<?php
/**
 * CodeIgniter
 *
 * An open source application development framework for PHP
 *
 * This content is released under the MIT License (MIT)
 *
 * Copyright (c) 2014-2019 British Columbia Institute of Technology
 * Copyright (c) 2019-2020 CodeIgniter Foundation
 *
 * Permission is hereby granted, free of charge, to any person obtaining a copy
 * of this software and associated documentation files (the "Software"), to deal
 * in the Software without restriction, including without limitation the rights
 * to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
 * copies of the Software, and to permit persons to whom the Software is
 * furnished to do so, subject to the following conditions:
 *
 * The above copyright notice and this permission notice shall be included in
 * all copies or substantial portions of the Software.
 *
 * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
 * IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
 * FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
 * AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
 * LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
 * OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN
 * THE SOFTWARE.
 *
 * @package    CodeIgniter
 * @author     CodeIgniter Dev Team
 * @copyright  2019-2020 CodeIgniter Foundation
 * @license    https://opensource.org/licenses/MIT	MIT License
 * @link       https://codeigniter.com
 * @since      Version 4.0.0
 * @filesource
 */

namespace CodeIgniter\Database\Postgre;

use CodeIgniter\Database\BaseConnection;
use CodeIgniter\Database\ConnectionInterface;
use CodeIgniter\Database\Exceptions\DatabaseException;

/**
 * Connection for Postgre
 */
class Connection extends BaseConnection implements ConnectionInterface
{

	/**
	 * Database driver
	 *
	 * @var string
	 */
	public $DBDriver = 'postgre';

	//--------------------------------------------------------------------

	/**
	 * Database schema
	 *
	 * @var string
	 */
	public $schema = 'public';

	/**
	 * Identifier escape character
	 *
	 * @var string
	 */
	public $escapeChar = '"';

	//--------------------------------------------------------------------

	/**
	 * Connect to the database.
	 *
	 * @param  boolean $persistent
	 * @return mixed
	 */
	public function connect(bool $persistent = false)
	{
		if (empty($this->DSN))
		{
			$this->buildDSN();
		}

		// Strip pgsql if exists
		if (mb_strpos($this->DSN, 'pgsql:') === 0)
		{
			$this->DSN = mb_substr($this->DSN, 6);
		}

		// Convert semicolons to spaces.
		$this->DSN = str_replace(';', ' ', $this->DSN);

		$this->connID = $persistent === true ? pg_pconnect($this->DSN) : pg_connect($this->DSN);

		if ($this->connID !== false)
		{
			if ($persistent === true && pg_connection_status($this->connID) === PGSQL_CONNECTION_BAD && pg_ping($this->connID) === false
			)
			{
				return false;
			}

			empty($this->schema) || $this->simpleQuery("SET search_path TO {$this->schema},public");

			if ($this->setClientEncoding($this->charset) === false)
			{
				return false;
			}
		}

		return $this->connID;
	}

	//--------------------------------------------------------------------

	/**
	 * Keep or establish the connection if no queries have been sent for
	 * a length of time exceeding the server's idle timeout.
	 *
	 * @return void
	 */
	public function reconnect()
	{
		if (pg_ping($this->connID) === false)
		{
			$this->connID = false;
		}
	}

	//--------------------------------------------------------------------

	/**
	 * Close the database connection.
	 *
	 * @return void
	 */
	protected function _close()
	{
		pg_close($this->connID);
	}

	//--------------------------------------------------------------------

	/**
	 * Select a specific database table to use.
	 *
	 * @param string $databaseName
	 *
	 * @return boolean
	 */
	public function setDatabase(string $databaseName): bool
	{
		return false;
	}

