// This is the core JavaScript for the Spectrogram Editor.
// It handles file loading (.spec), visualization, tool interaction, and saving.

// --- Global Variables ---
let currentSpecData = null; // Stores the currently displayed/edited spectrogram data
let originalSpecData = null; // Stores the pristine, initially loaded spectrogram data
let dctSize = 512; // Default DCT size, read from header

let undoStack = [];
let redoStack = [];
const MAX_HISTORY_SIZE = 50;

let activeTool = null; // 'line', 'ellipse', 'noise', etc.
let isDrawing = false;
let startX, startY; // For tracking mouse down position

let shapes = []; // Array to store all drawn shapes (lines, ellipses, etc.)

// --- File Handling ---
const specFileInput = document.getElementById('specFileInput');
specFileInput.addEventListener('change', handleFileSelect);

async function handleFileSelect(event) {
    const file = event.target.files[0];
    if (!file) {
        return;
    }

    try {
        const buffer = await file.arrayBuffer();
        const dataView = new DataView(buffer);

        // Parse SPEC header
        const header = {
            magic: String.fromCharCode(...new Uint8Array(buffer.slice(0, 4))),
            version: dataView.getInt32(4, true),
            dct_size: dataView.getInt32(8, true),
            num_frames: dataView.getInt32(12, true)
        };

        if (header.magic !== "SPEC" || header.version !== 1) {
            console.error("Invalid SPEC file format.");
            alert("Invalid SPEC file format. Please load a valid .spec file.");
            return;
        }

        dctSize = header.dct_size;
        const dataStart = 16;
        const numBytes = header.num_frames * header.dct_size * Float32Array.BYTES_PER_ELEMENT;
        const spectralDataFloat = new Float32Array(buffer, dataStart, header.num_frames * header.dct_size);

        originalSpecData = { header: header, data: new Float32Array(spectralDataFloat) }; // Store pristine copy
        currentSpecData = { header: header, data: new Float32Array(spectralDataFloat) }; // Editable copy

        shapes = []; // Clear shapes on new file load
        undoStack = []; // Clear undo history
        redoStack = []; // Clear redo history

        console.log("Loaded SPEC file:", header);
        redrawCanvas(); // Redraw with new data

    } catch (error) {
        console.error("Error loading SPEC file:", error);
        alert("Failed to load SPEC file. Check console for details.");
    }
}

// --- Spectrogram Visualization ---
const canvas = document.getElementById('spectrogramCanvas');
const ctx = canvas.getContext('2d');

// Add canvas event listeners
canvas.addEventListener('mousedown', handleMouseDown);
canvas.addEventListener('mousemove', handleMouseMove);
canvas.addEventListener('mouseup', handleMouseUp);
canvas.addEventListener('mouseout', handleMouseUp); // Treat mouse out as mouse up

// Function to get a color based on intensity (0 to 1)
function getColorForIntensity(intensity) {
    // Example: Blue to white/yellow gradient
    const h = (1 - intensity) * 240; // Hue from blue (240) to red (0), inverse for intensity
    const s = 100; // Saturation
    const l = intensity * 50 + 50; // Lightness from 50 to 100
    return `hsl(${h}, ${s}%, ${l}%)`;
}

function drawSpectrogram(specData) {
    const width = canvas.width; 
    const height = canvas.height;

    ctx.clearRect(0, 0, width, height);
    ctx.fillStyle = '#ffffff';
    ctx.fillRect(0, 0, width, height);

    if (!specData || !specData.data || specData.header.num_frames === 0 || specData.data.length === 0) {
        console.warn("No spectrogram data or invalid header/data to draw.");
        return;
    }

    const numFrames = specData.header.num_frames;
    const binHeight = height / dctSize; // Height of each frequency bin
    const frameWidth = width / numFrames; // Width of each time frame

    // Find max value for normalization (for better visualization)
    let maxAbsValue = 0;
    for (let i = 0; i < specData.data.length; i++) {
        maxAbsValue = Math.max(maxAbsValue, Math.abs(specData.data[i]));
    }
    if (maxAbsValue === 0) maxAbsValue = 1; // Avoid division by zero

    // Draw each frame's spectral data
    for (let frameIndex = 0; frameIndex < numFrames; frameIndex++) {
        const frameDataStart = frameIndex * dctSize;
        const xPos = frameIndex * frameWidth;

        for (let binIndex = 0; binIndex < dctSize; binIndex++) {
            const value = specData.data[frameDataStart + binIndex];
            const intensity = Math.min(1, Math.abs(value) / maxAbsValue); // Normalized intensity
            
            ctx.fillStyle = getColorForIntensity(intensity);
            ctx.fillRect(xPos, height - (binIndex * binHeight) - binHeight, frameWidth, binHeight);
        }
    }

