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

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

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 {

        let client = await getClient();
        const claims = jwt.decode(token)
        const query = `
        -- Recommandation de contenu similaire non vu basée sur les interactions utilisateur
        -- Paramètre: $1 = user_id
        WITH user_interactions AS (
            -- Récupérer tous les contenus avec lesquels l'utilisateur a interagi
            SELECT DISTINCT v.id as video_id, v.channel, t.id as tag_id, t.name as tag_name
            FROM videos v
            JOIN video_tags vt ON v.id = vt.video
            JOIN tags t ON vt.tag = t.id
            WHERE v.id IN (
                -- Vidéos likées par l'utilisateur
                SELECT DISTINCT l.video FROM likes l WHERE l.owner = $1
                UNION
                -- Vidéos commentées par l'utilisateur
                SELECT DISTINCT c.video FROM comments c WHERE c.author = $1
                UNION
                -- Vidéos ajoutées aux playlists de l'utilisateur
                SELECT DISTINCT pe.video
                FROM playlist_elements pe
                JOIN playlists p ON pe.playlist = p.id
                WHERE p.owner = $1
            )
        ),
        user_preferred_tags AS (
            -- Tags préférés basés sur les interactions
            SELECT tag_id, tag_name, COUNT(*) as interaction_count
            FROM user_interactions
            GROUP BY tag_id, tag_name
        ),
        user_preferred_channels AS (
            -- Chaînes préférées basées sur les interactions
            SELECT channel, COUNT(*) as interaction_count
            FROM user_interactions
            GROUP BY channel
        ),
        unseen_videos AS (
            -- Vidéos que l'utilisateur n'a jamais vues
            SELECT v.id, v.title, v.thumbnail, v.description, v.channel, v.visibility,
                   v.file, v.slug, v.format, v.release_date, ch.owner
            FROM videos v
            JOIN channels ch ON v.channel = ch.id
            WHERE v.visibility = 'public'
            AND v.id NOT IN (
                -- Exclure les vidéos déjà vues
                SELECT DISTINCT h.video FROM history h WHERE h.user_id = $1
                UNION
                -- Exclure les vidéos déjà likées
                SELECT DISTINCT l.video FROM likes l WHERE l.owner = $1
                UNION
                -- Exclure les vidéos déjà commentées
                SELECT DISTINCT c.video FROM comments c WHERE c.author = $1
                UNION
                -- Exclure les vidéos déjà ajoutées aux playlists
                SELECT DISTINCT pe.video
                FROM playlist_elements pe
                JOIN playlists p ON pe.playlist = p.id
                WHERE p.owner = $1
            )
        )
        -- Requête principale : recommander du contenu similaire
        SELECT
            uv.id,
            uv.title,
            uv.thumbnail,
            uv.description as video_description,
            uv.channel,
            uv.visibility,
            uv.file,
            uv.slug,
            uv.format,
            uv.release_date,
            uv.channel as channel_id,
            uv.owner,
            COALESCE(view_counts.views::text, '0') as views,
            json_build_object(
                'name', u.username,
                'profilePicture', u.picture,
                'description', ch.description
            ) as creator,
            'video' as type
        FROM unseen_videos uv
        JOIN channels ch ON uv.channel = ch.id
        JOIN users u ON ch.owner = u.id
        -- Compter les vues
        LEFT JOIN (
            SELECT video, COUNT(*) as views
            FROM history
            GROUP BY video
        ) view_counts ON uv.id = view_counts.video
        -- Score basé sur les tags similaires
        LEFT JOIN (
            SELECT
                vt.video,
                SUM(upt.interaction_count * 0.7) as score
            FROM video_tags vt
            JOIN user_preferred_tags upt ON vt.tag = upt.tag_id
            GROUP BY vt.video
        ) tag_score ON uv.id = tag_score.video
        -- Score basé sur les chaînes similaires
        LEFT JOIN (
            SELECT
                uv2.channel,
                MAX(upc.interaction_count * 0.3) as score
            FROM unseen_videos uv2
            JOIN user_preferred_channels upc ON uv2.channel = upc.channel
            GROUP BY uv2.channel
        ) channel_score ON uv.channel = channel_score.channel
        WHERE (tag_score.score > 0 OR channel_score.score > 0) -- Au moins une similarité
        GROUP BY uv.id, uv.title, uv.thumbnail, uv.description, uv.channel, uv.visibility,
                 uv.file, uv.slug, uv.format, uv.release_date, uv.owner, u.username, u.picture,
                 ch.description, view_counts.views, tag_score.score, channel_score.score
        ORDER BY (COALESCE(tag_score.score, 0) + COALESCE(channel_score.score, 0)) DESC, uv.release_date DESC
        LIMIT 20;

        `;
        let result = await client.query(query, [claims.id]);


        client.end()
        res.status(200).json(result.rows);
    }

}

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."});
    }
}