<?php
/**
 * This file is part of FacturaScripts
 * Copyright (C) 2015-2026 Carlos Garcia Gomez <carlos@facturascripts.com>
 *
 * This program is free software: you can redistribute it and/or modify
 * it under the terms of the GNU Lesser 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 Lesser General Public License for more details.
 *
 * You should have received a copy of the GNU Lesser General Public License
 * along with this program. If not, see <http://www.gnu.org/licenses/>.
 */

namespace FacturaScripts\Core\Base;

use FacturaScripts\Core\Base\DataBase\DataBaseEngine;
use FacturaScripts\Core\Base\DataBase\MysqlEngine;
use FacturaScripts\Core\Base\DataBase\PostgresqlEngine;
use FacturaScripts\Core\KernelException;
use FacturaScripts\Core\Tools;

/**
 * Generic class of access to the database, either MySQL or PostgreSQL.
 *
 * @author Carlos García Gómez           <carlos@facturascripts.com>
 * @author Jose Antonio Cuello Principal <yopli2000@gmail.com>
 */
final class DataBase
{
    const CHANNEL = 'database';

    /**
     * Link to the database engine selected in the configuration.
     *
     * @var DataBaseEngine
     */
    private static $engine;

    /**
     * The link with de database.
     *
     * @var resource
     */
    private static $link;

    /**
     * Manage the log of all controllers, models and database.
     *
     * @var MiniLog
     */
    private static $miniLog;

    /**
     * List of tables in the database.
     *
     * @var array
     */
    private static $tables = [];

    /**
     * Type of database engine.
     *
     * @var string
     */
    private static $type;

    /**
     * DataBase constructor and prepare the class to use it.
     */
    public function __construct()
    {
        if (Tools::config('db_name') && self::$link === null) {
            self::$miniLog = new MiniLog(self::CHANNEL);

            self::$type = strtolower(Tools::config('db_type'));
            switch (self::$type) {
                case 'postgresql':
                    self::$engine = new PostgresqlEngine();
                    break;

                default:
                    self::$engine = new MysqlEngine();
                    break;
            }
        }
    }

    /**
     * Start a transaction in the database.
     *
     * @return bool
     */
    public function beginTransaction(): bool
    {
        if ($this->inTransaction()) {
            return true;
        }

        self::$miniLog->debug('Begin Transaction');

        return self::$engine->beginTransaction(self::$link);
    }

    public function castInteger(string $col): string
    {
        return self::$engine->castInteger(self::$link, $col);
    }

    /**
     * Returns the random function for the database engine.
     *
     * @return string
     */
    public function random(): string
    {
        return self::$engine->random();
    }

    /**
     * Disconnect from the database.
     *
     * @return bool
     */
    public function close(): bool
    {
        if (false === $this->connected()) {
            return true;
        }

        if (self::$engine->inTransaction(self::$link) && !$this->rollback()) {
            return false;
        }

        if (self::$engine->close(self::$link)) {
            self::$link = null;
        }

        return false === $this->connected();
    }

    /**
     * Record the statements executed in the database.
     *
     * @return bool
     */
    public function commit(): bool
    {
        $result = self::$engine->commit(self::$link);
        if ($result) {
            self::$miniLog->debug('Commit Transaction');
        }

        return $result;
    }

    /**
     * Connect to the database.
     *
     * @return bool
     */
    public function connect(): bool
    {
        if ($this->connected()) {
            return true;
        }

        $error = '';
        self::$link = self::$engine->connect($error);
        if ($error !== '') {
            self::$miniLog->critical($error);
        }

        return $this->connected();
    }

    /**
     * Returns True if it is connected to the database.
     *
     * @return bool
     */
    public function connected(): bool
    {
        return (bool)self::$link;
    }

    /**
     * Escape the quotes from the column name.
     *
     * @param string $name
     *
     * @return string
     */
    public function escapeColumn(string $name): string
    {
        return self::$engine->escapeColumn(self::$link, $name);
    }

