package audit

import (
	"context"
	"fmt"
	"io"
	"os"
	"path/filepath"
	"sync/atomic"
	"time"

	"github.com/minio/minio-go/v7"
	"github.com/minio/minio-go/v7/pkg/credentials"
)

var (
	minioClient atomic.Value
	// clientSignature caches the config signature of the loaded client so a
	// hot reload that keeps the same endpoint/keys/bucket reuses the client
	// instead of rebuilding it on every request.
	clientSignature atomic.Value
)

// MinioClient wraps a minio client together with the target bucket.
type MinioClient struct {
	Client     *minio.Client
	BucketName string
}

// GetMinioClient atomically reads the global MinioClient (nil if not set).
func GetMinioClient() *MinioClient {
	v := minioClient.Load()
	if v == nil {
		return nil
	}
	return v.(*MinioClient)
}

// SetMinioClient atomically writes the global MinioClient.
func SetMinioClient(c *MinioClient) {
	minioClient.Store(c)
}

// newMinioClient builds a MinioClient and makes sure the bucket exists.
func newMinioClient(endPoint, accessKey, secretKey, bucketName string, useSSl bool) (*MinioClient, error) {
	client, err := minio.New(endPoint, &minio.Options{
		Creds:  credentials.NewStaticV4(accessKey, secretKey, ""),
		Secure: useSSl,
	})
	if err != nil {
		return nil, err
	}

	ctx := context.Background()
	exists, err := client.BucketExists(ctx, bucketName)
	if err != nil {
		return nil, err
	}
	if !exists {
		if err := client.MakeBucket(ctx, bucketName, minio.MakeBucketOptions{}); err != nil {
			return nil, err
		}
	}

	return &MinioClient{
		Client:     client,
		BucketName: bucketName,
	}, nil
}

// ReloadMinioClient rebuilds the global client when the file configuration
// changed. An empty configuration (before t_config has been populated) or a
// failed connection keeps the previously loaded client untouched.
func ReloadMinioClient(fileConfig FileConfigManager) {
	if fileConfig.endpoint == "" || fileConfig.bucket == "" ||
		fileConfig.accessKey == "" || fileConfig.secretKey == "" {
		return
	}

	signature := fmt.Sprintf("%s|%s|%s|%s|%t",
		fileConfig.endpoint, fileConfig.accessKey, fileConfig.secretKey, fileConfig.bucket, fileConfig.useSSL)
	if stored, ok := clientSignature.Load().(string); ok && stored == signature {
		return // configuration unchanged, keep the loaded client
	}

	client, err := newMinioClient(fileConfig.endpoint, fileConfig.accessKey, fileConfig.secretKey, fileConfig.bucket, fileConfig.useSSL)
	if err != nil {
		fmt.Printf("Minio client reload failed: %v, keep previous client\n", err)
		return
	}

	clientSignature.Store(signature)
	SetMinioClient(client)
}

// UploadFile uploads a local file and returns its object key.
func (m *MinioClient) UploadFile(ctx context.Context, localFilePath, objectName string) (string, error) {
	file, err := os.Open(localFilePath)
	if err != nil {
		return "", err
	}
	defer func() {
		_ = file.Close()
	}()

	fileStat, err := file.Stat()
	if err != nil {
		return "", err
	}

	uploadInfo, err := m.Client.PutObject(ctx, m.BucketName, objectName, file, fileStat.Size(), minio.PutObjectOptions{})
	if err != nil {
		return "", err
	}

	return uploadInfo.Key, nil
}

// DownloadFile downloads an object into a local temp file and returns the
// temp file path.
func (m *MinioClient) DownloadFile(ctx context.Context, fileKey string) (string, error) {
	fileName := filepath.Base(fileKey)
	if fileName == "" || fileName == "." || fileName == "/" {
		return "", fmt.Errorf("无效的FileKey:%s", fileKey)
	}

	tmpFile, err := os.CreateTemp("", fmt.Sprintf("log_restore_*_%s", fileName))
	if err != nil {
		return "", fmt.Errorf("创建临时文件失败: %w", err)
	}
	defer func() {
		_ = tmpFile.Close()
	}()

	object, err := m.Client.GetObject(ctx, m.BucketName, fileKey, minio.GetObjectOptions{})
	if err != nil {
		return "", fmt.Errorf("从 MinIO 获取对象失败: %w", err)
	}
	defer object.Close()

	if _, err = io.Copy(tmpFile, object); err != nil {
		return "", fmt.Errorf("写入临时文件失败: %w", err)
	}

	return tmpFile.Name(), nil
}

// GetTempDownloadURL returns a presigned private-bucket download URL.
func (m *MinioClient) GetTempDownloadURL(ctx context.Context, fileKey string, expire int32) (string, error) {
	url, err := m.Client.PresignedGetObject(ctx, m.BucketName, fileKey, time.Duration(expire)*time.Second, nil)
	if err != nil {
		return "", err
	}
	return url.String(), nil
}

// RemoveFile deletes an object from the bucket.
func (m *MinioClient) RemoveFile(ctx context.Context, fileKey string) error {
	if fileKey == "" {
		return fmt.Errorf("无效的FileKey:%s", fileKey)
	}
	if err := m.Client.RemoveObject(ctx, m.BucketName, fileKey, minio.RemoveObjectOptions{}); err != nil {
		return fmt.Errorf("remove object failed: %w", err)
	}
	return nil
}