<?php
/**
 * DbExporter - Chunk tabanlı veritabanı export
 * 
 * @package AllDataMigration
 * @subpackage Engine
 */

namespace AllDataMigration\Engine;

if (!defined('ABSPATH')) {
    exit;
}

class DbExporter
{

    private ChunkConfig $config;
    private ProgressState $progress;
    private string $outputDir;
    private array $tables = [];

    public function __construct(ChunkConfig $config, ProgressState $progress, string $outputDir)
    {
        $this->config = $config;
        $this->progress = $progress;
        $this->outputDir = rtrim($outputDir, '/\\') . '/db/';

        if (!is_dir($this->outputDir)) {
            wp_mkdir_p($this->outputDir);
        }
    }

    /**
     * Tablo listesini hazırlar
     */
    public function prepareTables(): array
    {
        global $wpdb;

        // phpcs:disable WordPress.DB.PreparedSQL.NotPrepared -- Dynamic table name
        // phpcs:ignore WordPress.DB.DirectDatabaseQuery.DirectQuery, WordPress.DB.DirectDatabaseQuery.NoCaching -- INFO query
        $tables = $wpdb->get_col("SHOW TABLES LIKE '{$wpdb->prefix}%'");
        // phpcs:enable WordPress.DB.PreparedSQL.NotPrepared

        $this->tables = [];
        foreach ($tables as $table) {
            // phpcs:ignore WordPress.DB.PreparedSQL.InterpolatedNotPrepared, WordPress.DB.DirectDatabaseQuery, PluginCheck.Security.DirectDB.UnescapedDBParameter
            $count = (int) $wpdb->get_var("SELECT COUNT(*) FROM `{$table}`");
            $this->tables[$table] = [
                'name' => $table,
                'rows' => $count,
                'chunks' => (int) ceil($count / $this->config->getDbRowsPerChunk()),
                'exported' => false
            ];
        }

        return $this->tables;
    }

    /**
     * Bir chunk export eder
     * 
     * @param int $tableIndex Tablo indeksi
     * @param int $offset Başlangıç satırı
     * @return array Sonraki chunk bilgisi veya null
     */
    public function exportChunk(int $tableIndex, int $offset): ?array
    {
        global $wpdb;

        $tableNames = array_keys($this->tables);

        if (!isset($tableNames[$tableIndex])) {
            return null; // Tüm tablolar bitti
        }

        $table = $tableNames[$tableIndex];
        $limit = $this->config->getDbRowsPerChunk();

        // Veriyi çek
        // phpcs:disable WordPress.DB.DirectDatabaseQuery
        // phpcs:disable WordPress.DB.PreparedSQL.InterpolatedNotPrepared -- Dynamic table name
        $rows = $wpdb->get_results(
            $wpdb->prepare(
                "SELECT * FROM `{$table}` LIMIT %d OFFSET %d",
                $limit,
                $offset
            ),
            ARRAY_A
        );
        // phpcs:enable

        if (empty($rows)) {
            // Bu tablo bitti, sonraki tabloya geç
            return [
                'table_index' => $tableIndex + 1,
                'offset' => 0,
                'completed_table' => $table
            ];
        }

        // SQL dosyası oluştur
        $chunkNumber = (int) floor($offset / $limit) + 1;
        $filename = sprintf('%s_%03d.sql', $table, $chunkNumber);
        $filepath = $this->outputDir . $filename;

        $sql = $this->generateSql($table, $rows);
        file_put_contents($filepath, $sql);

        // Sonraki chunk
        $newOffset = $offset + count($rows);
        $tableInfo = $this->tables[$table];

        if ($newOffset >= $tableInfo['rows']) {
            // Tablo bitti
            return [
                'table_index' => $tableIndex + 1,
                'offset' => 0,
                'completed_table' => $table
            ];
        }

        return [
            'table_index' => $tableIndex,
            'offset' => $newOffset,
            'file' => $filename
        ];
    }

    /**
     * SQL INSERT statement oluşturur
     */
    private function generateSql(string $table, array $rows): string
    {
        global $wpdb;

        if (empty($rows)) {
            return '';
        }

        $columns = array_keys($rows[0]);
        $columnList = '`' . implode('`, `', $columns) . '`';

        $sql = "-- Table: {$table}\n";
        $sql .= "-- Exported: " . gmdate('Y-m-d H:i:s') . "\n\n";

        $batchSize = $this->config->getSqlBatchSize();
        $batch = [];

        // WP Cloner özel encoding marker'ları
        // % karakteri SQL ve PHP'de sorun çıkarabilir, bu yüzden encode ediyoruz
        $specialChars = [
            '%' => '{{WPCLONER_PERCENT}}',
        ];

        foreach ($rows as $i => $row) {
            $values = [];
            foreach ($row as $value) {
                if ($value === null) {
                    $values[] = 'NULL';
                } else {
                    // Özel karakterleri encode et
                    $encoded = $value;
                    foreach ($specialChars as $char => $marker) {
                        $encoded = str_replace($char, $marker, $encoded);
                    }
                    $values[] = "'" . esc_sql($encoded) . "'";
                }
            }
            $batch[] = '(' . implode(', ', $values) . ')';

            if (count($batch) >= $batchSize || $i === count($rows) - 1) {
                $sql .= "INSERT INTO `{$table}` ({$columnList}) VALUES\n";
                $sql .= implode(",\n", $batch) . ";\n\n";
                $batch = [];
            }
        }

        return $sql;
    }

    /**
     * Tablo yapısını export eder
     */
    public function exportTableStructures(): string
    {
        global $wpdb;

        $filepath = $this->outputDir . '_schema.sql';
        $sql = "-- WP Cloner Database Schema\n";
        $sql .= "-- Exported: " . gmdate('Y-m-d H:i:s') . "\n\n";

        foreach (array_keys($this->tables) as $table) {
            // phpcs:disable WordPress.DB.DirectDatabaseQuery
            // phpcs:disable WordPress.DB.PreparedSQL.InterpolatedNotPrepared -- Variable table name
            // phpcs:disable WordPress.DB.DirectDatabaseQuery.SchemaChange
            // phpcs:disable PluginCheck.Security.DirectDB.UnescapedDBParameter -- Checked via SHOW TABLES
            $create = $wpdb->get_row("SHOW CREATE TABLE `{$table}`", ARRAY_A);
            // phpcs:enable
            if ($create && isset($create['Create Table'])) {
                $sql .= "DROP TABLE IF EXISTS `{$table}`;\n";
                $sql .= $create['Create Table'] . ";\n\n";
            }
        }

        file_put_contents($filepath, $sql);
        return $filepath;
    }

    public function getTables(): array
    {
        return $this->tables;
    }

    public function getTableCount(): int
    {
        return count($this->tables);
    }

    public function getTotalRows(): int
    {
        return array_sum(array_column($this->tables, 'rows'));
    }

    /**
     * Resume pointer'dan tablo listesini geri yükler
     */
    public function setTables(array $tables): void
    {
        $this->tables = $tables;
    }
}