// router.js - Simple SPA router
import { renderHomePage } from '../pages/HomePage.js';
import { renderAreaPage } from '../pages/AreaPage.js';
import { renderResourcesPage } from '../pages/ResourcesPage.js';
import { scrollToSection } from '../main.js';

class Router {
    constructor() {
        // Base routes (non-area pages)
        this.routes = {
            '/': 'home',
            '/home': 'home',
            '/about': 'resources'
        };
        
        // Generate area routes dynamically from window.areasData
        const areasData = window.areasData || {};
        Object.keys(areasData).forEach(areaId => {
            this.routes[`/${areaId}`] = areaId;
        });
        
        // Generate areas list dynamically
        this.areas = Object.keys(areasData);
        
        this.currentPage = null;
        this.currentArea = null;
        this.currentTopic = null;
        this.init();
    }

    init() {
        // Handle initial page load
        this.loadPage(window.location.pathname);
        
        // Handle browser back/forward
        window.addEventListener('popstate', (e) => {
            const path = window.location.pathname;
            const hash = window.location.hash;
            const fullUrl = path + hash;
            
            // Use navigateToUrl to ensure proper scroll behavior
            this.navigateToUrl(fullUrl, false); // false = don't push to history
        });
        
        // Handle hash changes for navigation
        window.addEventListener('hashchange', (e) => {
            const hash = window.location.hash.substring(1);
            if (hash) {
                // Scroll to the section after a short delay to ensure content is loaded
                setTimeout(() => scrollToSection(hash), 100);
            }
        });
        
        // Handle initial hash if present
        const initialHash = window.location.hash.substring(1);
        if (initialHash) {
            setTimeout(() => scrollToSection(initialHash), 200);
        }
        
        // Initialize unified navigation handling
        this.initializeNavigation();
    }

    async loadPage(path) {
        // Parse path to support /area/topic format
        const pathParts = path.split('/').filter(p => p);
        let route, area, topic;
        
        if (pathParts.length === 0) {
            // Root path
            route = 'home';
        } else if (pathParts.length === 1) {
            // Single segment: /efficiency or /home
            route = this.routes[path] || 'home';
            if (this.areas.includes(pathParts[0])) {
                area = pathParts[0];
            }
        } else if (pathParts.length === 2 && this.areas.includes(pathParts[0])) {
            // Two segments: /efficiency/environment
            area = pathParts[0];
            topic = pathParts[1];
            route = area;
        } else {
            // Unknown route, default to home
            route = 'home';
        }
        
        // Update current state
        this.currentPage = route;
        this.currentArea = area || null;
        this.currentTopic = topic || null;
        
        // Update Alpine.js store if available
        if (window.Alpine && window.Alpine.store) {
            const navStore = window.Alpine.store('navigation');
            if (navStore) {
                navStore.currentPage = this.currentPage;
                navStore.currentArea = this.currentArea;
                navStore.currentTopic = this.currentTopic;
                navStore.updateTopicNav();
            }
        }
        
        // Dispatch event for header and other components
        window.dispatchEvent(new CustomEvent('navigation-changed', {
            detail: {
                currentPage: this.currentPage,
                currentArea: this.currentArea,
                currentTopic: this.currentTopic
            }
        }));
        
        // Handle background for all pages
        await this.setPageBackground(route);

        try {
            // Route to appropriate page
            if (route === 'home') {
                await this.loadHomePage();
            } else if (route === 'resources') {
                await this.loadResourcesPage();
            } else if (this.areas.includes(route)) {
                // Dynamically handle any area page
                await this.loadAreaPage(route, topic);
            } else {
                // Unknown route, default to home
                await this.loadHomePage();
            }
            
        } catch (error) {
            console.error('Error loading page:', error);
            // Fallback to home page
            await this.loadHomePage();
        }
        
        return Promise.resolve();
    }

    async setPageBackground(route) {
        // Clear any existing background
        this.clearBackground();
        
        let backgroundImage, attribution, sourceUrl;
        