	//--------------------------------------------------------------------

	/**
	 * Returns a string containing the version of the database being used.
	 *
	 * @return string
	 */
	public function getVersion(): string
	{
		if (isset($this->dataCache['version']))
		{
			return $this->dataCache['version'];
		}

		if (! $this->connID || ( $pgVersion = pg_version($this->connID)) === false)
		{
			$this->initialize();
		}

		return isset($pgVersion['server']) ? $this->dataCache['version'] = $pgVersion['server'] : false;
	}

	//--------------------------------------------------------------------

	/**
	 * Executes the query against the database.
	 *
	 * @param string $sql
	 *
	 * @return mixed
	 */
	public function execute(string $sql)
	{
		try
		{
			return pg_query($this->connID, $sql);
		}
		catch (\ErrorException $e)
		{
			log_message('error', $e);
			if ($this->DBDebug)
			{
				throw $e;
			}
		}
		return false;
	}

	//--------------------------------------------------------------------

	/**
	 * Returns the total number of rows affected by this query.
	 *
	 * @return integer
	 */
	public function affectedRows(): int
	{
		return pg_affected_rows($this->resultID);
	}

	//--------------------------------------------------------------------

	/**
	 * "Smart" Escape String
	 *
	 * Escapes data based on type
	 *
	 * @param  mixed $str
	 * @return mixed
	 */
	public function escape($str)
	{
		if (! $this->connID)
		{
			$this->initialize();
		}

		if (is_string($str) || ( is_object($str) && method_exists($str, '__toString')))
		{
			return pg_escape_literal($this->connID, $str);
		}
		elseif (is_bool($str))
		{
			return $str ? 'TRUE' : 'FALSE';
		}

		return parent::escape($str);
	}

	//--------------------------------------------------------------------

	/**
	 * Platform-dependant string escape
	 *
	 * @param  string $str
	 * @return string
	 */
	protected function _escapeString(string $str): string
	{
		if (! $this->connID)
		{
			$this->initialize();
		}

		return pg_escape_string($this->connID, $str);
	}

	//--------------------------------------------------------------------

	/**
	 * Generates the SQL for listing tables in a platform-dependent manner.
	 *
	 * @param boolean $prefixLimit
	 *
	 * @return string
	 */
	protected function _listTables(bool $prefixLimit = false): string
	{
		$sql = 'SELECT "table_name" FROM "information_schema"."tables" WHERE "table_schema" = \'' . $this->schema . "'";

		if ($prefixLimit !== false && $this->DBPrefix !== '')
		{
			return $sql . ' AND "table_name" LIKE \''
					. $this->escapeLikeString($this->DBPrefix) . "%' "
					. sprintf($this->likeEscapeStr, $this->likeEscapeChar);
		}

		return $sql;
	}

	//--------------------------------------------------------------------

	/**
	 * Generates a platform-specific query string so that the column names can be fetched.
	 *
	 * @param string $table
	 *
	 * @return string
	 */
	protected function _listColumns(string $table = ''): string
	{
		return 'SELECT "column_name"
			FROM "information_schema"."columns"
			WHERE LOWER("table_name") = '
				. $this->escape($this->DBPrefix . strtolower($table));
	}

	//--------------------------------------------------------------------

	/**
	 * Returns an array of objects with field data
	 *
	 * @param  string $table
	 * @return \stdClass[]
	 * @throws DatabaseException
	 */
	public function _fieldData(string $table): array
	{
		$sql = 'SELECT "column_name", "data_type", "character_maximum_length", "numeric_precision", "column_default"
			FROM "information_schema"."columns"
			WHERE LOWER("table_name") = '
				. $this->escape(strtolower($table));

		if (($query = $this->query($sql)) === false)
		{
			throw new DatabaseException(lang('Database.failGetFieldData'));
		}
		$query = $query->getResultObject();

