/**
 * Drawer Manager for LiveComponents
 * 
 * Manages drawer/sidebar components with:
 * - Slide-in animation (CSS Transitions)
 * - Overlay backdrop management
 * - ESC key handling
 * - Focus management (focus trapping)
 * - Stack management for multiple drawers
 */

export class DrawerManager {
    constructor() {
        this.drawerStack = []; // Array of { componentId, drawerElement, overlayElement, zIndex, closeOnEscape, closeOnOverlay }
        this.baseZIndex = 1040;
        this.zIndexIncrement = 10;
        this.escapeHandler = null;
    }

    /**
     * Open drawer and add to stack
     * @param {string} componentId - Component ID
     * @param {Object} options - Drawer options
     * @returns {Object} Drawer instance
     */
    open(componentId, options = {}) {
        const {
            title = '',
            content = '',
            position = 'left',
            width = '400px',
            showOverlay = true,
            closeOnOverlay = true,
            closeOnEscape = true,
            animation = 'slide'
        } = options;

        // Calculate z-index
        const zIndex = this.baseZIndex + (this.drawerStack.length * this.zIndexIncrement);

        // Create overlay if needed
        let overlay = null;
        if (showOverlay) {
            overlay = this.createOverlay(zIndex, closeOnOverlay, componentId);
            document.body.appendChild(overlay);
        }

        // Create drawer element
        const drawer = this.createDrawerElement(componentId, title, content, position, width, animation, zIndex + 1);
        document.body.appendChild(drawer);

        // Track in stack
        const stackItem = {
            componentId,
            drawerElement: drawer,
            overlayElement: overlay,
            zIndex: zIndex + 1,
            closeOnEscape,
            closeOnOverlay
        };
        this.drawerStack.push(stackItem);

        // Setup event handlers
        this.setupDrawerHandlers(drawer, overlay, componentId, closeOnOverlay, closeOnEscape);

        // Update ESC handler
        this.updateEscapeHandler();

        // Animate in
        requestAnimationFrame(() => {
            if (overlay) {
                overlay.classList.add('drawer-overlay--show');
            }
            drawer.classList.add('drawer--show');
        });

        // Focus management
        this.focusDrawer(drawer);

        return {
            drawer: drawer,
            overlay: overlay,
            close: () => this.close(componentId),
            isOpen: () => drawer.classList.contains('drawer--show')
        };
    }

    /**
     * Close drawer and remove from stack
     * @param {string} componentId - Component ID
     */
    close(componentId) {
        const index = this.drawerStack.findIndex(item => item.componentId === componentId);
        if (index === -1) {
            return;
        }

        const { drawerElement, overlayElement } = this.drawerStack[index];

        // Animate out
        drawerElement.classList.remove('drawer--show');
        if (overlayElement) {
            overlayElement.classList.remove('drawer-overlay--show');
        }

        // Remove from DOM after animation
        setTimeout(() => {
            if (drawerElement.parentNode) {
                drawerElement.parentNode.removeChild(drawerElement);
            }
            if (overlayElement && overlayElement.parentNode) {
                overlayElement.parentNode.removeChild(overlayElement);
            }
        }, 300); // Match CSS transition duration

        // Remove from stack
        this.drawerStack.splice(index, 1);

        // Update ESC handler
        this.updateEscapeHandler();

        // Focus previous drawer or return focus to body
        if (this.drawerStack.length > 0) {
            const previousDrawer = this.drawerStack[this.drawerStack.length - 1];
            this.focusDrawer(previousDrawer.drawerElement);
        } else {
            // Return focus to previously focused element
            const activeElement = document.activeElement;
            if (activeElement && activeElement !== document.body) {
                activeElement.blur();
            }
            document.body.focus();
        }
    }

    /**
     * Close all drawers
     */
    closeAll() {
        while (this.drawerStack.length > 0) {
            const { componentId } = this.drawerStack[this.drawerStack.length - 1];
            this.close(componentId);
        }
    }

    /**
     * Get topmost drawer
     * @returns {Object|null}
     */
    getTopDrawer() {
        if (this.drawerStack.length === 0) {
            return null;
        }
        return this.drawerStack[this.drawerStack.length - 1];
    }

    /**
     * Check if drawer is open
     * @param {string} componentId - Component ID
     * @returns {boolean}
     */
    isOpen(componentId) {
        return this.drawerStack.some(item => item.componentId === componentId);
    }

