<?php
/**
 * @link http://www.yiiframework.com/
 * @copyright Copyright (c) 2008 Yii Software LLC
 * @license http://www.yiiframework.com/license/
 */

namespace yii\db\oci;

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

/**
 * Schema is the class for retrieving metadata from an Oracle database
 *
 * @todo mapping from physical types to abstract types
 *
 * @author Qiang Xue <qiang.xue@gmail.com>
 * @since 2.0
 */
class Schema extends \yii\db\Schema
{
	/**
	 * @inheritdoc
	 */
	public function init()
	{
		parent::init();
		if ($this->defaultSchema === null) {
			$this->defaultSchema = $this->db->username;
		}
	}

	/**
	 * @inheritdoc
	 */
	public function releaseSavepoint($name)
	{
		// does nothing as Oracle does not support this
	}

	/**
	 * @inheritdoc
	 */
	public function quoteSimpleTableName($name)
	{
		return '"' . $name . '"';
	}

	/**
	 * @inheritdoc
	 */
	public function quoteSimpleColumnName($name)
	{
		return '"' . $name . '"';
	}

	/**
	 * @inheritdoc
	 */
	public function createQueryBuilder()
	{
		return new QueryBuilder($this->db);
	}

	/**
	 * @inheritdoc
	 */
	public function loadTableSchema($name)
	{
		$table = new TableSchema();
		$this->resolveTableNames($table, $name);

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

	/**
	 * Resolves the table name and schema name (if any).
	 *
	 * @param TableSchema $table the table metadata object
	 * @param string $name the table name
	 */
	protected function resolveTableNames($table, $name)
	{
		$parts = explode('.', str_replace('"', '', $name));
		if (isset($parts[1])) {
			$table->schemaName = $parts[0];
			$table->name = $parts[1];
		} else {
			$table->schemaName = $this->defaultSchema;
			$table->name = $name;
		}

		$table->fullName = $table->schemaName !== $this->defaultSchema ? $table->schemaName . '.' . $table->name : $table->name;
	}

	/**
	 * Collects the table column metadata.
	 * @param TableSchema $table the table schema
	 * @return boolean whether the table exists
	 */
	protected function findColumns($table)
	{
		$schemaName = $table->schemaName;
		$tableName = $table->name;

		$sql = <<<EOD
SELECT a.column_name, a.data_type ||
    case
        when data_precision is not null
            then '(' || a.data_precision ||
                    case when a.data_scale > 0 then ',' || a.data_scale else '' end
                || ')'
        when data_type = 'DATE' then ''
        when data_type = 'NUMBER' then ''
        else '(' || to_char(a.data_length) || ')'
    end as data_type,
    a.nullable, a.data_default,
    (   SELECT D.constraint_type
        FROM ALL_CONS_COLUMNS C
        inner join ALL_constraints D on D.OWNER = C.OWNER and D.constraint_name = C.constraint_name
        WHERE C.OWNER = B.OWNER
           and C.table_name = B.object_name
           and C.column_name = A.column_name
           and D.constraint_type = 'P') as Key,
    com.comments as column_comment
FROM ALL_TAB_COLUMNS A
inner join ALL_OBJECTS B ON b.owner = a.owner and ltrim(B.OBJECT_NAME) = ltrim(A.TABLE_NAME)
LEFT JOIN user_col_comments com ON (A.table_name = com.table_name AND A.column_name = com.column_name)
WHERE
    a.owner = '{$schemaName}'
	and (b.object_type = 'TABLE' or b.object_type = 'VIEW')
	and b.object_name = '{$tableName}'
ORDER by a.column_id
EOD;

		try {
			$columns = $this->db->createCommand($sql)->queryAll();
		} catch (\Exception $e) {
			return false;
		}

		foreach ($columns as $column) {
			$c = $this->createColumn($column);
			$table->columns[$c->name] = $c;
			if ($c->isPrimaryKey) {
				$table->primaryKey[] = $c->name;
				$table->sequenceName = '';
				$c->autoIncrement = true;
			}
		}
		return true;
	}

	protected function createColumn($column)
	{
		$c = new ColumnSchema();
		$c->name = $column['COLUMN_NAME'];
		$c->allowNull = $column['NULLABLE'] === 'Y';
		$c->isPrimaryKey = strpos($column['KEY'], 'P') !== false;
		$c->comment = $column['COLUMN_COMMENT'] === null ? '' : $column['COLUMN_COMMENT'];

