/* ============================================
   IVY'S RSS HUB — Main Application
   Orchestrates the RSS feed aggregator
   ============================================ */

/**
 * Shared Utilities — Used by both App and Sidebar
 * Avoids code duplication across modules
 */
window.IvyUtils = {
    /**
     * Escape HTML to prevent XSS
     */
    escapeHtml(text) {
        if (!text) return "";
        const div = document.createElement("div");
        div.textContent = text;
        return div.innerHTML;
    },

    /**
     * Escape text for use in HTML attributes
     */
    escapeAttr(text) {
        if (!text) return "";
        return text
            .replace(/&/g, "&")
            .replace(/"/g, """)
            .replace(/'/g, "'")
            .replace(/</g, "&lt;")
            .replace(/>/g, "&gt;");
    },

    /**
     * Truncate text with ellipsis
     */
    truncate(text, maxLength) {
        if (!text || text.length <= maxLength) return text;
        return text.substring(0, maxLength) + "...";
    }
};

/**
 * RSSHub Application
 */
class RSSHubApp {
    constructor() {
        // Initialize parser
        this.parser = new RSSParser();

        // State
        this.feeds = [];
        this.feedResults = [];
        this.currentCategory = "all";
        this.currentLang = "all"; // Language filter: "all", "en", "fr"
        this.settings = this.loadSettings();
        this.isRefreshing = false; // Prevent double-refresh race conditions
        this.autoRefreshTimer = null; // Auto-refresh interval timer
        this.nextRefreshTime = null; // Timestamp of next auto-refresh
        this.countdownTimer = null; // Countdown display timer

        // DOM Elements
        this.elements = {
            feedsContainer: document.getElementById("feeds-container"),
            statusText: document.getElementById("status-text"),
            statusTime: document.getElementById("status-time"),
            btnRefresh: document.getElementById("btn-refresh"),
            btnTheme: document.getElementById("btn-theme"),
            btnSettings: document.getElementById("btn-settings"),
            btnAbout: document.getElementById("btn-about"),
            modalAbout: document.getElementById("modal-about"),
            modalSettings: document.getElementById("modal-settings"),
            modalCloseAbout: document.getElementById("modal-close-about"),
            modalCloseSettings: document.getElementById("modal-close-settings"),
            sourcesList: document.getElementById("sources-list"),
            navButtons: document.querySelectorAll(".nav-btn"),
            langButtons: document.querySelectorAll(".lang-btn"),
            sidebar: document.getElementById("sidebar")
        };

        // Initialize theme
        this.initTheme();

        // Initialize
        this.init();
    }

    /**
     * Initialize theme from localStorage or system preference
     */
    initTheme() {
        const savedTheme = localStorage.getItem("ivy-rss-hub-theme");

        if (savedTheme) {
            // User has a saved preference
            document.documentElement.setAttribute("data-theme", savedTheme);
            this.updateThemeIcon(savedTheme);
        } else {
            // Use system preference (CSS handles it, but we update the icon)
            const prefersDark = window.matchMedia("(prefers-color-scheme: dark)").matches;
            this.updateThemeIcon(prefersDark ? "dark" : "light");
        }

        // Listen for system theme changes
        window.matchMedia("(prefers-color-scheme: dark)").addEventListener("change", e => {
            if (!localStorage.getItem("ivy-rss-hub-theme")) {
                this.updateThemeIcon(e.matches ? "dark" : "light");
            }
        });
    }

    /**
     * Toggle between light and dark theme
     */
    toggleTheme() {
        const currentTheme = document.documentElement.getAttribute("data-theme");
        const prefersDark = window.matchMedia("(prefers-color-scheme: dark)").matches;

        // Determine current effective theme
        let effectiveTheme;
        if (currentTheme) {
            effectiveTheme = currentTheme;
        } else {
            effectiveTheme = prefersDark ? "dark" : "light";
        }

        // Toggle
        const newTheme = effectiveTheme === "dark" ? "light" : "dark";
        document.documentElement.setAttribute("data-theme", newTheme);
        localStorage.setItem("ivy-rss-hub-theme", newTheme);
        this.updateThemeIcon(newTheme);

        this.showToast(`${newTheme === "dark" ? "🌙 Dark" : "☀️ Light"} theme activated`, "info");
    }

    /**
     * Update theme toggle button icon
     */
    updateThemeIcon(theme) {
        if (this.elements.btnTheme) {
            this.elements.btnTheme.textContent = theme === "dark" ? "🌙" : "☀️";
            this.elements.btnTheme.title = `Switch to ${theme === "dark" ? "light" : "dark"} theme`;
        }
    }

    /**
     * Initialize the application
     */
    init() {
        // Load feeds from settings or defaults
        this.feeds = this.settings.feeds || [...window.FeedsConfig.DEFAULT_FEEDS];

        // Save if migration occurred
        if (this._needsMigrationSave) {
            console.log("[Migration] Saving migrated feed configuration");
            this.saveSettings();
            this._needsMigrationSave = false;
        }

        // Setup event listeners
        this.setupEventListeners();

        // Setup scroll propagation for nested scrollable containers
        this.setupScrollPropagation();

        // Render settings
        this.renderSourcesList();

        // Initialize sidebar
        this.sidebar = new SidebarManager(this);
        window.sidebar = this.sidebar; // Expose for event handlers

        // Initialize settings UI from saved values
        this.initSettingsUI();

        // Initial fetch
        this.refreshFeeds();

        // Start auto-refresh if enabled
        if (this.settings.autoRefresh) {
            this.startAutoRefresh();
        }
    }

