<?php
	$host = 'localhost';
	$user = 'bla';
	$pass = 'bla';
	$db = 'opendiet';

	if (isset($_POST['api_key']))
		$api_key = $_POST['api_key'];
	else
		send_error_response('You need to provide your api key');
	if (isset($_POST['api_sig']))
		$api_sig = $_POST['api_sig'];
	else
		send_error_response('You need sign your calls');
	if (isset($_POST['session']))
		$session = $_POST['session'];
	if (isset($_POST['request']))
		$request = $_POST['request'];
	else
		send_error_response('You have to provide a request');
	try {
		$conn = new PDO('mysql:host='.$host.';dbname='.$db.';charset=UTF-8', $user, $pass);
		$conn->setAttribute(PDO::ATTR_ERRMODE, PDO::ERRMODE_EXCEPTION);
	} catch (PDOException $ex) {
		send_error_response('Failed to connect to MySQL: ' . $ex->getMessage());
	}
	if(!check_sig())
		send_error_response('Invalid signature');
	if($request === 'update' || $request === 'add') {
		if(!isset($session))
			send_error_response('You need to provide a session for write calls');
		else if(!checkSession($_POST['api_key'], $_POST['session']))
			send_error_response("Invalid session");
	}
	process_response();
	function process_response() {
		global $request, $api_key, $conn;
		switch($request) {
			case 'auth':
				$token = uniqid();
				try {
					$stmt = $conn->prepare("UPDATE applications SET token = ? WHERE api_key = ?");
					$stmt->execute(array($token, $api_key));
					send_token_response($token);
				} catch (PDOException $ex) {
					send_error_response("MySQL error: " . $ex->getMessage());
				}
				break;
			case 'session':
				if(isset($_POST['token']))
					session($_POST['token']);
				else
					send_error_response('You have to provide a token in order to obtain a session');
				break;
			case 'check_session':
				if(isset($_POST['session']) && checkSession($api_key, $_POST['session']))
					send_session_response($_POST['session']);
				else send_error_response('Invalid session');
				break;
			case 'search':
				if(isset($_POST['query']))
					search($_POST['query']);
				else
					send_error_response('You have to provide a search query for the food you are looking for');
				break;
			case 'update':
				if(isset($_POST['id'])) {
					update($_POST['id']);
				}
				else
					send_error_response("You have to provide a valid integer >= 0 as the parameter id for update");
				break;
			case 'add':
				if(isset($_POST['data']))
					add($_POST['data']);
				else
					send_error_response("You did not provide any data to add");
				break;
			default:
				send_error_response('Undefined request');
		}
	}
	function send_token_response($token) {
		global $api_key;
		$data = array('api_key'=>$api_key,'token'=>$token);
		send_json_response($data);
	}
	function send_session_response($session) {
		global $api_key;
		$data = array('api_key'=>$api_key,'session'=>$session);
		send_json_response($data);
	}
	function add($data) {
		global $api_key, $conn;
		$data = json_decode($data, true);
		if(count($data) != 9)
			send_error_response("You have to provide all information for the food");
		$data['name'] = trim($data['name']);
		$hash = md5($data['name'] . $data['category'] . $data['brand']);
		try {
			$stmt = $conn->prepare("SELECT * FROM food WHERE hash = ?");
			$stmt->execute(array($hash));
			if(count($stmt->fetchAll(PDO::FETCH_ASSOC)) > 0)
				send_error_response("A food extactly like this already exists. Please use update");
		} catch (PDOException $ex) {
			send_error_response("MySQL error: " . $ex->getMessage());
		}
		try {
			$stmt = $conn->prepare("INSERT INTO food (name, carbs, fat, protein, alcohol, serving, serving_type, category, api_key, hash, brand)
					VALUES(:name, :carbs, :fat, :protein, :alcohol, :serving, :serving_type, :category, :api_key, :hash, :brand)");
			foreach ($data as $key=>$value) {
				if($key === 'serving_type' || $key === 'category')
					$stmt->bindValue(':'.$key, $value, PDO::PARAM_INT);
				else
					$stmt->bindValue(':'.$key, strval($value), PDO::PARAM_STR);
			}
			$stmt->bindValue(':api_key', $api_key);
			$stmt->bindValue(':hash', $hash);
			$stmt->debugDumpParams();
			$stmt->execute();
			send_ok_response();
		} catch (PDOException $ex) {
			send_error_response("MySQL error: " . $ex->getMessage());
		}
	}
	function update($id) {
		$whitelist = array("name","carbs","fat","protein","alcohol","serving","serving_type","category","brand");
		global $api_key, $conn;
		if(!ctype_digit($id))
			send_error_response("You have to provide a valid integer >= 0 as the parameter id for update");
		$query = "UPDATE food SET ";
		if(!isset($_POST['data']))
			send_error_response("You have to provide data that should be updated");
		$data = json_decode($_POST['data'], true);
		foreach ($data as $key=>$value) {
			if(!in_array($key, $whitelist))
				send_error_response($key . "isn't a valid key");
			$query .= $key . ' = :' . $key . ' , ';
		}
		$query .= "api_key = :api_key WHERE id = :id";
		$stmt = $conn->prepare($query);
		$stmt->bindValue(':api_key', $api_key, PDO::PARAM_STR);
		$stmt->bindValue(':id', $id, PDO::PARAM_INT);
		try {
			$stmt = $conn->prepare($query);
			foreach ($data as $key=>$value) {
				if($key === 'serving_type' || $key === 'category')
					$stmt->bindValue(':' . $key, $value, PDO::PARAM_INT);
				else
					$stmt->bindValue(':' . $key, $value, PDO::PARAM_STR);
				echo($key . ", ");
			}
			echo($count);
			$stmt->debugDumpParams();
			$stmt->execute();
			send_ok_response();
		} catch (PDOException $ex) {
			send_error_response("MySQL error: " . $ex->getMessage());
		}
	}
	function send_ok_response() {
		die("All ok");
	}
	function session($token) {
		global $api_key, $conn;
		try {
			$stmt = $conn->prepare("SELECT token FROM applications WHERE api_key = ?");
			$stmt->execute(array($api_key));
			$rows = $stmt->fetchAll(PDO::FETCH_ASSOC);
			if(count($rows)!= 1)
				send_error_response('Internal server error');
			if($token !== $rows[0]['token'])
				send_error_response('Invalid token');
			$session = str_replace('.', 'f', uniqid('', true));
			$query = "UPDATE applications SET token = null";
			$conn->exec($query);
			$stmt = $conn->prepare("INSERT INTO sessions (api_key, session) VALUES (?, ?)");
			$stmt->execute(array($api_key, $session));
			send_session_response($session);
		} catch (PDOException $ex) {
			send_error_response("MySQL error: " . $ex->getMessage());
		}
	}
	function search($query) {
		global $conn;
		$search_query = strtolower(trim($query));
		$search_keywords = explode(' ', $search_query);
		if(count($search_keywords) < 1)
			send_error_response('You have to provide a search query for the food you are looking for');
		$prepared_query = "SELECT * FROM food WHERE ";
		$params = array();
		for($i=0; $i < count($search_keywords); $i++) {
			$prepared_query .= "LCASE(name) LIKE ? ";
			if(($i + 1) < count($search_keywords))
				$prepared_query .= "OR ";
			$search_keywords[$i] = '%' . $search_keywords[$i] . '%';
		}
		$prepared_query .= "ORDER BY name";
		try {
			$stmt =$conn->prepare($prepared_query);
			$stmt->execute($search_keywords);
			$rows = $stmt->fetchAll(PDO::FETCH_ASSOC);
			send_search_response($rows);
		} catch (PDOException $ex) {
			send_error_response("MySQL error: " . $ex->getMessage());
		}
	}

