const { ObjectId } = require('mongodb');

class Images {

    constructor(db) {
        this.db = db;
    }

    async upload(file, userId) {
        await this.db.connect()
        const conn = this.db.getConnection();

        const imagesCollection = conn.collection('images');

        const newImage = {
            userId: userId,
            file_name: file.originalname,
            file_content: file.buffer.toString('base64'),
            mime_type: file.mimetype,
            created_at: new Date()
        };

        const result = await imagesCollection.insertOne(newImage);

        return result.insertedId;
    }

    async get(id) {
        await this.db.connect()
        const conn = this.db.getConnection();

        const imagesCollection = conn.collection('images');

        const result = await imagesCollection.findOne({ _id: ObjectId.createFromHexString(id) });

        if (!result) return null;

        return {
            file_name: result.file_name,
            file_content: Buffer.from(result.file_content, 'base64'),
            mime_type: result.mime_type
        };
    }

    async getImages(page, limit) {
        await this.db.connect()
        const conn = this.db.getConnection();

        const imagesCollection = conn.collection('images');

        const result = await imagesCollection.find({}).sort({created_at: 1});

        if (!result) return null;

        const objImages = result.slice((page - 1) * limit, page * limit).map(image => ({
            id: image.id,
            file_name: image.file_name,
            file_content: Buffer.from(image.file_content, 'base64'),
            mime_type: image.mime_type
        }));

        return objImages;
    }
}

module.exports = Images;