<?php

namespace App\Module\Cleanup\Logics;

use App\Module\Cleanup\Models\CleanupBackup;
use App\Module\Cleanup\Models\CleanupBackupFile;
use App\Module\Cleanup\Models\CleanupSqlBackup;
use App\Module\Cleanup\Models\CleanupPlan;
use App\Module\Cleanup\Models\CleanupTask;
use App\Module\Cleanup\Enums\BACKUP_TYPE;
use App\Module\Cleanup\Enums\BACKUP_STATUS;
use App\Module\Cleanup\Enums\COMPRESSION_TYPE;
use Illuminate\Support\Facades\DB;
use Illuminate\Support\Facades\Log;
use Illuminate\Support\Facades\Storage;
use Illuminate\Support\Str;

/**
 * 备份管理逻辑类
 * 
 * 负责数据备份和恢复功能
 */
class BackupLogic
{
    /**
     * 为计划创建数据备份
     *
     * @param int $planId 计划ID
     * @param array $backupOptions 备份选项
     * @return array 备份结果
     */
    public static function createPlanBackup(int $planId, array $backupOptions = []): array
    {
        try {
            $plan = CleanupPlan::with('contents')->findOrFail($planId);
            
            // 验证备份选项
            $validatedOptions = static::validateBackupOptions($backupOptions);
            
            // 创建备份记录
            $backup = CleanupBackup::create([
                'backup_name' => $validatedOptions['backup_name'] ?? "计划备份 - {$plan->plan_name}",
                'plan_id' => $planId,
                'backup_type' => $validatedOptions['backup_type'],
                'compression_type' => $validatedOptions['compression_type'],
                'status' => BACKUP_STATUS::PENDING->value,
                'file_count' => 0,
                'backup_size' => 0,
                'created_by' => $validatedOptions['created_by'] ?? 0,
            ]);

            // 执行备份
            $result = static::performBackup($backup, $plan->contents->where('backup_enabled', true));
            
            return $result;

        } catch (\Exception $e) {
            Log::error('创建计划备份失败', [
                'plan_id' => $planId,
                'backup_options' => $backupOptions,
                'error' => $e->getMessage(),
                'trace' => $e->getTraceAsString()
            ]);

            return [
                'success' => false,
                'message' => '创建计划备份失败: ' . $e->getMessage(),
                'data' => null
            ];
        }
    }

    /**
     * 为任务创建数据备份
     *
     * @param int $taskId 任务ID
     * @param array $backupOptions 备份选项
     * @return array 备份结果
     */
    public static function createTaskBackup(int $taskId, array $backupOptions = []): array
    {
        try {
            $task = CleanupTask::with('plan.contents')->findOrFail($taskId);
            
            if (!$task->plan) {
                throw new \Exception('任务关联的计划不存在');
            }

            // 验证备份选项
            $validatedOptions = static::validateBackupOptions($backupOptions);
            
            // 创建备份记录
            $backup = CleanupBackup::create([
                'backup_name' => $validatedOptions['backup_name'] ?? "任务备份 - {$task->task_name}",
                'task_id' => $taskId,
                'plan_id' => $task->plan_id,
                'backup_type' => $validatedOptions['backup_type'],
                'compression_type' => $validatedOptions['compression_type'],
                'status' => BACKUP_STATUS::PENDING->value,
                'file_count' => 0,
                'backup_size' => 0,
                'created_by' => $validatedOptions['created_by'] ?? 0,
            ]);

            // 更新任务的备份ID
            $task->update(['backup_id' => $backup->id]);

            // 执行备份
            $result = static::performBackup($backup, $task->plan->contents->where('backup_enabled', true));
            
            return $result;

        } catch (\Exception $e) {
            Log::error('创建任务备份失败', [
                'task_id' => $taskId,
                'backup_options' => $backupOptions,
                'error' => $e->getMessage(),
                'trace' => $e->getTraceAsString()
            ]);

            return [
                'success' => false,
                'message' => '创建任务备份失败: ' . $e->getMessage(),
                'data' => null
            ];
        }
    }

