// SVG Editor JavaScript Module for LayoutEditor
// Handles mouse events, keyboard shortcuts, and coordinate transformations

let svgElement = null;
let dotNetRef = null;
let isInitialized = false;

/**
 * Initialize the SVG editor with event listeners
 * @param {SVGElement} svg - The SVG element
 * @param {DotNetObjectReference} dotNet - Reference to Blazor component
 */
export function initEditor(svg, dotNet) {
    svgElement = svg;
    dotNetRef = dotNet;
    
    if (!svgElement || !dotNetRef) {
        console.error('SVG Editor: Invalid initialization parameters');
        return;
    }
    
    // Mouse events
    svgElement.addEventListener('mousemove', handleMouseMove);
    svgElement.addEventListener('mousedown', handleMouseDown);
    svgElement.addEventListener('mouseup', handleMouseUp);
    svgElement.addEventListener('wheel', handleWheel, { passive: false });
    svgElement.addEventListener('contextmenu', handleContextMenu);
    
    // Keyboard events (on document to capture even when SVG not focused)
    document.addEventListener('keydown', handleKeyDown);
    
    // Prevent default drag behavior
    svgElement.addEventListener('dragstart', (e) => e.preventDefault());
    
    isInitialized = true;
    console.log('SVG Editor initialized');
}

/**
 * Dispose the editor and remove event listeners
 */
export function disposeEditor() {
    if (svgElement) {
        svgElement.removeEventListener('mousemove', handleMouseMove);
        svgElement.removeEventListener('mousedown', handleMouseDown);
        svgElement.removeEventListener('mouseup', handleMouseUp);
        svgElement.removeEventListener('wheel', handleWheel);
        svgElement.removeEventListener('contextmenu', handleContextMenu);
    }
    
    document.removeEventListener('keydown', handleKeyDown);
    
    svgElement = null;
    dotNetRef = null;
    isInitialized = false;
    console.log('SVG Editor disposed');
}

/**
 * Convert screen coordinates to SVG coordinates
 * @param {number} screenX - Screen X coordinate
 * @param {number} screenY - Screen Y coordinate
 * @returns {{x: number, y: number}} SVG coordinates
 */
function screenToSvg(screenX, screenY) {
    if (!svgElement) return { x: 0, y: 0 };
    
    const pt = svgElement.createSVGPoint();
    pt.x = screenX;
    pt.y = screenY;
    
    const ctm = svgElement.getScreenCTM();
    if (!ctm) return { x: 0, y: 0 };
    
    const svgPt = pt.matrixTransform(ctm.inverse());
    return { x: svgPt.x, y: svgPt.y };
}

/**
 * Export screenToSvg for use from Blazor
 * @param {number} screenX - Screen X coordinate
 * @param {number} screenY - Screen Y coordinate
 * @returns {number[]} SVG coordinates as [x, y]
 */
export function screenToSvgArray(screenX, screenY) {
    const coords = screenToSvg(screenX, screenY);
    return [coords.x, coords.y];
}

/**
 * Handle mouse move event
 * @param {MouseEvent} e 
 */
function handleMouseMove(e) {
    if (!dotNetRef) return;
    
    const svgCoords = screenToSvg(e.clientX, e.clientY);
    // Also pass screen coordinates for panning and ctrl key state
    dotNetRef.invokeMethodAsync('OnMouseMove', svgCoords.x, svgCoords.y, e.clientX, e.clientY, e.ctrlKey);
}

/**
 * Handle mouse down event
 * @param {MouseEvent} e 
 */
function handleMouseDown(e) {
    if (!dotNetRef) return;
    
    const svgCoords = screenToSvg(e.clientX, e.clientY);
    
    // For left clicks, always pass to Blazor
    // For middle/right clicks, filter out node/edge clicks
    const target = e.target;
    if (e.button !== 0 && // Not left click
        (target.classList.contains('node') || 
         target.classList.contains('edge') ||
         target.classList.contains('edge-arrow'))) {
        return;
    }
    
    // Pass all left clicks to Blazor (CreateEdge mode needs clicks anywhere)
    // Also pass screen coordinates for panning
    dotNetRef.invokeMethodAsync('OnMouseDown', svgCoords.x, svgCoords.y, e.button, e.ctrlKey, e.clientX, e.clientY);
}

/**
 * Handle mouse up event
 * @param {MouseEvent} e 
 */
function handleMouseUp(e) {
    if (!dotNetRef) return;
    
    const svgCoords = screenToSvg(e.clientX, e.clientY);
    dotNetRef.invokeMethodAsync('OnMouseUp', svgCoords.x, svgCoords.y, e.button);
}

/**
 * Handle mouse wheel event (zoom)
 * @param {WheelEvent} e 
 */
function handleWheel(e) {
    if (!dotNetRef) return;
    
    e.preventDefault();
    
    const svgCoords = screenToSvg(e.clientX, e.clientY);
    dotNetRef.invokeMethodAsync('OnWheel', svgCoords.x, svgCoords.y, e.deltaY);
}

/**
 * Handle context menu (right click)
 * @param {MouseEvent} e 
 */
function handleContextMenu(e) {
    // Prevent default context menu
    e.preventDefault();
    // TODO: Show custom context menu
}

/**
 * Handle keyboard events
 * @param {KeyboardEvent} e 
 */
function handleKeyDown(e) {
    if (!dotNetRef) return;
    
    // Only handle if not typing in an input
    const activeElement = document.activeElement;
    if (activeElement && (
        activeElement.tagName === 'INPUT' ||
        activeElement.tagName === 'TEXTAREA' ||
        activeElement.isContentEditable)) {
        return;
    }
    
    // Check for shortcuts
    if (e.ctrlKey || e.metaKey) {
        switch (e.key.toLowerCase()) {
            case 'z':
                e.preventDefault();
                dotNetRef.invokeMethodAsync('OnKeyDown', 'z', true);
                break;
            case 'y':
                e.preventDefault();
                dotNetRef.invokeMethodAsync('OnKeyDown', 'y', true);
                break;
            case 's':
                e.preventDefault();
                dotNetRef.invokeMethodAsync('OnKeyDown', 's', true);
                break;
            case 'c':
                e.preventDefault();
                dotNetRef.invokeMethodAsync('OnKeyDown', 'c', true);
                break;
            case 'm':
                e.preventDefault();
                dotNetRef.invokeMethodAsync('OnKeyDown', 'm', true);
                break;
        }
    } else {
        switch (e.key) {
            case 'Delete':
                e.preventDefault();
                dotNetRef.invokeMethodAsync('OnKeyDown', 'Delete', false);
                break;
            case 'Escape':
                e.preventDefault();
                dotNetRef.invokeMethodAsync('OnKeyDown', 'Escape', false);
                break;
        }
    }
}

/**
 * Utility: Get current viewBox values
 * @returns {{x: number, y: number, width: number, height: number}}
 */
export function getViewBox() {
    if (!svgElement) return { x: 0, y: 0, width: 100, height: 100 };
    
    const viewBox = svgElement.viewBox.baseVal;
    return {
        x: viewBox.x,
        y: viewBox.y,
        width: viewBox.width,
        height: viewBox.height
    };
}

/**
 * Utility: Set viewBox values
 * @param {number} x 
 * @param {number} y 
 * @param {number} width 
 * @param {number} height 
 */
export function setViewBox(x, y, width, height) {
    if (!svgElement) return;
    
    svgElement.setAttribute('viewBox', `${x} ${y} ${width} ${height}`);
}