// init {{{

const menuBar = document.getElementById('menu-bar');
const toolBar = document.getElementById('tool-bar');
const layerBar = document.getElementById('layer-bar');
const canvasArea = document.getElementById('canvas-area');
const infoBar = document.getElementById('info-bar');
const canvasContainer = document.getElementById('canvas-container');
const brushPreview = document.getElementById('brush-preview');

const canvas = document.getElementById('canvas');
const ctx = canvas.getContext('2d');
ctx.imageSmoothingEnabled = false;
ctx.webkitImageSmoothingEnabled = false;
ctx.mozImageSmoothingEnabled = false;
ctx.fillStyle = 'white';
ctx.fillRect(0, 0, canvas.width, canvas.height);

canvas.width = 800;
canvas.height = 600;
let canvasWidth = canvas.width;
let canvasHeight = canvas.height;

let undoStack = [];
let redoStack = [];
let maxHistory = 30;

const dZoom = 0.001;

let zoom = 1;
let brushSize = 5;
let dBrushSize = 0.5;
let maxBrushSize = 500;
let color = 'rgb(0, 0, 0)';
let tool

let tempCanvas;
let startX, startY;
let endX, endY;
let dX, dY;
let canvasStartX
let canvasStartY;
let canvasEndX;
let canvasEndY;
let canvasDX
let canvasDY;

let isMouseDown = false;

const colorPreview = document.createElement('div');
colorPreview.id = 'color-preview';
colorPreview.className = 'puck';
colorPreview.style.backgroundColor = color;

menuBar.appendChild(colorPreview);


// }}}

// helpers {{{

function saveState() {
    if (undoStack.length >= maxHistory) {
        undoStack.shift(); // Remove the oldest state if the stack exceeds the limit
    }

    // Save the current canvas content and dimensions
    undoStack.push({
        imageData: canvas.toDataURL(),
        width: canvas.width,
        height: canvas.height
    });

    redoStack = []; // Clear the redo stack whenever a new action is performed
}

function undo() {
    if (undoStack.length > 0) {
        const currentState = {
            imageData: canvas.toDataURL(),
            width: canvas.width,
            height: canvas.height
        };

        redoStack.push(currentState); // Save current state to the redo stack
        const lastState = undoStack.pop(); // Get the last state from the undo stack

        // Restore the canvas dimensions
        canvas.width = lastState.width;
        canvas.height = lastState.height;
		canvas.style.width = canvas.width * zoom + 'px';
		canvas.style.height = canvas.height * zoom + 'px';
		canvasWidth = canvas.width;
		canvasHeight = canvas.height;

        // Restore the canvas content
        const img = new Image();
        img.src = lastState.imageData;
        img.onload = function() {
            ctx.clearRect(0, 0, canvas.width, canvas.height);
            ctx.drawImage(img, 0, 0);
        };
    }
}

function redo() {
    if (redoStack.length > 0) {
        const currentState = {
            imageData: canvas.toDataURL(),
            width: canvas.width,
            height: canvas.height
        };

        undoStack.push(currentState); // Save current state to the undo stack
        const nextState = redoStack.pop(); // Get the last state from the redo stack

        // Restore the canvas dimensions
        canvas.width = nextState.width;
        canvas.height = nextState.height;
		canvas.style.width = canvas.width * zoom + 'px';
		canvas.style.height = canvas.height * zoom + 'px';
		canvasWidth = canvas.width;
		canvasHeight = canvas.height;

        // Restore the canvas content
        const img = new Image();
        img.src = nextState.imageData;
        img.onload = function() {
            ctx.clearRect(0, 0, canvas.width, canvas.height);
            ctx.drawImage(img, 0, 0);
        };
    }
}

function getPositionOnCanvas(e) {
	const rect = canvas.getBoundingClientRect();
    return {
      x: Math.round((e.clientX - rect.left) / zoom),
      y: Math.round((e.clientY - rect.top) / zoom),
    };
}

function drawCircle(x, y) {
    ctx.beginPath();
    ctx.arc(x, y, brushSize / 2, 0, 2 * Math.PI, false);
    ctx.fillStyle = color;
    ctx.fill();
}

function drawLineWithCircles(x1, y1, x2, y2) {
    const dx = x2 - x1;
    const dy = y2 - y1;
    const distance = Math.sqrt(dx * dx + dy * dy);
    const steps = Math.ceil(distance / (brushSize / 5));

    for (let i = 0; i <= steps; i++) {
        const x = x1 + (dx * i) / steps;
        const y = y1 + (dy * i) / steps;
        drawCircle(x, y);
    }
}

function saveCanvasContents() {
	tempCanvas = document.createElement('canvas');
	tempCanvas.width = canvas.width;
	tempCanvas.height = canvas.height;
	const tempCtx = tempCanvas.getContext('2d');
	tempCtx.drawImage(canvas, 0, 0);
}