    /**
     * Create overlay element
     * @param {number} zIndex - Z-index value
     * @param {boolean} closeOnOverlay - Whether to close on overlay click
     * @param {string} componentId - Component ID
     * @returns {HTMLElement}
     */
    createOverlay(zIndex, closeOnOverlay, componentId) {
        const overlay = document.createElement('div');
        overlay.className = 'drawer-overlay';
        overlay.style.zIndex = zIndex.toString();
        overlay.setAttribute('role', 'presentation');
        overlay.setAttribute('aria-hidden', 'true');

        if (closeOnOverlay) {
            overlay.addEventListener('click', () => {
                this.close(componentId);
            });
        }

        return overlay;
    }

    /**
     * Create drawer element
     * @param {string} componentId - Component ID
     * @param {string} title - Drawer title
     * @param {string} content - Drawer content
     * @param {string} position - Position (left/right)
     * @param {string} width - Drawer width
     * @param {string} animation - Animation type
     * @param {number} zIndex - Z-index value
     * @returns {HTMLElement}
     */
    createDrawerElement(componentId, title, content, position, width, animation, zIndex) {
        const drawer = document.createElement('div');
        drawer.className = `drawer drawer--${position} drawer-animation-${animation}`;
        drawer.id = `drawer-${componentId}`;
        drawer.style.zIndex = zIndex.toString();
        drawer.style.width = width;
        drawer.setAttribute('role', 'dialog');
        drawer.setAttribute('aria-modal', 'true');
        drawer.setAttribute('aria-labelledby', title ? `drawer-title-${componentId}` : '');

        drawer.innerHTML = `
            <div class="drawer-content">
                ${title ? `
                    <div class="drawer-header">
                        <h3 class="drawer-title" id="drawer-title-${componentId}">${title}</h3>
                        <button class="drawer-close" aria-label="Close drawer">×</button>
                    </div>
                ` : ''}
                <div class="drawer-body">${content}</div>
            </div>
        `;

        return drawer;
    }

    /**
     * Setup event handlers for drawer
     * @param {HTMLElement} drawer - Drawer element
     * @param {HTMLElement|null} overlay - Overlay element
     * @param {string} componentId - Component ID
     * @param {boolean} closeOnOverlay - Whether to close on overlay click
     * @param {boolean} closeOnEscape - Whether to close on ESC key
     */
    setupDrawerHandlers(drawer, overlay, componentId, closeOnOverlay, closeOnEscape) {
        // Close button
        const closeBtn = drawer.querySelector('.drawer-close');
        if (closeBtn) {
            closeBtn.addEventListener('click', () => {
                this.close(componentId);
            });
        }

        // Overlay click (already handled in createOverlay, but ensure it's set)
        if (overlay && closeOnOverlay) {
            // Already set in createOverlay
        }
    }

    /**
     * Update ESC key handler
     */
    updateEscapeHandler() {
        // Remove existing handler
        if (this.escapeHandler) {
            document.removeEventListener('keydown', this.escapeHandler);
            this.escapeHandler = null;
        }

        // Add handler if there are drawers
        if (this.drawerStack.length > 0) {
            const topDrawer = this.getTopDrawer();
            if (topDrawer && topDrawer.closeOnEscape) {
                this.escapeHandler = (e) => {
                    if (e.key === 'Escape' && !e.defaultPrevented) {
                        e.preventDefault();
                        this.close(topDrawer.componentId);
                    }
                };
                document.addEventListener('keydown', this.escapeHandler);
            }
        }
    }

    /**
     * Focus drawer element
     * @param {HTMLElement} drawer - Drawer element
     */
    focusDrawer(drawer) {
        if (!drawer) {
            return;
        }

        // Find first focusable element
        const focusableSelectors = [
            'button:not([disabled])',
            '[href]',
            'input:not([disabled])',
            'select:not([disabled])',
            'textarea:not([disabled])',
            '[tabindex]:not([tabindex="-1"])'
        ].join(', ');

        const focusableElement = drawer.querySelector(focusableSelectors);
        if (focusableElement) {
            requestAnimationFrame(() => {
                focusableElement.focus();
            });
        } else {
            requestAnimationFrame(() => {
                drawer.focus();
            });
        }
    }

    /**
     * Cleanup all drawers
     */
    destroy() {
        this.closeAll();
        if (this.escapeHandler) {
            document.removeEventListener('keydown', this.escapeHandler);
            this.escapeHandler = null;
        }
    }
}