function clearFromLocalStorage() {
	localStorage.removeItem(LOCAL_STORAGE_CANVAS_NAME);
	localStorage.removeItem(LOCAL_STORAGE_DIMENSIONS_NAME);
}

// }}}

// history {{{

function saveState(undoStack, redoStack, maxHistory) {
    if (undoStack.length >= maxHistory) {
        undoStack.shift();
    }
    undoStack.push({
        imageData: canvas.toDataURL(),
        width: canvas.width,
        height: canvas.height
    });
    redoStack = [];
}

function undo(canvas, ctx, undoStack, redoStack) {
    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

        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;

        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

        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;

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

// }}}