    /**
     * Initialize settings UI elements from saved settings
     */
    initSettingsUI() {
        const groupBySourceCheckbox = document.getElementById("opt-group-by-source");
        const showDescriptionsCheckbox = document.getElementById("opt-show-descriptions");
        const maxItemsInput = document.getElementById("opt-max-items");
        const autoRefreshCheckbox = document.getElementById("opt-auto-refresh");
        const refreshIntervalSelect = document.getElementById("opt-refresh-interval");

        if (groupBySourceCheckbox) {
            groupBySourceCheckbox.checked = this.settings.groupBySource !== false;
        }
        if (showDescriptionsCheckbox) {
            showDescriptionsCheckbox.checked = this.settings.showDescriptions !== false;
        }
        if (maxItemsInput) {
            maxItemsInput.value = this.settings.maxItems || 10;
        }
        if (autoRefreshCheckbox) {
            autoRefreshCheckbox.checked = this.settings.autoRefresh === true;
        }
        if (refreshIntervalSelect) {
            refreshIntervalSelect.value = this.settings.refreshInterval || 10;
        }
        this.updateAutoRefreshStatus();
    }

    /**
     * Setup event listeners
     */
    setupEventListeners() {
        // Refresh button - normal click uses cache, shift+click forces refresh
        this.elements.btnRefresh.addEventListener("click", async e => {
            // Prevent double-click while already loading
            if (this.isRefreshing) {
                return;
            }

            if (e.shiftKey) {
                // Force refresh - clear all cache including IndexedDB
                await this.parser.clearAllCache();
                this.showToast("Cache cleared! Refreshing...", "info");
                console.log("🔄 Force refresh - cache cleared");
            }
            // Normal refresh uses cache if available
            this.refreshFeeds();
        });

        // Add tooltip hint
        this.elements.btnRefresh.title = "Refresh feeds (Shift+Click to force refresh)";

        // Theme toggle
        this.elements.btnTheme?.addEventListener("click", () => {
            this.toggleTheme();
        });

        // About modal
        this.elements.btnAbout.addEventListener("click", () => {
            this.elements.modalAbout.classList.add("active");
            // Focus the close button for accessibility
            setTimeout(() => this.elements.modalCloseAbout.focus(), 100);
        });
        this.elements.modalCloseAbout.addEventListener("click", () => {
            this.elements.modalAbout.classList.remove("active");
        });

        // Settings modal
        this.elements.btnSettings.addEventListener("click", () => {
            this.renderSourcesList();
            this.elements.modalSettings.classList.add("active");
            // Focus the close button for accessibility
            setTimeout(() => this.elements.modalCloseSettings.focus(), 100);
        });
        this.elements.modalCloseSettings.addEventListener("click", () => {
            this.elements.modalSettings.classList.remove("active");
        });

        // Close modals on overlay click
        [this.elements.modalAbout, this.elements.modalSettings].forEach(modal => {
            modal.addEventListener("click", e => {
                if (e.target === modal) {
                    modal.classList.remove("active");
                }
            });
        });

        // Focus trap for modals (accessibility)
        document.addEventListener("keydown", e => {
            if (e.key !== "Tab") return;

            // Check if a modal is open
            const activeModal = document.querySelector(".modal-overlay.active .modal");
            if (!activeModal) return;

            // Get all focusable elements in the modal
            const focusableElements = activeModal.querySelectorAll(
                'button, [href], input, select, textarea, [tabindex]:not([tabindex="-1"])'
            );
            const firstElement = focusableElements[0];
            const lastElement = focusableElements[focusableElements.length - 1];

            // Trap focus within modal
            if (e.shiftKey && document.activeElement === firstElement) {
                e.preventDefault();
                lastElement.focus();
            } else if (!e.shiftKey && document.activeElement === lastElement) {
                e.preventDefault();
                firstElement.focus();
            }
        });

        // Keyboard shortcuts
        document.addEventListener("keydown", e => {
            // Don't trigger shortcuts when typing in inputs
            if (e.target.tagName === "INPUT" || e.target.tagName === "TEXTAREA") {
                // Escape to blur inputs
                if (e.key === "Escape") e.target.blur();
                return;
            }

            // Escape to close modals and sidebar
            if (e.key === "Escape") {
                this.elements.modalAbout.classList.remove("active");
                this.elements.modalSettings.classList.remove("active");
                // Also close mobile sidebar
                this.elements.sidebar?.classList.remove("open");
            }

            // R to refresh (Shift+R for force refresh)
            if (e.key === "r" || e.key === "R") {
                e.preventDefault();
                if (e.shiftKey) {
                    this.parser.clearAllCache().then(() => {
                        this.showToast("Cache cleared! Refreshing...", "info");
                        this.refreshFeeds();
                    });
                } else {
                    this.refreshFeeds();
                }
            }

            // / to focus search
            if (e.key === "/") {
                e.preventDefault();
                const searchInput = document.getElementById("search-input");
                if (searchInput) {
                    searchInput.focus();
                    // Open sidebar on mobile
                    if (window.innerWidth <= 1100) {
                        this.elements.sidebar?.classList.add("open");
                    }
                }
            }

            // S to toggle sidebar on desktop
            if (e.key === "s" && !e.ctrlKey && !e.metaKey) {
                const sidebar = document.getElementById("sidebar");
                if (sidebar) sidebar.classList.toggle("hidden-desktop");
            }

            // T to toggle theme
            if (e.key === "t" && !e.ctrlKey && !e.metaKey) {
                this.toggleTheme();
            }

            // Home or ArrowUp (when not in input) to scroll to top
            if (e.key === "Home" || (e.key === "ArrowUp" && e.ctrlKey)) {
                e.preventDefault();
                this.scrollToTop();
            }
        });

        // Back to top button
        this.setupBackToTop();

        // Category navigation
        this.elements.navButtons.forEach(btn => {
            btn.addEventListener("click", () => {
                this.setCategory(btn.dataset.category);
            });
        });

