/**
 * GraphMinimap - Bản đồ thu nhỏ toàn bộ đồ thị
 * Hiển thị minimap ở góc màn hình, cho phép click/drag để điều hướng đồ thị chính.
 * Tự động ẩn khi số node < 20. Cung cấp nút toggle ẩn/hiện.
 * Requirements: 17.1, 17.2, 17.3, 17.4, 17.5
 */

class GraphMinimap {
    /**
     * @param {string} graphContainerId - ID of the main graph container element
     */
    constructor(graphContainerId) {
        /** @type {string} */
        this._graphContainerId = graphContainerId;

        /** @type {HTMLElement|null} Minimap overlay wrapper */
        this._wrapper = null;

        /** @type {HTMLElement|null} Canvas for minimap rendering */
        this._canvas = null;

        /** @type {HTMLElement|null} Viewport indicator rectangle */
        this._viewport = null;

        /** @type {HTMLElement|null} Toggle button */
        this._toggleBtn = null;

        /** @type {boolean} User preference: minimap visible */
        this._userVisible = true;

        /** @type {boolean} Auto-hidden because node count < threshold */
        this._autoHidden = false;

        /** @type {number} Threshold below which minimap auto-hides */
        this._autoHideThreshold = 20;

        /** @type {boolean} Whether user is dragging on the minimap */
        this._isDragging = false;

        /** @type {Function|null} Bound handler refs for cleanup */
        this._onMouseMoveBound = null;
        this._onMouseUpBound = null;

        /** @type {Function|null} EventBus unsubscribe for graph:rendered */
        this._unsubGraphRendered = null;

        /** @type {Function|null} EventBus unsubscribe for model:loaded */
        this._unsubModelLoaded = null;

        /** @type {number|null} requestAnimationFrame id */
        this._rafId = null;

        this._createDOM();
        this._bindEvents();
    }

    // ─── DOM Creation ──────────────────────────────────────────────────────────

    /**
     * Create the minimap overlay, canvas, viewport indicator, and toggle button.
     * @private
     */
    _createDOM() {
        // Wrapper – positioned in bottom-right corner of the graph container
        const wrapper = document.createElement('div');
        wrapper.className = 'graph-minimap-wrapper';
        wrapper.setAttribute('role', 'navigation');
        wrapper.setAttribute('aria-label', 'Graph minimap');
        wrapper.style.cssText = [
            'position: absolute',
            'bottom: 12px',
            'right: 12px',
            'width: 180px',
            'height: 130px',
            'background: rgba(255,255,255,0.95)',
            'border: 1px solid #ccc',
            'border-radius: 6px',
            'box-shadow: 0 2px 8px rgba(0,0,0,0.15)',
            'overflow: hidden',
            'z-index: 100',
            'display: none',
            'cursor: crosshair',
            'user-select: none'
        ].join(';');
        this._wrapper = wrapper;

        // Canvas for drawing the minimap graph
        const canvas = document.createElement('canvas');
        canvas.className = 'graph-minimap-canvas';
        canvas.width = 180;
        canvas.height = 130;
        canvas.style.cssText = 'width:100%;height:100%;display:block;';
        wrapper.appendChild(canvas);
        this._canvas = canvas;

        // Viewport indicator (semi-transparent rectangle showing visible area)
        const viewport = document.createElement('div');
        viewport.className = 'graph-minimap-viewport';
        viewport.style.cssText = [
            'position: absolute',
            'border: 2px solid #0d6efd',
            'background: rgba(13,110,253,0.1)',
            'pointer-events: none',
            'transition: none'
        ].join(';');
        wrapper.appendChild(viewport);
        this._viewport = viewport;

        // Toggle button – always visible near the minimap position
        const toggleBtn = document.createElement('button');
        toggleBtn.className = 'graph-minimap-toggle btn btn-sm btn-outline-secondary';
        toggleBtn.setAttribute('aria-label', 'Toggle minimap');
        toggleBtn.setAttribute('title', 'Toggle minimap');
        toggleBtn.innerHTML = '<i class="fas fa-map"></i>';
        toggleBtn.style.cssText = [
            'position: absolute',
            'bottom: 12px',
            'right: 12px',
            'z-index: 101',
            'display: none',
            'opacity: 0.8'
        ].join(';');
        this._toggleBtn = toggleBtn;

