/**
 * GraphLayoutSwitcher - Chuyển Đổi Layout Đồ Thị
 * Cung cấp dropdown cho phép chọn layout đồ thị: Top-Down, Left-Right, Circle, Force-Directed.
 * Lưu/khôi phục layout preference từ localStorage.
 * Requirements: 31.1, 31.2, 31.3, 31.4, 31.5
 */

const GraphLayoutSwitcher = (function () {
    'use strict';

    // ─── Layout Configurations ────────────────────────────────────────────────

    var LAYOUTS = {
        'top-down': {
            name: 'breadthfirst',
            label: 'Top-Down',
            icon: 'fa-arrow-down',
            options: {
                directed: true,
                spacingFactor: 1.2,
                padding: 20,
                avoidOverlap: true,
                nodeDimensionsIncludeLabels: true,
                animate: true,
                animationDuration: 500
            }
        },
        'left-right': {
            name: 'breadthfirst',
            label: 'Left-Right',
            icon: 'fa-arrow-right',
            options: {
                directed: true,
                spacingFactor: 1.5,
                padding: 20,
                avoidOverlap: true,
                nodeDimensionsIncludeLabels: true,
                animate: true,
                animationDuration: 500,
                transform: function (node, position) {
                    return { x: position.y, y: position.x };
                }
            }
        },
        'circle': {
            name: 'circle',
            label: 'Circle',
            icon: 'fa-circle-notch',
            options: {
                padding: 20,
                avoidOverlap: true,
                nodeDimensionsIncludeLabels: true,
                animate: true,
                animationDuration: 500
            }
        },
        'force-directed': {
            name: 'cose',
            label: 'Force-Directed',
            icon: 'fa-project-diagram',
            options: {
                animate: true,
                animationDuration: 500,
                nodeDimensionsIncludeLabels: true,
                nodeRepulsion: function () { return 4500; },
                idealEdgeLength: function () { return 50; },
                edgeElasticity: function () { return 100; }
            }
        }
    };

    var DEFAULT_LAYOUT = 'top-down';

    // ─── Class ────────────────────────────────────────────────────────────────

    class GraphLayoutSwitcher {
        /**
         * @param {string} [graphContainerSelector='#graphContainer'] - CSS selector cho container đồ thị
         * @param {string} [storageKey='onnx_explorer_graph_layout'] - Key localStorage
         */
        constructor(graphContainerSelector, storageKey) {
            /** @type {string} */
            this._containerSelector = graphContainerSelector || '#graphContainer';

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

            /** @type {string} */
            this._currentLayout = DEFAULT_LAYOUT;

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

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

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

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

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

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

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

        /**
         * Khởi tạo: tạo dropdown, khôi phục layout đã lưu, lắng nghe graph:rendered.
         */
        init() {
            if (this._initialized) return;

            // Restore saved layout preference
            this._currentLayout = this._loadPreference() || DEFAULT_LAYOUT;

            // Create the dropdown UI
            this._createDropdown();

            // Listen for graph:rendered to apply saved layout
            if (window.EventBus) {
                this._unsubscribeGraphRendered = window.EventBus.on(
                    CONFIG.EVENTS.GRAPH_RENDERED,
                    this._onGraphRendered.bind(this)
                );
            }

            this._initialized = true;
            console.log('[GraphLayoutSwitcher] Initialized with layout:', this._currentLayout);
        }

        /**
         * Áp dụng layout mới cho đồ thị.
         * @param {string} layoutName - 'top-down', 'left-right', 'circle', 'force-directed'
         */
        applyLayout(layoutName) {
            var layoutConfig = LAYOUTS[layoutName];
            if (!layoutConfig) {
                console.warn('[GraphLayoutSwitcher] Unknown layout:', layoutName);
                return;
            }

            var cy = this._getCytoscapeInstance();
            if (!cy) {
                console.warn('[GraphLayoutSwitcher] Cytoscape instance not available');
                return;
            }

            // Build layout options with the cytoscape layout name
            var options = Object.assign({}, layoutConfig.options, { name: layoutConfig.name });

            // Run the layout
            cy.layout(options).run();

            // Update current layout
            this._currentLayout = layoutName;

            // Save preference
            this._savePreference(layoutName);

            // Update dropdown UI
            this._updateDropdownLabel();

            console.log('[GraphLayoutSwitcher] Applied layout:', layoutName);
        }

        /**
         * Lấy layout hiện tại.
         * @returns {string}
         */
        getCurrentLayout() {
            return this._currentLayout;
        }

        /**
         * Hủy và dọn dẹp.
         */
        destroy() {
            if (this._unsubscribeGraphRendered) {
                this._unsubscribeGraphRendered();
                this._unsubscribeGraphRendered = null;
            }

            if (this._documentClickHandler) {
                document.removeEventListener('click', this._documentClickHandler);
                this._documentClickHandler = null;
            }

            if (this._dropdownWrapper && this._dropdownWrapper.parentNode) {
                this._dropdownWrapper.parentNode.removeChild(this._dropdownWrapper);
            }

            this._dropdownWrapper = null;
            this._dropdownMenu = null;
            this._toggleBtn = null;
            this._initialized = false;
        }

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

        /**
         * Create the dropdown UI and insert into the graph card header.
         */
        _createDropdown() {
            var exportContainer = document.getElementById('graphExportContainer');
            if (!exportContainer) {
                console.warn('[GraphLayoutSwitcher] #graphExportContainer not found');
                return;
            }

