package storage

import (
	"context"
	"fmt"
	"io"
	"net/url"
	"strings"

	"github.com/minio/minio-go/v7"
	"github.com/minio/minio-go/v7/pkg/credentials"
	"kefu-sys/server/internal/config"
)

// S3Storage 基于 minio-go 的 S3 兼容实现（MinIO / OSS / COS / AWS S3）
type S3Storage struct {
	client *minio.Client
	bucket string
	base   string
}

func NewS3(cfg config.StorageConfig) (*S3Storage, error) {
	endpoint := strings.TrimPrefix(strings.TrimPrefix(cfg.Endpoint, "https://"), "http://")
	client, err := minio.New(endpoint, &minio.Options{
		Creds:  credentials.NewStaticV4(cfg.AccessKey, cfg.SecretKey, ""),
		Secure: cfg.UseSSL,
		Region: cfg.Region,
	})
	if err != nil {
		return nil, fmt.Errorf("init s3 client: %w", err)
	}
	base := NormalizePublicBase(cfg.PublicBase)
	if base == "" {
		scheme := "http"
		if cfg.UseSSL {
			scheme = "https"
		}
		base = fmt.Sprintf("%s://%s/%s", scheme, endpoint, cfg.Bucket)
	}
	return &S3Storage{client: client, bucket: cfg.Bucket, base: base}, nil
}

func (s *S3Storage) HealthCheck(ctx context.Context) error {
	_, err := s.client.BucketExists(ctx, s.bucket)
	return err
}

func (s *S3Storage) EnsureBucket(ctx context.Context) error {
	exists, err := s.client.BucketExists(ctx, s.bucket)
	if err != nil {
		return err
	}
	if !exists {
		if err := s.client.MakeBucket(ctx, s.bucket, minio.MakeBucketOptions{}); err != nil {
			return err
		}
	}
	// 开发环境尽量开放公共读；生产用 CDN/桶策略配置
	policy := fmt.Sprintf(`{
	  "Version":"2012-10-17",
	  "Statement":[{
	    "Effect":"Allow",
	    "Principal":{"AWS":["*"]},
	    "Action":["s3:GetObject"],
	    "Resource":["arn:aws:s3:::%s/*"]
	  }]
	}`, s.bucket)
	_ = s.client.SetBucketPolicy(ctx, s.bucket, policy)
	return nil
}

func (s *S3Storage) Put(ctx context.Context, key string, r io.Reader, size int64, contentType string) (string, error) {
	if contentType == "" {
		contentType = "application/octet-stream"
	}
	_, err := s.client.PutObject(ctx, s.bucket, key, r, size, minio.PutObjectOptions{
		ContentType: contentType,
	})
	if err != nil {
		return "", err
	}
	return s.objectURL(key), nil
}

func (s *S3Storage) Delete(ctx context.Context, key string) error {
	return s.client.RemoveObject(ctx, s.bucket, key, minio.RemoveObjectOptions{})
}

func (s *S3Storage) PublicBase() string { return s.base }

func (s *S3Storage) objectURL(key string) string {
	// PublicBase 形如 http://localhost:9100/kefu（宿主机映射端口）
	return s.base + "/" + strings.TrimPrefix(key, "/")
}

// ParseKeyFromURL 从公网 URL 还原 object key（删除时用）
func (s *S3Storage) ParseKeyFromURL(publicURL string) (string, error) {
	if !strings.HasPrefix(publicURL, s.base+"/") {
		return "", fmt.Errorf("url not in bucket")
	}
	key := strings.TrimPrefix(publicURL, s.base+"/")
	if key == "" {
		return "", fmt.Errorf("empty key")
	}
	if u, err := url.PathUnescape(key); err == nil {
		return u, nil
	}
	return key, nil
}