const express = require('express');
const path = require('path');
const dbconnector = require('../database/db');
const Actions = require('./ActionSystem.js');
let UserConfig = {
	primaryKey: 'username',
	fields: [
		{
			key: "username",
			type: "text"
		}
	]
}

let Types = {
	Text: "text",
	Integer: "integer",
	Real: 3,
	Image: 4,
	Boolean: 5
}

var knex = undefined; 
const Repositories = []
class RepositorySystem {
	constructor() {
		this.Types = Types;
	}

	create(table,config) {
		return new Repository(table, config);
	}

	setDB(db) {
		knex = dbconnector(db);
		return this;
	}
}

var PromiseChain = Promise.resolve(true);

class Repository {
	constructor(table, config) {
		this.table = table;
		this.config = config;
		this.perPage = 10;
		this.checkIfExists();
	}

	getPage(page = 1, perPage = this.perPage) {
		page = page > 0 ? page - 1 : 0;
		return Actions.emitSync('getTable' + this.table, knex.table(this.table)).select('*').limit(perPage).offset(page * perPage);
	}

	get(field, value){
		return Actions.emitSync('getTable' + this.table, knex.table(this.table)).select('*').where(field, value);
	}

	insert(data){
		return knex.table(this.table).insert(data);
	}
	batchInsert(data) {
		return knex.batchInsert(this.table, data);
	}
	update(id, data) {
		return knex.table(this.table).where('id',id).update(data);
	}
	delete(id) {
		return knex.table(this.table).where('id', id).del();
	}

	count() {
		return knex.table(this.table).count('id as counter');
	}

	columns() {
		return knex.table(this.table).columnInfo();
	}

	raw() {
		return knex.table(this.table);
	}

	knex() {
		return knex;
	}

	checkIfExists() {
		if(!this.table)return;
		
		PromiseChain = PromiseChain.then(() => knex.schema.hasTable(this.table))
		.then((exists)=> {
		  if (!exists) {
		  	console.log("Table" , this.table, " creating...");
		    return knex.schema.createTable(this.table, (t) => {
				  t.increments().primary();
		    });
		  } else {
		  	return true;
		  }
		})
		.then(() => {
			let config = this.config || {};
	    	let fields = config.fields || [];
	    	let promises = [];
	    	for(let i in fields) {
	    		promises.push(
	    			knex.schema.hasColumn(this.table, fields[i].key)
	    			.then((exists) => {
	    				if(true) {
	    					// Implement full TO-DO TODO
	    					return knex.schema.alterTable(this.table,
	    					(t) => {
							  let column = t[fields[i].type](fields[i].key, fields[i].keyLength);
							  if(fields[i].default !== undefined) {
							  	column = column.defaultTo(fields[i].default);
							  } 
							  if(fields[i].notNull) {
							  	column = column.notNullable();
							  }
							  if(fields[i].unique === true) {
						  		column = column.unique(fields[i].key);
							  }
							  if(fields[i].fk && false) {
							  	column = column
							  	.unsigned().index().references(fields[i].fk.key).inTable(fields[i].fk.table);
							  }
							  if(exists) {
							  	column = column.alter();
							  }
							  return column;
							}).catch((e) => {
								console.log("Column error change");
								console.log(fields[i]);
								console.log("Error: ", e.sqlMessage);
								console.log("Command: ", e.sql);

							});
	    				}
	    				return true;
	    			})
	    		);
	    	}

	    	if(config.auto_increment) {
	    		promises.push(
	    			knex.schema.raw('ALTER TABLE '+this.table+' AUTO_INCREMENT = ' + config.auto_increment)
	    		);
	    	}
	    	
	    	return promises.reduce((promiseChain, currentTask) => {
			    return promiseChain.then(chainResults =>
			        currentTask.then(currentResult =>
			            [ ...chainResults, currentResult ]
			        )
			    );
			}, Promise.resolve([]));
		})
		.catch((e) => console.log("An error was detected", e));

		return PromiseChain;
	}
}

module.exports = new RepositorySystem()