    // Draw active shapes on top (previews for current drawing tool)
    shapes.forEach(shape => {
        drawShape(shape);
    });
}

function drawShape(shape) {
    // This draws the final, persistent shape. Preview is drawn in handleMouseMove.
    ctx.strokeStyle = shape.color || 'red';
    ctx.lineWidth = shape.width || 2;
    
    switch (shape.type) {
        case 'line':
            ctx.beginPath();
            ctx.moveTo(shape.x1, shape.y1);
            ctx.lineTo(shape.x2, shape.y2);
            ctx.stroke();
            break;
        case 'ellipse':
            ctx.beginPath();
            ctx.ellipse(shape.cx, shape.cy, shape.rx, shape.ry, 0, 0, 2 * Math.PI);
            ctx.stroke();
            break;
        case 'noise_rect': // Noise is visualized as a rectangle
            ctx.fillStyle = 'rgba(0, 0, 255, 0.2)';
            ctx.fillRect(shape.x, shape.y, shape.width, shape.height);
            ctx.strokeStyle = 'blue';
            ctx.strokeRect(shape.x, shape.y, shape.width, shape.height);
            break;
    }
}

// --- Mouse Event Handlers ---
function getMousePos(event) {
    const rect = canvas.getBoundingClientRect();
    return {
        x: event.clientX - rect.left,
        y: event.clientY - rect.top
    };
}

function handleMouseDown(event) {
    if (!activeTool || !currentSpecData) return;
    isDrawing = true;
    const pos = getMousePos(event);
    startX = pos.x;
    startY = pos.y;
}

function handleMouseMove(event) {
    if (!isDrawing || !activeTool) return;
    const pos = getMousePos(event);
    
    redrawCanvas(); // Clear and redraw persistent state

    ctx.strokeStyle = 'rgba(0, 0, 0, 0.5)'; // Preview color
    ctx.lineWidth = 1;
    ctx.setLineDash([5, 5]); // Dashed line for preview

    switch (activeTool) {
        case 'line':
            ctx.beginPath();
            ctx.moveTo(startX, startY);
            ctx.lineTo(pos.x, pos.y);
            ctx.stroke();
            break;
        case 'ellipse':
            // Draw preview ellipse based on start and current pos (bounding box)
            const rx = Math.abs(pos.x - startX) / 2;
            const ry = Math.abs(pos.y - startY) / 2;
            const cx = startX + (pos.x - startX) / 2;
            const cy = startY + (pos.y - startY) / 2;
            if (rx > 0 && ry > 0) {
                ctx.beginPath();
                ctx.ellipse(cx, cy, rx, ry, 0, 0, 2 * Math.PI);
                ctx.stroke();
            }
            break;
        case 'noise':
            // Draw preview rectangle for noise area
            const rectX = Math.min(startX, pos.x);
            const rectY = Math.min(startY, pos.y);
            const rectW = Math.abs(pos.x - startX);
            const rectH = Math.abs(pos.y - startY);
            ctx.strokeRect(rectX, rectY, rectW, rectH);
            break;
    }
    ctx.setLineDash([]); // Reset line dash
}

function handleMouseUp(event) {
    if (!isDrawing || !activeTool || !currentSpecData) return;
    isDrawing = false;
    const endPos = getMousePos(event);

    let newShape = null;

    switch (activeTool) {
        case 'line': {
            const startCoords = canvasToSpectrogramCoords(startX, startY, currentSpecData);
            const endCoords = canvasToSpectrogramCoords(endPos.x, endPos.y, currentSpecData);
            newShape = {
                type: 'line',
                x1: startX, y1: startY,
                x2: endPos.x, y2: endPos.y,
                frame1: startCoords.frame, bin1: startCoords.bin,
                frame2: endCoords.frame, bin2: endCoords.bin,
                amplitude: 0.5, // Default amplitude
                width: 2,       // Default width (in canvas pixels for drawing, bins for spec)
                color: 'red',
            };
            break;
        }
        case 'ellipse': {
            const rx = Math.abs(endPos.x - startX) / 2;
            const ry = Math.abs(endPos.y - startY) / 2;
            const cx = startX + (endPos.x - startX) / 2;
            const cy = startY + (endPos.y - startY) / 2;

