<?php

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

namespace yii\db\pgsql;

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

/**
 * Schema is the class for retrieving metadata from a PostgreSQL database 
 * (version 9.x and above).
 *
 * @author Gevik Babakhani <gevikb@gmail.com>
 * @since 2.0
 */
class Schema extends \yii\db\Schema
{

	/**
	 * The default schema used for the current session. This value is 
	 * automatically set to "public" by the PDO driver. 
	 * @var string 
	 */
	public static $DEFAULT_SCHEMA;

	/**
	 * @var array mapping from physical column types (keys) to abstract 
	 * column types (values)
	 */
	public $typeMap = array(
	    'abstime' => self::TYPE_TIMESTAMP,
	    'bit' => self::TYPE_STRING,
	    'boolean' => self::TYPE_BOOLEAN,
	    'box' => self::TYPE_STRING,
	    'character' => self::TYPE_STRING,
	    'bytea' => self::TYPE_BINARY,
	    'char' => self::TYPE_STRING,
	    'cidr' => self::TYPE_STRING,
	    'circle' => self::TYPE_STRING,
	    'date' => self::TYPE_DATE,
	    'real' => self::TYPE_FLOAT,
	    'double precision' => self::TYPE_DECIMAL,
	    'inet' => self::TYPE_STRING,
	    'smallint' => self::TYPE_SMALLINT,
	    'integer' => self::TYPE_INTEGER,
	    'bigint' => self::TYPE_BIGINT,
	    'interval' => self::TYPE_STRING,
	    'json' => self::TYPE_STRING,
	    'line' => self::TYPE_STRING,
	    'macaddr' => self::TYPE_STRING,
	    'money' => self::TYPE_MONEY,
	    'name' => self::TYPE_STRING,
	    'numeric' => self::TYPE_STRING,
	    'numrange' => self::TYPE_DECIMAL,
	    'oid' => self::TYPE_BIGINT, // should not be used. it's pg internal!
	    'path' => self::TYPE_STRING,
	    'point' => self::TYPE_STRING,
	    'polygon' => self::TYPE_STRING,
	    'text' => self::TYPE_TEXT,
	    'time without time zone' => self::TYPE_TIME,
	    'timestamp without time zone' => self::TYPE_TIMESTAMP,
	    'timestamp with time zone' => self::TYPE_TIMESTAMP,
	    'time with time zone' => self::TYPE_TIMESTAMP,
	    'unknown' => self::TYPE_STRING,
	    'uuid' => self::TYPE_STRING,
	    'bit varying' => self::TYPE_STRING,
	    'character varying' => self::TYPE_STRING,
	    'xml' => self::TYPE_STRING
	);

	/**
	 * Creates a query builder for the MySQL database.
	 * @return QueryBuilder query builder instance
	 */
	public function createQueryBuilder() {
		return new QueryBuilder($this->db);
	}

	/**
	 * 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->name = $parts[0];
		}
		if ($table->schemaName === null) {
			$table->schemaName = self::$DEFAULT_SCHEMA;
		}
	}

	/**
	 * Quotes a table name for use in a query.
	 * A simple table name has no schema prefix.
	 * @param string $name table name
	 * @return string the properly quoted table name
	 */
	public function quoteSimpleTableName($name) {
		return strpos($name, '"') !== false ? $name : '"' . $name . '"';
	}

	/**
	 * Loads the metadata for the specified table.
	 * @param string $name table name
	 * @return TableSchema|null driver dependent table metadata. Null if the table does not exist.
	 */
	public function loadTableSchema($name) {
		$table = new TableSchema();
		$this->resolveTableNames($table, $name);
		if ($this->findColumns($table)) {
			$this->findConstraints($table);
			return $table;
		}
	}

	/**
	 * Collects the foreign key column details for the given table.
	 * @param TableSchema $table the table metadata
	 */
	protected function findConstraints($table) {

		$tableName = $this->quoteValue($table->name);
		$tableSchema = $this->quoteValue($table->schemaName);
		$database = $this->quoteValue($this->db->pdo->getCurrentDatabase());

		//We need to extract the constraints de hard way since:
		//http://www.postgresql.org/message-id/26677.1086673982@sss.pgh.pa.us

		$sql = <<<SQL
select 
	ct.conname as containst,
	c.relname as table_name,
	ns.nspname as table_schema,
	current_database() as table_catalog,
	(select string_agg(attname,',') attname from pg_attribute where attrelid=ct.conrelid and attnum = any(ct.conkey)) as columns,
	fc.relname as foreign_table_name,
	fns.nspname as foreign_table_schema,
	current_database() as foreign_table_catalog,
	(select string_agg(attname,',') attname from pg_attribute where attrelid=ct.confrelid and attnum = any(ct.confkey)) as foreign_columns
from
	pg_constraint ct 
	inner join pg_class c on c.oid=ct.conrelid
	inner join pg_namespace ns on c.relnamespace=ns.oid
	left join pg_class fc on fc.oid=ct.confrelid
	left join pg_namespace fns on fc.relnamespace=fns.oid
	
where
	ct.contype='f'
	and c.relname={$tableName}
	and ns.nspname={$tableSchema}
	and current_database() = {$database}	
SQL;

		try {
			$constraints = $this->db->createCommand($sql)->queryAll();
		} catch (\Exception $e) {
			return false;
		}
		foreach ($constraints as $constraint) {
			$columns = explode(',', $constraint['columns']);
			$fcolumns = explode(',', $constraint['foreign_columns']);
			$citem = array($constraint['foreign_table_name']);
			foreach ($columns as $idx => $column) {
				$citem[] = array($fcolumns[$idx] => $column);
			}
			$table->foreignKeys[] = $citem;
		}
		return true;
	}