    /**
     * 执行备份操作
     *
     * @param CleanupBackup $backup 备份记录
     * @param \Illuminate\Support\Collection $contents 内容集合
     * @return array 备份结果
     */
    private static function performBackup(CleanupBackup $backup, $contents): array
    {
        $startTime = microtime(true);
        $totalSize = 0;
        $fileCount = 0;
        $errors = [];

        try {
            // 更新备份状态为进行中
            $backup->update([
                'status' => BACKUP_STATUS::RUNNING->value,
                'started_at' => now(),
            ]);

            $backupType = BACKUP_TYPE::from($backup->backup_type);
            $compressionType = COMPRESSION_TYPE::from($backup->compression_type);

            foreach ($contents as $content) {
                try {
                    $result = static::backupTable($backup, $content->table_name, $backupType, $compressionType);
                    
                    if ($result['success']) {
                        $totalSize += $result['file_size'];
                        $fileCount++;
                    } else {
                        $errors[] = "表 {$content->table_name}: " . $result['message'];
                    }

                } catch (\Exception $e) {
                    $errors[] = "表 {$content->table_name}: " . $e->getMessage();
                    Log::error("备份表失败", [
                        'backup_id' => $backup->id,
                        'table_name' => $content->table_name,
                        'error' => $e->getMessage()
                    ]);
                }
            }

            $executionTime = round(microtime(true) - $startTime, 3);

            // 更新备份完成状态
            $finalStatus = empty($errors) ? BACKUP_STATUS::COMPLETED : BACKUP_STATUS::FAILED;
            $backup->update([
                'status' => $finalStatus->value,
                'file_count' => $fileCount,
                'backup_size' => $totalSize,
                'execution_time' => $executionTime,
                'completed_at' => now(),
                'error_message' => empty($errors) ? null : implode('; ', $errors),
            ]);

            return [
                'success' => $finalStatus === BACKUP_STATUS::COMPLETED,
                'message' => $finalStatus === BACKUP_STATUS::COMPLETED ? '备份创建成功' : '备份创建完成，但有错误',
                'data' => [
                    'backup_id' => $backup->id,
                    'backup_name' => $backup->backup_name,
                    'file_count' => $fileCount,
                    'backup_size' => $totalSize,
                    'execution_time' => $executionTime,
                    'errors' => $errors,
                ]
            ];

        } catch (\Exception $e) {
            // 更新备份失败状态
            $backup->update([
                'status' => BACKUP_STATUS::FAILED->value,
                'execution_time' => round(microtime(true) - $startTime, 3),
                'completed_at' => now(),
                'error_message' => $e->getMessage(),
            ]);

            throw $e;
        }
    }

    /**
     * 备份单个表
     *
     * @param CleanupBackup $backup 备份记录
     * @param string $tableName 表名
     * @param BACKUP_TYPE $backupType 备份类型
     * @param COMPRESSION_TYPE $compressionType 压缩类型
     * @return array 备份结果
     */
    private static function backupTable(CleanupBackup $backup, string $tableName, BACKUP_TYPE $backupType, COMPRESSION_TYPE $compressionType): array
    {
        try {
            // 数据库备份类型直接存储到数据库
            if ($backupType === BACKUP_TYPE::DATABASE) {
                return static::backupTableToDatabase($backup, $tableName);
            }

            // 生成备份文件名
            $fileName = static::generateBackupFileName($backup, $tableName, $backupType);
            $filePath = "cleanup/backups/{$backup->id}/{$fileName}";

            // 根据备份类型执行备份
            $content = match ($backupType) {
                BACKUP_TYPE::SQL => static::exportTableToSQL($tableName),
                BACKUP_TYPE::JSON => static::exportTableToJSON($tableName),
                BACKUP_TYPE::CSV => static::exportTableToCSV($tableName),
            };

            // 压缩内容（如果需要）
            if ($compressionType !== COMPRESSION_TYPE::NONE) {
                $content = static::compressContent($content, $compressionType);
                $fileName .= static::getCompressionExtension($compressionType);
                $filePath .= static::getCompressionExtension($compressionType);
            }

            // 保存文件
            Storage::disk('local')->put($filePath, $content);
            $fileSize = Storage::disk('local')->size($filePath);