        // Add custom feed (use AbortController pattern to prevent duplicate listeners)
        const addFeedBtn = document.getElementById("btn-add-feed");
        if (addFeedBtn && !addFeedBtn.dataset.listenerAttached) {
            addFeedBtn.addEventListener("click", () => this.addCustomFeed());
            addFeedBtn.dataset.listenerAttached = "true";
        }

        // Settings options
        document.getElementById("opt-group-by-source")?.addEventListener("change", e => {
            this.settings.groupBySource = e.target.checked;
            this.saveSettings();
            this.renderFeeds();
        });

        document.getElementById("opt-show-descriptions")?.addEventListener("change", e => {
            this.settings.showDescriptions = e.target.checked;
            this.saveSettings();
            this.renderFeeds();
        });

        document.getElementById("opt-max-items")?.addEventListener("change", e => {
            this.settings.maxItems = parseInt(e.target.value) || 20;
            this.saveSettings();
            this.renderFeeds();
        });

        // Auto-refresh settings
        document.getElementById("opt-auto-refresh")?.addEventListener("change", e => {
            this.settings.autoRefresh = e.target.checked;
            this.saveSettings();
            if (e.target.checked) {
                this.startAutoRefresh();
                this.showToast("Auto-refresh enabled! ⏰", "success");
            } else {
                this.stopAutoRefresh();
                this.showToast("Auto-refresh disabled", "info");
            }
        });

        document.getElementById("opt-refresh-interval")?.addEventListener("change", e => {
            this.settings.refreshInterval = parseInt(e.target.value) || 10;
            this.saveSettings();
            // Restart timer with new interval if auto-refresh is enabled
            if (this.settings.autoRefresh) {
                this.startAutoRefresh();
                this.showToast(`Refresh interval set to ${e.target.value} minutes`, "success");
            }
        });

        // Enable/Disable all feeds buttons
        document.getElementById("btn-enable-all")?.addEventListener("click", () => {
            this.feeds.forEach(f => (f.enabled = true));
            this.saveSettings();
            this.renderSourcesList();
            this.showToast("All feeds enabled!", "success");
        });

        document.getElementById("btn-disable-all")?.addEventListener("click", () => {
            this.feeds.forEach(f => (f.enabled = false));
            this.saveSettings();
            this.renderSourcesList();
            this.showToast("All feeds disabled", "info");
        });

        // Language filter buttons
        this.elements.langButtons.forEach(btn => {
            btn.addEventListener("click", () => {
                this.setLanguage(btn.dataset.lang);
            });
        });

        // Reset all data button
        document.getElementById("btn-reset-all")?.addEventListener("click", () => {
            this.resetAllData();
        });
    }

    /**
     * Set active category filter
     */
    setCategory(category) {
        this.currentCategory = category;

        // Update nav buttons
        this.elements.navButtons.forEach(btn => {
            btn.classList.toggle("active", btn.dataset.category === category);
        });

        // Re-render feeds
        this.renderFeeds();
    }

    /**
     * Setup scroll propagation for nested scrollable containers
     * Fixes the issue where scroll gets "trapped" inside .source-articles
     * when reaching the top or bottom of the container
     */
    setupScrollPropagation() {
        // Use event delegation on the feeds container
        this.elements.feedsContainer.addEventListener(
            "wheel",
            e => {
                const target = e.target.closest(".source-articles");
                if (!target) return;

                const { scrollTop, scrollHeight, clientHeight } = target;
                const isAtTop = scrollTop <= 0;
                const isAtBottom = scrollTop + clientHeight >= scrollHeight - 1;

                // If scrolling up and at top, or scrolling down and at bottom,
                // let the event propagate to the parent
                if ((e.deltaY < 0 && isAtTop) || (e.deltaY > 0 && isAtBottom)) {
                    // Don't prevent default - let parent scroll
                    return;
                }

                // Otherwise, prevent the event from reaching the parent
                // This keeps scroll inside the container when not at bounds
                if (scrollHeight > clientHeight) {
                    e.stopPropagation();
                }
            },
            { passive: true }
        );
    }

    /**
     * Setup Back to Top button behavior
     */
    setupBackToTop() {
        const backToTopBtn = document.getElementById("back-to-top");
        if (!backToTopBtn) return;

        // Show/hide button based on scroll position
        let ticking = false;
        window.addEventListener(
            "scroll",
            () => {
                if (!ticking) {
                    requestAnimationFrame(() => {
                        const scrollY = window.scrollY || document.documentElement.scrollTop;
                        // Show button after scrolling 400px
                        if (scrollY > 400) {
                            backToTopBtn.classList.add("visible");
                        } else {
                            backToTopBtn.classList.remove("visible");
                        }
                        ticking = false;
                    });
                    ticking = true;
                }
            },
            { passive: true }
        );

        // Click handler
        backToTopBtn.addEventListener("click", () => {
            this.scrollToTop();
        });
    }

    /**
     * Smooth scroll to top of page
     */
    scrollToTop() {
        window.scrollTo({
            top: 0,
            behavior: "smooth"
        });
    }

    /* ============================================
       AUTO-REFRESH SYSTEM
       ============================================ */

    /**
     * Start auto-refresh timer
     */
    startAutoRefresh() {
        // Clear any existing timer
        this.stopAutoRefresh();

        const intervalMinutes = this.settings.refreshInterval || 10;
        const intervalMs = intervalMinutes * 60 * 1000;

        // Set next refresh time
        this.nextRefreshTime = Date.now() + intervalMs;

        // Start main refresh timer
        this.autoRefreshTimer = setInterval(() => {
            console.log("[RSS] Auto-refresh triggered");
            this.refreshFeeds();
            // Reset next refresh time
            this.nextRefreshTime = Date.now() + intervalMs;
        }, intervalMs);

