/**
 * Progressive Enhancement for LiveComponents
 *
 * Provides automatic AJAX handling for links and forms within data-lc-boost containers.
 * Falls back gracefully to normal navigation/submit when JavaScript is disabled.
 *
 * Features:
 * - Automatic AJAX for links and forms
 * - Graceful degradation (works without JS)
 * - Integration with LiveComponents system
 * - SPA Router coordination (if available)
 */

export class ProgressiveEnhancement {
    constructor(liveComponentManager) {
        this.liveComponentManager = liveComponentManager;
        this.boostContainers = new Set();
        this.initialized = false;
    }

    /**
     * Initialize progressive enhancement
     *
     * Sets up event listeners for boost containers and their links/forms.
     */
    init() {
        if (this.initialized) {
            console.warn('[ProgressiveEnhancement] Already initialized');
            return;
        }

        // Find all boost containers
        this.findBoostContainers();

        // Setup mutation observer to handle dynamically added boost containers
        this.setupMutationObserver();

        // Setup global click handler for links
        document.addEventListener('click', (e) => this.handleLinkClick(e), true);

        // Setup global submit handler for forms
        document.addEventListener('submit', (e) => this.handleFormSubmit(e), true);

        this.initialized = true;
        console.log('[ProgressiveEnhancement] Initialized');
    }

    /**
     * Find all boost containers and setup handlers
     */
    findBoostContainers() {
        const containers = document.querySelectorAll('[data-lc-boost="true"]');
        containers.forEach(container => {
            this.setupBoostContainer(container);
        });
    }

    /**
     * Setup boost container
     *
     * @param {HTMLElement} container - Boost container element
     */
    setupBoostContainer(container) {
        if (this.boostContainers.has(container)) {
            return; // Already setup
        }

        this.boostContainers.add(container);

        // Mark links and forms as boosted (for identification)
        container.querySelectorAll('a[href], form[action]').forEach(element => {
            if (!element.hasAttribute('data-lc-boost')) {
                element.setAttribute('data-lc-boost', 'true');
            }
        });
    }

    /**
     * Setup mutation observer to detect new boost containers
     */
    setupMutationObserver() {
        const observer = new MutationObserver((mutations) => {
            mutations.forEach((mutation) => {
                mutation.addedNodes.forEach((node) => {
                    if (node.nodeType === Node.ELEMENT_NODE) {
                        // Check if node itself is a boost container
                        if (node.hasAttribute && node.hasAttribute('data-lc-boost') && 
                            node.getAttribute('data-lc-boost') === 'true') {
                            this.setupBoostContainer(node);
                        }

                        // Check for boost containers within added node
                        const boostContainers = node.querySelectorAll?.('[data-lc-boost="true"]');
                        if (boostContainers) {
                            boostContainers.forEach(container => {
                                this.setupBoostContainer(container);
                            });
                        }

                        // Check for links/forms within boost containers
                        const links = node.querySelectorAll?.('a[href], form[action]');
                        if (links) {
                            links.forEach(element => {
                                const boostContainer = element.closest('[data-lc-boost="true"]');
                                if (boostContainer && !element.hasAttribute('data-lc-boost')) {
                                    element.setAttribute('data-lc-boost', 'true');
                                }
                            });
                        }
                    }
                });
            });
        });

        observer.observe(document.body, {
            childList: true,
            subtree: true
        });
    }

    /**
     * Handle link clicks
     *
     * @param {Event} event - Click event
     */
    handleLinkClick(event) {
        const link = event.target.closest('a[href]');
        if (!link) return;

        // Check if link is in a boost container
        const boostContainer = link.closest('[data-lc-boost="true"]');
        if (!boostContainer) return;

        // Check if link explicitly opts out
        if (link.hasAttribute('data-lc-boost') && link.getAttribute('data-lc-boost') === 'false') {
            return; // Let normal navigation happen
        }

        // Check for special link types that should not be boosted
        const href = link.getAttribute('href');
        if (!href || href === '#' || href.startsWith('javascript:') || href.startsWith('mailto:') || href.startsWith('tel:')) {
            return; // Let normal behavior happen
        }

        // Check if target is _blank (new window)
        if (link.getAttribute('target') === '_blank') {
            return; // Let normal behavior happen
        }

        // Prevent default navigation
        event.preventDefault();

        // Try to use SPA Router if available
        if (window.SPARouter && typeof window.SPARouter.navigate === 'function') {
            window.SPARouter.navigate(href);
            return;
        }

        // Fallback: Use fetch to load content
        this.loadContentViaAjax(href, link);
    }

