<?php
/**
 * @copyright Copyright (C) 2020, Friendica
 *
 * @license GNU AGPL version 3 or any later version
 *
 * This program is free software: you can redistribute it and/or modify
 * it under the terms of the GNU Affero General Public License as
 * published by the Free Software Foundation, either version 3 of the
 * License, or (at your option) any later version.
 *
 * This program is distributed in the hope that it will be useful,
 * but WITHOUT ANY WARRANTY; without even the implied warranty of
 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
 * GNU Affero General Public License for more details.
 *
 * You should have received a copy of the GNU Affero General Public License
 * along with this program.  If not, see <https://www.gnu.org/licenses/>.
 *
 */

namespace Friendica\Database;

use Friendica\DI;
use mysqli;
use mysqli_result;
use mysqli_stmt;
use PDO;
use PDOStatement;

/**
 * This class is for the low level database stuff that does driver specific things.
 */
class DBA
{
	/**
	 * Lowest possible date value
	 */
	const NULL_DATE     = '0001-01-01';
	/**
	 * Lowest possible datetime value
	 */
	const NULL_DATETIME = '0001-01-01 00:00:00';

	public static function connect()
	{
		return DI::dba()->connect();
	}

	/**
	 * Disconnects the current database connection
	 */
	public static function disconnect()
	{
		DI::dba()->disconnect();
	}

	/**
	 * Perform a reconnect of an existing database connection
	 */
	public static function reconnect()
	{
		return DI::dba()->reconnect();
	}

	/**
	 * Return the database object.
	 * @return PDO|mysqli
	 */
	public static function getConnection()
	{
		return DI::dba()->getConnection();
	}

	/**
	 * Return the database driver string
	 *
	 * @return string with either "pdo" or "mysqli"
	 */
	public static function getDriver()
	{
		return DI::dba()->getDriver();
	}

	/**
	 * Returns the MySQL server version string
	 *
	 * This function discriminate between the deprecated mysql API and the current
	 * object-oriented mysqli API. Example of returned string: 5.5.46-0+deb8u1
	 *
	 * @return string
	 */
	public static function serverInfo()
	{
		return DI::dba()->serverInfo();
	}

	/**
	 * Returns the selected database name
	 *
	 * @return string
	 * @throws \Exception
	 */
	public static function databaseName()
	{
		return DI::dba()->databaseName();
	}

	/**
	 * Escape all SQL unsafe data
	 *
	 * @param string $str
	 * @return string escaped string
	 */
	public static function escape($str)
	{
		return DI::dba()->escape($str);
	}

	/**
	 * Checks if the database is connected
	 *
	 * @return boolean is the database connected?
	 */
	public static function connected()
	{
		return DI::dba()->connected();
	}

	/**
	 * Replaces ANY_VALUE() function by MIN() function,
	 * if the database server does not support ANY_VALUE().
	 *
	 * Considerations for Standard SQL, or MySQL with ONLY_FULL_GROUP_BY (default since 5.7.5).
	 * ANY_VALUE() is available from MySQL 5.7.5 https://dev.mysql.com/doc/refman/5.7/en/miscellaneous-functions.html
	 * A standard fall-back is to use MIN().
	 *
	 * @param string $sql An SQL string without the values
	 * @return string The input SQL string modified if necessary.
	 */
	public static function anyValueFallback($sql)
	{
		return DI::dba()->anyValueFallback($sql);
	}

	/**
	 * beautifies the query - useful for "SHOW PROCESSLIST"
	 *
	 * This is safe when we bind the parameters later.
	 * The parameter values aren't part of the SQL.
	 *
	 * @param string $sql An SQL string without the values
	 * @return string The input SQL string modified if necessary.
	 */
	public static function cleanQuery($sql)
	{
		$search = ["\t", "\n", "\r", "  "];
		$replace = [' ', ' ', ' ', ' '];
		do {
			$oldsql = $sql;
			$sql = str_replace($search, $replace, $sql);
		} while ($oldsql != $sql);

		return $sql;
	}

	/**
	 * Convert parameter array to an universal form
	 * @param array $args Parameter array
	 * @return array universalized parameter array
	 */
	public static function getParam($args)
	{
		unset($args[0]);

		// When the second function parameter is an array then use this as the parameter array
		if ((count($args) > 0) && (is_array($args[1]))) {
			return $args[1];
		} else {
			return $args;
		}
	}