function updateColorPreview() {
	colorPreview.style.backgroundColor = color;
}

function hexToRgbArray(hex) {
    if (hex.startsWith('#')) {
        hex = hex.slice(1);
    }

    if (hex.length === 3) {
        hex = hex.split('').map(char => char + char).join('');
    }

    const bigint = parseInt(hex, 16);
    return [(bigint >> 16) & 255, (bigint >> 8) & 255, bigint & 255];
}

function floodFill(x, y, fillColor) {
    const imageData = ctx.getImageData(0, 0, canvas.width, canvas.height);
    const data = imageData.data;

    const targetColor = getColorAtPixel(data, x, y);
    const fillColorArray = hexToRgbArray(fillColor);

    if (colorsMatch(targetColor, fillColorArray)) {
        return; // The clicked point is already the fill color
    }

    const stack = [{x, y}];

    while (stack.length > 0) {
        const {x, y} = stack.pop();
        const currentColor = getColorAtPixel(data, x, y);

        if (colorsMatch(currentColor, targetColor)) {
            setColorAtPixel(data, x, y, fillColorArray);

            if (x > 0) stack.push({x: x - 1, y});
            if (x < canvas.width - 1) stack.push({x: x + 1, y});
            if (y > 0) stack.push({x, y: y - 1});
            if (y < canvas.height - 1) stack.push({x, y: y + 1});
        }
    }

    ctx.putImageData(imageData, 0, 0);
}

function getColorAtPixel(data, x, y) {
    const index = (y * canvas.width + x) * 4;
    return [data[index], data[index + 1], data[index + 2], data[index + 3]];
}

function setColorAtPixel(data, x, y, color) {
    const index = (y * canvas.width + x) * 4;
    data[index] = color[0];
    data[index + 1] = color[1];
    data[index + 2] = color[2];
    data[index + 3] = 255; // Set alpha to fully opaque
}

function colorsMatch(a, b) {
    return a[0] === b[0] && a[1] === b[1] && a[2] === b[2] && a[3] === b[3];
}

// }}}

// mousedown {{{

canvasArea.addEventListener('mousedown', (e) => {
	if (e.target.closest('.puck')) return;

	startX = e.clientX;
	startY = e.clientY;
	canvasStartX = getPositionOnCanvas(e).x;
	canvasStartY = getPositionOnCanvas(e).y;
	saveCanvasContents();
	isMouseDown = true;

	if (
		tool === 'draw' ||
		tool === 'content-move' ||
		tool === 'resize' ||
		tool === 'zoom' ||
		tool === 'bucket-fill'
	) {
		saveState();
	}

	if (tool === 'draw') {
		drawCircle(canvasStartX, canvasStartY);
	} else if (tool === 'bucket-fill') {
        floodFill(canvasStartX, canvasStartY, color);
        return;
	} else if (tool === 'move') {
		startX = e.clientX - canvasContainer.offsetLeft;
		startY = e.clientY - canvasContainer.offsetTop;
	} else if (tool === 'color-picker') {
        const imageData = ctx.getImageData(canvasStartX, canvasStartY, 1, 1).data;
        const pickedColor = `rgb(${imageData[0]}, ${imageData[1]}, ${imageData[2]})`;
        color = pickedColor;
        console.log('Picked Color:', pickedColor);
        updateColorPreview();
        return;
	}
});

// }}}

// mousemove {{{

canvasArea.addEventListener('mousemove', (e) => {

	endX = e.clientX;
	endY = e.clientY;
	dX = endX - startX;
	dY = endY - startY;

	canvasEndX = getPositionOnCanvas(e).x;
	canvasEndY = getPositionOnCanvas(e).y;
	canvasDX = canvasEndX - canvasStartX;
	canvasDY = canvasEndY - canvasStartY;

	if (tool == 'brush-size') {
		brushPreview.style.display = 'block';
		brushPreview.style.width = brushSize + 'px';
		brushPreview.style.height = brushSize + 'px';
		brushPreview.style.left = e.clientX - brushSize / 2 + 'px';
		brushPreview.style.top = e.clientY - brushSize / 2 + 'px';
	}

	if (isMouseDown) {

		if (tool === 'brush-size') {
			brushSize += dX * dBrushSize;
			if (brushSize < 1) brushSize = 1;
			if (brushSize > maxBrushSize) brushSize = maxBrushSize;
			startX = endX;
		} else if (tool === 'draw') {
			drawLineWithCircles(canvasStartX, canvasStartY, canvasEndX, canvasEndY);

			canvasStartX = canvasEndX;
			canvasStartY = canvasEndY;