        // Start countdown display timer (update every 10 seconds)
        this.countdownTimer = setInterval(() => {
            this.updateAutoRefreshStatus();
        }, 10000);

        // Update status immediately
        this.updateAutoRefreshStatus();

        console.log(`[RSS] Auto-refresh started: every ${intervalMinutes} minutes`);
    }

    /**
     * Stop auto-refresh timer
     */
    stopAutoRefresh() {
        if (this.autoRefreshTimer) {
            clearInterval(this.autoRefreshTimer);
            this.autoRefreshTimer = null;
        }
        if (this.countdownTimer) {
            clearInterval(this.countdownTimer);
            this.countdownTimer = null;
        }
        this.nextRefreshTime = null;
        this.updateAutoRefreshStatus();
    }

    /**
     * Update auto-refresh status display
     */
    updateAutoRefreshStatus() {
        const statusEl = document.getElementById("auto-refresh-status");
        if (!statusEl) return;

        if (!this.settings.autoRefresh || !this.nextRefreshTime) {
            statusEl.textContent = "Auto-refresh is disabled";
            statusEl.style.color = "";
            return;
        }

        const remaining = this.nextRefreshTime - Date.now();
        if (remaining <= 0) {
            statusEl.textContent = "Refreshing now...";
            statusEl.style.color = "var(--ivy-green)";
            return;
        }

        const minutes = Math.floor(remaining / 60000);
        const seconds = Math.floor((remaining % 60000) / 1000);

        if (minutes > 0) {
            statusEl.textContent = `⏰ Next refresh in ${minutes}m ${seconds}s`;
        } else {
            statusEl.textContent = `⏰ Next refresh in ${seconds}s`;
        }
        statusEl.style.color = "var(--ivy-green)";
    }

    /**
     * Set active language filter
     */
    setLanguage(lang) {
        this.currentLang = lang;

        // Update lang buttons
        this.elements.langButtons.forEach(btn => {
            btn.classList.toggle("active", btn.dataset.lang === lang);
        });

        // Re-render feeds
        this.renderFeeds();
    }

    /**
     * Refresh all feeds
     */
    async refreshFeeds() {
        // Prevent concurrent refresh calls
        if (this.isRefreshing) {
            console.debug("[RSS] Refresh already in progress, skipping");
            return;
        }
        this.isRefreshing = true;

        try {
            // Show loading state
            this.elements.btnRefresh.classList.add("spinning");
            this.elements.btnRefresh.setAttribute("aria-busy", "true");
            this.setStatus("Loading feeds...", "");
            this.renderLoading();

            // Get enabled feeds
            const enabledFeeds = this.feeds.filter(f => f.enabled);

            if (enabledFeeds.length === 0) {
                this.setStatus("No feeds enabled", "");
                this.renderEmpty("No feeds enabled. Go to Settings to enable some feeds.");
                return;
            }

            // Use progressive loading with callback
            this.feedResults = [];

            await this.parser.fetchAllFeedsProgressive(enabledFeeds, (results, loaded, total) => {
                // Update results
                this.feedResults = results;

                // Calculate stats
                const successful = results.filter(r => r.status === "success").length;
                const fromCache = results.filter(r => r.fromCache).length;
                const maxItems = this.settings.maxItems || 10;

                // Count DISPLAYED articles (limited by maxItems per source)
                const displayedArticles = results
                    .filter(r => r.feed)
                    .reduce((sum, r) => sum + Math.min(r.feed.items.length, maxItems), 0);

                // Update status with progress
                const cacheInfo = fromCache > 0 ? ` (${fromCache} cached)` : "";
                this.setStatus(
                    `${successful}/${loaded} sources loaded${cacheInfo} • ~${displayedArticles} articles`,
                    loaded < total ? `Loading ${loaded}/${total}...` : `Last updated: ${this.formatTime(new Date())}`
                );

                // Render feeds progressively
                this.renderFeeds();
            });

            // Final update
            const successful = this.feedResults.filter(r => r.status === "success").length;
            const total = this.feedResults.length;
            const fromCache = this.feedResults.filter(r => r.fromCache).length;
            const maxItems = this.settings.maxItems || 10;
            const displayedArticles = this.feedResults
                .filter(r => r.feed)
                .reduce((sum, r) => sum + Math.min(r.feed.items.length, maxItems), 0);

            const cacheInfo = fromCache > 0 ? ` (${fromCache} ⚡)` : "";
            this.setStatus(
                `${successful}/${total} sources${cacheInfo} • ${displayedArticles} articles`,
                `Last updated: ${this.formatTime(new Date())}`
            );

            // Render feeds
            this.renderFeeds();

            // Update sidebar with article data
            if (this.sidebar) {
                this.sidebar.updateWithArticles(this.feedResults);
            }
        } catch (error) {
            console.error("[RSS] Error during refresh:", error);
            this.setStatus("Error loading feeds", "");
            this.showToast("Failed to load some feeds. Please try again.", "error");
        } finally {
            // Always cleanup - stop spinner and reset flag
            this.elements.btnRefresh.classList.remove("spinning");
            this.elements.btnRefresh.setAttribute("aria-busy", "false");
            this.isRefreshing = false;
        }
    }

    /**
     * Render loading state
     */
    renderLoading() {
        const enabledCount = this.feeds.filter(f => f.enabled).length;
        this.elements.feedsContainer.innerHTML = `
            <div class="loading-state">
                <div class="loading-spinner"></div>
                <p>Fetching ${enabledCount} feeds...</p>
                <p class="hint">First load may take a moment. Shift+R to force refresh.</p>
            </div>
        `;
    }

