var tcrudSetup   = require('./../tcrud-setup');
var debug        = require('debug')('ff:tcrud:backend:database');

module.exports = {
	loadModule: function(key,dbModule) {
		tcrudSetup.pluginLoad(new DatabasePlugin(key,dbModule));
	},
	loadPostgres: function(key,dbPool,pgDBNamed) {
		tcrudSetup.pluginLoad(new DatabasePlugin(key,new PostgresModule(dbPool,pgDBNamed)));
	},
	loadMysql2: function(key,pool) {
		tcrudSetup.pluginLoad(new DatabasePlugin(key,new Mysql2Module(pool)));
	},
	loadMssql: function(key,driver,conn) {
		tcrudSetup.pluginLoad(new DatabasePlugin(key,new MssqlModule(driver,conn)));
	}
}

//------- PostgresModule Object

function PostgresModule(dbPool,pgDBNamed) {
	this.dbPool = dbPool;
	this.pgDBNamed = pgDBNamed;
}
PostgresModule.prototype.query = function(sqlQuery,params, cb) {
	var self = this;
	self.dbPool.connect(function(err, client, done) {
		self.pgDBNamed.patch(client);
		client.query(sqlQuery, params, function(err, result) {
			done(); // release client from pool
			cb(err,result);
		});
	});
}

function Mysql2Module(pool) {
	this.pool = pool;
}
Mysql2Module.prototype.query = function(sqlQuery,params, cb) {
	var self = this;
	self.pool.getConnection(function(err, connection) {
		connection.config.namedPlaceholders = true;
		connection.execute(sqlQuery,params, function(err, rows) {
			connection.release();
			cb(err,rows);
		});
	});
}

function MssqlModule(driver,conn) {
	this.driver = driver;
	this.conn = conn;
}
MssqlModule.prototype.query = function(sqlQuery,params, cb) {
	var self = this;
	var request = new self.driver.Request(self.conn);
	request.query(sqlQuery,params,function(err, rows) {
		cb(err,rows);
	});
}

//------- DatabasePlugin Object

function DatabasePlugin(key,dbModule) {
	this.key = key;
	this.dbModule = dbModule;
}

DatabasePlugin.prototype.configPlugin = function (ctx) {
	ctx.key='db#'+this.key;
	ctx.description='Database api adapter for '+this.key;
};

DatabasePlugin.prototype.createBackend = function() {
	return new DatabaseBackend(this);
}

DatabasePlugin.prototype.query = function(sqlQuery,params, cb) {
	this.dbModule.query(sqlQuery,params,cb);
}

// -------- DatabaseBackend

function findKeysView(tview) {
	return tview.tkeys;
}

function findKeysModel(tview) {
	return tview.tmeta.tmodel.tkeys;
}

function selectField(tview,crudType) {
	var result = [];
	tview[crudType].tfields.forEach(function (tfieldKey) {
		var tfield = tview.tmeta.tfields[tfieldKey];
		result.push(tfield.tid);
	});
	var resultSql = '';
	for (var i = 0; i < result.length; i++) {
		var key = result[i];
		resultSql += key;
		if (i < (result.length - 1)) {
			resultSql += ',';
		}
	}
	return resultSql;
}

function whereKeys(tview) {
	var resultSql = '';
	for (var i = 0; i < tview.tmeta.tmodel.tkeys.length; i++) {
		var key = tview.tmeta.tmodel.tkeys[i];
		//resultSql += key +' = $'+(i+1);
		resultSql += key +' = $'+key;
		if (i < (tview.tmeta.tmodel.tkeys.length - 1)) {
			resultSlug += ' AND ';
		}
	}
	return resultSql;
}

function updateValues(tview,data) {
	var resultSql = 'SET ';
	var dataKeys = Object.keys(data);
	for (var i = 0; i < dataKeys.length; i++) {
		var key = dataKeys[i];
		
		var skip = false;
		for (var ii = 0; ii < tview.tmeta.tmodel.tkeys.length; ii++) {
			var keyPK = tview.tmeta.tmodel.tkeys[ii];
			if (key === keyPK) {
				skip = true;
				break;
			}
		}
		if (skip === true) {
			continue;
		}
		resultSql += key +' = $'+key;
		if (i < (dataKeys.length - 1)) {
			resultSql += ',';
		}
	}
	return resultSql;
}

function DatabaseBackend(plugin) {
	this.plugin = plugin;
}

DatabaseBackend.prototype.getKey = function() {
	return this.plugin.key;
}

DatabaseBackend.prototype.findAll = function(tview,crudType) {
	var self = this;
	return function(data, dataParam, cb) {
		var querySql = 'SELECT '+selectField(tview,crudType)+' FROM '+tview.tmeta.tmodel.tid+'';
		debug('findAll %s',querySql);
		var query = self.plugin.query(querySql,[],function (err, result) {
			if (err) {
				debug(err);
				cb(err);
			} else {
				cb(err,result.rows);
			}
		});
	};
}

DatabaseBackend.prototype.createNew = function(tview,crudType) {
	var self = this;
	return function(data, dataParam, cb) {
		
	};
}

DatabaseBackend.prototype.findOne = function(tview,crudType) {
	var self = this;
	return function(data, dataParam, cb) {
		var querySql = 'SELECT '+selectField(tview,crudType)+' FROM '+tview.tmeta.tmodel.tid+' WHERE '+whereKeys(tview)+'';
		debug('findOne param %s',JSON.stringify(dataParam));
		debug('findOne sql %s',querySql);
		var query = self.plugin.query(querySql, dataParam, function (err, result) {
			if (err) {
				debug(err);
				cb(err);
			} else {
				cb(err,result.rows[0]);
			}
		});
	};
}

DatabaseBackend.prototype.updateOne = function(tview,crudType) {
	var self = this;
	return function(data, dataParam, cb) {
		var querySql = 'UPDATE '+tview.tmeta.tmodel.tid+' '+updateValues(tview,data)+' WHERE '+whereKeys(tview);
		debug('updateOne param %s',JSON.stringify(dataParam));
		debug('updateOne data %s',JSON.stringify(data));
		debug('updateOne sql %s',querySql);
		var query = self.plugin.query(querySql, data, function (err, result) {
			if (err) {
				debug(err);
				cb(err);
			} else {
				cb(err,result.rows[0]);
			}
		});
	};
}

DatabaseBackend.prototype.deleteOne = function(tview,crudType) {
	var self = this;
	return function(data, dataParam, cb) {
		var querySql = 'DELETE FROM '+tview.tmeta.tmodel.tid+' WHERE '+whereKeys(tview);
		debug('deleteOne param %s',JSON.stringify(dataParam));
		debug('deleteOne sql %s',querySql);
		var query = self.plugin.query(querySql, dataParam, function (err, result) {
			if (err) {
				debug(err);
				cb(err);
			} else {
				cb(err,result.rows[0]);
			}
		});
	};
}

DatabaseBackend.prototype.findAllCount = function(tview,crudType) {
	var self = this;
	return function(data, dataParam, cb) {
		var querySql = 'SELECT count(*) FROM '+tview.tmeta.tmodel.tid; //+' WHERE '+whereKeys(tview);
		debug('findAllCount param %s',JSON.stringify(dataParam));
		debug('findAllCount sql %s',querySql);
		var query = self.plugin.query(querySql, dataParam, function (err, result) {
			if (err) {
				debug(err);
				cb(err);
			} else {
				cb(err,result.rows[0]);
			}
		});
	};
}