"use strict";
const { ROOT_PATH, LIB_PATH, MODELS_PATH, HANDLERS_PATH } = process.env;

async function getPage( page, elements, Model, filter=null, projection=null){
    const skip = elements * page;
	const total = await Model.count( filter );
	const list = await Model.find( filter , projection, { skip : skip , limit : elements } );
	return {
        total : total,
        limit : elements,
        skip : skip,
		data : list 
	}
}

async function getPageQuery(page, elements, Model, filter=null, projection=null){
    const skip = elements * page;
	const total = await Model.count( filter );
	return {
		query : Model.find( filter , projection, { skip : skip , limit : elements } ),
		total : total,
		skip : skip
	};
}

class GenericHandler{
    constructor( Model, search_param, populate_list=null ) {
        this.Model = Model;
        this.search_param = search_param;
        this.populate_list = populate_list || [];
    }

    async populateQuey( query ){
        if( this.populate_list.length > 0 ){
            query.populate( this.populate_list );
        }
        return await query.exec();
    }

    async getList( page, elements, filter=null, projection=null ){
        const { query } = await getPageQuery( page , elements, this.Model, filter, projection );
        return await this.populateQuey( query );
    }
    
    async findList( find_string, page, elements, projection=null ){
        const search_param = this.search_param;
        const re = new RegExp( find_string );
        const filter = {};
        filter[ search_param ] =  { $regex: re, $options: 'i' };
        return await this.getList( page, elements, filter, projection );
    }
    
    async getById( id, projection=null ){
        const query = Model.findById( id, projection );
        return await this.populateQuey( query );
    }
};

module.exports = { getPage, getPageQuery, GenericHandler };