	/**
	 * Executes a prepared statement that returns data
	 * Example: $r = p("SELECT * FROM `post` WHERE `guid` = ?", $guid);
	 *
	 * Please only use it with complicated queries.
	 * For all regular queries please use DBA::select or DBA::exists
	 *
	 * @param string $sql SQL statement
	 * @return bool|object statement object or result object
	 * @throws \Exception
	 */
	public static function p($sql)
	{
		$params = self::getParam(func_get_args());

		return DI::dba()->p($sql, $params);
	}

	/**
	 * Executes a prepared statement like UPDATE or INSERT that doesn't return data
	 *
	 * Please use DBA::delete, DBA::insert, DBA::update, ... instead
	 *
	 * @param string $sql SQL statement
	 * @return boolean Was the query successfull? False is returned only if an error occurred
	 * @throws \Exception
	 */
	public static function e($sql) {

		$params = self::getParam(func_get_args());

		return DI::dba()->e($sql, $params);
	}

	/**
	 * Check if data exists
	 *
	 * @param string|array $table     Table name or array [schema => table]
	 * @param array        $condition array of fields for condition
	 *
	 * @return boolean Are there rows for that condition?
	 * @throws \Exception
	 */
	public static function exists($table, $condition)
	{
		return DI::dba()->exists($table, $condition);
	}

	/**
	 * Fetches the first row
	 *
	 * Please use DBA::selectFirst or DBA::exists whenever this is possible.
	 *
	 * @param string $sql SQL statement
	 * @return array first row of query
	 * @throws \Exception
	 */
	public static function fetchFirst($sql)
	{
		$params = self::getParam(func_get_args());

		return DI::dba()->fetchFirst($sql, $params);
	}

	/**
	 * Returns the number of affected rows of the last statement
	 *
	 * @return int Number of rows
	 */
	public static function affectedRows()
	{
		return DI::dba()->affectedRows();
	}

	/**
	 * Returns the number of columns of a statement
	 *
	 * @param object Statement object
	 * @return int Number of columns
	 */
	public static function columnCount($stmt)
	{
		return DI::dba()->columnCount($stmt);
	}
	/**
	 * Returns the number of rows of a statement
	 *
	 * @param PDOStatement|mysqli_result|mysqli_stmt Statement object
	 * @return int Number of rows
	 */
	public static function numRows($stmt)
	{
		return DI::dba()->numRows($stmt);
	}

	/**
	 * Fetch a single row
	 *
	 * @param mixed $stmt statement object
	 * @return array current row
	 */
	public static function fetch($stmt)
	{
		return DI::dba()->fetch($stmt);
	}

	/**
	 * Insert a row into a table
	 *
	 * @param string|array $table          Table name or array [schema => table]
	 * @param array        $param          parameter array
	 * @param int          $duplicate_mode What to do on a duplicated entry
	 *
	 * @return boolean was the insert successful?
	 * @throws \Exception
	 */
	public static function insert($table, array $param, int $duplicate_mode = Database::INSERT_DEFAULT)
	{
		return DI::dba()->insert($table, $param, $duplicate_mode);
	}

	/**
	 * Inserts a row with the provided data in the provided table.
	 * If the data corresponds to an existing row through a UNIQUE or PRIMARY index constraints, it updates the row instead.
	 *
	 * @param string|array $table Table name or array [schema => table]
	 * @param array        $param parameter array
	 *
	 * @return boolean was the insert successful?
	 * @throws \Exception
	 */
	public static function replace($table, $param)
	{
		return DI::dba()->replace($table, $param);
	}

	/**
	 * Fetch the id of the last insert command
	 *
	 * @return integer Last inserted id
	 */
	public static function lastInsertId()
	{
		return DI::dba()->lastInsertId();
	}

	/**
	 * Locks a table for exclusive write access
	 *
	 * This function can be extended in the future to accept a table array as well.
	 *
	 * @param string|array $table Table name or array [schema => table]
	 *
	 * @return boolean was the lock successful?
	 * @throws \Exception
	 */
	public static function lock($table)
	{
		return DI::dba()->lock($table);
	}

	/**
	 * Unlocks all locked tables
	 *
	 * @return boolean was the unlock successful?
	 * @throws \Exception
	 */
	public static function unlock()
	{
		return DI::dba()->unlock();
	}

	/**
	 * Starts a transaction
	 *
	 * @return boolean Was the command executed successfully?
	 */
	public static function transaction()
	{
		return DI::dba()->transaction();
	}

	/**
	 * Does a commit
	 *
	 * @return boolean Was the command executed successfully?
	 */
	public static function commit()
	{
		return DI::dba()->commit();
	}

