<?php

namespace Vn\Db;

use Vn\Lib\Type;

class Connection {
	private $conn = NULL;
	private $isOpen = FALSE;
	var $enableDebug = FALSE;

	function __construct() {
		$this->initHandler();
	}

	/**
	 * Opens a new connection to the database.
	 *
	 * @param string $host The host name
	 * @param string $user The user name to authenticate
	 * @param string $pass The user password
	 * @param string $name The default schema name
	 *
	 * @return boolean %TRUE on success, %FALSE otherwise
	 */
	function open($host, $user, $pass, $name, $port = NULL) {
		$conn = $this->initHandler();
		$conn->options(MYSQLI_OPT_LOCAL_INFILE, TRUE);
		$conn->real_connect($host, $user, $pass, $name, $port);
	
		if (mysqli_connect_errno()) {
			sleep(3);
			throw new Exception(mysqli_connect_errno(), mysqli_connect_error());
			return FALSE;
		}

		$this->isOpen = TRUE;
		$this->query('SET CHARACTER SET utf8');
		return TRUE;
	}

	/**
	 * Closes the current connection, if it's closed does nothing.
	 */
	function close() {
		if ($this->isOpen) {
			$this->conn->close();
			$this->conn = NULL;
		}

		$this->isOpen = FALSE;
	}

	/**
	 * Initializes the internal database connection handler.
	 *
	 * @return Objetct The connection handler
	 */
	function initHandler() {
		if (!$this->conn)
			$this->conn = new \mysqli();
			
		return $this->conn;
	}
	
	/**
	 * Returns the internal database connection handler. This function shoud be
	 * used to set options for specific databases that could not be set using 
	 * the Connection class methods.
	 *
	 * @return Objetct The connection handler
	 */
	function getHandler() {
		return $this->conn;
	}

	/**
	 * Changes the default schema for the current connection.
	 *
	 * @param string $schema The schema name
	 * @return boolean %TRUE if success, %FALSE otherwise
	 */
	function selectDb($dbName) {
		return $this->conn->select_db($dbName);
	}
	
	/**
	 * Executes the query and gets the result.
	 *
	 * @param string $query The SQL query
	 * @param mixed[] $params The query parameters
	 *
	 * @return mixed The value or %NULL if error
	 */
	function query($query, $params = NULL) {
		$result = $this->conn->query($this->renderDebug($query, $params));
		
		if (!$result)
			$this->checkError();
		else
		while ($this->moreResults())
			$this->nextResult();

		return $result;	
	}
	
	/**
	 * Checks whether the connection is open.
	 *
	 * @return boolean %TRUE if connection is open, %FALSE otherwise
	 */
	function isOpen() {
		return $this->isOpen;
	}
	
	/**
	 * Gets the first row value of the first column from a result.
	 *
	 * @param resource $result The database result
	 *
	 * @return mixed[] An associative array with the first row, %NULL if error
	 */
	function getRowFromResult($result) {
		if ($result) {
			$row = $result->fetch_assoc();
			$result->free();
			return $row;
		}

		return NULL;
	}
	
	/**
	 * Gets the first row value of the first column from a result.
	 *
	 * @param resource $result The database result
	 *
	 * @return object An object with the first row, %NULL if error
	 */
	function getObjectFromResult($result) {
		if ($result) {
			$row = $result->fetch_object();
			$result->free();
			return $row;
		}

		return NULL;
	}

	/**
	 * Gets the first row value of the first column from a result.
	 *
	 * @param resource $result The database result
	 *
	 * @return mixed The value or %NULL if error
	 */
	function getValueFromResult($result) {
		$value = NULL;

		if ($result) {
			$row = $result->fetch_row();
		
			if ($row && count($row) > 0)
				$value = $row[0];
			
			$result->free();
		}

		return $value;	
	}
	
	/**
	 * Executes the query and gets it's first row.
	 *
	 * @param string $query The SQL query
	 * @param mixed[] $params The query parameters
	 *
	 * @return mixed[] An associative array with the first row, %NULL if error
	 */
	function getRow($query, $params = NULL) {
		$result = $this->query($query, $params);
		return $this->getRowFromResult($result);
	}
	