            const centerCoords = canvasToSpectrogramCoords(cx, cy, currentSpecData);
            const radiusXFrames = Math.floor((rx / canvas.width) * currentSpecData.header.num_frames);
            const radiusYBins = Math.floor((ry / canvas.height) * dctSize);

            newShape = {
                type: 'ellipse',
                cx: cx, cy: cy,
                rx: rx, ry: ry,
                frameC: centerCoords.frame, binC: centerCoords.bin,
                radiusFrames: radiusXFrames, radiusBins: radiusYBins,
                amplitude: 0.5,
                color: 'green',
            };
            break;
        }
        case 'noise': {
            const rectX = Math.min(startX, endPos.x);
            const rectY = Math.min(startY, endPos.y);
            const rectW = Math.abs(endPos.x - startX);
            const rectH = Math.abs(endPos.y - startY);

            const startCoords = canvasToSpectrogramCoords(rectX, rectY, currentSpecData);
            const endCoords = canvasToSpectrogramCoords(rectX + rectW, rectY + rectH, currentSpecData);

            newShape = {
                type: 'noise_rect',
                x: rectX, y: rectY,
                width: rectW, height: rectH,
                frame1: startCoords.frame, bin1: startCoords.bin,
                frame2: endCoords.frame, bin2: endCoords.bin,
                amplitude: 0.3, // Default noise amplitude
                density: 0.5,   // Default noise density
                color: 'blue',
            };
            break;
        }
    }

    if (newShape) {
        // Capture the state *before* applying the new shape for undo
        const previousDataSnapshot = new Float32Array(currentSpecData.data);
        const previousShapesSnapshot = shapes.map(s => ({ ...s })); // Deep copy shapes

        applyShapeToSpectrogram(newShape, currentSpecData); // Modify currentSpecData directly
        shapes.push(newShape);
        addAction({ 
            type: 'add_shape', 
            shape: newShape, 
            undo: () => {
                // Revert shapes array
                shapes = previousShapesSnapshot; 
                // Revert currentSpecData.data to the snapshot before this action
                currentSpecData.data = previousDataSnapshot;
            },
            redo: () => {
                // Re-apply the shape and update currentSpecData.data
                shapes.push(newShape);
                applyShapeToSpectrogram(newShape, currentSpecData);
            }
        });
    }
    redrawCanvas(); // Final redraw after action
    updateUndoRedoButtons();
}

function applyShapeToSpectrogram(shape, targetSpecData) {
    if (!targetSpecData || !targetSpecData.data || targetSpecData.header.num_frames === 0) return;

    const numFrames = targetSpecData.header.num_frames;

    switch (shape.type) {
        case 'line':
            // Bresenham's-like line drawing to apply to spectrogram data
            let x0 = shape.frame1, y0 = shape.bin1;
            let x1 = shape.frame2, y1 = shape.bin2;

            const dx = Math.abs(x1 - x0);
            const dy = Math.abs(y1 - y0);
            const sx = (x0 < x1) ? 1 : -1;
            const sy = (y0 < y1) ? 1 : -1;
            let err = dx - dy;

            let currentX = x0;
            let currentY = y0;

            while (true) {
                if (currentX >= 0 && currentX < numFrames && currentY >= 0 && currentY < dctSize) {
                    const index = currentX * dctSize + currentY;
                    // Apply amplitude and width
                    for (let b = -shape.width; b <= shape.width; b++) {
                        const binToAffect = currentY + b;
                        if (binToAffect >= 0 && binToAffect < dctSize) {
                            targetSpecData.data[currentX * dctSize + binToAffect] += shape.amplitude;
                            // Clamp value
                            targetSpecData.data[currentX * dctSize + binToAffect] = Math.max(-1, Math.min(1, targetSpecData.data[currentX * dctSize + binToAffect]));
                        }
                    }
                }

                if (currentX === x1 && currentY === y1) break;
                const e2 = 2 * err;
                if (e2 > -dy) { err -= dy; currentX += sx; }
                if (e2 < dx) { err += dx; currentY += sy; }
            }
            break;
        case 'ellipse':
            // Apply ellipse to spectrogram data
            // TODO: Implement ellipse algorithm
            console.log("Applying ellipse to spectrogram data (TODO).");
            break;
        case 'noise_rect':
            // Apply noise to a rectangular region
            const frameStart = Math.max(0, Math.min(numFrames - 1, shape.frame1));
            const frameEnd = Math.max(0, Math.min(numFrames - 1, shape.frame2));
            const binStart = Math.max(0, Math.min(dctSize - 1, shape.bin1));
            const binEnd = Math.max(0, Math.min(dctSize - 1, shape.bin2));

