<?php
namespace Core;

class DB
{
	private static $_instance = null;
	
	private $_PDO;
	private $_query;

	private $_query_counter = 0;
	public $_escape_output = false;
	
	// Handle instances
	public final static function get_instance(){
		if(self::$_instance == null){
			self::$_instance = new static();
		}
		
		return self::$_instance;
	}
	
	// Initialise PDO object
	private final function __construct(){
		$host = Config::get_safe('mysql_host', false);
		$socket = Config::get_safe('mysql_socket', false);
		
		if($socket === false && $host === false){
			throw new DBException("Mysql host or socket must be defined");
		}
		
		// Socket or host
		$server = ($socket !== false ? 'unix_socket=' : 'host=').$socket;
		
		// Try to connect
		try {
			$this->_PDO = new \PDO(
				// Server
				'mysql:'.$server.';'.
				// DB
				'dbname='.Config::get('db_name').';'.
				// Charset
				'charset=utf8',
				// Username
				Config::get('mysql_user'),
				// Password
				Config::get_safe('mysql_pass', '')
			);
			$this->_PDO->exec('SET NAMES utf8'); 
		} catch (\PDOException $e) {
			throw new DBException($e->getMessage());
		}
		
		// When is this not set, chat does dot work, odd behavior
		$this->_PDO->setAttribute(\PDO::ATTR_EMULATE_PREPARES, false);
		
		// Throwing exceptions
		$this->_PDO->setAttribute(\PDO::ATTR_ERRMODE, \PDO::ERRMODE_EXCEPTION);
		//$this->_PDO->setAttribute(\PDO::MYSQL_ATTR_USE_BUFFERED_QUERY, true);
	}
	
	// Just flattern array to be binded : [key1, key2, [key3, [key4]]] => [key1, key2, key3, key4]
	private final function bind_value($key, $value){
		if(is_array($value)){
			foreach($value as $one_value){
				$key = $this->bind_value($key, $one_value);
			}
			
			return $key;
		}
		
		$this->_query->bindValue($key, $value);
		return ++$key;
	}
	
	// Process Query
	// query ($sql)
	// query ($sql, $bind_param_01, $bind_param_02, ...)
	// query ($sql, [$bind_param_01, $bind_param_02, ...])
	public final function query(){
		// Second parm is binded values
		$params = func_get_args();
		
		// First parameter is sql
		$sql = $params[0];
		unset($params[0]);
		
		// Debug mode
		if(Config::get_safe('debug', false)){
			echo "<!-- ".$sql." + ".json_encode($params)." -->\n";
		}
		
		// Try to prepare MySQL statement
		try {
			// Prepare PDO statement
			$this->_query = $this->_PDO->prepare($sql);
			
			// Bind values
			$this->bind_value(1, $params);
			
			// Execute
			$this->_query->execute();
		} catch (\PDOException $e) {
			throw new DBException($e->getMessage());
		}
		
		$this->_query_counter++;
		return $this;
	}
	
	// Insert into table
	public final function insert($table_name, $fields = null){
		// If empty line
		if(empty($fields)){
			return $this->query("INSERT INTO `{$table_name}` () VALUES ()");
		}
		
		// If multiple
		if(isset($fields[0])){
			// Turn array into PDO prepered statement format
			$keys = array_keys($fields[0]);
			
			// Build query
			$query = "INSERT INTO `{$table_name}` (`".implode('`, `', $keys)."`) VALUES ";
			
			// Insert values
			$first = true;
			$prepared_data = array();
			foreach($fields as $field){
				if($first){
					$first = false;
				} else {
					$query .= ',';
				}
				
				end($field);
				$last_key = key($field);
				
				$query .= '(';
				foreach($field as $key => $value){
					if($value === "NOW()"){
						$query .= 'NOW()';
					} else {
						$query .= '?';
						$prepared_data[] = $value;
					}
					
					if($last_key != $key){
						$query .= ',';
					}
				}
				$query .= ')';
			}
			
			// Execute query
			return $this->query($query, $prepared_data);
		}
		
		// If only single
		return $this->insert($table_name, array($fields));
	}
	
	// Update table
	// update ($table_name, $fields)
	// update ($table_name, $fields, $sql)
	// update ($table_name, $fields, $sql, $bind_param_01, $bind_param_02, ...)
	// update ($table_name, $fields, $sql, [$bind_param_01, $bind_param_02, ...])
	public final function update(){
		// Fourt param is binded values
		$params = func_get_args();
		
		// First is table_name
		$table_name = $params[0];
		unset($params[0]);
		
		// Second is fields
		$fields = $params[1];
		unset($params[1]);
		
		// Third is sql
		$sql = $params[2];
		unset($params[2]);
		
		// If fields are not array, do nothing
		if(!is_array($fields)){
			return $this;
		}
		
		end($fields);
		$last_key = key($fields);
		
		// Support for NOW()
		$prepared_data = array();
		$set_data = null;
		foreach($fields as $key => $value){
			if($value === "NOW()"){
				$set_data .="`{$key}` = NOW()";
			} else {
				$set_data .= "`{$key}` = ?";
				$prepared_data[] = $value;
			}
			
			if($last_key != $key){
				$set_data .= ',';
			}
		}
		
		// If params are not array, make it
		if(!is_array($params)){
			$params = array($params);
		}
		
		// Merge fields array and additional SQL data
		foreach($params as $param){
			$prepared_data[] = $param;
		}
		
		// Build query
		$query = "UPDATE `{$table_name}` SET {$set_data} ".$sql;
		
		// Execute query
		return $this->query($query, $prepared_data);
	}
	
	// Alias for all
	public final function results(){
		trigger_error("Using deprecated method <strong>DB::results();</strong>. Use <strong>DB::all();</strong> instead.");
		return $this->all();
	}
	
	// Get all rows
	public final function all($type = \PDO::FETCH_ASSOC){
		$rows = $this->_query->fetchAll($type);
		
		if($this->_escape_output){
			foreach($rows as &$row){
				foreach($row as &$col){
					$col = htmlspecialchars($col);
				}
			}
		}

		return $rows;
	}
	
	// Get all values to one dimensional array
	public final function columns($column = 0){
		return $this->_query->fetchAll(\PDO::FETCH_COLUMN, $column);
	}
	
	// Get first row from result
	public final function first($key = null){
		$results = $this->all();
		
		if($key !== null){
			return @$results[0][$key];
		}
		
		return @$results[0];
	}
	
	// Get last inserted ID
	public final function last_id(){
		return $this->_PDO->lastInsertId();
	}
	
	// Exec
	public final function exec($sql){
		// Try to execute MySQL
		try {
			$this->_PDO->exec($sql);
		} catch (\PDOException $e) {
			throw new DBException($e->getMessage());
		}
		
		return $this;
	}
	
	public final function total_queries(){
		return $this->_query_counter;
	}
}

// Handle DB errors
class DBException extends \Exception{}