    /**
     * Escape the quotes from the text string.
     *
     * @param string $str
     *
     * @return string
     */
    public function escapeString($str)
    {
        return self::$engine->escapeString(self::$link, $str);
    }

    /**
     * Execute SQL statements on the database (inserts, updates or deletes).
     * To make selects, it is better to use select () or selectLimit ().
     * If there is no open transaction, one starts, queries are executed
     * If the transaction has opened it in the call, it closes it confirming
     * or discarding according to whether it has gone well or has given an error
     *
     * @param string $sql
     *
     * @return bool
     */
    public function exec(string $sql): bool
    {
        $result = $this->connected();
        if ($result) {
            // clean the list of tables, since there could be changes when executing this sql.
            self::$tables = [];

            $inTransaction = $this->inTransaction();
            $this->beginTransaction();

            // execute sql
            $start = microtime(true);
            $result = self::$engine->exec(self::$link, $sql);
            $stop = microtime(true);

            // adds the sql query to the history
            self::$miniLog->debug($sql, ['duration' => $stop - $start]);

            // check errors
            if (!$result || self::$engine->hasError()) {
                self::$miniLog->error(self::$engine->errorMessage(self::$link), ['sql' => $sql]);
                self::$engine->clearError();
            }

            if ($inTransaction) {
                return $result;
            }

            // We only operate if the transaction has been initiated in this call
            if ($result) {
                return $this->commit();
            }

            $this->rollback();
        }

        return $result;
    }

    /**
     * Returns an array with the columns of a given table.
     *
     * @param string $tableName
     *
     * @return array
     */
    public function getColumns(string $tableName): array
    {
        $result = [];
        $data = $this->select(self::$engine->getSQL()->sqlColumns($tableName));
        foreach ($data as $row) {
            $column = self::$engine->columnFromData($row);
            $result[$column['name']] = $column;
        }

        return $result;
    }

    /**
     * Returns an array with the constraints of a table.
     *
     * @param string $tableName
     * @param bool $extended
     *
     * @return array
     */
    public function getConstraints(string $tableName, bool $extended = false): array
    {
        $sql = $extended ?
            self::$engine->getSQL()->sqlConstraintsExtended($tableName) :
            self::$engine->getSQL()->sqlConstraints($tableName);
        $data = $this->select($sql);
        return $data ? array_values($data) : [];
    }

    /**
     * Return the database engine used
     *
     * @return DataBaseEngine
     */
    public function getEngine()
    {
        return self::$engine;
    }

    /**
     * Returns an array with the indices of a given table.
     *
     * @param string $tableName
     *
     * @return array
     */
    public function getAllIndexes(string $tableName): array
    {
        $result = [];
        $data = $this->select(self::$engine->getSQL()->sqlIndexes($tableName));
        foreach ($data as $row) {
            $result[] = [
                'name' => $row['Key_name'] ?? $row['key_name'] ?? '',
                'column' => $row['Column_name'] ?? $row['column_name'] ?? '',
            ];
        }

        return $result;
    }

    /**
     * Returns an array with the FacturaScripts indexes of a given table.
     *
     * @param string $tableName
     *
     * @return array
     */
    public function getIndexes(string $tableName): array
    {
        $result = array_filter($this->getAllIndexes($tableName), function ($dbIdx) {
            return false !== strpos($dbIdx['name'], 'fs_');
        });

        $result = array_values($result);

        return $result;
    }

    /**
     * Gets the operator for the database engine
     *
     * @param string $operator
     *
     * @return string
     */
    public function getOperator(string $operator): string
    {
        return self::$engine->getOperator($operator);
    }

    /**
     * Returns an array with the names of the tables in the database.
     *
     * @return array
     */
    public function getTables(): array
    {
        if (false === $this->connected()) {
            return [];
        } elseif (empty(self::$tables)) {
            self::$tables = self::$engine->listTables(self::$link);
        }

        return self::$tables;
    }

    /**
     * Indicates if there is an open transaction.
     *
     * @return bool
     */
    public function inTransaction(): bool
    {
        return self::$engine->inTransaction(self::$link);
    }

