// ==================================================================
// Main application JavaScript for the frontend
// Handles theme switching, sidebar navigation, and content display.
// ==================================================================

// Wait for the DOM to be fully loaded before executing scripts
document.addEventListener('DOMContentLoaded', function() {

    // 1. Initialize Theme (Dark/Light Mode)
    initTheme();
    setupThemeToggle();

    // 2. Setup Sidebar Navigation System
    setupSidebarNavigation();

    // 3. Setup Feedback Form Validation (Basic)
    setupFeedbackForm();

    // NOTE: Old setup functions for direct page selection are removed/commented out
    // setupSubjectSelection(); // Replaced by sidebar logic
    // setupCategorySelection(); // Replaced by sidebar logic
    // setupTextSelection(); // Replaced by sidebar logic
});


// ==================================================================
// THEME SWITCHING FUNCTIONS
// ==================================================================

/**
 * Initializes the theme (dark/light) based on localStorage preference or system default.
 */
function initTheme() {
    // Default to 'light' if no preference is found
    const userPreference = localStorage.getItem('theme') || 'light';
    document.documentElement.setAttribute('data-theme', userPreference);
    updateThemeIcon(userPreference); // Set the correct icon on load
}

/**
 * Sets up the event listener for the theme toggle button.
 */
function setupThemeToggle() {
    const themeToggle = document.getElementById('theme-toggle');
    if (!themeToggle) {
        console.warn("Theme toggle button (#theme-toggle) not found.");
        return;
    }

    themeToggle.addEventListener('click', function() {
        const currentTheme = document.documentElement.getAttribute('data-theme');
        const newTheme = currentTheme === 'dark' ? 'light' : 'dark';

        // Apply the new theme
        document.documentElement.setAttribute('data-theme', newTheme);

        // Save preference to localStorage
        localStorage.setItem('theme', newTheme);

        // Update the button icon
        updateThemeIcon(newTheme);

        // Optional: Send theme preference to the server (if needed)
        // saveThemePreference(newTheme);
    });
}

/**
 * Updates the icon (sun/moon) inside the theme toggle button.
 * @param {string} theme - The current theme ('light' or 'dark').
 */
function updateThemeIcon(theme) {
    const themeToggle = document.getElementById('theme-toggle');
    if (!themeToggle) return; // Exit if button not found

    if (theme === 'dark') {
        themeToggle.innerHTML = '<i class="fas fa-sun"></i>'; // Show sun icon
        themeToggle.setAttribute('title', 'Activer le mode clair');
    } else {
        themeToggle.innerHTML = '<i class="fas fa-moon"></i>'; // Show moon icon
        themeToggle.setAttribute('title', 'Activer le mode sombre');
    }
}

/**
 * Optional: Sends the chosen theme preference to the server.
 * Uncomment the call in setupThemeToggle if needed.
 * @param {string} theme - The theme to save ('light' or 'dark').
 */
function saveThemePreference(theme) {
    const formData = new FormData();
    formData.append('theme', theme);

    fetch('/set_theme', { // Ensure this endpoint exists in your Flask app
        method: 'POST',
        body: formData
    })
    .then(response => {
        if (!response.ok) {
            console.error(`Error saving theme: ${response.statusText}`);
            return response.json().catch(() => ({})); // Try to parse error body
        }
        return response.json();
    })
    .then(data => {
        console.log('Theme preference saved on server:', data);
    })
    .catch(error => {
        console.error('Error sending theme preference to server:', error);
    });
}


// ==================================================================
// SIDEBAR NAVIGATION FUNCTIONS
// ==================================================================

