp: new Date(),
                });
        });
    });
};
/** MOUSE DEBUG */
/*
mouse.listen.window.right.onclick.on(() =>
    console.debug('mouse.listen.window.right.onclick')
);

mouse.listen.window.right.ondclick.on(() =>
    console.debug('mouse.listen.window.right.ondclick')
);
mouse.listen.window.right.ondragstart.on(() =>
    console.debug('mouse.listen.window.right.ondragstart')
);
mouse.listen.window.right.ondrag.on(() =>
    console.debug('mouse.listen.window.right.ondrag')
);
mouse.listen.window.right.ondragend.on(() =>
    console.debug('mouse.listen.window.right.ondragend')
);

mouse.listen.window.right.onpaintstart.on(() =>
    console.debug('mouse.listen.window.right.onpaintstart')
);
mouse.listen.window.right.onpaint.on(() =>
    console.debug('mouse.listen.window.right.onpaint')
);
mouse.listen.window.right.onpaintend.on(() =>
    console.debug('mouse.listen.window.right.onpaintend')
);
*/

/**
 * Mouse input processing
 */