    /**
     * Render empty state
     */
    renderEmpty(message) {
        this.elements.feedsContainer.innerHTML = `
            <div class="empty-state">
                <div class="empty-icon">📭</div>
                <p>${message}</p>
                <p class="hint">Try changing filters or enabling more sources in Settings.</p>
            </div>
        `;
    }

    /**
     * Render feeds to DOM
     */
    renderFeeds() {
        // Filter by category
        let filteredResults = this.feedResults;
        if (this.currentCategory !== "all") {
            filteredResults = this.feedResults.filter(r => r.category === this.currentCategory);
        }

        // Filter by language
        if (this.currentLang !== "all") {
            filteredResults = filteredResults.filter(r => r.lang === this.currentLang);
        }

        // Filter to only successful feeds
        const successfulFeeds = filteredResults.filter(r => r.status === "success" && r.feed);

        if (successfulFeeds.length === 0) {
            const langLabel = this.currentLang === "en" ? "English" : this.currentLang === "fr" ? "French" : "";
            this.renderEmpty(`No articles found for this filter.${langLabel ? ` (${langLabel} only)` : ""}`);
            return;
        }

        // Group by source (default: true)
        if (this.settings.groupBySource !== false) {
            this.renderGroupedBySource(successfulFeeds);
        } else {
            this.renderMergedList(successfulFeeds);
        }

        // Show failed feeds if any (collapsed by default)
        const failedFeeds = filteredResults.filter(r => r.status === "error");
        if (failedFeeds.length > 0) {
            this.renderFailedFeeds(failedFeeds);
        }
    }

    /**
     * Render a section showing failed feeds
     */
    renderFailedFeeds(failedFeeds) {
        const html = `
            <section class="source-section error collapsed" data-source="failed-feeds">
                <header class="source-header" onclick="app.toggleSource('failed-feeds')" role="button" tabindex="0" aria-expanded="false">
                    <div class="source-title">
                        <span class="source-icon">⚠️</span>
                        <span class="source-name">Failed to load (${failedFeeds.length})</span>
                    </div>
                    <div class="source-meta">
                        <span class="source-count" style="background: #ef4444;">${failedFeeds.length}</span>
                        <span class="source-toggle">▼</span>
                    </div>
                </header>
                <ul class="source-articles">
                    ${failedFeeds
                        .map(
                            feed => `
                        <div class="article-item-wrapper">
                            <div class="article-item" style="cursor: default;">
                                <div class="article-title">${this.escapeHtml(feed.name)}</div>
                                <div class="article-meta">
                                    <span style="color: #ef4444;">❌ ${this.escapeHtml(feed.error || "Unknown error")}</span>
                                </div>
                            </div>
                        </div>
                    `
                        )
                        .join("")}
                </ul>
            </section>
        `;

        this.elements.feedsContainer.insertAdjacentHTML("beforeend", html);
    }

    /**
     * Render feeds grouped by source (optimized with innerHTML batching)
     */
    renderGroupedBySource(feedResults) {
        const maxItems = this.settings.maxItems || 10;

        // Build all HTML at once for better performance (single DOM reflow)
        const htmlParts = feedResults.map((result, index) => {
            const items = result.feed.items.slice(0, maxItems);
            const categoryInfo = window.FeedsConfig.CATEGORIES[result.category] || {};
            const isFavorite = this.sidebar?.isSourceFavorite(result.id);
            const favoriteClass = isFavorite ? "saved" : "";
            const colorIndex = this.getSourceColorIndex(result.id);

            // Determine status class based on result
            const statusClass = result.fromCache ? "cached" : "fresh";
            const statusIcon = result.fromCache ? "⚡" : "";

            return `
                <section class="source-section" data-source="${result.id}" data-color-index="${colorIndex}" role="region" aria-label="${this.escapeHtml(result.name)} feed">
                    <header class="source-header" role="button" tabindex="0" aria-expanded="true" onclick="app.toggleSource('${result.id}')" onkeydown="if(event.key==='Enter'||event.key===' '){event.preventDefault();app.toggleSource('${result.id}')}">
                        <button class="source-favorite ${favoriteClass}"
                                onclick="event.stopPropagation(); app.toggleSourceFavorite('${result.id}', '${this.escapeHtml(result.name)}', '${result.icon}')"
                                onkeydown="event.stopPropagation()"
                                aria-label="${isFavorite ? "Remove from favorites" : "Add to favorites"}"
                                title="${isFavorite ? "Remove from favorites" : "Add to favorites"}">
                            ${isFavorite ? "★" : "☆"}
                        </button>
                        <div class="source-title">
                            <span class="source-icon" aria-hidden="true">${result.icon}</span>
                            <span class="source-name">${result.name}</span>
                        </div>
                        <div class="source-meta">
                            <span class="source-count" aria-label="${items.length} articles">${items.length}</span>
                            <span class="source-status ${statusClass}" title="${result.fromCache ? "Loaded from cache" : "Fresh from source"}">
                                ${statusIcon} ${this.formatTimeAgo(result.lastFetched)}
                            </span>
                            <span class="source-toggle" aria-hidden="true">▼</span>
                        </div>
                    </header>
                    <ul class="source-articles">
                        ${items.map(item => this.renderArticleItem(item)).join("")}
                    </ul>
                </section>
            `;
        });

        // Single DOM update for better performance
        this.elements.feedsContainer.innerHTML = htmlParts.join("");
    }

    /**
     * Toggle favorite state for a source
     */
    toggleSourceFavorite(sourceId, sourceName, sourceIcon) {
        if (!this.sidebar) return;
        const wasAdded = this.sidebar.toggleFavoriteSource(sourceId, sourceName, sourceIcon);
        this.showToast(
            wasAdded ? `${sourceName} added to favorites! ⭐` : `${sourceName} removed from favorites`,
            wasAdded ? "success" : "info"
        );
        this.renderFeeds();
    }