/**
 * Sets up all event listeners and logic for the sidebar navigation.
 */
function setupSidebarNavigation() {
    // Get references to all necessary DOM elements
    const burgerMenu = document.getElementById('burger-menu');
    const sidebarMatieres = document.getElementById('sidebar-matieres');
    const sidebarSousCategories = document.getElementById('sidebar-sous-categories');
    const sidebarOverlay = document.getElementById('sidebar-overlay');
    const matieresList = document.getElementById('matieres-list-sidebar');
    const sousCategoriesList = document.getElementById('sous-categories-list-sidebar');
    const backButton = document.getElementById('sidebar-back-button');
    const closeButtons = document.querySelectorAll('.close-sidebar-btn');
    const initialInstructions = document.getElementById('initial-instructions');
    const contentSection = document.getElementById('content-section');

    // --- Helper Function to Close All Sidebars ---
    const closeAllSidebars = () => {
        if (sidebarMatieres) sidebarMatieres.classList.remove('active');
        if (sidebarSousCategories) sidebarSousCategories.classList.remove('active');
        if (sidebarOverlay) sidebarOverlay.classList.remove('active');
        // Optional: Reset scroll position of lists when closing
        // if (matieresList) matieresList.scrollTop = 0;
        // if (sousCategoriesList) sousCategoriesList.scrollTop = 0;
    };

    // --- Event Listeners ---

    // 1. Open Sidebar 1 (Matières) with Burger Menu
    if (burgerMenu && sidebarMatieres && sidebarOverlay) {
        burgerMenu.addEventListener('click', (e) => {
            e.stopPropagation(); // Prevent immediate closing if overlay listener fires
            closeAllSidebars(); // Ensure only one sidebar is open initially
            sidebarMatieres.classList.add('active');
            sidebarOverlay.classList.add('active');
        });
    } else {
        console.warn("Burger menu, matières sidebar, or overlay not found.");
    }

    // 2. Close sidebars via Overlay click
    if (sidebarOverlay) {
        sidebarOverlay.addEventListener('click', closeAllSidebars);
    }

    // 3. Close sidebars via dedicated Close buttons (X)
    closeButtons.forEach(button => {
        button.addEventListener('click', closeAllSidebars);
    });

    // 4. Handle click on a Matière in Sidebar 1
    if (matieresList && sidebarSousCategories && sidebarMatieres) {
        matieresList.addEventListener('click', (e) => {
            // Use closest to handle clicks even if icon is clicked
            const listItem = e.target.closest('li');
            if (listItem) {
                const matiereId = listItem.getAttribute('data-matiere-id');
                const matiereNom = listItem.getAttribute('data-matiere-nom') || 'Inconnu'; // Fallback name

                if (matiereId) {
                    // Update Sidebar 2 title
                    const titleElement = document.getElementById('sidebar-sous-categories-title');
                    if (titleElement) {
                        titleElement.textContent = `Sous-catégories (${matiereNom})`;
                    }
                    // Load sous-categories into Sidebar 2's list
                    loadSubCategoriesForSidebar(matiereId, sousCategoriesList);

                    // Switch Sidebars: Hide 1, Show 2
                    sidebarMatieres.classList.remove('active'); // Slide out sidebar 1
                    sidebarSousCategories.classList.add('active'); // Slide in sidebar 2
                    // Keep overlay active
                    if (sidebarOverlay) sidebarOverlay.classList.add('active');
                }
            }
        });
    } else {
        console.warn("Matières list, sous-catégories sidebar, or matières sidebar not found.");
    }

    // 5. Handle click on Back Button in Sidebar 2
    if (backButton && sidebarMatieres && sidebarSousCategories) {
        backButton.addEventListener('click', () => {
            sidebarSousCategories.classList.remove('active'); // Slide out sidebar 2
            sidebarMatieres.classList.add('active'); // Slide in sidebar 1
            // Keep overlay active
            if (sidebarOverlay) sidebarOverlay.classList.add('active');
        });
    } else {
        console.warn("Sidebar back button, matières sidebar, or sous-catégories sidebar not found.");
    }