            // 计算文件哈希
            $fileHash = hash('sha256', $content);

            // 记录备份文件
            CleanupBackupFile::create([
                'backup_id' => $backup->id,
                'table_name' => $tableName,
                'file_name' => $fileName,
                'file_path' => $filePath,
                'file_size' => $fileSize,
                'file_hash' => $fileHash,
                'backup_type' => $backupType->value,
                'compression_type' => $compressionType->value,
            ]);

            return [
                'success' => true,
                'message' => "表 {$tableName} 备份成功",
                'file_size' => $fileSize,
                'file_path' => $filePath,
            ];

        } catch (\Exception $e) {
            return [
                'success' => false,
                'message' => $e->getMessage(),
                'file_size' => 0,
            ];
        }
    }

    /**
     * 导出表为SQL格式
     *
     * @param string $tableName 表名
     * @return string SQL内容
     */
    private static function exportTableToSQL(string $tableName): string
    {
        $sql = "-- 表 {$tableName} 的数据备份\n";
        $sql .= "-- 备份时间: " . now()->toDateTimeString() . "\n\n";

        // 获取表结构
        $createTable = DB::select("SHOW CREATE TABLE `{$tableName}`")[0];
        $sql .= $createTable->{'Create Table'} . ";\n\n";

        // 获取表数据
        $records = DB::table($tableName)->get();
        
        if ($records->isNotEmpty()) {
            $sql .= "-- 数据插入\n";
            $sql .= "INSERT INTO `{$tableName}` VALUES\n";
            
            $values = [];
            foreach ($records as $record) {
                $recordArray = (array) $record;
                $escapedValues = array_map(function ($value) {
                    return $value === null ? 'NULL' : "'" . addslashes($value) . "'";
                }, $recordArray);
                $values[] = '(' . implode(', ', $escapedValues) . ')';
            }
            
            $sql .= implode(",\n", $values) . ";\n";
        }

        return $sql;
    }

    /**
     * 导出表为JSON格式
     *
     * @param string $tableName 表名
     * @return string JSON内容
     */
    private static function exportTableToJSON(string $tableName): string
    {
        $data = [
            'table_name' => $tableName,
            'backup_time' => now()->toDateTimeString(),
            'records' => DB::table($tableName)->get()->toArray(),
        ];

        return json_encode($data, JSON_PRETTY_PRINT | JSON_UNESCAPED_UNICODE);
    }

    /**
     * 导出表为CSV格式
     *
     * @param string $tableName 表名
     * @return string CSV内容
     */
    private static function exportTableToCSV(string $tableName): string
    {
        $records = DB::table($tableName)->get();
        
        if ($records->isEmpty()) {
            return '';
        }

        $csv = '';
        $headers = array_keys((array) $records->first());
        $csv .= implode(',', $headers) . "\n";

        foreach ($records as $record) {
            $recordArray = (array) $record;
            $escapedValues = array_map(function ($value) {
                return '"' . str_replace('"', '""', $value ?? '') . '"';
            }, $recordArray);
            $csv .= implode(',', $escapedValues) . "\n";
        }

        return $csv;
    }

    /**
     * 备份表到数据库
     *
     * @param CleanupBackup $backup 备份记录
     * @param string $tableName 表名
     * @return array 备份结果
     */
    private static function backupTableToDatabase(CleanupBackup $backup, string $tableName): array
    {
        try {
            // 获取表数据
            $records = DB::table($tableName)->get();

            if ($records->isEmpty()) {
                // 即使没有数据也创建记录，记录表结构
                $sqlContent = "-- 表 {$tableName} 的数据备份\n";
                $sqlContent .= "-- 备份时间: " . now()->toDateTimeString() . "\n";
                $sqlContent .= "-- 该表无数据记录\n\n";

                // 获取表结构
                $createTable = DB::select("SHOW CREATE TABLE `{$tableName}`")[0];
                $sqlContent .= $createTable->{'Create Table'} . ";\n";

                $recordsCount = 0;
            } else {
                // 生成INSERT语句
                $sqlContent = static::generateInsertStatements($tableName, $records);
                $recordsCount = $records->count();
            }