        // Append to graph container's parent (so they overlay the graph)
        const graphContainer = document.getElementById(this._graphContainerId);
        if (graphContainer) {
            // Ensure parent is positioned for absolute children
            const parent = graphContainer.parentElement;
            if (parent) {
                const pos = window.getComputedStyle(parent).position;
                if (pos === 'static') {
                    parent.style.position = 'relative';
                }
                parent.appendChild(wrapper);
                parent.appendChild(toggleBtn);
            }
        }
    }

    // ─── Event Binding ─────────────────────────────────────────────────────────

    /**
     * Bind all event listeners.
     * @private
     */
    _bindEvents() {
        // Toggle button click
        if (this._toggleBtn) {
            this._toggleBtn.addEventListener('click', (e) => {
                e.stopPropagation();
                this.toggle();
            });
        }

        // Minimap click → navigate main graph
        if (this._wrapper) {
            this._wrapper.addEventListener('mousedown', (e) => {
                e.preventDefault();
                e.stopPropagation();
                this._isDragging = true;
                this._navigateToPosition(e);
            });

            this._onMouseMoveBound = (e) => {
                if (this._isDragging) {
                    e.preventDefault();
                    this._navigateToPosition(e);
                }
            };

            this._onMouseUpBound = () => {
                this._isDragging = false;
            };

            document.addEventListener('mousemove', this._onMouseMoveBound);
            document.addEventListener('mouseup', this._onMouseUpBound);
        }

        // Listen for graph:rendered to update minimap
        if (typeof EventBus !== 'undefined' && typeof CONFIG !== 'undefined') {
            this._unsubGraphRendered = EventBus.on(CONFIG.EVENTS.GRAPH_RENDERED, () => {
                this._onGraphUpdated();
            });

            this._unsubModelLoaded = EventBus.on(CONFIG.EVENTS.MODEL_LOADED, () => {
                // Small delay to let graph render finish
                setTimeout(() => this._onGraphUpdated(), 300);
            });
        }
    }

    // ─── Core Logic ────────────────────────────────────────────────────────────

    /**
     * Called when the main graph is updated/rendered.
     * Determines visibility and redraws the minimap.
     * @private
     */
    _onGraphUpdated() {
        const cy = this._getCytoscapeInstance();
        if (!cy) {
            this._hide();
            return;
        }

        const nodeCount = cy.nodes().length;

        // Auto-hide when fewer than threshold nodes
        if (nodeCount < this._autoHideThreshold) {
            this._autoHidden = true;
            this._hide();
            if (this._toggleBtn) {
                this._toggleBtn.style.display = 'none';
            }
            return;
        }

        this._autoHidden = false;

        // Show toggle button
        if (this._toggleBtn) {
            this._toggleBtn.style.display = 'block';
        }

        // Show minimap if user preference is visible
        if (this._userVisible) {
            this._show();
        }

        this._drawMinimap(cy);
        this._updateViewport(cy);
        this._listenToCytoscapeEvents(cy);
    }

    /**
     * Draw the minimap representation of the graph onto the canvas.
     * @param {cytoscape.Core} cy
     * @private
     */
    _drawMinimap(cy) {
        if (!this._canvas) return;

        const ctx = this._canvas.getContext('2d');
        if (!ctx) return;

        const cw = this._canvas.width;
        const ch = this._canvas.height;

        ctx.clearRect(0, 0, cw, ch);

        // Get bounding box of all elements
        const bb = cy.elements().boundingBox();
        if (!bb || bb.w === 0 || bb.h === 0) return;

        // Compute scale to fit graph into minimap with padding
        const padding = 8;
        const scaleX = (cw - padding * 2) / bb.w;
        const scaleY = (ch - padding * 2) / bb.h;
        const scale = Math.min(scaleX, scaleY);

        const offsetX = padding + ((cw - padding * 2) - bb.w * scale) / 2;
        const offsetY = padding + ((ch - padding * 2) - bb.h * scale) / 2;