    // 6. Handle click on a Sous-catégorie in Sidebar 2
    if (sousCategoriesList && initialInstructions && contentSection) {
        sousCategoriesList.addEventListener('click', (e) => {
            const listItem = e.target.closest('li');
            if (listItem && listItem.getAttribute('data-category-id')) { // Ensure it's a valid category item
                const categoryId = listItem.getAttribute('data-category-id');

                // Load and display the content for the first text in this category
                loadAndDisplayFirstTexte(categoryId);

                // Hide initial instructions, show content section
                if (initialInstructions) initialInstructions.classList.add('d-none');
                if (contentSection) contentSection.classList.remove('d-none');

                // Close both sidebars and overlay after selection
                closeAllSidebars();
            }
        });
    } else {
        console.warn("Sous-catégories list, initial instructions, or content section not found.");
    }
}

/**
 * Fetches and loads subcategories for a given matiereId into the specified list element.
 * @param {string} matiereId - The ID of the selected matière.
 * @param {HTMLElement} listElement - The UL element to populate.
 */
function loadSubCategoriesForSidebar(matiereId, listElement) {
    if (!listElement) {
        console.error("Target list element for subcategories is missing.");
        return;
    }
    listElement.innerHTML = '<li>Chargement...</li>'; // Show loading state

    fetch(`/get_sous_categories/${matiereId}`) // Ensure this endpoint exists in Flask
        .then(response => {
            if (!response.ok) {
                throw new Error(`Erreur HTTP: ${response.status} ${response.statusText}`);
            }
            return response.json();
        })
        .then(data => {
            listElement.innerHTML = ''; // Clear loading/previous items
            if (data && data.length > 0) {
                data.forEach(category => {
                    const item = document.createElement('li');
                    item.setAttribute('data-category-id', category.id);
                    item.textContent = category.nom; // Use category name

                    // Add chevron icon for visual cue
                    const icon = document.createElement('i');
                    icon.className = 'fas fa-chevron-right float-end';
                    item.appendChild(icon);

                    listElement.appendChild(item);
                });
            } else {
                listElement.innerHTML = '<li>Aucune sous-catégorie trouvée.</li>';
            }
        })
        .catch(error => {
            console.error('Erreur lors du chargement des sous-catégories:', error);
            listElement.innerHTML = `<li>Erreur: ${error.message}</li>`;
        });
}

/**
 * Fetches the list of texts for a category and displays the first one found.
 * @param {string} categoryId - The ID of the selected sous-catégorie.
 */
function loadAndDisplayFirstTexte(categoryId) {
    fetch(`/get_textes/${categoryId}`) // Ensure this endpoint exists and returns a list of texts [{id, titre}, ...]
        .then(response => {
            if (!response.ok) {
                throw new Error(`Erreur HTTP: ${response.status} ${response.statusText}`);
            }
            return response.json();
        })
        .then(data => {
            if (data && data.length > 0) {
                const firstTexteId = data[0].id; // Get the ID of the very first text
                if (firstTexteId) {
                    displayTexte(firstTexteId); // Call displayTexte with this ID
                } else {
                     throw new Error("Le premier texte reçu n'a pas d'ID.");
                }
            } else {
                // Handle case where a category has no texts associated with it
                const contentTitle = document.getElementById('content-title');
                const contentBlocks = document.getElementById('content-blocks');
                const contentSection = document.getElementById('content-section');
                if (contentTitle) contentTitle.textContent = "Contenu non disponible";
                if (contentBlocks) contentBlocks.innerHTML = '<div class="alert alert-info">Aucun texte trouvé pour cette sous-catégorie.</div>';
                if (contentSection) contentSection.classList.remove('d-none'); // Ensure section is visible
            }
        })
        .catch(error => {
            console.error('Erreur lors du chargement des textes pour la catégorie:', error);
            // Display error message in the content area
            const contentTitle = document.getElementById('content-title');
            const contentBlocks = document.getElementById('content-blocks');
            const contentSection = document.getElementById('content-section');
            if (contentTitle) contentTitle.textContent = "Erreur";
            if (contentBlocks) contentBlocks.innerHTML = `<div class="alert alert-danger">Impossible de charger le contenu. ${error.message}</div>`;
            if (contentSection) contentSection.classList.remove('d-none'); // Ensure section is visible
        });
}