		$retVal = [];
		for ($i = 0, $c = count($query); $i < $c; $i ++)
		{
			$retVal[$i]             = new \stdClass();
			$retVal[$i]->name       = $query[$i]->column_name;
			$retVal[$i]->type       = $query[$i]->data_type;
			$retVal[$i]->default    = $query[$i]->column_default;
			$retVal[$i]->max_length = $query[$i]->character_maximum_length > 0 ? $query[$i]->character_maximum_length : $query[$i]->numeric_precision;
		}

		return $retVal;
	}

	//--------------------------------------------------------------------

	/**
	 * Returns an array of objects with index data
	 *
	 * @param  string $table
	 * @return \stdClass[]
	 * @throws DatabaseException
	 */
	public function _indexData(string $table): array
	{
		$sql = 'SELECT "indexname", "indexdef"
			FROM "pg_indexes"
			WHERE LOWER("tablename") = ' . $this->escape(strtolower($table)) . '
			AND "schemaname" = ' . $this->escape('public');

		if (($query = $this->query($sql)) === false)
		{
			throw new DatabaseException(lang('Database.failGetIndexData'));
		}
		$query = $query->getResultObject();

		$retVal = [];
		foreach ($query as $row)
		{
			$obj         = new \stdClass();
			$obj->name   = $row->indexname;
			$_fields     = explode(',', preg_replace('/^.*\((.+?)\)$/', '$1', trim($row->indexdef)));
			$obj->fields = array_map(function ($v) {
				return trim($v);
			}, $_fields);

			if (strpos($row->indexdef, 'CREATE UNIQUE INDEX pk') === 0)
			{
				$obj->type = 'PRIMARY';
			}
			else
			{
				$obj->type = (strpos($row->indexdef, 'CREATE UNIQUE') === 0) ? 'UNIQUE' : 'INDEX';
			}

			$retVal[$obj->name] = $obj;
		}

		return $retVal;
	}

	//--------------------------------------------------------------------

	/**
	 * Returns an array of objects with Foreign key data
	 *
	 * @param  string $table
	 * @return \stdClass[]
	 * @throws DatabaseException
	 */
	public function _foreignKeyData(string $table): array
	{
		$sql = 'SELECT
                            tc.constraint_name, tc.table_name, kcu.column_name,
                            ccu.table_name AS foreign_table_name,
                            ccu.column_name AS foreign_column_name
                        FROM information_schema.table_constraints AS tc
                        JOIN information_schema.key_column_usage AS kcu
                            ON tc.constraint_name = kcu.constraint_name
                        JOIN information_schema.constraint_column_usage AS ccu
                            ON ccu.constraint_name = tc.constraint_name
                        WHERE constraint_type = ' . $this->escape('FOREIGN KEY') . ' AND
                            tc.table_name = ' . $this->escape($table);

		if (($query = $this->query($sql)) === false)
		{
			throw new DatabaseException(lang('Database.failGetForeignKeyData'));
		}
		$query = $query->getResultObject();

		$retVal = [];
		foreach ($query as $row)
		{
			$obj                      = new \stdClass();
			$obj->constraint_name     = $row->constraint_name;
			$obj->table_name          = $row->table_name;
			$obj->column_name         = $row->column_name;
			$obj->foreign_table_name  = $row->foreign_table_name;
			$obj->foreign_column_name = $row->foreign_column_name;
			$retVal[]                 = $obj;
		}

		return $retVal;
	}

	//--------------------------------------------------------------------

	/**
	 * Returns platform-specific SQL to disable foreign key checks.
	 *
	 * @return string
	 */
	protected function _disableForeignKeyChecks()
	{
		return 'SET CONSTRAINTS ALL DEFERRED';
	}

	//--------------------------------------------------------------------

	/**
	 * Returns platform-specific SQL to enable foreign key checks.
	 *
	 * @return string
	 */
	protected function _enableForeignKeyChecks()
	{
		return 'SET CONSTRAINTS ALL IMMEDIATE;';
	}

	//--------------------------------------------------------------------

	/**
	 * Returns the last error code and message.
	 *
	 * Must return an array with keys 'code' and 'message':
	 *
	 *  return ['code' => null, 'message' => null);
	 *
	 * @return array
	 */
	public function error(): array
	{
		return [
			'code'    => '',
			'message' => pg_last_error($this->connID),
		];
	}