            $contentSize = strlen($sqlContent);
            $contentHash = hash('sha256', $sqlContent);

            // 保存到数据库
            CleanupSqlBackup::create([
                'backup_id' => $backup->id,
                'table_name' => $tableName,
                'sql_content' => $sqlContent,
                'records_count' => $recordsCount,
                'content_size' => $contentSize,
                'content_hash' => $contentHash,
                'backup_conditions' => null, // 暂时不支持条件备份
            ]);

            return [
                'success' => true,
                'message' => "表 {$tableName} 数据库备份成功",
                'file_size' => $contentSize, // 用内容大小代替文件大小
                'records_count' => $recordsCount,
            ];

        } catch (\Exception $e) {
            return [
                'success' => false,
                'message' => $e->getMessage(),
                'file_size' => 0,
                'records_count' => 0,
            ];
        }
    }

    /**
     * 生成INSERT语句
     *
     * @param string $tableName 表名
     * @param \Illuminate\Support\Collection $records 记录集合
     * @return string SQL内容
     */
    private static function generateInsertStatements(string $tableName, $records): string
    {
        $sql = "-- 表 {$tableName} 的数据备份\n";
        $sql .= "-- 备份时间: " . now()->toDateTimeString() . "\n";
        $sql .= "-- 记录数量: " . $records->count() . "\n\n";

        // 获取表结构
        $createTable = DB::select("SHOW CREATE TABLE `{$tableName}`")[0];
        $sql .= $createTable->{'Create Table'} . ";\n\n";

        // 生成INSERT语句
        if ($records->isNotEmpty()) {
            $sql .= "-- 数据插入\n";

            // 获取字段名
            $firstRecord = (array) $records->first();
            $columns = array_keys($firstRecord);
            $columnList = '`' . implode('`, `', $columns) . '`';

            $sql .= "INSERT INTO `{$tableName}` ({$columnList}) VALUES\n";

            $values = [];
            foreach ($records as $record) {
                $recordArray = (array) $record;
                $escapedValues = array_map(function ($value) {
                    if ($value === null) {
                        return 'NULL';
                    } elseif (is_numeric($value)) {
                        return $value;
                    } else {
                        return "'" . addslashes($value) . "'";
                    }
                }, $recordArray);
                $values[] = '(' . implode(', ', $escapedValues) . ')';
            }

            $sql .= implode(",\n", $values) . ";\n";
        }

        return $sql;
    }

    /**
     * 压缩内容
     *
     * @param string $content 原始内容
     * @param COMPRESSION_TYPE $compressionType 压缩类型
     * @return string 压缩后的内容
     */
    private static function compressContent(string $content, COMPRESSION_TYPE $compressionType): string
    {
        return match ($compressionType) {
            COMPRESSION_TYPE::GZIP => gzencode($content),
            COMPRESSION_TYPE::ZIP => static::createZipContent($content),
            default => $content,
        };
    }

    /**
     * 创建ZIP内容
     *
     * @param string $content 原始内容
     * @return string ZIP内容
     */
    private static function createZipContent(string $content): string
    {
        $zip = new \ZipArchive();
        $tempFile = tempnam(sys_get_temp_dir(), 'backup_');
        
        if ($zip->open($tempFile, \ZipArchive::CREATE) === TRUE) {
            $zip->addFromString('data.sql', $content);
            $zip->close();
            
            $zipContent = file_get_contents($tempFile);
            unlink($tempFile);
            
            return $zipContent;
        }
        
        throw new \Exception('创建ZIP文件失败');
    }

    /**
     * 获取压缩扩展名
     *
     * @param COMPRESSION_TYPE $compressionType 压缩类型
     * @return string 扩展名
     */
    private static function getCompressionExtension(COMPRESSION_TYPE $compressionType): string
    {
        return match ($compressionType) {
            COMPRESSION_TYPE::GZIP => '.gz',
            COMPRESSION_TYPE::ZIP => '.zip',
            default => '',
        };
    }