	function send_json_response($data) {
		header('Content-type : application/json');
		echo json_encode($data);
	}
	function send_search_response($result) {
		send_json_response($result);
	}
	function check_sig() {
		global $api_key, $api_sig, $conn;
		$sorted_parms = $_POST;
		ksort($sorted_parms);
		$parm_string = '';
		foreach ($sorted_parms as $key=>$value)
			if($key !== 'api_sig')
				$parm_string .= $key.$value;
		if(!preg_match("/^[a-f0-9]{23}$/", $api_key))
			send_error_response('Invalid api key format');
		try {
		 	$stmt = $conn->prepare("SELECT api_secret FROM applications WHERE api_key = ?");
		 	$stmt->execute(array($api_key));
			$rows = $stmt->fetchAll(PDO::FETCH_ASSOC);
			if(count($rows) != 1 || empty($rows[0]['api_secret']))
				send_error_response('Internal server error');
			$parm_string .= $rows[0]['api_secret'];
			$hash = md5($parm_string);
			return $hash === $api_sig;
		} catch (PDOException $ex) {
			send_error_response("MySQL error: " . $ex->getMessage());
		}
	}

	function send_error_response ($message) {
		header("HTTP/1.0 400 Bad Request");
		die($message);
	}
	function checkSession($api_key, $session) {
		global $conn;
		try {
			$stmt = $conn->prepare("SELECT api_key FROM sessions WHERE session = ?");
			$stmt->execute(array($session));
			$rows = $stmt->fetchAll(PDO::FETCH_ASSOC);
			for($i = 0; $i < count($rows); $i++) {
				if($rows[$i]['api_key'] === $api_key)
					return true;
			}
		} catch (PDOException $ex) {
			send_error_response("MySQL error: " . $ex->getMessage());
		}
	}
?>