	//--------------------------------------------------------------------

	/**
	 * Insert ID
	 *
	 * @return integer
	 */
	public function insertID(): int
	{
		$v = pg_version($this->connID);
		// 'server' key is only available since PostgreSQL 7.4
		$v = explode(' ', $v['server'])[0] ?? 0;

		$table  = func_num_args() > 0 ? func_get_arg(0) : null;
		$column = func_num_args() > 1 ? func_get_arg(1) : null;

		if ($table === null && $v >= '8.1')
		{
			$sql = 'SELECT LASTVAL() AS ins_id';
		}
		elseif ($table !== null)
		{
			if ($column !== null && $v >= '8.0')
			{
				$sql   = "SELECT pg_get_serial_sequence('{$table}', '{$column}') AS seq";
				$query = $this->query($sql);
				$query = $query->getRow();
				$seq   = $query->seq;
			}
			else
			{
				// seq_name passed in table parameter
				$seq = $table;
			}

			$sql = "SELECT CURRVAL('{$seq}') AS ins_id";
		}
		else
		{
			return pg_last_oid($this->resultID);
		}

		$query = $this->query($sql);
		$query = $query->getRow();
		return (int) $query->ins_id;
	}

	//--------------------------------------------------------------------

	/**
	 * Build a DSN from the provided parameters
	 *
	 * @return void
	 */
	protected function buildDSN()
	{
		$this->DSN === '' || $this->DSN = '';

		// If UNIX sockets are used, we shouldn't set a port
		if (strpos($this->hostname, '/') !== false)
		{
			$this->port = '';
		}

		$this->hostname === '' || $this->DSN = "host={$this->hostname} ";

		if (! empty($this->port) && ctype_digit($this->port))
		{
			$this->DSN .= "port={$this->port} ";
		}

		if ($this->username !== '')
		{
			$this->DSN .= "user={$this->username} ";

			// An empty password is valid!
			// password must be set to null to ignore it.

			$this->password === null || $this->DSN .= "password='{$this->password}' ";
		}

		$this->database === '' || $this->DSN .= "dbname={$this->database} ";

		// We don't have these options as elements in our standard configuration
		// array, but they might be set by parse_url() if the configuration was
		// provided via string> Example:
		//
		// postgre://username:password@localhost:5432/database?connect_timeout=5&sslmode=1
		foreach (['connect_timeout', 'options', 'sslmode', 'service'] as $key)
		{
			if (isset($this->{$key}) && is_string($this->{$key}) && $this->{$key} !== '')
			{
				$this->DSN .= "{$key}='{$this->{$key}}' ";
			}
		}

		$this->DSN = rtrim($this->DSN);
	}

	//--------------------------------------------------------------------

	/**
	 * Set client encoding
	 *
	 * @param  string $charset The client encoding to which the data will be converted.
	 * @return boolean
	 */
	protected function setClientEncoding(string $charset): bool
	{
		return pg_set_client_encoding($this->connID, $charset) === 0;
	}

	//--------------------------------------------------------------------

	/**
	 * Begin Transaction
	 *
	 * @return boolean
	 */
	protected function _transBegin(): bool
	{
		return (bool) pg_query($this->connID, 'BEGIN');
	}

	// --------------------------------------------------------------------

	/**
	 * Commit Transaction
	 *
	 * @return boolean
	 */
	protected function _transCommit(): bool
	{
		return (bool) pg_query($this->connID, 'COMMIT');
	}

	// --------------------------------------------------------------------

	/**
	 * Rollback Transaction
	 *
	 * @return boolean
	 */
	protected function _transRollback(): bool
	{
		return (bool) pg_query($this->connID, 'ROLLBACK');
	}

	// --------------------------------------------------------------------
}
