<?php
/**
 * Driver class file.
 *
 * @link http://www.yiiframework.com/
 * @copyright Copyright &copy; 2008 Yii Software LLC
 * @license http://www.yiiframework.com/license/
 */

namespace yii\db\sqlite;

use yii\db\TableSchema;
use yii\db\ColumnSchema;

/**
 * Driver is the class for retrieving metadata from a SQLite (2/3) database.
 *
 * @author Qiang Xue <qiang.xue@gmail.com>
 * @since 2.0
 */
class Driver extends \yii\db\Driver
{
	/**
	 * @var array mapping from physical column types (keys) to abstract column types (values)
	 */
	public $typeMap = array(
		'tinyint' => self::TYPE_SMALLINT,
		'bit' => self::TYPE_SMALLINT,
		'smallint' => self::TYPE_SMALLINT,
		'mediumint' => self::TYPE_INTEGER,
		'int' => self::TYPE_INTEGER,
		'integer' => self::TYPE_INTEGER,
		'bigint' => self::TYPE_BIGINT,
		'float' => self::TYPE_FLOAT,
		'double' => self::TYPE_FLOAT,
		'real' => self::TYPE_FLOAT,
		'decimal' => self::TYPE_DECIMAL,
		'numeric' => self::TYPE_DECIMAL,
		'tinytext' => self::TYPE_TEXT,
		'mediumtext' => self::TYPE_TEXT,
		'longtext' => self::TYPE_TEXT,
		'text' => self::TYPE_TEXT,
		'varchar' => self::TYPE_STRING,
		'string' => self::TYPE_STRING,
		'char' => self::TYPE_STRING,
		'datetime' => self::TYPE_DATETIME,
		'year' => self::TYPE_DATE,
		'date' => self::TYPE_DATE,
		'time' => self::TYPE_TIME,
		'timestamp' => self::TYPE_TIMESTAMP,
		'enum' => self::TYPE_STRING,
	);

	/**
	 * Creates a query builder for the MySQL database.
	 * This method may be overridden by child classes to create a DBMS-specific query builder.
	 * @return QueryBuilder query builder instance
	 */
	public function createQueryBuilder()
	{
		return new QueryBuilder($this->connection);
	}

	/**
	 * Returns all table names in the database.
	 * @param string $schema the schema of the tables. Defaults to empty string, meaning the current or default schema.
	 * If not empty, the returned table names will be prefixed with the schema name.
	 * @return array all table names in the database.
	 */
	protected function findTableNames($schema = '')
	{
		$sql = "SELECT DISTINCT tbl_name FROM sqlite_master WHERE tbl_name<>'sqlite_sequence'";
		return $this->connection->createCommand($sql)->queryColumn();
	}

	/**
	 * Loads the metadata for the specified table.
	 * @param string $name table name
	 * @return \yii\db\TableSchema driver dependent table metadata. Null if the table does not exist.
	 */
	protected function loadTableSchema($name)
	{
		$table = new TableSchema;
		$table->name = $name;
		$table->quotedName = $this->quoteTableName($name);

		if ($this->findColumns($table)) {
			$this->findConstraints($table);
			return $table;
		}
	}

	/**
	 * Collects the table column metadata.
	 * @param \yii\db\TableSchema $table the table metadata
	 * @return boolean whether the table exists in the database
	 */
	protected function findColumns($table)
	{
		$sql = "PRAGMA table_info({$table->quotedName})";
		$columns = $this->connection->createCommand($sql)->queryAll();
		if (empty($columns)) {
			return false;
		}

		foreach ($columns as $column) {
			$column = $this->createColumn($column);
			$table->columns[$column->name] = $column;
			if ($column->isPrimaryKey) {
				$table->primaryKey[] = $column->name;
			}
		}
		if (count($table->primaryKey) === 1 && !strncasecmp($table->columns[$table->primaryKey[0]]->dbType, 'int', 3)) {
			$table->sequenceName = '';
			$table->columns[$table->primaryKey[0]]->autoIncrement = true;
		}

		return true;
	}

	/**
	 * Collects the foreign key column details for the given table.
	 * @param \yii\db\TableSchema $table the table metadata
	 */
	protected function findConstraints($table)
	{
		$sql = "PRAGMA foreign_key_list({$table->quotedName})";
		$keys = $this->connection->createCommand($sql)->queryAll();
		foreach ($keys as $key) {
			$table->foreignKeys[] = array($key['table'], $key['from'] => $key['to']);
		}
	}

	/**
	 * Creates a table column.
	 * @param array $column column metadata
	 * @return ColumnSchema normalized column metadata
	 */
	protected function createColumn($column)
	{
		$c = new ColumnSchema;
		$c->name = $column['name'];
		$c->quotedName = $this->quoteSimpleColumnName($c->name);
		$c->allowNull = !$column['notnull'];
		$c->isPrimaryKey = $column['pk'] != 0;

		$c->dbType = $column['type'];
		$this->resolveColumnType($c);
		$c->resolvePhpType();

		$this->resolveColumnDefault($c, $column['dflt_value']);

		return $c;
	}

	/**
	 * Resolves the abstract data type for the column.
	 * @param \yii\db\ColumnSchema $column the column metadata object
	 */
	public function resolveColumnType($column)
	{
		$column->type = self::TYPE_STRING;
		$column->unsigned = strpos($column->dbType, 'unsigned') !== false;

		if (preg_match('/^(\w+)(?:\(([^\)]+)\))?/', $column->dbType, $matches)) {
			$type = $matches[1];
			if (isset($this->typeMap[$type])) {
				$column->type = $this->typeMap[$type];
			}

			if (!empty($matches[2])) {
				$values = explode(',', $matches[2]);
				$column->size = $column->precision = (int)$values[0];
				if (isset($values[1])) {
					$column->scale = (int)$values[1];
				}
				if ($column->size === 1 && ($type === 'tinyint' || $type === 'bit')) {
					$column->type = 'boolean';
				} elseif ($type === 'bit') {
					if ($column->size > 32) {
						$column->type = 'bigint';
					} elseif ($column->size === 32) {
						$column->type = 'integer';
					}
				}
			}
		}
	}

	/**
	 * Resolves the default value for the column.
	 * @param \yii\db\ColumnSchema $column the column metadata object
	 * @param string $value the default value fetched from database
	 */
	protected function resolveColumnDefault($column, $value)
	{
		if ($column->type === 'string') {
			$column->defaultValue = trim($value, "'\"");
		} else {
			$column->defaultValue = $column->typecast(strcasecmp($value, 'null') ? $value : null);
		}
	}
}