    /**
     * Returns the last ID assigned when doing an INSERT in the database.
     *
     * @return int|bool
     */
    public function lastval()
    {
        $aux = $this->select(self::$engine->getSQL()->sqlLastValue());
        return empty($aux) ? false : $aux[0]['num'];
    }

    /**
     * Undo the statements executed in the database.
     *
     * @return bool
     */
    public function rollback(): bool
    {
        self::$miniLog->debug('Rollback Transaction');
        return self::$engine->rollback(self::$link);
    }

    /**
     * Execute a SQL statement of type select, and return
     * an array with the results, or an empty array in case of failure.
     *
     * @param string $sql
     *
     * @return array
     */
    public function select(string $sql): array
    {
        return $this->selectLimit($sql, 0);
    }

    /**
     * Execute a SQL statement of type select, but with pagination,
     * and return an array with the results or an empty array in case of failure.
     * Limit is the number of items you want to return. Offset is the result
     * number from which you want it to start.
     *
     * @param string $sql
     * @param int $limit
     * @param int $offset
     *
     * @return array
     */
    public function selectLimit(string $sql, int $limit = FS_ITEM_LIMIT, int $offset = 0): array
    {
        if (false === $this->connected()) {
            return [];
        }

        if ($limit > 0) {
            // add limit and offset to sql query
            $sql .= ' LIMIT ' . $limit . ' OFFSET ' . $offset . ';';
        }

        $start = microtime(true);
        $result = self::$engine->select(self::$link, $sql);
        $stop = microtime(true);

        // add the sql query to the history
        self::$miniLog->debug($sql, ['duration' => $stop - $start]);

        if (!empty($result)) {
            return $result;
        }

        // some error?
        $error = self::$engine->errorMessage(self::$link);
        if (!empty($error)) {
            self::$miniLog->error($error, ['sql' => $sql]);
        }

        return [];
    }

    /**
     * Returns True if the table exists, False otherwise.
     *
     * @param string $tableName
     * @param array $list
     *
     * @return bool
     */
    public function tableExists(string $tableName, array $list = []): bool
    {
        if (empty($list)) {
            $list = $this->getTables();
        }

        return in_array($tableName, $list, false);
    }

    public function type(): string
    {
        return self::$type ?? '';
    }

    /**
     * @param string $tableName
     * @param array $fields
     */
    public function updateSequence(string $tableName, array $fields)
    {
        self::$engine->updateSequence(self::$link, $tableName, $fields);
    }

    /**
     * Transforms a variable into a valid text string to be used in a SQL query.
     *
     * @param mixed $val
     *
     * @return string
     */
    public function var2str($val): string
    {
        if ($val === null) {
            return 'NULL';
        }

        if (is_bool($val)) {
            return $val ? 'TRUE' : 'FALSE';
        }

        // If it's an array
        if (is_array($val)) {
            throw new KernelException('DatabaseError', 'Array not allowed in var2str function');
        }

        // If it's an object
        if (is_object($val)) {
            throw new KernelException('DatabaseError', 'Object not allowed in var2str function');
        }

        // If it's a date
        if (preg_match("/^([\d]{1,2})-([\d]{1,2})-([\d]{4})$/i", $val)) {
            $date = date(self::$engine->dateStyle(), strtotime($val));
            return $date === '1970-01-01' ?
                "'" . $this->escapeString($val) . "'" :
                "'" . $date . "'";
        }

        // If it's a date time
        if (preg_match("/^([\d]{1,2})-([\d]{1,2})-([\d]{4}) ([\d]{1,2}):([\d]{1,2}):([\d]{1,2})$/i", $val)) {
            $date = date(self::$engine->dateStyle() . ' H:i:s', strtotime($val));
            return $date === '1970-01-01 00:00:00' ?
                "'" . $this->escapeString($val) . "'" :
                "'" . $date . "'";
        }

        return "'" . $this->escapeString($val) . "'";
    }

    /**
     * Returns the used database engine and the version.
     *
     * @return string
     */
    public function version(): string
    {
        return $this->connected() ? self::$engine->version(self::$link) : '';
    }
}