        // Use global data loaded in index.html <head>
        if (route === 'home' || route === 'resources') {
            const homeBackgroundImage = window.homeBackgroundImage;
            backgroundImage = homeBackgroundImage.image;
            attribution = homeBackgroundImage.attribution;
            sourceUrl = homeBackgroundImage.sourceUrl;
        } else {
            // Area pages
            const areasData = window.areasData;
            const area = areasData[route];
            backgroundImage = area.image;
            attribution = area.imageAttribution;
            sourceUrl = area.imageSourceUrl;
        }
        
        // Create background element at document level
        const backgroundDiv = document.createElement('div');
        backgroundDiv.id = 'page-background';
        backgroundDiv.className = 'fixed opacity-40 z-0';
        
        // The positioning logic is now in updatePageBackgroundPosition, call it after adding to DOM
        document.body.insertAdjacentElement('afterbegin', backgroundDiv);
        updatePageBackgroundPosition(); // Set initial position
        
        backgroundDiv.innerHTML = `
            <!-- Background Image Main Content -->
            <img src="/images/${backgroundImage}" alt="" class="w-full h-full pointer-events-none">
            <div id="bg-attribution" class="absolute bottom-4 right-4 bg-black bg-opacity-75 text-white text-xs px-2 py-1 rounded opacity-0 transition-opacity duration-200 max-w-xs z-50">
                <a href="${sourceUrl}" target="_blank" class="text-blue-300 hover:text-blue-100">
                    ${attribution}
                </a>
            </div>
        `;
        
        // Add hover functionality for attribution
        this.initializeBackgroundAttribution();
    }
    
    clearBackground() {
        const existingBg = document.getElementById('page-background');
        if (existingBg) {
            existingBg.remove();
        }
    }
    
    initializeBackgroundAttribution() {
        const backgroundContainer = document.getElementById('page-background');
        const attribution = document.getElementById('bg-attribution');
        
        if (!backgroundContainer || !attribution) return;
        
        backgroundContainer.addEventListener('mouseenter', () => {
            attribution.style.opacity = '1';
        });
        
        backgroundContainer.addEventListener('mouseleave', () => {
            attribution.style.opacity = '0';
        });
    }

    async loadHomePage() {
        const mainContent = document.getElementById('main-content');
        
        if (!mainContent) {
            return;
        }

        try {
            // Get page content
            const homePage = renderHomePage();
            
            // Update content - render directly to main content
            mainContent.innerHTML = homePage.content;
            
            // Initialize page
            if (homePage.init) {
                homePage.init();
            }

            // Update navigation state
            this.updateNavigation('home');
        } catch (error) {
            console.error('Error loading home page:', error);
            console.error('Error stack:', error.stack);
            console.error('Error message:', error.message);
            
            // Fallback to error content
            mainContent.innerHTML = `
                <div class="bg-white rounded-lg shadow-sm p-8">
                    <h1 class="text-3xl font-bold text-red-600 mb-6">Error Loading Page</h1>
                    <p class="text-gray-700 mb-4">Sorry, there was an error loading the home page.</p>
                    <pre class="text-sm bg-gray-100 p-4 rounded overflow-auto">${error.message}\n\n${error.stack}</pre>
                </div>
            `;
        }
    }

    async loadAreaPage(area, topic = null) {
        const mainContent = document.getElementById('main-content');
        
        if (!mainContent) {
            return;
        }

        try {
            // Get area page content (pass topic parameter)
            const areaPage = renderAreaPage(area, topic);
            
            // Update content - render directly to main content (no wrapper needed)
            mainContent.innerHTML = areaPage.content;
            
            // Initialize page
            if (areaPage.init) {
                areaPage.init();
            }
            
            // Scroll to top of page after content loads
            window.scrollTo({ top: 0, behavior: 'smooth' });

        } catch (error) {
            console.error(`Error loading ${area} page:`, error);
            
            // Fallback content
            mainContent.innerHTML = `
                <div class="bg-white rounded-lg shadow-sm p-8 mx-4">
                    <h1 class="text-3xl font-bold text-red-600 mb-6">Error Loading Page</h1>
                    <p class="text-gray-700">Sorry, there was an error loading the ${area} page.</p>
                </div>
            `;
        }
        
        this.updateNavigation(area);
    }

    async loadResourcesPage() {
        const mainContent = document.getElementById('main-content');
        
        if (!mainContent) return;

        try {
            // Get resources page content
            const resourcesPage = renderResourcesPage();
            