	/**
	 * Does a rollback
	 *
	 * @return boolean Was the command executed successfully?
	 */
	public static function rollback()
	{
		return DI::dba()->rollback();
	}

	/**
	 * Delete a row from a table
	 *
	 * @param string|array $table      Table name
	 * @param array        $conditions Field condition(s)
	 *
	 * @return boolean was the delete successful?
	 * @throws \Exception
	 */
	public static function delete($table, array $conditions, array $options = [])
	{
		return DI::dba()->delete($table, $conditions, $options);
	}

	/**
	 * Updates rows in the database.
	 *
	 * When $old_fields is set to an array,
	 * the system will only do an update if the fields in that array changed.
	 *
	 * Attention:
	 * Only the values in $old_fields are compared.
	 * This is an intentional behaviour.
	 *
	 * Example:
	 * We include the timestamp field in $fields but not in $old_fields.
	 * Then the row will only get the new timestamp when the other fields had changed.
	 *
	 * When $old_fields is set to a boolean value the system will do this compare itself.
	 * When $old_fields is set to "true" the system will do an insert if the row doesn't exists.
	 *
	 * Attention:
	 * Only set $old_fields to a boolean value when you are sure that you will update a single row.
	 * When you set $old_fields to "true" then $fields must contain all relevant fields!
	 *
	 * @param string|array  $table      Table name or array [schema => table]
	 * @param array         $fields     contains the fields that are updated
	 * @param array         $condition  condition array with the key values
	 * @param array|boolean $old_fields array with the old field values that are about to be replaced (true = update on duplicate)
	 *
	 * @return boolean was the update successfull?
	 * @throws \Exception
	 */
	public static function update($table, $fields, $condition, $old_fields = [])
	{
		return DI::dba()->update($table, $fields, $condition, $old_fields);
	}

	/**
	 * Retrieve a single record from a table and returns it in an associative array
	 *
	 * @param string|array $table     Table name or array [schema => table]
	 * @param array        $fields
	 * @param array        $condition
	 * @param array        $params
	 * @return bool|array
	 * @throws \Exception
	 * @see   self::select
	 */
	public static function selectFirst($table, array $fields = [], array $condition = [], $params = [])
	{
		return DI::dba()->selectFirst($table, $fields, $condition, $params);
	}

	/**
	 * Select rows from a table and fills an array with the data
	 *
	 * @param string|array $table     Table name or array [schema => table]
	 * @param array        $fields    Array of selected fields, empty for all
	 * @param array        $condition Array of fields for condition
	 * @param array        $params    Array of several parameters
	 *
	 * @return array Data array
	 * @throws \Exception
	 * @see   self::select
	 */
	public static function selectToArray($table, array $fields = [], array $condition = [], array $params = [])
	{
		return DI::dba()->selectToArray($table, $fields, $condition, $params);
	}

	/**
	 * Select rows from a table
	 *
	 * @param string|array $table     Table name or array [schema => table]
	 * @param array        $fields    Array of selected fields, empty for all
	 * @param array        $condition Array of fields for condition
	 * @param array        $params    Array of several parameters
	 *
	 * @return boolean|object
	 *
	 * Example:
	 * $table = "post";
	 * $fields = array("id", "uri", "uid", "network");
	 *
	 * $condition = array("uid" => 1, "network" => 'dspr');
	 * or:
	 * $condition = array("`uid` = ? AND `network` IN (?, ?)", 1, 'dfrn', 'dspr');
	 *
	 * $params = array("order" => array("id", "received" => true), "limit" => 10);
	 *
	 * $data = DBA::select($table, $fields, $condition, $params);
	 * @throws \Exception
	 */
	public static function select($table, array $fields = [], array $condition = [], array $params = [])
	{
		return DI::dba()->select($table, $fields, $condition, $params);
	}

	/**
	 * Counts the rows from a table satisfying the provided condition
	 *
	 * @param string|array $table     Table name or array [schema => table]
	 * @param array        $condition array of fields for condition
	 * @param array        $params    Array of several parameters
	 *
	 * @return int
	 *
	 * Example:
	 * $table = "post";
	 *
	 * $condition = ["uid" => 1, "network" => 'dspr'];
	 * or:
	 * $condition = ["`uid` = ? AND `network` IN (?, ?)", 1, 'dfrn', 'dspr'];
	 *
	 * $count = DBA::count($table, $condition);
	 * @throws \Exception
	 */
	public static function count($table, array $condition = [], array $params = [])
	{
		return DI::dba()->count($table, $condition, $params);
	}