	/**
	 * Executes the query and gets it's first row.
	 *
	 * @param string $query The SQL query
	 * @param mixed[] $params The query parameters
	 *
	 * @return object An object with the first row, %NULL if error
	 */
	function getObject($query, $params = NULL) {
		$result = $this->query($query, $params);
		return $this->getObjectFromResult($result);
	}
	
	/**
	 * Executes the query and gets the first value of the first row.
	 *
	 * @param string $query The SQL query
	 * @param mixed[] $params The query parameters
	 *
	 * @return mixed The value or %NULL if error
	 */
	function getValue($query, $params = NULL) {
		$result = $this->query($query, $params);
		return $this->getValueFromResult($result);
	}
	
	/**
	 * Loads a query from a file and renders it.
	 *
	 * @param string $file The file path
	 * @param mixed[] $params The query parameters
	 *
	 * @return mixed The query string
	 */
	function loadFromFile($file, $params = NULL) {
		$query = file_get_contents($file .'.sql');
		
		if ($query === FALSE)
			throw new Exception(NULL, 'Can not load query from file');
		
		return $this->render($query, $params);
	}
	
	/**
	 * Executes the query stored in the specified file and gets the result.
	 *
	 * @param string $file The file path
	 * @param mixed[] $params The query parameters
	 *
	 * @return mixed The value or %NULL if error
	 */
	function queryFromFile($file, $params = NULL) {
		$query = $this->loadFromFile($file, $params);
		
		if ($query)
			return $this->query($query);
			
		return NULL;
	}
	
	/**
	 * Executes the file query and gets it's first row.
	 *
	 * @param string $file The file path
	 * @param mixed[] $params The query parameters
	 *
	 * @return mixed[] An associative array with the first row, %NULL if error
	 */
	function getRowFromFile($file, $params = NULL) {
		$result = $this->queryFromFile($file, $params);
		return $this->getRowFromResult($result);
	}
	
	/**
	 * Executes the file query and gets the first value of the first row.
	 *
	 * @param string $file The file path
	 * @param mixed[] $params The query parameters
	 *
	 * @return mixed The value or %NULL if error
	 */
	function getValueFromFile($file, $params = NULL) {
		$result = $this->queryFromFile($file, $params);
		return $this->getValueFromResult($result);		
	}

	/**
	 * Execute multiple queries separated by semicolons.
	 *
	 * @param string $query The SQL query
	 * @param mixed[] $params The query parameters
	 *
	 * @return mixed The value or %NULL if error
	 */
	function multiQuery($query, $params = NULL) {
		$success = $this->conn->multi_query($this->renderDebug($query, $params));
		
		if (!$success)
			$this->checkError();

		return $success;
	}
	
	/**
	 * Prepare an SQL statement for execution.
	 *
	 * @param string $query The SQL query
	 *
	 * @return mixed The statement object or %FALSE if an error occurred
	 */
	function prepare($query) {
		return $this->conn->prepare($query);
	}
	
	function storeResult() {
		$result = $this->conn->store_result();
		
		if (!$result)
			$this->checkError();

		return $result;
	}
	
	function moreResults() {
		return $this->conn->more_results();
	}
	
	function nextResult() {
		$hasNext = $this->conn->next_result();
		$this->checkError();
		return $hasNext;
	}

	/**
	 * Check if there has been an error in the last query or multiquery,
	 * throwing a @Exception exception if any.
	 */
	function checkError() {
		if ($this->conn->errno) {
			if ($this->conn->errno != 1644)
				throw new Exception($this->conn->errno, $this->conn->error);
			else
				throw new \Vn\Lib\UserException($this->conn->error, $this->conn->errno);
		}
	}

	/**
	 * Check if there have been warnings in the last query.
	 *
	 * @return boolean %TRUE if there have been warnings %FALSE otherwise
	 */
	function checkWarnings() {
		return $this->conn->warning_count > 0;
	}