        // Draw edges
        ctx.strokeStyle = 'rgba(150,150,150,0.4)';
        ctx.lineWidth = 0.5;
        cy.edges().forEach(function (edge) {
            const src = edge.source().position();
            const tgt = edge.target().position();
            const x1 = (src.x - bb.x1) * scale + offsetX;
            const y1 = (src.y - bb.y1) * scale + offsetY;
            const x2 = (tgt.x - bb.x1) * scale + offsetX;
            const y2 = (tgt.y - bb.y1) * scale + offsetY;
            ctx.beginPath();
            ctx.moveTo(x1, y1);
            ctx.lineTo(x2, y2);
            ctx.stroke();
        });

        // Draw nodes
        cy.nodes().forEach(function (node) {
            var pos = node.position();
            var x = (pos.x - bb.x1) * scale + offsetX;
            var y = (pos.y - bb.y1) * scale + offsetY;

            var color = '#87CEEB'; // default
            if (node.hasClass('input-node')) color = '#28a745';
            else if (node.hasClass('output-node')) color = '#dc3545';
            else if (node.hasClass('initializer-node')) color = '#6c757d';
            else if (node.hasClass('highlighted')) color = '#FFD700';

            ctx.fillStyle = color;
            ctx.beginPath();
            ctx.arc(x, y, 2, 0, Math.PI * 2);
            ctx.fill();
        });

        // Store transform info for click-to-navigate
        this._transform = { bb: bb, scale: scale, offsetX: offsetX, offsetY: offsetY };
    }

    /**
     * Update the viewport indicator rectangle to reflect the main graph's visible area.
     * @param {cytoscape.Core} cy
     * @private
     */
    _updateViewport(cy) {
        if (!this._viewport || !this._canvas || !this._transform) return;

        var t = this._transform;
        var ext = cy.extent(); // visible area in model coordinates

        var left = (ext.x1 - t.bb.x1) * t.scale + t.offsetX;
        var top = (ext.y1 - t.bb.y1) * t.scale + t.offsetY;
        var width = ext.w * t.scale;
        var height = ext.h * t.scale;

        // Clamp to canvas bounds
        var cw = this._canvas.width;
        var ch = this._canvas.height;
        left = Math.max(0, Math.min(left, cw));
        top = Math.max(0, Math.min(top, ch));
        width = Math.min(width, cw - left);
        height = Math.min(height, ch - top);

        this._viewport.style.left = left + 'px';
        this._viewport.style.top = top + 'px';
        this._viewport.style.width = Math.max(width, 4) + 'px';
        this._viewport.style.height = Math.max(height, 4) + 'px';
    }

    /**
     * Listen to Cytoscape viewport events (zoom, pan) to keep minimap in sync.
     * @param {cytoscape.Core} cy
     * @private
     */
    _listenToCytoscapeEvents(cy) {
        // Remove previous listeners to avoid duplicates
        cy.off('viewport.minimap');

        cy.on('viewport.minimap', () => {
            if (this._rafId) cancelAnimationFrame(this._rafId);
            this._rafId = requestAnimationFrame(() => {
                this._updateViewport(cy);
            });
        });
    }

    /**
     * Navigate the main graph to the position clicked/dragged on the minimap.
     * @param {MouseEvent} e
     * @private
     */
    _navigateToPosition(e) {
        if (!this._wrapper || !this._transform) return;

        var cy = this._getCytoscapeInstance();
        if (!cy) return;

        var rect = this._wrapper.getBoundingClientRect();
        var clickX = e.clientX - rect.left;
        var clickY = e.clientY - rect.top;

        var t = this._transform;

        // Convert minimap coordinates back to graph model coordinates
        var modelX = (clickX - t.offsetX) / t.scale + t.bb.x1;
        var modelY = (clickY - t.offsetY) / t.scale + t.bb.y1;