            for (let f = frameStart; f <= frameEnd; f++) {
                for (let b = binStart; b <= binEnd; b++) {
                    if (Math.random() < shape.density) {
                        targetSpecData.data[f * dctSize + b] += (Math.random() * 2 - 1) * shape.amplitude; // Random value between -amp and +amp
                        // Clamp value
                        targetSpecData.data[f * dctSize + b] = Math.max(-1, Math.min(1, targetSpecData.data[f * dctSize + b]));
                    }
                }
            }
            break;
    }
}

// --- Tool Interactions (Button Clicks) ---
const lineToolButton = document.getElementById('lineTool');
const ellipseToolButton = document.getElementById('ellipseTool');
const noiseToolButton = document.getElementById('noiseTool');
const undoButton = document.getElementById('undoButton');
const redoButton = document.getElementById('redoButton'); // New redo button

lineToolButton.addEventListener('click', () => { activeTool = 'line'; console.log('Line tool selected'); });
ellipseToolButton.addEventListener('click', () => { activeTool = 'ellipse'; console.log('Ellipse tool selected'); });
noiseToolButton.addEventListener('click', () => { activeTool = 'noise'; console.log('Noise tool selected'); });

undoButton.addEventListener('click', handleUndo);
redoButton.addEventListener('click', handleRedo); // Redo button listener

// --- Undo/Redo Logic ---
function addAction(action) {
    undoStack.push(action);
    if (undoStack.length > MAX_HISTORY_SIZE) {
        undoStack.shift(); 
    }
    redoStack = []; 
    updateUndoRedoButtons();
}

function handleUndo() {
    if (undoStack.length === 0) {
        console.log('Undo stack is empty.');
        return;
    }
    const actionToUndo = undoStack.pop();
    actionToUndo.undo(); // Execute the inverse operation stored in the action
    redoStack.push(actionToUndo);
    redrawCanvas(); 
    updateUndoRedoButtons();
}

function handleRedo() {
    if (redoStack.length === 0) {
        console.log('Redo stack is empty.');
        return;
    }

    const actionToRedo = redoStack.pop();
    actionToRedo.redo(); // Re-apply the action
    undoStack.push(actionToRedo);
    redrawCanvas(); 
    updateUndoRedoButtons();
}

function redrawCanvas() {
    console.log('Redrawing canvas...');
    if (!originalSpecData) {
        ctx.clearRect(0, 0, canvas.width, canvas.height);
        ctx.fillStyle = '#ffffff';
        ctx.fillRect(0, 0, canvas.width, canvas.height);
        return;
    }

    // Start with a fresh copy of the original data
    currentSpecData.data = new Float32Array(originalSpecData.data); 

    // Replay all shapes from the `shapes` array to `currentSpecData`
    shapes.forEach(shape => {
        applyShapeToSpectrogram(shape, currentSpecData); 
    });

    drawSpectrogram(currentSpecData); 
}

function updateUndoRedoButtons() {
    undoButton.disabled = undoStack.length === 0;
    redoButton.disabled = redoStack.length === 0; // Update redo button state
}

// --- Utility to map canvas coords to spectrogram bins/frames ---
function canvasToSpectrogramCoords(canvasX, canvasY, specData) {
    const canvasWidth = canvas.width;
    const canvasHeight = canvas.height;
    const numFrames = specData.header.num_frames;

    const frameIndex = Math.floor((canvasX / canvasWidth) * numFrames);
    const binIndex = Math.floor(((canvasHeight - canvasY) / canvasHeight) * dctSize);

    return { frame: frameIndex, bin: binIndex };
}

function spectrogramToCanvasCoords(frameIndex, binIndex, specData) {
    const canvasWidth = canvas.width;
    const canvasHeight = canvas.height;
    const numFrames = specData.header.num_frames;

    const canvasX = (frameIndex / numFrames) * canvasWidth;
    const canvasY = canvasHeight - ((binIndex / dctSize) * canvasHeight);

    return { x: canvasX, y: canvasY };
}

// Initial setup for canvas size (can be updated on window resize)
window.addEventListener('resize', () => {
    if (originalSpecData) {
        canvas.width = window.innerWidth * 0.7;
        canvas.height = 400; // Fixed height
        redrawCanvas();
    }
});

// Initial call to set button states
updateUndoRedoButtons();