interpreter.js

/*
	USAGE:

	// bellow query is the same as
	// SELECT appid FROM tbl_user_app WHERE userid IN (SELECT id FROM tbl_user WHERE email='$0');
	var ql = '{tbl_user(email)=>(id)|tbl_user_app(id>userid)=>[appid]}';

	var obj = parse(ql);
	var data = { email: '[email protected]' };

	query(obj, data, function(err, result){
		console.log('RESULT', err, result);
	});

*/


function parse(str) {
	if (!str || str[0] !== '{')
		return;

	if (str.indexOf(';') > -1)
		return console.log('Interpreter error: Illegal character ";"');

	str = str.substring(1, str.length - 1);
	var cmd = str.split('|');
	if (!cmd || !cmd.length)
		return;

	var queries = [];

	cmd.forEach(function(c, cmdindex){
		var pos = c.indexOf('=>');
		var obj = { map: {}, outmap: {} };		

		if (pos < 0) {
			obj.table = c;
		} else {
			obj.table = c.substring(0, pos);
			obj.select = c.substring(pos + 2);
		}

		var index = obj.table.indexOf('(');
		if (index > -1) {
			var fields = obj.table.substring(index + 1, obj.table.length - 1);
			obj.table = obj.table.substring(0, index);
			
			if (fields[0] === '(') {
				fields = fields.substring(1, fields.indexOf(')'));
			}

			fields = fields.split(',').trim();

			fields.forEach(function(f, i){
				if (f.indexOf('>') > -1) {
					f = f.split('>');
					fields[i] = f[0];
					obj.map[f[0]] = f[1];
				}
			});

			obj.queryfields = fields;
		}

		if (obj.select) {

			if (obj.select[0] === '(') {
				obj.select = obj.select.substring(1, obj.select.indexOf(')'));
			} else if (obj.select[0] === '[') {				
				obj.select = obj.select.substring(1, obj.select.indexOf(']'));
				obj.multi = true;
			}

			var tmp = [];

			var split = obj.select.split(',');
			split.forEach(function(f, i){

				f = f.split('>');
				if (f[1])
					obj.outmap[f[0]] = f[1];

				obj.value = f[1] || f[0];

				f = f[0];

				var index = f.indexOf('.');
				if (index > -1)
					f = f.substring(0, index);

				tmp.push(f);
			});

			obj.select = tmp.join(',');

			if (tmp.length !== 1 || cmdindex !== cmd.length - 1)
				obj.value = false;
		}

		var query = 'SELECT {0} FROM {1}'.format(obj.select || '*', obj.table);
		var qf = obj.queryfields;
		if (qf && qf.length) {
			query += ' WHERE ';
			qf.forEach(function(f, index){
				if (index)
					query += ' AND ';
				query += '{0} = {{1}}'.format(obj.map[f] ? obj.map[f] : f, f);
			});
		}
		query += ';';

		if (!qf && !obj.multi)
			qf = ['id'];

		queries.push({ query: query, params: qf, multi: obj.multi, value: obj.value, map: Object.keys(obj.outmap).length ? obj.outmap : false });
	});

	return queries;
};

function query(arr, data, callback) {
	var queue = [];
	var db = DBMS();
	var result;
	data = [data];

	arr.forEach(function(q, index){

		queue.push(function(next){

			var paramsOk = true;
			var data2 = data[index];

			q.params.forEach(function(p){
				var d = data2[p];
				if (d === undefined || d === null)
					return (paramsOk = false);
				var td = typeof(d);
				if (td === 'string')
					data2[p] = '\'' + d + '\'';

				if (td === 'boolean')
					data2[p] = d ? 'TRUE' : 'FALSE';
			});

			if (!paramsOk)
				return callback('Data missing params');

			var q2 = q.query.arg(data2);
			console.log('q2', q2);
			db.query(q2).callback(function(err, response){
				if (err || !response)
					return callback(err || response);

				if (!q.multi) {
					response = response[0];

					if (q.map)
						response = remap(response, q.map);

					// last query returns value rather then object with a key/value when only single prop is to be returned
					if (q.value && arr.length === index + 1) {
						if (q.value.indexOf('.') > -1)
							response = U.get(response, q.value);
						else
							response = response[q.value];
					}

				} else {
					response.forEach(function(r, i){
						if (q.map)
							response[i] = remap(r, q.map);

						if (q.value && arr.length === index + 1)
							response[i] = response[i][q.value];
					});
				}

				data[index + 1] = response;

				next();
			});
		});
	});

	queue.async(function(){
		callback(null, data[arr.length]);
	});
};

function remap(obj, map) {
	var tmp = {};
	Object.keys(map).forEach(function(key){
		tmp[map[key]] = key.indexOf('.') > -1 ? U.get(obj, key) : obj[key];
	});
	return tmp;
};

ON('ready', function(){
	if (!global.DBMS)
		throw new Error('Interpreter requires DBMS module!');
});

exports.query = query;
exports.parse = parse;