<?php

/**
 * This file is part of CodeIgniter 4 framework.
 *
 * (c) CodeIgniter Foundation <admin@codeigniter.com>
 *
 * For the full copyright and license information, please view
 * the LICENSE file that was distributed with this source code.
 */

namespace CodeIgniter\Database\SQLite3;

use CodeIgniter\Database\BaseConnection;
use CodeIgniter\Database\Exceptions\DatabaseException;
use CodeIgniter\Database\Forge as BaseForge;

/**
 * Forge for SQLite3
 */
class Forge extends BaseForge
{
    /**
     * @var Connection
     */
    protected $db;

    /**
     * UNSIGNED support
     *
     * @var array|bool
     */
    protected $_unsigned = false;

    /**
     * NULL value representation in CREATE/ALTER TABLE statements
     *
     * @var string
     *
     * @internal
     */
    protected $null = 'NULL';

    /**
     * Constructor.
     */
    public function __construct(BaseConnection $db)
    {
        parent::__construct($db);

        if (version_compare($this->db->getVersion(), '3.3', '<')) {
            $this->createTableIfStr = false;
            $this->dropTableIfStr   = false;
        }
    }

    /**
     * Create database
     *
     * @param bool $ifNotExists Whether to add IF NOT EXISTS condition
     */
    public function createDatabase(string $dbName, bool $ifNotExists = false): bool
    {
        // In SQLite, a database is created when you connect to the database.
        // We'll return TRUE so that an error isn't generated.
        return true;
    }

    /**
     * Drop database
     *
     * @throws DatabaseException
     */
    public function dropDatabase(string $dbName): bool
    {
        // In SQLite, a database is dropped when we delete a file
        if (! is_file($dbName)) {
            if ($this->db->DBDebug) {
                throw new DatabaseException('Unable to drop the specified database.');
            }

            return false;
        }

        // We need to close the pseudo-connection first
        $this->db->close();
        if (! @unlink($dbName)) {
            if ($this->db->DBDebug) {
                throw new DatabaseException('Unable to drop the specified database.');
            }

            return false;
        }

        if (! empty($this->db->dataCache['db_names'])) {
            $key = array_search(strtolower($dbName), array_map('strtolower', $this->db->dataCache['db_names']), true);
            if ($key !== false) {
                unset($this->db->dataCache['db_names'][$key]);
            }
        }

        return true;
    }

    /**
     * @param mixed $field
     *
     * @return array|string|null
     */
    protected function _alterTable(string $alterType, string $table, $field)
    {
        switch ($alterType) {
            case 'DROP':
                $sqlTable = new Table($this->db, $this);

                $sqlTable->fromTable($table)
                    ->dropColumn($field)
                    ->run();

                return '';

            case 'CHANGE':
                (new Table($this->db, $this))
                    ->fromTable($table)
                    ->modifyColumn($field)
                    ->run();

                return null;

            default:
                return parent::_alterTable($alterType, $table, $field);
        }
    }

    /**
     * Process column
     */
    protected function _processColumn(array $field): string
    {
        if ($field['type'] === 'TEXT' && strpos($field['length'], "('") === 0) {
            $field['type'] .= ' CHECK(' . $this->db->escapeIdentifiers($field['name'])
                . ' IN ' . $field['length'] . ')';
        }

        return $this->db->escapeIdentifiers($field['name'])
            . ' ' . $field['type']
            . $field['auto_increment']
            . $field['null']
            . $field['unique']
            . $field['default'];
    }

    /**
     * Process indexes
     */
    protected function _processIndexes(string $table): array
    {
        $sqls = [];

        for ($i = 0, $c = count($this->keys); $i < $c; $i++) {
            $this->keys[$i] = (array) $this->keys[$i];

            for ($i2 = 0, $c2 = count($this->keys[$i]); $i2 < $c2; $i2++) {
                if (! isset($this->fields[$this->keys[$i][$i2]])) {
                    unset($this->keys[$i][$i2]);
                }
            }
            if (count($this->keys[$i]) <= 0) {
                continue;
            }

            if (in_array($i, $this->uniqueKeys, true)) {
                $sqls[] = 'CREATE UNIQUE INDEX ' . $this->db->escapeIdentifiers($table . '_' . implode('_', $this->keys[$i]))
                    . ' ON ' . $this->db->escapeIdentifiers($table)
                    . ' (' . implode(', ', $this->db->escapeIdentifiers($this->keys[$i])) . ');';

                continue;
            }

            $sqls[] = 'CREATE INDEX ' . $this->db->escapeIdentifiers($table . '_' . implode('_', $this->keys[$i]))
                . ' ON ' . $this->db->escapeIdentifiers($table)
                . ' (' . implode(', ', $this->db->escapeIdentifiers($this->keys[$i])) . ');';
        }

        return $sqls;
    }

    /**
     * Field attribute TYPE
     *
     * Performs a data type mapping between different databases.
     */
    protected function _attributeType(array &$attributes)
    {
        switch (strtoupper($attributes['TYPE'])) {
            case 'ENUM':
            case 'SET':
                $attributes['TYPE'] = 'TEXT';
                break;

            default:
                break;
        }
    }

    /**
     * Field attribute AUTO_INCREMENT
     */
    protected function _attributeAutoIncrement(array &$attributes, array &$field)
    {
        if (! empty($attributes['AUTO_INCREMENT']) && $attributes['AUTO_INCREMENT'] === true
            && stripos($field['type'], 'int') !== false) {
            $field['type']           = 'INTEGER PRIMARY KEY';
            $field['default']        = '';
            $field['null']           = '';
            $field['unique']         = '';
            $field['auto_increment'] = ' AUTOINCREMENT';

            $this->primaryKeys = [];
        }
    }

    /**
     * Foreign Key Drop
     *
     * @throws DatabaseException
     */
    public function dropForeignKey(string $table, string $foreignName): bool
    {
        // If this version of SQLite doesn't support it, we're done here
        if ($this->db->supportsForeignKeys() !== true) {
            return true;
        }

        // Otherwise we have to copy the table and recreate
        // without the foreign key being involved now
        $sqlTable = new Table($this->db, $this);

        return $sqlTable->fromTable($this->db->DBPrefix . $table)
            ->dropForeignKey($foreignName)
            ->run();
    }
}
