/**
 * SidebarToggle - Toggle Ẩn/Hiện Thanh Bên Trái
 * Cung cấp nút toggle để ẩn/hiện sidebar, mở rộng vùng nội dung chính.
 * Lưu trạng thái vào localStorage và khôi phục khi tải lại trang.
 * Requirements: 27.1, 27.2, 27.3, 27.4, 27.5, 27.6
 */

const SidebarToggle = (function () {
    const STORAGE_KEY_DEFAULT = 'onnx_explorer_sidebar_state';
    const STATE_VISIBLE = 'visible';
    const STATE_HIDDEN = 'hidden';

    class SidebarToggle {
        /**
         * @param {string} sidebarSelector - CSS selector cho sidebar
         * @param {string} mainContentSelector - CSS selector cho vùng nội dung chính
         * @param {string} [storageKey] - Key localStorage
         */
        constructor(sidebarSelector, mainContentSelector, storageKey) {
            /** @type {string} */
            this._sidebarSelector = sidebarSelector;

            /** @type {string} */
            this._mainContentSelector = mainContentSelector;

            /** @type {string} */
            this._storageKey = storageKey || STORAGE_KEY_DEFAULT;

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

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

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

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

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

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

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

        /**
         * Khởi tạo: tìm elements, tạo nút toggle, khôi phục trạng thái, gắn events.
         */
        init() {
            if (this._initialized) return;

            this._sidebarEl = document.querySelector(this._sidebarSelector);
            this._mainContentEl = document.querySelector(this._mainContentSelector);

            if (!this._sidebarEl) {
                console.warn('[SidebarToggle] Sidebar element not found:', this._sidebarSelector);
                return;
            }
            if (!this._mainContentEl) {
                console.warn('[SidebarToggle] Main content element not found:', this._mainContentSelector);
                return;
            }

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

        /**
         * Ẩn thanh bên trái.
         */
        hideSidebar() {
            if (this._hidden) return;

            this._sidebarEl.classList.add('sidebar-hidden');
            this._mainContentEl.classList.add('sidebar-collapsed');
            this._hidden = true;
            this._updateButtonIcon();
            this._saveState();
        }

        /**
         * Hiện thanh bên trái.
         */
        showSidebar() {
            if (!this._hidden) return;

            this._sidebarEl.classList.remove('sidebar-hidden');
            this._mainContentEl.classList.remove('sidebar-collapsed');
            this._hidden = false;
            this._updateButtonIcon();
            this._saveState();
        }

        /**
         * Toggle trạng thái ẩn/hiện.
         */
        toggle() {
            if (this._hidden) {
                this.showSidebar();
            } else {
                this.hideSidebar();
            }
        }

        /**
         * Kiểm tra sidebar đang ẩn hay hiện.
         * @returns {boolean}
         */
        isHidden() {
            return this._hidden;
        }

        /**
         * Hủy và dọn dẹp event listeners, DOM.
         */
        destroy() {
            if (this._onTransitionEndBound && this._sidebarEl) {
                this._sidebarEl.removeEventListener('transitionend', this._onTransitionEndBound);
                this._onTransitionEndBound = null;
            }

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

            if (this._sidebarEl) {
                this._sidebarEl.classList.remove('sidebar-hidden');
            }
            if (this._mainContentEl) {
                this._mainContentEl.classList.remove('sidebar-collapsed');
            }

            this._sidebarEl = null;
            this._mainContentEl = null;
            this._hidden = false;
            this._initialized = false;
        }

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

        /**
         * Create the toggle button and insert it before the logo in the header.
         */
        _createButton() {
            const navbarBrand = document.querySelector('.navbar-brand');
            if (!navbarBrand || !navbarBrand.parentNode) {
                console.warn('[SidebarToggle] .navbar-brand not found');
                return;
            }

            const btn = document.createElement('button');
            btn.className = 'btn btn-outline-light btn-sm me-2 sidebar-toggle-btn';
            btn.id = 'sidebarToggleBtn';
            btn.title = 'Toggle Sidebar';
            btn.innerHTML = '<i class="fas fa-bars"></i>';

            navbarBrand.parentNode.insertBefore(btn, navbarBrand);

            this._btn = btn;
        }

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

            this._onTransitionEndBound = this._onTransitionEnd.bind(this);
            if (this._sidebarEl) {
                this._sidebarEl.addEventListener('transitionend', this._onTransitionEndBound);
            }
        }

        /**
         * Handle transitionend: resize the Cytoscape graph to fit new dimensions.
         * @param {TransitionEvent} e
         */
        _onTransitionEnd(e) {
            // Only react to transitions on the sidebar element itself
            if (e.target !== this._sidebarEl) return;

            this._resizeGraph();
        }

        /**
         * Update button icon based on current state.
         * fa-bars when sidebar is visible, fa-chevron-right when hidden.
         */
        _updateButtonIcon() {
            if (!this._btn) return;

            const icon = this._btn.querySelector('i');
            if (!icon) return;

            if (this._hidden) {
                icon.className = 'fas fa-chevron-right';
                this._btn.title = 'Show Sidebar';
            } else {
                icon.className = 'fas fa-bars';
                this._btn.title = 'Toggle Sidebar';
            }
        }

        /**
         * Save current state to localStorage.
         */
        _saveState() {
            try {
                localStorage.setItem(this._storageKey, this._hidden ? STATE_HIDDEN : STATE_VISIBLE);
            } catch (err) {
                console.warn('[SidebarToggle] Could not save state:', err);
            }
        }

        /**
         * Restore state from localStorage on init.
         */
        _restoreState() {
            try {
                const saved = localStorage.getItem(this._storageKey);
                if (saved === STATE_HIDDEN) {
                    this.hideSidebar();
                }
            } catch (err) {
                console.warn('[SidebarToggle] Could not restore state:', err);
            }
        }

        /**
         * Call cy.resize() 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('[SidebarToggle] Could not resize graph:', err);
            }
        }
    }

    return SidebarToggle;
})();

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