        // Pan so the clicked model point is centered in the viewport
        var zoom = cy.zoom();
        cy.pan({
            x: cy.width() / 2 - modelX * zoom,
            y: cy.height() / 2 - modelY * zoom
        });

        // Update viewport indicator immediately
        this._updateViewport(cy);
    }

    /**
     * Get the Cytoscape instance from the GraphVisualizer.
     * @returns {cytoscape.Core|null}
     * @private
     */
    _getCytoscapeInstance() {
        // Try via the exposed _onnxApp debug interface
        if (window._onnxApp && typeof window._onnxApp.getGraphVisualizer === 'function') {
            var gv = window._onnxApp.getGraphVisualizer();
            if (gv && gv._cy) {
                return gv._cy;
            }
        }
        return null;
    }

    // ─── Visibility ────────────────────────────────────────────────────────────

    /**
     * Show the minimap overlay.
     * @private
     */
    _show() {
        if (this._wrapper) {
            this._wrapper.style.display = 'block';
        }
        // Shift toggle button to the left of the minimap
        if (this._toggleBtn) {
            this._toggleBtn.style.right = '198px';
        }
    }

    /**
     * Hide the minimap overlay.
     * @private
     */
    _hide() {
        if (this._wrapper) {
            this._wrapper.style.display = 'none';
        }
        // Reset toggle button position
        if (this._toggleBtn) {
            this._toggleBtn.style.right = '12px';
        }
    }

    // ─── Public API ────────────────────────────────────────────────────────────

    /**
     * Toggle minimap visibility (user preference).
     */
    toggle() {
        if (this._autoHidden) return; // Can't toggle when auto-hidden

        this._userVisible = !this._userVisible;
        if (this._userVisible) {
            this._show();
            // Redraw in case graph changed while hidden
            var cy = this._getCytoscapeInstance();
            if (cy) {
                this._drawMinimap(cy);
                this._updateViewport(cy);
            }
        } else {
            this._hide();
        }
    }

    /**
     * Show the minimap (programmatic).
     */
    show() {
        this._userVisible = true;
        if (!this._autoHidden) {
            this._show();
        }
    }

    /**
     * Hide the minimap (programmatic).
     */
    hide() {
        this._userVisible = false;
        this._hide();
    }

    /**
     * Force a redraw of the minimap. Call after external graph changes.
     */
    refresh() {
        this._onGraphUpdated();
    }

    /**
     * Check if the minimap is currently visible.
     * @returns {boolean}
     */
    isVisible() {
        return this._wrapper ? this._wrapper.style.display !== 'none' : false;
    }

    /**
     * Destroy and clean up all resources.
     */
    destroy() {
        // Cancel pending animation frame
        if (this._rafId) {
            cancelAnimationFrame(this._rafId);
            this._rafId = null;
        }

        // Remove document-level listeners
        if (this._onMouseMoveBound) {
            document.removeEventListener('mousemove', this._onMouseMoveBound);
            this._onMouseMoveBound = null;
        }
        if (this._onMouseUpBound) {
            document.removeEventListener('mouseup', this._onMouseUpBound);
            this._onMouseUpBound = null;
        }

        // Unsubscribe EventBus
        if (this._unsubGraphRendered) {
            this._unsubGraphRendered();
            this._unsubGraphRendered = null;
        }
        if (this._unsubModelLoaded) {
            this._unsubModelLoaded();
            this._unsubModelLoaded = null;
        }

        // Remove Cytoscape viewport listener
        var cy = this._getCytoscapeInstance();
        if (cy) {
            cy.off('viewport.minimap');
        }

        // Remove DOM elements
        if (this._wrapper && this._wrapper.parentNode) {
            this._wrapper.parentNode.removeChild(this._wrapper);
        }
        if (this._toggleBtn && this._toggleBtn.parentNode) {
            this._toggleBtn.parentNode.removeChild(this._toggleBtn);
        }

        this._wrapper = null;
        this._canvas = null;
        this._viewport = null;
        this._toggleBtn = null;
        this._transform = null;
    }
}

// Export as global for browser usage
window.GraphMinimap = GraphMinimap;