3RESIT/backend/app/controllers/recommendation.controller.js

import {getClient} from "../utils/database.js";


export async function getRecommendations(req, res) {

    const token = req.headers.authorization?.split(' ')[1];

    if (!req.headers.authorization || !token) {

        // GET MOST USED TAGS
        let client = await getClient();
        let queryMostUsedTags = `SELECT id, name FROM tags ORDER BY usage_count DESC LIMIT 3;`;
        let result = await client.query(queryMostUsedTags);

        // GET 10 VIDEOS WITH THE TAGS

        let tagIds = result.rows.map(tag => tag.id);
        let queryVideosWithTags = `
            
            SELECT
                v.id,
                v.title,
                v.thumbnail,
                v.description AS video_description,
                v.channel,
                v.visibility,
                v.file,
                v.slug,
                v.release_date,
                v.channel AS channel_id,
                c.owner,
                COUNT(h.id) AS views,
                json_build_object(
                    'name', c.name,
                    'profilePicture', u.picture,
                    'description', c.description
                ) AS creator,
                'video' AS type
            FROM public.videos v
            INNER JOIN public.video_tags vt ON v.id = vt.video
            INNER JOIN public.tags t ON vt.tag = t.id
            INNER JOIN public.channels c ON v.channel = c.id
            INNER JOIN public.users u ON c.owner = u.id
            LEFT JOIN public.history h ON h.video = v.id
            WHERE t.id = ANY($1::int[])
            AND v.visibility = 'public'
            GROUP BY 
                v.id,
                v.title,
                v.thumbnail,
                v.description,
                v.channel,
                v.visibility,
                v.file,
                v.slug,
                v.release_date,
                c.owner,
                c.name,
                u.picture,
                c.description
            ORDER BY views DESC, v.release_date DESC
            LIMIT 10;
            
        `;
        let videoResult = await client.query(queryVideosWithTags, [tagIds]);
        const recommendations = videoResult.rows;
        res.status(200).json(recommendations);

    } else {

        // Recuperer les 20 derniere vu de l'historique
        let client = await getClient();
        let queryLastVideos = `SELECT video_id FROM history WHERE user_id = $1 ORDER BY viewed_at DESC LIMIT 20;`;
        // TODO: Implement retrieval of recommendations based on user history and interactions

        // Recuperer les likes de l'utilisateur sur les 20 derniere videos recuperees

        // Recuperer les commentaires de l'utilisateur sur les 20 derniere videos recuperees

        // Recuperer les 3 tags avec lesquels l'utilisateur a le plus interagi

        // Recuperer 10 videos avec les 3 tags ayant le plus d'interaction avec l'utilisateur

        client.end()
        res.status(200).json({
            message: "Recommendations based on user history and interactions are not yet implemented."
        });
    }

}

export async function getTrendingVideos(req, res) {
    try {
        // GET 10 VIDEOS WITH THE MOST LIKES AND COMMENTS
        let client = await getClient();
        let queryTrendingVideos = `
        SELECT v.id, v.title, v.description, v.release_date, v.thumbnail, v.visibility, 
            COUNT(DISTINCT l.id) AS like_count, COUNT(DISTINCT c.id) AS comment_count
        FROM videos v
        LEFT JOIN likes l ON v.id = l.video
        LEFT JOIN comments c ON v.id = c.video
        WHERE v.visibility = 'public'
        GROUP BY v.id
        ORDER BY like_count DESC, comment_count DESC
        LIMIT 10
    `;
        let result = await client.query(queryTrendingVideos);
        const trendingVideos = result.rows;

        for (let video of trendingVideos) {
            // Get the number of views for each video
            let viewsQuery = `SELECT COUNT(*) AS view_count FROM history WHERE video = $1;`;
            let viewsResult = await client.query(viewsQuery, [video.id]);
            video.views = viewsResult.rows[0].view_count;

            // Get the creator of each video
            let creatorQuery = `SELECT c.id, c.name FROM channels c JOIN videos v ON c.id = v.channel WHERE v.id = $1;`;
            let creatorResult = await client.query(creatorQuery, [video.id]);
            if (creatorResult.rows.length > 0) {
                video.creator = creatorResult.rows[0];
            } else {
                video.creator = {id: null, name: "Unknown"};
            }

            // GET THE PROFILE PICTURE OF THE CREATOR
            let profilePictureQuery = `SELECT u.picture FROM users u JOIN channels c ON u.id = c.owner WHERE c.id = $1;`;
            let profilePictureResult = await client.query(profilePictureQuery, [video.creator.id]);
            if (profilePictureResult.rows.length > 0) {
                video.creator.profilePicture = profilePictureResult.rows[0].picture;
            } else {
                video.creator.profilePicture = null; // Default or placeholder image can be set here
            }

        }

        client.end();
        res.status(200).json(trendingVideos);
    } catch (error) {
        console.error("Error fetching trending videos:", error);
        res.status(500).json({error: "Internal server error while fetching trending videos."});
    }
}

export async function getTopCreators(req, res) {
    try {
        // GET TOP 5 CREATORS BASED ON NUMBER OF SUBSCRIBERS
        let client = await getClient();
        let queryTopCreators = `
        SELECT c.id, c.name, c.description, u.picture AS profilePicture, COUNT(s.id) AS subscriber_count
        FROM channels c
        JOIN users u ON c.owner = u.id
        LEFT JOIN subscriptions s ON c.id = s.channel
        GROUP BY c.id, u.picture
        ORDER BY subscriber_count DESC
        LIMIT 10;
    `;
        let result = await client.query(queryTopCreators);
        const topCreators = result.rows;

        client.end();
        res.status(200).json(topCreators);
    } catch (error) {
        console.error("Error fetching top creators:", error);
        res.status(500).json({error: "Internal server error while fetching top creators."});
    }
}