	/**
	 * Build the table query substring from one or more tables, with or without a schema.
	 *
	 * Expected formats:
	 * - table
	 * - [table1, table2, ...]
	 * - [schema1 => table1, schema2 => table2, table3, ...]
	 *
	 * @param string|array $tables
	 * @return string
	 */
	public static function buildTableString($tables)
	{
		if (is_string($tables)) {
			$tables = [$tables];
		}

		$quotedTables = [];

		foreach ($tables as $schema => $table) {
			if (is_numeric($schema)) {
				$quotedTables[] = self::quoteIdentifier($table);
			} else {
				$quotedTables[] = self::quoteIdentifier($schema) . '.' . self::quoteIdentifier($table);
			}
		}

		return implode(', ', $quotedTables);
	}

	/**
	 * Escape an identifier (table or field name)
	 *
	 * @param $identifier
	 * @return string
	 */
	public static function quoteIdentifier($identifier)
	{
		return '`' . str_replace('`', '``', $identifier) . '`';
	}

	/**
	 * Returns the SQL condition string built from the provided condition array
	 *
	 * This function operates with two modes.
	 * - Supplied with a field/value associative array, it builds simple strict
	 *   equality conditions linked by AND.
	 * - Supplied with a flat list, the first element is the condition string and
	 *   the following arguments are the values to be interpolated
	 *
	 * $condition = ["uid" => 1, "network" => 'dspr'];
	 * or:
	 * $condition = ["`uid` = ? AND `network` IN (?, ?)", 1, 'dfrn', 'dspr'];
	 *
	 * In either case, the provided array is left with the parameters only
	 *
	 * @param array $condition
	 * @return string
	 */
	public static function buildCondition(array &$condition = [])
	{
		$condition = self::collapseCondition($condition);
		
		$condition_string = '';
		if (count($condition) > 0) {
			$condition_string = " WHERE (" . array_shift($condition) . ")";
		}

		return $condition_string;
	}

	/**
	 * Collapse an associative array condition into a SQL string + parameters condition array.
	 *
	 * ['uid' => 1, 'network' => ['dspr', 'apub']]
	 *
	 * gets transformed into
	 *
	 * ["`uid` = ? AND `network` IN (?, ?)", 1, 'dspr', 'apub']
	 *
	 * @param array $condition
	 * @return array
	 */
	public static function collapseCondition(array $condition)
	{
		// Ensures an always true condition is returned
		if (count($condition) < 1) {
			return ['1'];
		}

		reset($condition);
		$first_key = key($condition);

		if (is_int($first_key)) {
			// Already collapsed
			return $condition;
		}

		$values = [];
		$condition_string = "";
		foreach ($condition as $field => $value) {
			if ($condition_string != "") {
				$condition_string .= " AND ";
			}

			if (is_array($value)) {
				if (count($value)) {
					/* Workaround for MySQL Bug #64791.
					 * Never mix data types inside any IN() condition.
					 * In case of mixed types, cast all as string.
					 * Logic needs to be consistent with DBA::p() data types.
					 */
					$is_int = false;
					$is_alpha = false;
					foreach ($value as $single_value) {
						if (is_int($single_value)) {
							$is_int = true;
						} else {
							$is_alpha = true;
						}
					}

					if ($is_int && $is_alpha) {
						foreach ($value as &$ref) {
							if (is_int($ref)) {
								$ref = (string)$ref;
							}
						}
						unset($ref); //Prevent accidental re-use.
					}

					$values = array_merge($values, array_values($value));
					$placeholders = substr(str_repeat("?, ", count($value)), 0, -2);
					$condition_string .= self::quoteIdentifier($field) . " IN (" . $placeholders . ")";
				} else {
					// Empty value array isn't supported by IN and is logically equivalent to no match
					$condition_string .= "FALSE";
				}
			} elseif (is_null($value)) {
				$condition_string .= self::quoteIdentifier($field) . " IS NULL";
			} else {
				$values[$field] = $value;
				$condition_string .= self::quoteIdentifier($field) . " = ?";
			}
		}

		$condition = array_merge([$condition_string], array_values($values));

		return $condition;
	}

	/**
	 * Merges the provided conditions into a single collapsed one
	 *
	 * @param array ...$conditions One or more condition arrays
	 * @return array A collapsed condition
	 * @see DBA::collapseCondition() for the condition array formats
	 */
	public static function mergeConditions(array ...$conditions)
	{
		if (count($conditions) == 1) {
			return current($conditions);
		}

		$conditionStrings = [];
		$result = [];

		foreach ($conditions as $key => $condition) {
			if (!$condition) {
				continue;
			}

			$condition = self::collapseCondition($condition);