	/**
	 * Renders an SQL string using the given parameters.
	 *
	 * @param string $query The SQL string
	 * @param mixed[] $paramsMap The query parameters
	 *
	 * @return string The rendered SQL string
	 */
	function render($query, $paramsMap = NULL) {
		if (isset($paramsMap) && is_array($paramsMap) && count($paramsMap) > 0) {
			$i = 0;
			$params = [];
	
			foreach ($paramsMap as $key => $value)
				$params[$key] = $this->renderValue($value);
				
			$replaceFunc = function($matches) use(&$params, &$i) {
				$key = substr($matches[0], 1);
				
				if (strlen($key) == 0)
					$key = $i++;	
				if (isset($params[$key]))
					return $params[$key];
			
				return '#'. $key;
			};

			return preg_replace_callback('/#\w*/', $replaceFunc, $query);
		}
		else
			return $query;
	}
	
	/**
	 * Gets an SQL respresentation from a PHP value.
	 *
	 * @param mixed $value The value
	 *
	 * @return string The SQL value
	 */
	function renderValue($value) {
		if ($value !== NULL)
		switch (Type::get($value)) {
			case Type::BOOLEAN:
				return($value) ? 'TRUE' : 'FALSE';
			case Type::STRING:
				return '\'' . $this->escapeString($value) . '\'';
			case Type::DATE:
				return strftime('\'%Y-%m-%d\'', $value->getTimestamp());
			case Type::TIME:
				return strftime('\'%T\'', $value->getTimestamp());
			case Type::DATE_TIME:
				return strftime('\'%Y-%m-%d %T\'', $value->getTimestamp());
			default:
				return '\'' . $this->escapeString($value) . '\'';
		}
		else
			return 'NULL';
	}

	/**
	 * Escapes an string, escaping special characters when necessary.
	 * 
	 * @param string $string The string
	 * @return string The escaped string
	 */
	function escapeString($string) {
		return $this->conn->real_escape_string($string);
	}

	/**
	 * Quotes an identifier, escaping special characters when necessary.
	 * 
	 * @param string $identifier The identifier without quotes
	 * @return string The quoted identifier
	 */
	function quote($identifier) {
		return "`". str_replace("`", "``", $identifier) ."`";
	}

	/**
	 * Renders an SQL string using the given parameters, also debugs the
	 * rendered string if $enableDebug property is set to %true.
	 *
	 * @param string $query The SQL string
	 * @param mixed[] $paramsMap The query parameters
	 *
	 * @return string The rendered SQL string
	 */
	function renderDebug($query, $params = NULL) {
		$renderedQuery = $this->render($query, $params);

		if ($this->enableDebug)
			error_log($renderedQuery);

		return $renderedQuery;
	}

	function commit() {
		return $this->query('COMMIT');
	}

	function rollback() {
		return $this->query('ROLLBACK');
	}

	function startTransaction() {
		return $this->query('START TRANSACTION');
	}

	function lastInsertId() {
		return $this->getValue('SELECT LAST_INSERT_ID()');
	}

	function call($procName, $values) {
		return $this->query(
			"CALL {$this->quote($procName)}({$this->renderList($values)})"
		);
	}

	function insert($table, $values) {
		return $this->query("INSERT INTO {$this->quote($table)}
	SET {$this->renderFields($values)}");
	}

	function update($table, $values, $where) {
		return $this->query("UPDATE {$this->quote($table)}
	SET {$this->renderFields($values)}
	WHERE {$this->renderWhere($where)}");
	}

	function renderFields($values) {
		return $this->renderAssoc($values, ', ');
	}

	function renderWhere($operands) {
		return $this->renderAssoc($operands, ' AND ');
	}

	function renderAssoc($list, $separator) {
		$fields = '';
		$isFirst = true;

		foreach ($list as $field => $value) {
			if ($isFirst)
				$isFirst = false;
			else
				$fields .= $separator;

			$fields .= $this->quote($field) .' = '. $this->renderValue($value);
		}

		return $fields;
	}

	function renderList($list, $separator = ', ') {
		$values = '';
		$isFirst = true;

		foreach ($list as $value) {
			if ($isFirst)
				$isFirst = false;
			else
				$values .= $separator;

			$values .= $this->renderValue($value);
		}

		return $values;
	}
}