    /**
     * Render all articles in a merged list sorted by date
     */
    renderMergedList(feedResults) {
        const maxItems = this.settings.maxItems || 10;

        // Collect all articles with source info
        const allArticles = feedResults.flatMap(result =>
            result.feed.items.map(item => ({
                ...item,
                sourceName: result.name,
                sourceIcon: result.icon,
                sourceId: result.id
            }))
        );

        // Sort by date (newest first)
        allArticles.sort((a, b) => {
            const dateA = a.pubDate || new Date(0);
            const dateB = b.pubDate || new Date(0);
            return dateB - dateA;
        });

        // Limit total
        const limitedArticles = allArticles.slice(0, maxItems * feedResults.length);

        const html = `
            <section class="source-section">
                <header class="source-header">
                    <div class="source-title">
                        <span class="source-icon">📰</span>
                        <span class="source-name">All Articles</span>
                    </div>
                    <div class="source-meta">
                        <span class="source-count">${limitedArticles.length}</span>
                    </div>
                </header>
                <ul class="source-articles">
                    ${limitedArticles.map(item => this.renderArticleItem(item, true)).join("")}
                </ul>
            </section>
        `;

        this.elements.feedsContainer.innerHTML = html;
    }

    /**
     * Render a single article item
     */
    renderArticleItem(item, showSource = false) {
        const dateStr = item.pubDate ? this.formatTimeAgo(item.pubDate) : "";
        const fullDate = item.pubDate ? this.formatFullDate(item.pubDate) : "";
        const sourceStr =
            showSource && item.sourceName
                ? `<span class="article-source">${item.sourceIcon} ${item.sourceName}</span>`
                : "";

        // Check if article is recent (less than 2 hours old)
        const isRecent = item.pubDate && Date.now() - item.pubDate.getTime() < 2 * 60 * 60 * 1000;
        const recentClass = isRecent ? "recent" : "";

        // Show description preview if available and enabled in settings
        const showDescriptions = this.settings.showDescriptions !== false;
        const descriptionStr =
            showDescriptions && item.description
                ? `<div class="article-description">${this.escapeHtml(item.description.substring(0, 120))}${item.description.length > 120 ? "..." : ""}</div>`
                : "";

        const isBookmarked = this.sidebar?.isBookmarked(item.link);
        const bookmarkClass = isBookmarked ? "saved" : "";
        // Use data attributes to avoid XSS and JSON parsing issues in onclick
        const safeTitle = this.escapeAttr(item.title);
        const safeLink = this.escapeAttr(item.link);
        const safeSource = this.escapeAttr(item.sourceName || "Unknown");

        return `
            <div class="article-item-wrapper ${recentClass}">
                <a class="article-item" href="${this.escapeHtml(item.link)}" target="_blank" rel="noopener">
                    <div class="article-title">${isRecent ? '<span class="new-badge">NEW</span>' : ""}${this.escapeHtml(item.title)}</div>
                    ${descriptionStr}
                    <div class="article-meta">
                        ${sourceStr}
                        ${dateStr ? `<span class="article-date" title="${fullDate}">🕐 ${dateStr}</span>` : ""}
                    </div>
                </a>
                <button class="article-bookmark ${bookmarkClass}"
                        data-title="${safeTitle}"
                        data-link="${safeLink}"
                        data-source="${safeSource}"
                        onclick="app.toggleBookmarkFromElement(this)"
                        aria-label="${isBookmarked ? "Remove bookmark" : "Add bookmark"}"
                        title="${isBookmarked ? "Remove bookmark" : "Add bookmark"}">
                    ${isBookmarked ? "★" : "☆"}
                </button>
            </div>
        `;
    }

    /**
     * Toggle bookmark for an article (from data attributes)
     */
    toggleBookmarkFromElement(element) {
        if (!this.sidebar) return;

        const articleData = {
            title: element.dataset.title,
            link: element.dataset.link,
            sourceName: element.dataset.source
        };

        if (this.sidebar.isBookmarked(articleData.link)) {
            this.sidebar.removeBookmark(articleData.link);
            this.showToast("Bookmark removed", "info");
        } else {
            this.sidebar.addBookmark(articleData);
            this.showToast("Bookmark added! ⭐", "success");
        }

        // Re-render to update bookmark states
        this.renderFeeds();
    }

    /**
     * Show toast notification
     */
    showToast(message, type = "info") {
        // Remove existing toast if any
        const existing = document.querySelector(".toast-notification");
        if (existing) existing.remove();

        const toast = document.createElement("div");
        toast.className = `toast-notification toast-${type}`;
        toast.setAttribute("role", "status");
        toast.setAttribute("aria-live", "polite");
        toast.innerHTML = `<span>${message}</span>`;
        document.body.appendChild(toast);

        // Trigger animation
        requestAnimationFrame(() => toast.classList.add("show"));

        // Auto-dismiss
        setTimeout(() => {
            toast.classList.remove("show");
            setTimeout(() => toast.remove(), 300);
        }, 2500);
    }

    /**
     * Toggle source section collapse
     */
    toggleSource(sourceId) {
        const section = document.querySelector(`.source-section[data-source="${sourceId}"]`);
        if (section) {
            section.classList.toggle("collapsed");
            // Update aria-expanded
            const header = section.querySelector(".source-header");
            if (header) {
                const isCollapsed = section.classList.contains("collapsed");
                header.setAttribute("aria-expanded", !isCollapsed);
            }
        }
    }