    /**
     * Handle form submissions
     *
     * @param {Event} event - Submit event
     */
    handleFormSubmit(event) {
        const form = event.target;
        if (!form || form.tagName !== 'FORM') return;

        // Check if form is in a boost container
        const boostContainer = form.closest('[data-lc-boost="true"]');
        if (!boostContainer) return;

        // Check if form explicitly opts out
        if (form.hasAttribute('data-lc-boost') && form.getAttribute('data-lc-boost') === 'false') {
            return; // Let normal submit happen
        }

        // Check if form has data-live-action (handled by LiveComponents)
        if (form.hasAttribute('data-live-action')) {
            return; // Let LiveComponents handle it
        }

        // Prevent default submission
        event.preventDefault();

        // Submit form via AJAX
        this.submitFormViaAjax(form);
    }

    /**
     * Load content via AJAX
     *
     * @param {string} url - URL to load
     * @param {HTMLElement} link - Link element that triggered the load
     */
    async loadContentViaAjax(url, link) {
        try {
            // Show loading state
            link.setAttribute('aria-busy', 'true');
            link.classList.add('lc-loading');

            // Fetch content
            const response = await fetch(url, {
                method: 'GET',
                headers: {
                    'X-Requested-With': 'XMLHttpRequest',
                    'Accept': 'text/html'
                }
            });

            if (!response.ok) {
                throw new Error(`HTTP ${response.status}: ${response.statusText}`);
            }

            const html = await response.text();

            // Try to extract main content (look for <main> tag)
            const parser = new DOMParser();
            const doc = parser.parseFromString(html, 'text/html');
            const mainContent = doc.querySelector('main') || doc.body;

            // Update page content
            const currentMain = document.querySelector('main') || document.body;
            if (currentMain) {
                currentMain.innerHTML = mainContent.innerHTML;
            } else {
                document.body.innerHTML = mainContent.innerHTML;
            }

            // Update URL without reload
            window.history.pushState({}, '', url);

            // Reinitialize LiveComponents
            if (this.liveComponentManager) {
                const components = document.querySelectorAll('[data-live-component]');
                components.forEach(component => {
                    this.liveComponentManager.init(component);
                });
            }

            // Dispatch custom event
            window.dispatchEvent(new CustomEvent('lc:boost:navigated', {
                detail: { url, link }
            }));

        } catch (error) {
            console.error('[ProgressiveEnhancement] Failed to load content:', error);
            
            // Fallback to normal navigation on error
            window.location.href = url;
        } finally {
            // Remove loading state
            link.removeAttribute('aria-busy');
            link.classList.remove('lc-loading');
        }
    }

    /**
     * Submit form via AJAX
     *
     * @param {HTMLFormElement} form - Form element
     */
    async submitFormViaAjax(form) {
        try {
            // Show loading state
            form.setAttribute('aria-busy', 'true');
            form.classList.add('lc-loading');

            const formData = new FormData(form);
            const method = form.method.toUpperCase() || 'POST';
            const action = form.action || window.location.href;

            // Fetch response
            const response = await fetch(action, {
                method: method,
                body: formData,
                headers: {
                    'X-Requested-With': 'XMLHttpRequest',
                    'Accept': 'text/html'
                }
            });

            if (!response.ok) {
                throw new Error(`HTTP ${response.status}: ${response.statusText}`);
            }

            const html = await response.text();

            // Check if response is a redirect
            if (response.redirected) {
                // Follow redirect
                await this.loadContentViaAjax(response.url, form);
                return;
            }

            // Try to extract main content
            const parser = new DOMParser();
            const doc = parser.parseFromString(html, 'text/html');
            const mainContent = doc.querySelector('main') || doc.body;

            // Update page content
            const currentMain = document.querySelector('main') || document.body;
            if (currentMain) {
                currentMain.innerHTML = mainContent.innerHTML;
            } else {
                document.body.innerHTML = mainContent.innerHTML;
            }

            // Update URL if form has action
            if (form.action && form.action !== window.location.href) {
                window.history.pushState({}, '', form.action);
            }

            // Reinitialize LiveComponents
            if (this.liveComponentManager) {
                const components = document.querySelectorAll('[data-live-component]');
                components.forEach(component => {
                    this.liveComponentManager.init(component);
                });
            }

            // Dispatch custom event
            window.dispatchEvent(new CustomEvent('lc:boost:submitted', {
                detail: { form, action }
            }));

        } catch (error) {
            console.error('[ProgressiveEnhancement] Failed to submit form:', error);
            
            // Fallback to normal submit on error
            form.submit();
        } finally {
            // Remove loading state
            form.removeAttribute('aria-busy');
            form.classList.remove('lc-loading');
        }
    }
}

export default ProgressiveEnhancement;