            // Update content - render directly to main content
            mainContent.innerHTML = resourcesPage.content;
            
            // Initialize page
            if (resourcesPage.init) {
                resourcesPage.init();
            }

        } catch (error) {
            // Fallback content
            mainContent.innerHTML = `
                <div class="bg-white rounded-lg shadow-sm p-8 mx-4">
                    <h1 class="text-3xl font-bold text-red-600 mb-6">Error Loading Page</h1>
                    <p class="text-gray-700">Sorry, there was an error loading the resources page.</p>
                </div>
            `;
        }
        
        this.updateNavigation('resources');
    }

    updateNavigation(currentPage) {
        // Update header navigation active states
        const navLinks = document.querySelectorAll('header nav a');
        navLinks.forEach(link => {
            // Remove active state
            link.classList.remove('text-blue-600', 'bg-blue-50', 'font-semibold');
            
            const href = link.getAttribute('href');
            // Add active state to current page
            if ((currentPage === 'home' && (href === '/' || href === '/home')) ||
                (currentPage === 'resources' && href === '/about') ||
                (currentPage !== 'home' && currentPage !== 'resources' && href === `/${currentPage}`)) {
                link.classList.add('text-blue-600', 'bg-blue-50', 'font-semibold');
            }
        });
    }


    initializeNavigation() {
        // Use event delegation to handle all navigation links
        document.addEventListener('click', (e) => {
            const link = e.target.closest('a');
            if (!link) return;
            
            const href = link.getAttribute('href');
            if (!href) return;
            
            // Handle different types of links
            if (href.startsWith('/') && !href.startsWith('/js/') && !href.startsWith('/css/') && !href.startsWith('/images/')) {
                // Check if this is a known SPA route or area/topic route
                const path = href.split('#')[0];
                const pathParts = path.split('/').filter(p => p);
                const isKnownRoute = this.routes[path] || 
                                    (pathParts.length === 2 && this.areas.includes(pathParts[0]));
                
                if (isKnownRoute) {
                    e.preventDefault();
                    this.navigateToUrl(href);
                }
            } else if (href.startsWith('#')) {
                // Same-page hash navigation
                e.preventDefault();
                scrollToSection(href.substring(1));
            }
            // External links are handled normally by browser
        });
    }

    navigateToUrl(fullUrl, pushState = true) {
        // Parse URL into path and hash
        const [path, hash] = fullUrl.split('#');
        
        // Update browser URL if needed
        if (pushState) {
            window.history.pushState({}, '', fullUrl);
        }
        
        // Load page and then handle hash
        this.loadPage(path).then(() => {
            if (hash) {
                setTimeout(() => scrollToSection(hash), 100);
            } else {
                // No hash - scroll to top of page with a delay to ensure content is rendered
                setTimeout(() => {
                    window.scrollTo({ top: 0, behavior: 'smooth' });
                }, 100);
            }
        });
    }

}

// Export router instance
export const router = new Router();

// Make router globally accessible for Alpine.js and other scripts
window.router = router;

// New function to update the position and size of the page background
function updatePageBackgroundPosition() {
    const backgroundDiv = document.getElementById('page-background');
    if (!backgroundDiv) return;

    const headerHeight = getComputedStyle(document.documentElement).getPropertyValue('--header-height');
    const searchSidebar = document.getElementById('search-sidebar');

    const rightSidebarWidth = searchSidebar && !searchSidebar.classList.contains('translate-x-full') ? searchSidebar.offsetWidth : 0;

    backgroundDiv.style.cssText = `
        top: ${headerHeight};
        left: 0;
        right: ${rightSidebarWidth}px;
        bottom: 0;
        width: calc(100% - ${rightSidebarWidth}px);
        height: calc(100vh - ${headerHeight});
        transition: width 0.3s ease-in-out, right 0.3s ease-in-out;
    `;
}

// Export the new function so main.js can call it
export { updatePageBackgroundPosition };