    /**
     * Render sources list in settings
     */
    renderSourcesList() {
        const html = this.feeds
            .map(feed => {
                const categoryInfo = window.FeedsConfig.CATEGORIES[feed.category] || {};
                const langFlag = feed.lang === "fr" ? "🇫🇷" : feed.lang === "en" ? "🇬🇧" : "🌍";
                const deleteBtn = feed.custom
                    ? `<button class="source-delete-btn" onclick="event.stopPropagation(); app.deleteCustomFeed('${feed.id}')" title="Delete custom feed">🗑️</button>`
                    : "";
                return `
                <div class="source-toggle-item" data-feed-id="${feed.id}">
                    <input type="checkbox"
                           id="feed-${feed.id}"
                           ${feed.enabled ? "checked" : ""}
                           onchange="app.toggleFeedEnabled('${feed.id}', this.checked)"
                           aria-label="Enable ${this.escapeHtml(feed.name)}">
                    <div class="source-toggle-info">
                        <div class="source-toggle-name">${feed.icon} ${this.escapeHtml(feed.name)} ${feed.custom ? "<span class='custom-badge'>Custom</span>" : ""}</div>
                        <div class="source-toggle-url">${this.escapeHtml(feed.url)}</div>
                    </div>
                    <span class="source-toggle-lang" title="${feed.lang === "fr" ? "French" : "English"}">${langFlag}</span>
                    <span class="source-toggle-category">${categoryInfo.icon || ""} ${categoryInfo.name || feed.category}</span>
                    ${deleteBtn}
                </div>
            `;
            })
            .join("");

        this.elements.sourcesList.innerHTML = html;
    }

    /**
     * Delete a custom feed
     */
    deleteCustomFeed(feedId) {
        const feed = this.feeds.find(f => f.id === feedId);
        if (!feed || !feed.custom) {
            this.showToast("Cannot delete built-in feeds", "error");
            return;
        }

        if (!confirm(`Delete "${feed.name}"?`)) return;

        this.feeds = this.feeds.filter(f => f.id !== feedId);
        this.saveSettings();
        this.renderSourcesList();
        this.showToast(`"${feed.name}" deleted`, "info");
        this.refreshFeeds();
    }

    /**
     * Toggle feed enabled state
     */
    toggleFeedEnabled(feedId, enabled) {
        const feed = this.feeds.find(f => f.id === feedId);
        if (feed) {
            feed.enabled = enabled;
            this.saveSettings();
            this.showToast(`${feed.name} ${enabled ? "enabled" : "disabled"}`, enabled ? "success" : "info");
        }
    }

    /**
     * Add custom feed with validation
     */
    async addCustomFeed() {
        const nameInput = document.getElementById("custom-feed-name");
        const urlInput = document.getElementById("custom-feed-url");
        const categorySelect = document.getElementById("custom-feed-category");
        const addBtn = document.getElementById("btn-add-feed");

        const name = nameInput.value.trim();
        const url = urlInput.value.trim();
        const category = categorySelect.value;

        if (!name || !url) {
            this.showToast("Please enter both name and URL", "error");
            return;
        }

        // Validate URL format
        try {
            new URL(url);
        } catch {
            this.showToast("Please enter a valid URL", "error");
            return;
        }

        // Show loading state
        const originalText = addBtn.textContent;
        addBtn.textContent = "Testing...";
        addBtn.disabled = true;

        // Test if the URL is actually a valid RSS feed
        try {
            const result = await this.parser.fetchFeed({ url, name, id: "test" });
            if (result.status !== "success") {
                throw new Error(result.error || "Invalid RSS feed");
            }
        } catch (e) {
            addBtn.textContent = originalText;
            addBtn.disabled = false;
            this.showToast(`Invalid feed: ${e.message}`, "error");
            return;
        }

        // Restore button
        addBtn.textContent = originalText;
        addBtn.disabled = false;

        // Generate unique ID
        const id = "custom_" + Date.now();

        // Detect language from category or default to 'en'
        const langSelect = document.getElementById("custom-feed-lang");
        const lang = langSelect ? langSelect.value : "en";

        // Add to feeds
        this.feeds.push({
            id,
            name,
            url,
            icon: "📡",
            category,
            lang,
            enabled: true,
            custom: true
        });

        // Save and refresh
        this.saveSettings();
        this.renderSourcesList();
        this.showToast(`Feed "${name}" added! 🎉`, "success");

        // Clear inputs
        nameInput.value = "";
        urlInput.value = "";

        // Refresh feeds
        this.refreshFeeds();
    }

    /**
     * Load settings from localStorage
     */
    loadSettings() {
        try {
            const saved = localStorage.getItem("ivy-rss-hub-settings");
            if (saved) {
                const parsed = JSON.parse(saved);
                // Ensure groupBySource defaults to true if not set
                if (parsed.groupBySource === undefined) {
                    parsed.groupBySource = true;
                }
                // Ensure showDescriptions defaults to true if not set
                if (parsed.showDescriptions === undefined) {
                    parsed.showDescriptions = true;
                }

                // Run migrations for existing users
                if (parsed.feeds) {
                    parsed.feeds = this.migrateFeeds(parsed.feeds);
                }

                return parsed;
            }
        } catch (e) {
            console.warn("Failed to load settings:", e);
        }

        // Defaults
        return {
            groupBySource: true,
            showDescriptions: true,
            maxItems: 10,
            feeds: null // Will use defaults
        };
    }

