<?php
	/**
	 * Abstract class to keep track of and provide static access to 
	 * DB datatypes. Only real convenient const is SQLITE_PK, 
	 * however this can be expanded on. Used more as a reference.
	 */
	abstract class DB_DATATYPES {
		const SQLITE_NULL = "NULL";
		const SQLITE_PK = "INTEGER PRIMARY KEY";
		const SQLITE_INTEGER = "INTEGER";
		const SQLITE_REAL = "REAL";
		const SQLITE_TEXT = "TEXT";
		const SQLITE_BLOB = "BLOB";
	}
	
	/**
	 * Wrapper class for PDO->SQLITE connections.
	 *     provides CRUD functions for recordsets as well as 
	 *     tables.
	 *     Also included is a wrapper function to send raw query 
	 *     strings directly to the PDO object.
	 * 
	 *     Caveat: No string escapes are done in the class. Sanitize 
	 *             yo shit.
	 */
	class PDO_SQLITE {
		// Database object, accessible only through the class
		protected $db_hwd = null;
		
		/**
		 * Constructor/destructor functions. If we fail at 
		 * opening a database connection, destroy this object.
		 */
		function __construct($filename) {
			try { $this->db_hwd = new PDO("sqlite:$filename"); }
			catch (PDOException $e) { $this->db_hwd = null; }
			
			if($this->db_hwd === null) {
				$this->__destruct();
			}
		}
		public function __destruct() {
			unset($this->db_hwd);
			unset($this);
		}
		
		/**
		 * CRUD function block for recordsets.
		 *     create(): INSERT INTO a table.
		 *     read(): SELECT * FROM a table.
		 *     update(): UPDATE a table recordset.
		 *     delete(): DELETE FROM a table.
		 */
		public function create($table, array $record) {
			foreach($record as $field_name=>$value) {
				$implodable_fields[] = "'" . $field_name . "'";
				$implodable_values[] = "'" . $value . "'";
			}
			$q = "INSERT INTO $table (" . implode(", ", $implodable_fields) . ") VALUES (" . implode(", ", $implodable_values) . ");";
			return $this->db_hwd->exec($q);
		}
		public function read($table, array $needles = null) {
			$q = "SELECT * FROM $table;";
			if(is_array($needles) && count($needles) > 0) {
				foreach($needles as $needle=>$value) {
					$implodable[] = "$needle='$value'";
				}
				$q = "SELECT * FROM $table WHERE " . implode(" AND ", $implodable) . ";";
			}
			return $this->db_hwd->query($q);
		}
		public function update($table, $record, $needles, $limit = 1) {
			foreach($record as $field_name=>$value) {
				$implodable_record[] = "$field_name='$value'";
			}
			foreach($needles as $needle=>$value) {
				$implodable_needles[] = "$needle='$value'";
			}
			$q = "UPDATE $table SET " . implode(", ", $implodable_record) . " WHERE " . implode(" AND ", $implodable_needles) . " LIMIT $limit;";
			return $this->db_hwd->exec($q);
		}
		public function delete($table, $needles, $limit = 1) {
			foreach($needles as $needle=>$value) {
				$implodable_needles[] = "$needle='$value'";
			}
			$q = "DELETE FROM $table WHERE " . implode(" AND ", $implodable_needles) . " LIMIT $limit";
			return $this->db_hwd->exec($q);
		}

		/**
		 * CRUD function block for tables.
		 *     table_create(): CREATE TABLE a new table.
		 *     table_read(): SELECT * FROM sqlite_master to 
		 *                   return the table structure in 
		 *                   CREATE TABLE sql statement format.
		 *     table_update(): ALTER TABLE to add a new column.
		 *     table_delete(): Little Bobby Drop Tables, 
		 *                     we call him.
		 */
		public function table_create($table, array $fields) {
			foreach($fields as $field_name=>$field_type) {
				$implodable[] = "$field_name $field_type";
			}
			$q = "CREATE TABLE $table (" . implode(", ", $implodable) . ");";
			return $this->db_hwd->exec($q);
		}
		public function table_read($table) {
			$q = "SELECT * FROM sqlite_master WHERE name='$table' AND type='table';";
			return $this->db_hwd->query($q);
		}
		public function table_update($table, array $field) {
			/**
			 * Caveat: 
			 *     SQLite can only rename tables or add 
			 *     columns with ALTER TABLE, and only allows 
			 *     one column added per call. This function 
			 *     WILL return boolean false if multiple 
			 *     fields are passed into $field.
			 */
			foreach($field as $field_name=>$field_type) {
				$implodable[] = "$field_name $field_type";
			}
			$q = "ALTER TABLE $table ADD COLUMN " . implode(", ", $implodable) . ";";
			return $this->db_hwd->exec($q);
		}
		public function table_delete($table) {
			return $this->db_hwd->exec("DROP TABLE $table;");
		}
		
		
		/**
		 * Raw Query function, on the off chance a non-standard 
		 * query needs to be executed on the database.
		 */
		public function raw_query($q) {
			return $this->db_hwd->query($q);
		}
	}
?>