/* eslint-disable @typescript-eslint/explicit-function-return-type */
import _ from 'lodash';
import DL from 'dataloader';
import { EngineModel } from '@seed/engine/EngineModel';

export class DataLoader<K, V, C = K> extends DL<K, V, C> {
    async loadMany(keys: ArrayLike<K>): Promise<Array<V>> {
        const nkeys = _.without(keys, undefined, null) as any;
        const res = await super.loadMany(nkeys);
        return _.without(res, undefined, null) as any;
    }
}

/* V1 - Graph Model */

export const batchFunction = async <T>(model: T, _ids: any, field: string) => {
    const results = await (await (model as any).db()).find({ [`${field}`]: { $in: _ids } }).toArray();
    return _ids.map((_id) => results.find((result) => result[field] === _id));
};

export const batchOneToManyFunction = async <T>(model: T, _ids: any, field: string) => {
    const results = await (await (model as any).db()).find({ [`${field}`]: { $in: _ids } }).toArray();
    return _ids.map((_id) => _.filter(results, { [`${field}`]: _id }));
};

export const batchOneToManyFilterFunction = async <T>(model: T, _ids: any, field: string, filter: any) => {
    const results = await (await (model as any).db()).find({ [`${field}`]: { $in: _ids }, ...filter }).toArray();
    return _ids.map((_id) => _.filter(results, { [`${field}`]: _id }));
};

export const buildLoader = <T, V = T>(model: T, field = '_id') => {
    return new DataLoader<string, V>((keys) => {
        return batchFunction(model, keys, field);
    });
};

export const buildOneToManyLoader = <T, V = T>(model: T, field = '_id') => {
    return new DataLoader<string, Array<V>>((keys) => {
        return batchOneToManyFunction(model, keys, field);
    });
};

export const buildOneToManyFilterLoader = <T, V = T>(model: T, field = '_id', filter: any) => {
    return new DataLoader<string, Array<V>>((keys) => {
        return batchOneToManyFilterFunction(model, keys, field, filter);
    });
};

/* V2 - Engine Model */
export const batchEngineFunction = async <T extends EngineModel<any, any, any>>(model: T, _ids: any, field: string) => {
    const results = await model.getAll({ query: { [`${field}`]: { $in: _ids } } });
    return _ids.map((_id) => results.find((result) => result[field] === _id));
};

export const buildEngineLoader = <T extends EngineModel<any, any, any>, V = T>(model: T, field = '_id') => {
    return new DataLoader<string, V>((keys) => {
        return batchEngineFunction(model, keys, field);
    });
};