            // Wrapper
            var wrapper = document.createElement('div');
            wrapper.className = 'graph-layout-switcher d-inline-block';
            wrapper.style.position = 'relative';

            // Toggle button
            var btn = document.createElement('button');
            btn.className = 'btn btn-outline-secondary btn-sm me-2';
            btn.id = 'graphLayoutBtn';
            btn.title = 'Change Graph Layout';
            btn.type = 'button';
            this._updateBtnContent(btn, this._currentLayout);
            wrapper.appendChild(btn);

            // Dropdown menu
            var menu = document.createElement('div');
            menu.className = 'graph-layout-dropdown';
            menu.id = 'graphLayoutDropdown';
            menu.style.display = 'none';

            var layoutKeys = Object.keys(LAYOUTS);
            for (var i = 0; i < layoutKeys.length; i++) {
                var key = layoutKeys[i];
                var config = LAYOUTS[key];

                var option = document.createElement('button');
                option.className = 'graph-layout-option';
                option.type = 'button';
                option.dataset.layout = key;
                option.innerHTML = '<i class="fas ' + config.icon + ' me-2"></i>' + config.label;

                if (key === this._currentLayout) {
                    option.classList.add('active');
                }

                menu.appendChild(option);
            }

            wrapper.appendChild(menu);

            // Insert before the export container's first child (so it appears to the left)
            exportContainer.insertBefore(wrapper, exportContainer.firstChild);

            this._dropdownWrapper = wrapper;
            this._dropdownMenu = menu;
            this._toggleBtn = btn;

            // Bind events
            this._bindEvents();
        }

        /**
         * Bind click events for the dropdown.
         */
        _bindEvents() {
            var self = this;

            // Toggle dropdown on button click
            if (this._toggleBtn) {
                this._toggleBtn.addEventListener('click', function (e) {
                    e.stopPropagation();
                    var isVisible = self._dropdownMenu.style.display !== 'none';
                    self._dropdownMenu.style.display = isVisible ? 'none' : 'block';
                });
            }

            // Handle layout option click
            if (this._dropdownMenu) {
                this._dropdownMenu.addEventListener('click', function (e) {
                    var option = e.target.closest('.graph-layout-option');
                    if (!option) return;

                    var layoutName = option.dataset.layout;
                    self._dropdownMenu.style.display = 'none';
                    self.applyLayout(layoutName);
                });
            }

            // Close dropdown when clicking outside
            this._documentClickHandler = function () {
                if (self._dropdownMenu) {
                    self._dropdownMenu.style.display = 'none';
                }
            };
            document.addEventListener('click', this._documentClickHandler);
        }

        /**
         * Handle graph:rendered event - apply saved layout.
         * @param {Object} payload - { cy: cytoscape instance }
         */
        _onGraphRendered(payload) {
            // Only apply non-default layout (default is already breadthfirst top-down)
            if (this._currentLayout && this._currentLayout !== DEFAULT_LAYOUT) {
                // Small delay to let the initial layout settle
                var self = this;
                setTimeout(function () {
                    self.applyLayout(self._currentLayout);
                }, 100);
            }
        }

        /**
         * Update the toggle button content to show current layout.
         * @param {HTMLButtonElement} btn
         * @param {string} layoutName
         */
        _updateBtnContent(btn, layoutName) {
            var config = LAYOUTS[layoutName] || LAYOUTS[DEFAULT_LAYOUT];
            btn.innerHTML = '<i class="fas ' + config.icon + ' me-1"></i>Layout';
        }

        /**
         * Update dropdown label and active state after layout change.
         */
        _updateDropdownLabel() {
            if (this._toggleBtn) {
                this._updateBtnContent(this._toggleBtn, this._currentLayout);
            }

            // Update active state on options
            if (this._dropdownMenu) {
                var options = this._dropdownMenu.querySelectorAll('.graph-layout-option');
                for (var i = 0; i < options.length; i++) {
                    if (options[i].dataset.layout === this._currentLayout) {
                        options[i].classList.add('active');
                    } else {
                        options[i].classList.remove('active');
                    }
                }
            }
        }

        /**
         * Get the Cytoscape instance from the app's GraphVisualizer.
         * @returns {object|null}
         */
        _getCytoscapeInstance() {
            try {
                if (window._onnxApp && typeof window._onnxApp.getGraphVisualizer === 'function') {
                    var visualizer = window._onnxApp.getGraphVisualizer();
                    if (visualizer && visualizer._cy) {
                        return visualizer._cy;
                    }
                }
            } catch (err) {
                console.warn('[GraphLayoutSwitcher] Could not access Cytoscape instance:', err);
            }
            return null;
        }

        /**
         * Save layout preference to localStorage.
         * @param {string} layoutName
         */
        _savePreference(layoutName) {
            try {
                localStorage.setItem(this._storageKey, layoutName);
            } catch (_) { /* ignore quota/security errors */ }
        }

        /**
         * Load layout preference from localStorage.
         * @returns {string|null}
         */
        _loadPreference() {
            try {
                var value = localStorage.getItem(this._storageKey);
                if (value && LAYOUTS[value]) {
                    return value;
                }
            } catch (_) { /* ignore */ }
            return null;
        }
    }

    return GraphLayoutSwitcher;
})();

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