		} else if (tool === 'content-move') {
			ctx.clearRect(0, 0, canvas.width, canvas.height);
			ctx.drawImage(tempCanvas, dX, dY);
		} else if (tool === 'move') {
			canvasContainer.style.left = dX + 'px';
			canvasContainer.style.top = dY + 'px';
		} else if (tool === 'zoom') {
			zoom += dX * dZoom;
			if (zoom < 0.1) zoom = 0.1;
			canvas.style.height = canvasHeight * zoom + 'px';
			canvas.style.width = canvasWidth * zoom + 'px';
			startX = endX;
		} else if (tool === 'resize') {
			let newWidth = canvasWidth + dX / zoom;
			let newHeight = canvasHeight + dY / zoom;
			if (newWidth > 0 && newHeight > 0) {
				canvas.width = newWidth;
				canvas.height = newHeight;
				canvas.style.width = newWidth * zoom + 'px';
				canvas.style.height = newHeight * zoom + 'px';
				ctx.clearRect(0, 0, canvas.width, canvas.height);
				ctx.drawImage(tempCanvas, 0, 0);
			}
		} else if (tool === 'color-mix') {
            const imageData = ctx.getImageData(canvasEndX, canvasEndY, 1, 1).data;
            const canvasColor = `rgb(${imageData[0]}, ${imageData[1]}, ${imageData[2]})`;

            const distance = Math.sqrt(Math.pow(e.clientX - startX, 2) + Math.pow(e.clientY - startY, 2));
            const t = Math.min(1, distance / 300);

            const mixedColor = mixbox.lerp(color, canvasColor, t);

            color = mixedColor;

            startX = e.clientX;
            startY = e.clientY;

        } 

	}	
	
	updateInfos();
	updateColorPreview();
});

// }}}

// mouseup {{{

canvasArea.addEventListener('mouseup', (e) => {
	isMouseDown = false;
	if (tool === 'draw') {
		ctx.closePath();
	} else if (tool === 'resize') {
		canvasWidth = canvas.width;
		canvasHeight = canvas.height;
	}

	updateColorPreview();
});

// }}}

// mouseleave {{{

canvasArea.addEventListener('mouseleave', (e) => {
	brushPreview.style.display = 'none';
});

// }}}

// tools {{{

var toolButtons = [];

function createToolButton(icon, buttonTool) {
	const button = document.createElement('div');
	button.classList.add('button');
	button.classList.add('tool');
	button.innerHTML = icon;
	button.title = buttonTool;
	button.addEventListener('click', () => {
		buttons = document.getElementsByClassName('tool-button');
		toolButtons.forEach(button => button.button.classList.remove('active'));
		button.classList.add('active');
		tool = buttonTool;
		updateInfos();
	});
	toolBar.appendChild(button);
	return button;
}

toolButtons.push({'name': 'draw', 'button': createToolButton('<i class="fa-solid fa-paintbrush"></i>', 'draw')});
toolButtons.push({'name': 'content-move', 'button': createToolButton('<i class="fa-regular fa-hand"></i>', 'content-move')});
toolButtons.push({'name': 'move', 'button': createToolButton('<i class="fa-solid fa-arrows-up-down-left-right"></i>', 'move')});
toolButtons.push({'name': 'zoom', 'button': createToolButton('<i class="fa-solid fa-magnifying-glass"></i>', 'zoom')});
toolButtons.push({'name': 'resize', 'button': createToolButton('<i class="fa-solid fa-ruler-combined"></i>', 'resize')});
toolButtons.push({'name': 'color-picker', 'button': createToolButton('<i class="fa-solid fa-eye-dropper"></i>', 'color-picker')});
toolButtons.push({'name': 'color-mix', 'button': createToolButton('<i class="fa-solid fa-mortar-pestle"></i>', 'color-mix')});
toolButtons.push({'name': 'brush-size', 'button': createToolButton('<i class="fa-regular fa-circle-dot"></i>', 'brush-size')});
toolButtons.push({'name': 'bucket-fill', 'button': createToolButton('<i class="fa-solid fa-fill"></i>', 'bucket-fill')});

