window.App = window.App || {};
App.videos = App.videos || {};

(function() {
    const state = App.state;

    const observer = new IntersectionObserver((entries) => {
        if (entries[0].isIntersecting) App.videos.loadVideos();
    }, {
        threshold: 1.0
    });

    App.videos.observeSentinel = function() {
        const sentinel = document.getElementById('sentinel');
        if (sentinel) {
            observer.observe(sentinel);
        }
    };

    App.videos.formatDuration = function(seconds) {
        if (!seconds || seconds <= 0) return '';
        const totalSeconds = Math.floor(seconds);
        const hours = Math.floor(totalSeconds / 3600);
        const minutes = Math.floor((totalSeconds % 3600) / 60);
        if (hours > 0) {
            return `${hours}h ${String(minutes).padStart(2, '0')}m`;
        }
        return `${minutes}m`;
    };

    // Fetches the next page of videos and renders them into the grid.
    App.videos.loadVideos = async function() {
        const session = App.storage.getSession();
        if (!session) return;
        if (state.isLoading || !state.hasNextPage) return;

        const searchInput = document.getElementById('search-input');
        const query = searchInput ? searchInput.value : "";

        let body = {
            channel: session.channel.id,
            query: query || "",
            page: state.currentPage,
            perPage: state.perPage,
            server: session.server
        };

        Object.entries(session.options).forEach(([key, value]) => {
            if (Array.isArray(value)) {
                body[key] = value.map((entry) => entry.id).join(", ");
            } else if (value && value.id) {
                body[key] = value.id;
            }
        });

        try {
            state.isLoading = true;
            App.videos.updateLoadMoreState();
            state.currentLoadController = new AbortController();
            const response = await fetch('/api/videos', {
                method: 'POST',
                headers: {
                    'Content-Type': 'application/json'
                },
                body: JSON.stringify(body),
                signal: state.currentLoadController.signal
            });
            const videos = await response.json();
            App.videos.renderVideos(videos);
            state.hasNextPage = videos && videos.pageInfo ? videos.pageInfo.hasNextPage !== false : true;
            state.currentPage++;
            App.videos.ensureViewportFilled();
        } catch (err) {
            if (err.name !== 'AbortError') {
                console.error("Failed to load videos:", err);
            }
        } finally {
            state.isLoading = false;
            state.currentLoadController = null;
            App.videos.updateLoadMoreState();
        }
    };

    // Renders new cards for videos, wiring favorites + playback behavior.
    App.videos.renderVideos = function(videos) {
        const grid = document.getElementById('video-grid');
        if (!grid) return;

        const items = videos && Array.isArray(videos.items) ? videos.items : [];
        const favoritesSet = App.favorites.getSet();
        items.forEach(v => {
            if (state.renderedVideoIds.has(v.id)) return;

            const card = document.createElement('div');
            card.className = 'video-card';
            const durationText = App.videos.formatDuration(v.duration);
            const favoriteKey = App.favorites.getKey(v);
            card.innerHTML = `
                <button class="favorite-btn" type="button" aria-pressed="false" aria-label="Add to favorites" data-fav-key="${favoriteKey || ''}">♡</button>
                <img src="${v.thumb}" alt="${v.title}">
                <h4>${v.title}</h4>
                <p class="video-meta">${v.channel}</p>
                ${durationText ? `<p class="video-duration">${durationText}</p>` : ''}
            `;
            const favoriteBtn = card.querySelector('.favorite-btn');
            if (favoriteBtn && favoriteKey) {
                App.favorites.setButtonState(favoriteBtn, favoritesSet.has(favoriteKey));
                favoriteBtn.onclick = (event) => {
                    event.stopPropagation();
                    App.favorites.toggle(v);
                };
            }
            card.onclick = () => App.player.open(v.url);
            grid.appendChild(card);
            state.renderedVideoIds.add(v.id);
        });

        App.videos.ensureViewportFilled();
    };

    App.videos.handleSearch = function(value) {
        state.currentPage = 1;
        state.hasNextPage = true;
        state.renderedVideoIds.clear();
        const grid = document.getElementById('video-grid');
        if (grid) grid.innerHTML = "";
        App.videos.updateLoadMoreState();
        App.videos.loadVideos();
    };

    App.videos.resetAndReload = function() {
        if (state.currentLoadController) {
            state.currentLoadController.abort();
            state.currentLoadController = null;
            state.isLoading = false;
        }
        state.currentPage = 1;
        state.hasNextPage = true;
        state.renderedVideoIds.clear();
        const grid = document.getElementById('video-grid');
        if (grid) grid.innerHTML = "";
        App.videos.updateLoadMoreState();
        App.videos.loadVideos();
    };

    App.videos.ensureViewportFilled = function() {
        if (!state.hasNextPage || state.isLoading) return;
        const grid = document.getElementById('video-grid');
        if (!grid) return;
        const docHeight = document.documentElement.scrollHeight;
        if (docHeight <= window.innerHeight + 120) {
            window.setTimeout(() => App.videos.loadVideos(), 0);
        }
    };

    App.videos.updateLoadMoreState = function() {
        const loadMoreBtn = document.getElementById('load-more-btn');
        if (!loadMoreBtn) return;
        loadMoreBtn.disabled = state.isLoading || !state.hasNextPage;
        loadMoreBtn.style.display = state.hasNextPage ? 'flex' : 'none';
    };
})();