    /**
     * 生成备份文件名
     *
     * @param CleanupBackup $backup 备份记录
     * @param string $tableName 表名
     * @param BACKUP_TYPE $backupType 备份类型
     * @return string 文件名
     */
    private static function generateBackupFileName(CleanupBackup $backup, string $tableName, BACKUP_TYPE $backupType): string
    {
        $timestamp = now()->format('Y-m-d_H-i-s');
        $extension = match ($backupType) {
            BACKUP_TYPE::SQL => '.sql',
            BACKUP_TYPE::JSON => '.json',
            BACKUP_TYPE::CSV => '.csv',
        };
        
        return "{$tableName}_{$timestamp}{$extension}";
    }

    /**
     * 验证备份选项
     *
     * @param array $backupOptions 备份选项
     * @return array 验证后的选项
     */
    private static function validateBackupOptions(array $backupOptions): array
    {
        return [
            'backup_name' => $backupOptions['backup_name'] ?? null,
            'backup_type' => $backupOptions['backup_type'] ?? BACKUP_TYPE::SQL->value,
            'compression_type' => $backupOptions['compression_type'] ?? COMPRESSION_TYPE::GZIP->value,
            'created_by' => $backupOptions['created_by'] ?? 0,
        ];
    }

    /**
     * 清理过期备份
     *
     * @param int $retentionDays 保留天数
     * @return array 清理结果
     */
    public static function cleanExpiredBackups(int $retentionDays = 30): array
    {
        try {
            $expiredDate = now()->subDays($retentionDays);

            // 获取过期的备份
            $expiredBackups = CleanupBackup::where('created_at', '<', $expiredDate)
                ->where('status', BACKUP_STATUS::COMPLETED->value)
                ->get();

            $deletedCount = 0;
            $freedSpace = 0;
            $errors = [];

            foreach ($expiredBackups as $backup) {
                try {
                    $result = static::deleteBackup($backup->id);
                    if ($result['success']) {
                        $deletedCount++;
                        $freedSpace += $backup->backup_size;
                    } else {
                        $errors[] = "备份 {$backup->id}: " . $result['message'];
                    }
                } catch (\Exception $e) {
                    $errors[] = "备份 {$backup->id}: " . $e->getMessage();
                }
            }

            return [
                'success' => true,
                'message' => "清理完成，删除 {$deletedCount} 个过期备份",
                'data' => [
                    'deleted_count' => $deletedCount,
                    'total_expired' => $expiredBackups->count(),
                    'freed_space' => $freedSpace,
                    'errors' => $errors,
                ]
            ];

        } catch (\Exception $e) {
            Log::error('清理过期备份失败', [
                'retention_days' => $retentionDays,
                'error' => $e->getMessage()
            ]);

            return [
                'success' => false,
                'message' => '清理过期备份失败: ' . $e->getMessage(),
                'data' => null
            ];
        }
    }

    /**
     * 删除备份
     *
     * @param int $backupId 备份ID
     * @return array 删除结果
     */
    public static function deleteBackup(int $backupId): array
    {
        try {
            DB::beginTransaction();

            $backup = CleanupBackup::with(['files', 'sqlBackups'])->findOrFail($backupId);

            // 删除备份文件
            foreach ($backup->files as $file) {
                try {
                    if (Storage::disk('local')->exists($file->file_path)) {
                        Storage::disk('local')->delete($file->file_path);
                    }
                } catch (\Exception $e) {
                    Log::warning('删除备份文件失败', [
                        'file_path' => $file->file_path,
                        'error' => $e->getMessage()
                    ]);
                }
            }

            // 删除备份文件记录
            $backup->files()->delete();

            // 删除SQL备份记录
            $backup->sqlBackups()->delete();

            // 删除备份记录
            $backup->delete();

            DB::commit();

            return [
                'success' => true,
                'message' => '备份删除成功',
                'data' => [
                    'backup_id' => $backupId,
                    'deleted_files' => $backup->files->count(),
                ]
            ];

        } catch (\Exception $e) {
            DB::rollBack();
            Log::error('删除备份失败', [
                'backup_id' => $backupId,
                'error' => $e->getMessage()
            ]);

            return [
                'success' => false,
                'message' => '删除备份失败: ' . $e->getMessage(),
                'data' => null
            ];
        }
    }

