/**
 * FullscreenManager - Quản Lý Chế Độ Toàn Màn Hình
 * Cung cấp nút "Fullscreen" để mở rộng card đồ thị chiếm toàn bộ viewport.
 * Sử dụng Fullscreen API gốc của trình duyệt.
 * Requirements: 26.1, 26.2, 26.3, 26.4, 26.5, 26.6
 */

const FullscreenManager = (function () {
    class FullscreenManager {
        /**
         * @param {string} graphCardSelector - CSS selector cho card chứa đồ thị
         */
        constructor(graphCardSelector) {
            /** @type {string} */
            this._cardSelector = graphCardSelector;

            /** @type {HTMLElement|null} */
            this._cardElement = null;

            /** @type {HTMLButtonElement|null} */
            this._btn = null;

            /** @type {Function|null} */
            this._onFullscreenChangeBound = null;

            /** @type {boolean} */
            this._initialized = false;
        }

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

        /**
         * Khởi tạo: tìm card element, tạo nút fullscreen, gắn event listeners.
         */
        init() {
            if (this._initialized) return;

            this._cardElement = this._resolveCardElement();
            if (!this._cardElement) {
                console.warn('[FullscreenManager] Card element not found for selector:', this._cardSelector);
                return;
            }

            this._createButton();
            this._bindEvents();
            this._initialized = true;
            console.log('[FullscreenManager] Initialized');
        }

        /**
         * Vào chế độ toàn màn hình cho card đồ thị.
         */
        enterFullscreen() {
            if (!this._cardElement) return;
            if (this.isFullscreen()) return;

            const el = this._cardElement;
            if (el.requestFullscreen) {
                el.requestFullscreen();
            } else if (el.webkitRequestFullscreen) {
                el.webkitRequestFullscreen();
            } else if (el.msRequestFullscreen) {
                el.msRequestFullscreen();
            }
        }

        /**
         * Thoát chế độ toàn màn hình.
         */
        exitFullscreen() {
            if (!this.isFullscreen()) return;

            if (document.exitFullscreen) {
                document.exitFullscreen();
            } else if (document.webkitExitFullscreen) {
                document.webkitExitFullscreen();
            } else if (document.msExitFullscreen) {
                document.msExitFullscreen();
            }
        }

        /**
         * Toggle giữa fullscreen và normal.
         */
        toggle() {
            if (this.isFullscreen()) {
                this.exitFullscreen();
            } else {
                this.enterFullscreen();
            }
        }

        /**
         * Kiểm tra trạng thái fullscreen hiện tại.
         * @returns {boolean}
         */
        isFullscreen() {
            return !!(
                document.fullscreenElement ||
                document.webkitFullscreenElement ||
                document.msFullscreenElement
            );
        }

        /**
         * Hủy và dọn dẹp event listeners, DOM.
         */
        destroy() {
            if (this._onFullscreenChangeBound) {
                document.removeEventListener('fullscreenchange', this._onFullscreenChangeBound);
                document.removeEventListener('webkitfullscreenchange', this._onFullscreenChangeBound);
                this._onFullscreenChangeBound = null;
            }

            if (this._btn && this._btn.parentNode) {
                this._btn.parentNode.removeChild(this._btn);
                this._btn = null;
            }

            if (this._cardElement) {
                this._cardElement.classList.remove('graph-card-fullscreen');
                this._cardElement = null;
            }

            this._initialized = false;
        }

        // ─── Private ────────────────────────────────────────────────────────

        /**
         * Resolve the card element from the selector.
         * The selector targets the card that is the parent of #graphContainer.
         * @returns {HTMLElement|null}
         */
        _resolveCardElement() {
            if (this._cardSelector) {
                // Try direct selector first
                const el = document.querySelector(this._cardSelector);
                if (el) return el;
            }

            // Fallback: find the .card ancestor of #graphContainer
            const graphContainer = document.getElementById('graphContainer');
            if (graphContainer) {
                return graphContainer.closest('.card');
            }

            return null;
        }

        /**
         * Create the fullscreen toggle button and insert it into #graphExportContainer.
         */
        _createButton() {
            const exportContainer = document.getElementById('graphExportContainer');
            if (!exportContainer) {
                console.warn('[FullscreenManager] #graphExportContainer not found');
                return;
            }

            const btn = document.createElement('button');
            btn.className = 'btn btn-outline-secondary btn-sm ms-2 fullscreen-btn';
            btn.id = 'fullscreenBtn';
            btn.title = 'Toggle Fullscreen';
            btn.innerHTML = '<i class="fas fa-expand me-1"></i>Fullscreen';

            exportContainer.appendChild(btn);
            this._btn = btn;
        }

        /**
         * Bind click and fullscreenchange events.
         */
        _bindEvents() {
            // Button click
            if (this._btn) {
                this._btn.addEventListener('click', () => {
                    this.toggle();
                });
            }

            // Fullscreen change event
            this._onFullscreenChangeBound = this._onFullscreenChange.bind(this);
            document.addEventListener('fullscreenchange', this._onFullscreenChangeBound);
            document.addEventListener('webkitfullscreenchange', this._onFullscreenChangeBound);
        }

        /**
         * Handle fullscreenchange event: update button icon/text, apply styles, resize graph.
         */
        _onFullscreenChange() {
            const isFs = this.isFullscreen();

            // Update button icon and text
            this._updateButton(isFs);

            // Toggle fullscreen CSS class on the card
            if (this._cardElement) {
                if (isFs) {
                    this._cardElement.classList.add('graph-card-fullscreen');
                    this._cardElement.style.background = '#fff';
                } else {
                    this._cardElement.classList.remove('graph-card-fullscreen');
                    this._cardElement.style.background = '';
                }
            }

            // Adjust #graphContainer height
            this._adjustGraphContainerHeight(isFs);

            // Resize the Cytoscape graph after a short delay to let the DOM settle
            setTimeout(() => {
                this._resizeGraph();
            }, 100);
        }

        /**
         * Update button icon and text based on fullscreen state.
         * @param {boolean} isFs
         */
        _updateButton(isFs) {
            if (!this._btn) return;

            if (isFs) {
                this._btn.innerHTML = '<i class="fas fa-compress me-1"></i>Exit Fullscreen';
                this._btn.title = 'Exit Fullscreen';
            } else {
                this._btn.innerHTML = '<i class="fas fa-expand me-1"></i>Fullscreen';
                this._btn.title = 'Toggle Fullscreen';
            }
        }

        /**
         * Adjust the #graphContainer height for fullscreen mode.
         * @param {boolean} isFs
         */
        _adjustGraphContainerHeight(isFs) {
            const graphContainer = document.getElementById('graphContainer');
            if (!graphContainer) return;

            if (isFs) {
                // In fullscreen, expand to fill viewport minus card header (~60px)
                graphContainer.style.height = 'calc(100vh - 60px)';
            } else {
                // Restore original height
                graphContainer.style.height = '';
            }
        }

        /**
         * Call cy.resize() and cy.fit() on the Cytoscape instance to adjust to new dimensions.
         */
        _resizeGraph() {
            try {
                if (window._onnxApp && typeof window._onnxApp.getGraphVisualizer === 'function') {
                    const visualizer = window._onnxApp.getGraphVisualizer();
                    if (visualizer && visualizer._cy) {
                        visualizer._cy.resize();
                        visualizer._cy.fit();
                    }
                }
            } catch (err) {
                console.warn('[FullscreenManager] Could not resize graph:', err);
            }
        }
    }

    return FullscreenManager;
})();

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