			$conditionStrings[] = array_shift($condition);
			// The result array holds the eventual parameter values
			$result = array_merge($result, $condition);
		}

		if (count($conditionStrings)) {
			// We prepend the condition string at the end to form a collapsed condition array again
			array_unshift($result, implode(' AND ', $conditionStrings));
		}

		return $result;
	}

	/**
	 * Returns the SQL parameter string built from the provided parameter array
	 *
	 * Expected format for each key:
	 *
	 * group_by:
	 *  - list of column names
	 *
	 * order:
	 *  - numeric keyed column name => ASC
	 *  - associative element with boolean value => DESC (true), ASC (false)
	 *  - associative element with string value => 'ASC' or 'DESC' literally
	 *
	 * limit:
	 *  - single numeric value => count
	 *  - list with two numeric values => offset, count
	 *
	 * @param array $params
	 * @return string
	 */
	public static function buildParameter(array $params = [])
	{
		$groupby_string = '';
		if (!empty($params['group_by'])) {
			$groupby_string = " GROUP BY " . implode(', ', array_map(['self', 'quoteIdentifier'], $params['group_by']));
		}

		$order_string = '';
		if (isset($params['order'])) {
			$order_string = " ORDER BY ";
			foreach ($params['order'] AS $fields => $order) {
				if ($order === 'RAND()') {
					$order_string .= "RAND(), ";
				} elseif (!is_int($fields)) {
					if ($order !== 'DESC' && $order !== 'ASC') {
						$order = $order ? 'DESC' : 'ASC';
					}

					$order_string .= self::quoteIdentifier($fields) . " " . $order . ", ";
				} else {
					$order_string .= self::quoteIdentifier($order) . ", ";
				}
			}
			$order_string = substr($order_string, 0, -2);
		}

		$limit_string = '';
		if (isset($params['limit']) && is_numeric($params['limit'])) {
			$limit_string = " LIMIT " . intval($params['limit']);
		}

		if (isset($params['limit']) && is_array($params['limit'])) {
			$limit_string = " LIMIT " . intval($params['limit'][0]) . ", " . intval($params['limit'][1]);
		}

		return $groupby_string . $order_string . $limit_string;
	}

	/**
	 * Fills an array with data from a query
	 *
	 * @param object $stmt     statement object
	 * @param bool   $do_close Close database connection after last row
	 * @param int    $count    maximum number of rows to be fetched
	 *
	 * @return array Data array
	 */
	public static function toArray($stmt, $do_close = true, int $count = 0)
	{
		return DI::dba()->toArray($stmt, $do_close, $count);
	}

	/**
	 * Cast field types according to the table definition
	 *
	 * @param string $table
	 * @param array  $fields
	 * @return array casted fields
	 */
	public static function castFields(string $table, array $fields)
	{
		return DI::dba()->castFields($table, $fields);
	}

	/**
	 * Returns the error number of the last query
	 *
	 * @return string Error number (0 if no error)
	 */
	public static function errorNo()
	{
		return DI::dba()->errorNo();
	}

	/**
	 * Returns the error message of the last query
	 *
	 * @return string Error message ('' if no error)
	 */
	public static function errorMessage()
	{
		return DI::dba()->errorMessage();
	}

	/**
	 * Closes the current statement
	 *
	 * @param object $stmt statement object
	 * @return boolean was the close successful?
	 */
	public static function close($stmt)
	{
		return DI::dba()->close($stmt);
	}

	/**
	 * Return a list of database processes
	 *
	 * @return array
	 *      'list' => List of processes, separated in their different states
	 *      'amount' => Number of concurrent database processes
	 * @throws \Exception
	 */
	public static function processlist()
	{
		return DI::dba()->processlist();
	}

	/**
	 * Fetch a database variable
	 *
	 * @param string $name
	 * @return string content
	 */
	public static function getVariable(string $name)
	{
		return DI::dba()->getVariable($name);
	}

	/**
	 * Checks if $array is a filled array with at least one entry.
	 *
	 * @param mixed $array A filled array with at least one entry
	 *
	 * @return boolean Whether $array is a filled array or an object with rows
	 */
	public static function isResult($array)
	{
		return DI::dba()->isResult($array);
	}

	/**
	 * Escapes a whole array
	 *
	 * @param mixed   $arr           Array with values to be escaped
	 * @param boolean $add_quotation add quotation marks for string values
	 * @return void
	 */
	public static function escapeArray(&$arr, $add_quotation = false)
	{
		DI::dba()->escapeArray($arr, $add_quotation);
	}
}