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

class MongodbTable {

    constructor(client, provider, opts = {}) {
        
        this.client = client;
        this.provider = provider;

        this.name = opts.name;

    }

    //Data Search

    find(query, opts = {}) { //opts: { projection: ... }
        query = this._handleData(query);
        return new Promise((resolve, reject) => {
            if(!this.provider._initialized) return reject(new Error('MongoDB is not connected.'));
            this.collection.find(query, opts, async (error, cursor) => {
                if(error) return reject(error);
                return resolve(await cursor.toArray());
            });
        });
    }

    findOne(query, opts = {}) { //opts: { projection: ..., sort: ... }
        query = this._handleData(query);
        return new Promise((resolve, reject) => {
            if(!this.provider._initialized) return reject(new Error('MongoDB is not connected.'));
            this.collection.findOne(query, opts, async (error, item) => {
                if(error) return reject(error);
                return resolve(item);
            });
        });
    }

    aggregate(query) {
        query = this._handleData(query);
        return new Promise((resolve, reject) => {
            if(!this.provider._initialized) return reject(new Error('MongoDB is not connected.'));
            this.collection.aggregate(query, (error, item) => {
                if(error) return reject(error);
                return resolve(item.toArray());
            });
        });
    }
    
    random(query, amount = 1) {
        query = this._handleData(query);
        if(amount > 100) amount = 100;
        return new Promise((resolve, reject) => {
            if(!this.provider._initialized) return reject(new Error('MongoDB is not connected.'));
            this.collection.aggregate([{ $match: query }, { $sample: { size: amount } }], (error, item) => {
                if(error) return reject(error);
                return resolve(item);
            });
        });
    } 

    //Data Manipulation

    insertOne(data) {
        data = this._handleData(data);
        return new Promise((resolve, reject) => {
            if(!this.provider._initialized) return reject(new Error('MongoDB is not connected.'));
            this.collection.insertOne(data, (error, result) => {
                if(error) return reject(error);
                return resolve(result);
            });
        });
    }

    //NOTE: insertMany?

    deleteOne(query) {
        query = this._handleData(query);
        return new Promise((resolve, reject) => {
            if(!this.provider._initialized) return reject(new Error('MongoDB is not connected.'));
            this.collection.deleteOne(query, (error, result) => {
                if(error) return reject(error);
                return resolve(result);
            });
        });
    }

    deleteMany(query) {
        query = this._handleData(query);
        return new Promise((resolve, reject) => {
            if(!this.provider._initialized) return reject(new Error('MongoDB is not connected.'));
            this.collection.deleteMany(query, (error, result) => {
                if(error) return reject(error);
                return resolve(result);
            });
        });
    }

    updateOne(query, data, upsert = true) {
        query = this._handleData(query);
        return new Promise((resolve, reject) => {
            if(!this.provider._initialized) return reject(new Error('MongoDB is not connected.'));
            this.collection.updateOne(query, { $set: data }, { upsert }, async(error, result) => {
                if(error) return reject(error);

                const { matchedCount, upsertedCount, modifiedCount } = result;
                return resolve({ matched: matchedCount, upserted: upsertedCount, modified: modifiedCount });
            });
        }); 
    }

    removeProperty(query, data) {
        query = this._handleData(query);
        return new Promise((resolve, reject) => {
            if(!this.provider._initialized) return reject(new Error('MongoDB is not connected.'));

            const unset = {};
            for(const field of data) unset[field] = '';
            this.collection.updateOne(query, { $unset: unset }, async (error, result) => {
                if(error) return reject(error);
                const { matchedCount, modifiedCount } = result;
                return resolve({ matched: matchedCount, modified: modifiedCount });
            });

        });
    }

    push(query, data, upsert = true) {
        query = this._handleData(query);
        return new Promise((resolve, reject) => {
            if(!this.provider._initialized) return reject(new Error('MongoDB is not connected.'));
            this.collection.updateOne(query, { $push: data }, { upsert }, async(error, result) => {
                if(error) return reject(error);
                return resolve(result);
            });
        });
    }

    //Statistics
    stats(options = {}) {
        return new Promise((resolve, reject) => {
            if(!this.provider._initialized) return reject(new Error('MongoDB is not connected.'));
            this.collection.stats(options, (error, statistics) => {
                if(error) return reject(error);
                const { ns, size, count, avgObjSize, freeStorageSize, capped } = statistics;
                return resolve({
                    index: ns,
                    averageSize: avgObjSize,
                    currentSize: size,
                    remainingSize: freeStorageSize,
                    maximumSize: size+freeStorageSize,
                    count,
                    capped
                });
            });
        });
    }

    count(query, options = {}) {
        return new Promise((resolve, reject) => {
            if(!this.provider._initialized) return reject(new Error('MongoDB is not connected.'));
            this.collection.countDocuments(query, options, (error, result) => {
                if(error) return reject(error);
                return resolve(result);
            });
        });
    }

    //Lazy Function
    _handleData(data) { //Convert data._id to Mongo ObjectIds (gets converted to plaintext through shard communication)
        if(data._id) {
            if(typeof data._id === 'string') data._id = ObjectId(data._id);
            else if(typeof data._id === 'object') data._id = {
                $in: Object.values(data._id)[0].map((id) => {
                    return ObjectId(id);
                })
            };
        }
        return data;
    }


    //Getters

    get collection() {
        return this.provider.db.collection(this.name);
    }
    

}

module.exports = MongodbTable;