    /**
     * 获取备份详情
     *
     * @param int $backupId 备份ID
     * @return array 备份详情
     */
    public static function getBackupDetails(int $backupId): array
    {
        try {
            $backup = CleanupBackup::with(['files', 'plan', 'task'])->findOrFail($backupId);

            return [
                'success' => true,
                'data' => [
                    'backup' => [
                        'id' => $backup->id,
                        'backup_name' => $backup->backup_name,
                        'backup_type' => $backup->backup_type,
                        'backup_type_name' => BACKUP_TYPE::from($backup->backup_type)->getDescription(),
                        'compression_type' => $backup->compression_type,
                        'compression_type_name' => COMPRESSION_TYPE::from($backup->compression_type)->getDescription(),
                        'status' => $backup->status,
                        'status_name' => BACKUP_STATUS::from($backup->status)->getDescription(),
                        'file_count' => $backup->file_count,
                        'backup_size' => $backup->backup_size,
                        'execution_time' => $backup->execution_time,
                        'started_at' => $backup->started_at,
                        'completed_at' => $backup->completed_at,
                        'error_message' => $backup->error_message,
                        'created_at' => $backup->created_at,
                    ],
                    'files' => $backup->files->map(function ($file) {
                        return [
                            'id' => $file->id,
                            'table_name' => $file->table_name,
                            'file_name' => $file->file_name,
                            'file_size' => $file->file_size,
                            'file_hash' => $file->file_hash,
                            'backup_type' => $file->backup_type,
                            'compression_type' => $file->compression_type,
                        ];
                    }),
                    'plan' => $backup->plan ? [
                        'id' => $backup->plan->id,
                        'plan_name' => $backup->plan->plan_name,
                    ] : null,
                    'task' => $backup->task ? [
                        'id' => $backup->task->id,
                        'task_name' => $backup->task->task_name,
                    ] : null,
                ]
            ];

        } catch (\Exception $e) {
            Log::error('获取备份详情失败', [
                'backup_id' => $backupId,
                'error' => $e->getMessage()
            ]);

            return [
                'success' => false,
                'message' => '获取备份详情失败: ' . $e->getMessage(),
                'data' => null
            ];
        }
    }

    /**
     * 验证备份完整性
     *
     * @param int $backupId 备份ID
     * @return array 验证结果
     */
    public static function verifyBackupIntegrity(int $backupId): array
    {
        try {
            $backup = CleanupBackup::with('files')->findOrFail($backupId);

            $verifiedFiles = 0;
            $corruptedFiles = 0;
            $missingFiles = 0;
            $errors = [];

            foreach ($backup->files as $file) {
                try {
                    if (!Storage::disk('local')->exists($file->file_path)) {
                        $missingFiles++;
                        $errors[] = "文件缺失: {$file->file_name}";
                        continue;
                    }

                    $content = Storage::disk('local')->get($file->file_path);
                    $currentHash = hash('sha256', $content);

                    if ($currentHash === $file->file_hash) {
                        $verifiedFiles++;
                    } else {
                        $corruptedFiles++;
                        $errors[] = "文件损坏: {$file->file_name}";
                    }

                } catch (\Exception $e) {
                    $errors[] = "验证失败: {$file->file_name} - " . $e->getMessage();
                }
            }

            $isIntact = $corruptedFiles === 0 && $missingFiles === 0;

            return [
                'success' => true,
                'data' => [
                    'backup_id' => $backupId,
                    'is_intact' => $isIntact,
                    'total_files' => $backup->files->count(),
                    'verified_files' => $verifiedFiles,
                    'corrupted_files' => $corruptedFiles,
                    'missing_files' => $missingFiles,
                    'errors' => $errors,
                ]
            ];

        } catch (\Exception $e) {
            Log::error('验证备份完整性失败', [
                'backup_id' => $backupId,
                'error' => $e->getMessage()
            ]);

            return [
                'success' => false,
                'message' => '验证备份完整性失败: ' . $e->getMessage(),
                'data' => null
            ];
        }
    }
}