// }}}

// menu functons {{{

function flipCanvasHorizontally(e) {
	saveState();
	ctx.save();
	saveCanvasContents();
	ctx.clearRect(0, 0, canvas.width, canvas.height);
	ctx.scale(-1, 1);
	ctx.translate(-canvas.width, 0);
	ctx.drawImage(tempCanvas, 0, 0);
	ctx.restore();
}

function flipCanvasVertically(e) {
	saveState();
	ctx.save();
	saveCanvasContents();
	ctx.clearRect(0, 0, canvas.width, canvas.height);
	ctx.scale(1, -1);
	ctx.translate(0, -canvas.height);
	ctx.drawImage(tempCanvas, 0, 0);
	ctx.restore();
}

function saveCanvas(e) {
	const link = document.createElement('a');
	link.download = 'canvas.png';
	link.href = canvas.toDataURL();
	link.click();
}

function openCanvas(e) {
	const input = document.createElement('input');
	input.type = 'file';
	input.accept = 'image/*';
	input.onchange = (e) => {
		const file = e.target.files[0];
		const reader = new FileReader();
		reader.onload = (e) => {
			const img = new Image();
			img.onload = () => {
				canvas.width = img.width;
				canvas.height = img.height;
				ctx.drawImage(img, 0, 0);
			}
			img.src = e.target.result;
		}
		reader.readAsDataURL(file);
	}
	input.click();
}

function clearCanvas(e) {
	saveState();
	ctx.clearRect(0, 0, canvas.width, canvas.height);
}

function resetZoom(e) {
	zoom = 1;
	canvas.style.width = canvas.width * zoom + 'px';
	canvas.style.height = canvas.height * zoom + 'px';
	canvasWidth = canvas.width;
	canvasHeight = canvas.height;

	canvasAreaRect = canvasArea.getBoundingClientRect();

	canvasContainer.style.left = `${canvasAreaRect.left}px`;
	canvasContainer.style.top = `${canvasAreaRect.top}px`;
}

// }}}

// menu {{{

var menuButtons = [];

function createMenuButton(icon, name, clickFunction) {
	const button = document.createElement('div');
	button.className = 'button';
	button.innerHTML = icon;
	button.title = name;
	if (clickFunction) {
		button.addEventListener('click', (e) => {
			clickFunction(e)
			updateInfos();
		});
	}
	menuBar.appendChild(button);
	return button;
}

menuButtons.push(createMenuButton('<i class="fa-regular fa-folder-open"></i>', 'Open', openCanvas));
menuButtons.push(createMenuButton('<i class="fa-solid fa-floppy-disk"></i>', 'Save', saveCanvas));
menuButtons.push(createMenuButton('<i class="fa-solid fa-left-right"></i>', 'Flip Horizontally', flipCanvasHorizontally));
menuButtons.push(createMenuButton('<i class="fa-solid fa-up-down"></i>', 'Flip Vertically', flipCanvasVertically));
menuButtons.push(createMenuButton('<i class="fa-solid fa-undo"></i>', 'Undo', undo));
menuButtons.push(createMenuButton('<i class="fa-solid fa-redo"></i>', 'Redo', redo));
menuButtons.push(createMenuButton('<i class="fa-regular fa-trash-can"></i>', 'Clear', clearCanvas));
menuButtons.push(createMenuButton('<i class="fa-solid fa-search-minus"></i>', 'Reset Zoom', resetZoom));

// }}}

// pucks {{{

function createPuck(c) {
	const puck = document.createElement('div');
	puck.className = 'puck';
	puck.style.backgroundColor = c;

	puck.addEventListener('click', () => {
		color = c;
		updateColorPreview();
		updateInfos();
	});

	menuBar.appendChild(puck);
}

createPuck('rgb(255, 0, 0)');
createPuck('rgb(0, 255, 0)');
createPuck('rgb(0, 0, 255)');
createPuck('rgb(255, 255, 0)');
createPuck('rgb(255, 0, 255)');
createPuck('rgb(0, 255, 255)');
createPuck('rgb(0, 0, 0)');
createPuck('rgb(255, 255, 255)');

// }}}

// info {{{

var infos = [];

function createInfo(name, updateFunction) {
	const info = document.createElement('span');
	info.className = 'info';
	const key = document.createElement('span');
	key.className = 'key';
	key.innerHTML = name + ':';
	const value = document.createElement('span');
	value.className = 'value';
	value.innerHTML = '0';
	info.appendChild(key);
	info.appendChild(value);
	infoBar.appendChild(info);
	function update() {
		let v = updateFunction();
		if (v === undefined) v = '?';
		value.innerHTML = v;
	}
	return update;
}

infos.push(createInfo('tool', function() { return tool; }));
infos.push(createInfo('zoom', function() { 
	var percent = zoom * 100;
	return percent.toFixed(0) + '%';
}));
infos.push(createInfo('brush', function() { return brushSize; }));
infos.push(createInfo('x', function() { return canvasEndX; }));
infos.push(createInfo('y', function() { return canvasEndY; }));
infos.push(createInfo('color', function() { return color; }));
infos.push(createInfo('width', function() { return canvas.width; }));
infos.push(createInfo('height', function() { return canvas.height; }));

function updateInfos() {
	infos.forEach(info => info());
}

// }}}

// start {{{

updateInfos();
toolButtons[0]['button'].click();

// }}}