		$this->extractColumnType($c, $column['DATA_TYPE']);
		$this->extractColumnSize($c, $column['DATA_TYPE']);

		if (stripos($column['DATA_DEFAULT'], 'timestamp') !== false) {
			$c->defaultValue = null;
		} else {
			$c->defaultValue = $c->typecast($column['DATA_DEFAULT']);
		}

		return $c;
	}

	protected function findConstraints($table)
	{
		$sql = <<<EOD
		SELECT D.constraint_type as CONSTRAINT_TYPE, C.COLUMN_NAME, C.position, D.r_constraint_name,
                E.table_name as table_ref, f.column_name as column_ref,
            	C.table_name
        FROM ALL_CONS_COLUMNS C
        inner join ALL_constraints D on D.OWNER = C.OWNER and D.constraint_name = C.constraint_name
        left join ALL_constraints E on E.OWNER = D.r_OWNER and E.constraint_name = D.r_constraint_name
        left join ALL_cons_columns F on F.OWNER = E.OWNER and F.constraint_name = E.constraint_name and F.position = c.position
        WHERE C.OWNER = '{$table->schemaName}'
           and C.table_name = '{$table->name}'
           and D.constraint_type <> 'P'
        order by d.constraint_name, c.position
EOD;
		$command = $this->db->createCommand($sql);
		foreach ($command->queryAll() as $row) {
			if ($row['CONSTRAINT_TYPE'] === 'R') {
				$name = $row["COLUMN_NAME"];
				$table->foreignKeys[$name] = [$row["TABLE_REF"], $row["COLUMN_REF"]];
			}
		}
	}

	/**
	 * @inheritdoc
	 */
	protected function findTableNames($schema = '')
	{
		if ($schema === '') {
			$sql = <<<EOD
SELECT table_name, '{$schema}' as table_schema FROM user_tables
EOD;
			$command = $this->db->createCommand($sql);
		} else {
			$sql = <<<EOD
SELECT object_name as table_name, owner as table_schema FROM all_objects
WHERE object_type = 'TABLE' AND owner=:schema
EOD;
			$command = $this->db->createCommand($sql);
			$command->bindParam(':schema', $schema);
		}

		$rows = $command->queryAll();
		$names = [];
		foreach ($rows as $row) {
			$names[] = $row['TABLE_NAME'];
		}
		return $names;
	}

	/**
	 * Extracts the data types for the given column
	 * @param ColumnSchema $column
	 * @param string $dbType DB type
	 */
	protected function extractColumnType($column, $dbType)
	{
		$column->dbType = $dbType;

		if (strpos($dbType, 'FLOAT') !== false) {
			$column->type = 'double';
		} elseif (strpos($dbType, 'NUMBER') !== false || strpos($dbType, 'INTEGER') !== false) {
			if (strpos($dbType, '(') && preg_match('/\((.*)\)/', $dbType, $matches)) {
				$values = explode(',', $matches[1]);
				if (isset($values[1]) and (((int)$values[1]) > 0)) {
					$column->type = 'double';
				} else {
					$column->type = 'integer';
				}
			} else {
				$column->type = 'double';
			}
		} else {
			$column->type = 'string';
		}
	}

	/**
	 * Extracts size, precision and scale information from column's DB type.
	 * @param ColumnSchema $column
	 * @param string $dbType the column's DB type
	 */
	protected function extractColumnSize($column, $dbType)
	{
		if (strpos($dbType, '(') && preg_match('/\((.*)\)/', $dbType, $matches)) {
			$values = explode(',', $matches[1]);
			$column->size = $column->precision = (int)$values[0];
			if (isset($values[1])) {
				$column->scale = (int)$values[1];
			}
		}
	}
}