// ==================================================================
// CONTENT DISPLAY FUNCTION
// ==================================================================

/**
 * Fetches and displays the content (title and blocks) for a specific texteId.
 * @param {string} texteId - The ID of the text to display.
 */
function displayTexte(texteId) {
    const contentSection = document.getElementById('content-section');
    const contentTitle = document.getElementById('content-title');
    const contentBlocks = document.getElementById('content-blocks');

    // Check if essential elements exist
    if (!contentSection || !contentTitle || !contentBlocks) {
        console.error("Éléments d'affichage du contenu (#content-section, #content-title, #content-blocks) introuvables.");
        alert("Erreur interne: Impossible d'afficher le contenu.");
        return;
    }

    // Indicate loading state visually
    contentTitle.textContent = "Chargement du contenu...";
    contentBlocks.innerHTML = '<div class="text-center p-3"><i class="fas fa-spinner fa-spin fa-2x"></i></div>'; // Simple spinner

    fetch(`/get_texte/${texteId}`) // Ensure this endpoint exists and returns detailed text object {titre, contenu, blocks, color_code, ...}
        .then(response => {
            if (!response.ok) {
                throw new Error(`Erreur HTTP: ${response.status} ${response.statusText}`);
            }
            return response.json();
        })
        .then(data => {
            // --- Update Content Title ---
            contentTitle.textContent = data.titre || "Titre non disponible";

            // --- Update Theme/Color Styling ---
            const dynamicStyleId = 'dynamic-block-styles';
            let style = document.getElementById(dynamicStyleId);
            if (!style) { // Create style tag if it doesn't exist
                style = document.createElement('style');
                style.id = dynamicStyleId;
                document.head.appendChild(style);
            }

            if (data.color_code) {
                // Apply color to title underline and block border/title
                contentTitle.style.borderBottomColor = data.color_code;
                style.textContent = `
                    #content-section .content-block-title { border-bottom-color: ${data.color_code} !important; }
                    #content-section .content-block { border-left: 4px solid ${data.color_code} !important; }
                `;
            } else {
                // Reset styles if no color code is provided (use CSS defaults)
                contentTitle.style.borderBottomColor = ''; // Reset specific style
                style.textContent = ''; // Clear dynamic rules
            }

            // --- Render Content Blocks ---
            contentBlocks.innerHTML = ''; // Clear loading indicator/previous content

            if (data.blocks && Array.isArray(data.blocks) && data.blocks.length > 0) {
                // Sort blocks by 'order' property if it exists, otherwise render as received
                const sortedBlocks = data.blocks.sort((a, b) => (a.order ?? 0) - (b.order ?? 0));

                sortedBlocks.forEach(block => {
                    const blockDiv = document.createElement('div');
                    blockDiv.className = 'content-block fade-in'; // Add animation class

                    // Block with Image
                    if (block.image && block.image.src) {
                        blockDiv.classList.add('block-with-image', `image-${block.image_position || 'left'}`);

                        // Image Container
                        const imageDiv = document.createElement('div');
                        imageDiv.className = 'block-image-container';
                        const imageEl = document.createElement('img');
                        imageEl.className = 'block-image';
                        imageEl.src = block.image.src; // Ensure backend provides full URL if needed
                        imageEl.alt = block.image.alt || 'Illustration';
                        imageEl.loading = 'lazy'; // Add lazy loading for images
                        imageDiv.appendChild(imageEl);
                        blockDiv.appendChild(imageDiv);