	/**
	 * Collects the metadata of table columns.
	 * @param TableSchema $table the table metadata
	 * @return boolean whether the table exists in the database
	 */
	protected function findColumns($table) {
		$dbname = $this->db->quoteValue($this->db->pdo->getCurrentDatabase());
		$tableName = $this->db->quoteValue($table->name);
		$schemaName = $this->db->quoteValue($table->schemaName);
		$sql = <<<SQL
SELECT 
	current_database() as table_catalog,
	d.nspname AS table_schema,        
        c.relname AS table_name,
        a.attname AS column_name,
        t.typname AS data_type,
        a.attlen AS character_maximum_length,
        pg_catalog.col_description(c.oid, a.attnum) AS column_comment,
        a.atttypmod AS modifier,
        a.attnotnull = false AS is_nullable,	
        CAST(pg_get_expr(ad.adbin, ad.adrelid) AS varchar) AS column_default,
        coalesce(pg_get_expr(ad.adbin, ad.adrelid) ~ 'nextval',false) AS is_autoinc,
        array_to_string((select array_agg(enumlabel) from pg_enum where enumtypid=a.atttypid)::varchar[],',') as enum_values,
	CASE atttypid
		 WHEN 21 /*int2*/ THEN 16
		 WHEN 23 /*int4*/ THEN 32
		 WHEN 20 /*int8*/ THEN 64
		 WHEN 1700 /*numeric*/ THEN
		      CASE WHEN atttypmod = -1
			   THEN null
			   ELSE ((atttypmod - 4) >> 16) & 65535
			   END
		 WHEN 700 /*float4*/ THEN 24 /*FLT_MANT_DIG*/
		 WHEN 701 /*float8*/ THEN 53 /*DBL_MANT_DIG*/
		 ELSE null
	  END   AS numeric_precision,
	  CASE 
	    WHEN atttypid IN (21, 23, 20) THEN 0
	    WHEN atttypid IN (1700) THEN            
		CASE 
		    WHEN atttypmod = -1 THEN null       
		    ELSE (atttypmod - 4) & 65535
		END
	       ELSE null
	  END AS numeric_scale,
	CAST(
             information_schema._pg_char_max_length(information_schema._pg_truetypid(a, t), information_schema._pg_truetypmod(a, t))
             AS numeric
	) AS size,
	a.attnum = any (ct.conkey) as is_pkey			
FROM
	pg_class c
	LEFT JOIN pg_attribute a ON a.attrelid = c.oid
	LEFT JOIN pg_attrdef ad ON a.attrelid = ad.adrelid AND a.attnum = ad.adnum
	LEFT JOIN pg_type t ON a.atttypid = t.oid
	LEFT JOIN pg_namespace d ON d.oid = c.relnamespace
	LEFT join pg_constraint ct on ct.conrelid=c.oid and ct.contype='p'
WHERE
	a.attnum > 0
	and c.relname = {$tableName}
	and d.nspname = {$schemaName}
	and current_database() = {$dbname}
ORDER BY
	a.attnum;
SQL;

		try {
			$columns = $this->db->createCommand($sql)->queryAll();
		} catch (\Exception $e) {
			return false;
		}
		foreach ($columns as $column) {
			$column = $this->loadColumnSchema($column);
			$table->columns[$column->name] = $column;
			if ($column->isPrimaryKey === true) {
				$table->primaryKey[] = $column->name;
				if ($table->sequenceName === null && preg_match("/nextval\('\w+'(::regclass)?\)/", $column->defaultValue) === 1) {
					$table->sequenceName = preg_replace(array('/nextval/', '/::/', '/regclass/', '/\'\)/', '/\(\'/'), '', $column->defaultValue);
				}
			}
		}
		return true;
	}

	/**
	 * Loads the column information into a [[ColumnSchema]] object.
	 * @param array $info column information
	 * @return ColumnSchema the column schema object
	 */
	protected function loadColumnSchema($info) {
		$column = new ColumnSchema();
		$column->allowNull = $info['is_nullable'];
		$column->autoIncrement = $info['is_autoinc'];
		$column->comment = $info['column_comment'];
		$column->dbType = $info['data_type'];
		$column->defaultValue = $info['column_default'];
		$column->enumValues = explode(',', str_replace(array("''"), array("'"), $info['enum_values']));
		$column->unsigned = false; // has no meanining in PG
		$column->isPrimaryKey = $info['is_pkey'];
		$column->name = $info['column_name'];
		$column->precision = $info['numeric_precision'];
		$column->scale = $info['numeric_scale'];
		$column->size = $info['size'];

		if (isset($this->typeMap[$column->dbType])) {
			$column->type = $this->typeMap[$column->dbType];
		} else {
			$column->type = self::TYPE_STRING;
		}
		$column->phpType = $this->getColumnPhpType($column);
		return $column;
	}

}