    /**
     * Migrate old feed configurations to new ones
     * This handles breaking changes like the arXiv RSS -> API migration
     */
    migrateFeeds(feeds) {
        // Migration v1: Replace old arXiv RSS feeds with new API feed
        // Old feeds: arxiv-ai, arxiv-ml, arxiv-cl, arxiv-cv, arxiv-ne, arxiv-combined
        // New feed: arxiv-ai-api
        const oldArxivIds = ["arxiv-ai", "arxiv-ml", "arxiv-cl", "arxiv-cv", "arxiv-ne", "arxiv-combined"];
        const newArxivId = "arxiv-ai-api";

        const hasOldArxiv = feeds.some(f => oldArxivIds.includes(f.id));
        const hasNewArxiv = feeds.some(f => f.id === newArxivId);

        if (hasOldArxiv && !hasNewArxiv) {
            console.log("[Migration] Replacing old arXiv RSS feeds with new API feed");

            // Check if any old arXiv feed was enabled
            const wasEnabled = feeds.some(f => oldArxivIds.includes(f.id) && f.enabled);

            // Remove old arXiv feeds
            feeds = feeds.filter(f => !oldArxivIds.includes(f.id));

            // Add new combined API feed at the beginning of AI category
            const newArxivFeed = {
                id: "arxiv-ai-api",
                name: "arXiv — AI & ML (Recent)",
                url: "https://export.arxiv.org/api/query?search_query=cat:cs.AI+OR+cat:cs.LG+OR+cat:cs.CL+OR+cat:cs.CV+OR+cat:cs.NE&max_results=100&sortBy=submittedDate&sortOrder=descending",
                icon: "🎓",
                category: "ai",
                lang: "en",
                enabled: wasEnabled,
                isAtom: true
            };

            // Insert at the beginning
            feeds.unshift(newArxivFeed);

            // Mark that we need to save after init
            this._needsMigrationSave = true;
        }

        return feeds;
    }

    /**
     * Reset all data (localStorage + IndexedDB)
     */
    async resetAllData() {
        if (
            !confirm(
                "Are you sure you want to reset ALL data?\n\nThis will delete:\n• All settings\n• Custom feeds\n• Bookmarks\n• Cached data\n\nThis action cannot be undone."
            )
        ) {
            return;
        }

        try {
            // Clear localStorage entries for this app
            localStorage.removeItem("ivy-rss-hub-settings");
            localStorage.removeItem("ivy-rss-hub-theme");
            localStorage.removeItem("ivy-rss-hub-bookmarks");
            localStorage.removeItem("ivy-rss-hub-favorites");
            localStorage.removeItem("ivy-rss-hub-sidebar");

            // Clear IndexedDB (Dexie cache)
            if (this.parser && this.parser.db) {
                await this.parser.db.delete();
                console.log("🗑️ IndexedDB cleared");
            }

            this.showToast("All data cleared! Reloading...", "success");

            // Reload page after a short delay
            setTimeout(() => {
                window.location.reload();
            }, 1000);
        } catch (e) {
            console.error("Reset failed:", e);
            this.showToast("Reset failed: " + e.message, "error");
        }
    }

    /**
     * Save settings to localStorage with quota handling
     */
    saveSettings() {
        try {
            this.settings.feeds = this.feeds;
            const data = JSON.stringify(this.settings);

            // Check approximate size (rough estimate)
            const sizeKB = new Blob([data]).size / 1024;
            if (sizeKB > 4500) {
                // Approaching 5MB limit - warn user
                console.warn(`Settings size: ${sizeKB.toFixed(1)}KB - approaching limit`);
                this.showToast("Storage nearly full. Consider removing some feeds.", "error");
            }

            localStorage.setItem("ivy-rss-hub-settings", data);
        } catch (e) {
            if (e.name === "QuotaExceededError") {
                this.showToast("Storage full! Please delete some feeds.", "error");
            }
            console.warn("Failed to save settings:", e);
        }
    }

    /**
     * Set status bar text
     */
    setStatus(text, time) {
        this.elements.statusText.textContent = text;
        this.elements.statusTime.textContent = time;
    }

    /**
     * Format time to readable string
     */
    formatTime(date) {
        return date.toLocaleTimeString([], { hour: "2-digit", minute: "2-digit" });
    }

    /**
     * Format full date and time for tooltips
     */
    formatFullDate(date) {
        if (!date) return "";

        return date.toLocaleString("fr-FR", {
            weekday: "short",
            day: "numeric",
            month: "short",
            year: "numeric",
            hour: "2-digit",
            minute: "2-digit"
        });
    }

    /**
     * Format time ago string
     */
    formatTimeAgo(date) {
        if (!date) return "";

        const now = new Date();
        const diffMs = now - date;
        const diffMins = Math.floor(diffMs / 60000);
        const diffHours = Math.floor(diffMins / 60);
        const diffDays = Math.floor(diffHours / 24);

        if (diffMins < 1) return "just now";
        if (diffMins < 60) return `${diffMins}m ago`;
        if (diffHours < 24) return `${diffHours}h ago`;
        if (diffDays < 7) return `${diffDays}d ago`;

        return date.toLocaleDateString();
    }

    /**
     * Escape HTML to prevent XSS (delegates to shared utility)
     */
    escapeHtml(text) {
        return window.IvyUtils.escapeHtml(text);
    }

    /**
     * Escape text for use in HTML attributes (delegates to shared utility)
     */
    escapeAttr(text) {
        return window.IvyUtils.escapeAttr(text);
    }

    /**
     * Get a consistent color index (0-11) based on source ID
     * Uses simple hash for consistent colors per source
     */
    getSourceColorIndex(sourceId) {
        let hash = 0;
        for (let i = 0; i < sourceId.length; i++) {
            hash = (hash << 5) - hash + sourceId.charCodeAt(i);
            hash = hash & hash; // Convert to 32-bit integer
        }
        return Math.abs(hash) % 12; // 12 color variations
    }
}

// Initialize app when DOM is ready
let app;
document.addEventListener("DOMContentLoaded", () => {
    app = new RSSHubApp();
    window.app = app; // Expose for event handlers
});