                        // Content Container (Text part)
                        const contentDiv = document.createElement('div');
                        contentDiv.className = 'block-content-container';
                        if (block.title) {
                            const titleEl = document.createElement('h3');
                            titleEl.className = 'content-block-title';
                            titleEl.textContent = block.title;
                            contentDiv.appendChild(titleEl);
                        }
                        const contentEl = document.createElement('div');
                        contentEl.className = 'content-block-content';
                        // IMPORTANT: Sanitize HTML content if it comes from user input or untrusted sources
                        // For now, assuming safe HTML from backend:
                        contentEl.innerHTML = block.content ? block.content.replace(/\n/g, '<br>') : '';
                        contentDiv.appendChild(contentEl);
                        blockDiv.appendChild(contentDiv);

                    } else { // Block without Image
                        if (block.title) {
                            const titleEl = document.createElement('h3');
                            titleEl.className = 'content-block-title';
                            titleEl.textContent = block.title;
                            blockDiv.appendChild(titleEl);
                        }
                        const contentEl = document.createElement('div');
                        contentEl.className = 'content-block-content';
                         // IMPORTANT: Sanitize HTML content
                        contentEl.innerHTML = block.content ? block.content.replace(/\n/g, '<br>') : '';
                        blockDiv.appendChild(contentEl);
                    }
                    contentBlocks.appendChild(blockDiv);
                });
            } else if (data.contenu) { // Fallback: Use simple 'contenu' field if no blocks
                const blockDiv = document.createElement('div');
                blockDiv.className = 'content-block';
                 // IMPORTANT: Sanitize HTML content
                blockDiv.innerHTML = data.contenu.replace(/\n/g, '<br>');
                contentBlocks.appendChild(blockDiv);
            } else {
                // No blocks and no simple content
                contentBlocks.innerHTML = '<div class="alert alert-warning">Le contenu de ce texte est vide ou non structuré.</div>';
            }

            // --- Final Steps ---
            // Ensure the content section is visible
            contentSection.classList.remove('d-none');

            // Scroll to the top of the content title for better UX
            contentTitle.scrollIntoView({ behavior: 'smooth', block: 'start' });

        })
        .catch(error => {
            console.error(`Erreur lors du chargement du texte ID ${texteId}:`, error);
             // Display error message in the content area
            contentTitle.textContent = "Erreur de chargement";
            contentBlocks.innerHTML = `<div class="alert alert-danger">Impossible de charger le contenu demandé. ${error.message}</div>`;
            // Ensure section is visible even on error
            contentSection.classList.remove('d-none');
        });
}


// ==================================================================
// FEEDBACK FORM SETUP
// ==================================================================

/**
 * Sets up basic validation for the feedback form.
 */
function setupFeedbackForm() {
    const feedbackForm = document.getElementById('feedback-form');
    if (feedbackForm) {
        feedbackForm.addEventListener('submit', function(e) {
            const feedbackMessage = document.getElementById('feedback-message');
            // Simple check if message textarea is empty or only whitespace
            if (!feedbackMessage || !feedbackMessage.value.trim()) {
                e.preventDefault(); // Stop form submission
                alert('Veuillez entrer un message avant d\'envoyer votre avis.');
                if (feedbackMessage) feedbackMessage.focus(); // Focus the textarea
            }
            // Add more complex validation here if needed
        });
    }
}


// ==================================================================
// OLD FUNCTIONS (Removed/Commented Out) - Kept for reference only
// ==================================================================

/*
function setupSubjectSelection() { // No longer used directly on page
    // ... old logic targeting .subject-card elements on the main page ...
}

function loadSubCategories(matiereId) { // Replaced by loadSubCategoriesForSidebar
    // ... old logic targeting #sous-categories-list on the main page ...
}

function setupCategorySelection() { // No longer used directly on page
    // ... old logic targeting #sous-categorie-select or similar ...
}

function loadTextes(categoryId) { // Logic integrated into loadAndDisplayFirstTexte
    // ... old logic targeting #textes-list on the main page ...
}

function setupTextSelection() { // No longer used directly on page
    // ... old logic targeting #texte-select or similar ...
}
*/

// ==================================================================
// END OF FILE
// ==================================================================