package services

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

	"github.com/aliyun/alibabacloud-oss-go-sdk-v2/oss"
	"github.com/aliyun/alibabacloud-oss-go-sdk-v2/oss/credentials"

	"git.beifan.cn/trace-system/backend-go/config"
)

// OSSService 封装阿里云 OSS 上传。
type OSSService struct {
	cfg config.OSSConfig
}

func NewOSSService() OSSService {
	return OSSService{cfg: config.GetAppConfig().OSS}
}

func (s OSSService) UploadObject(objectKey string, reader io.Reader, contentType string) error {
	if err := s.validateConfig(); err != nil {
		return err
	}

	request := &oss.PutObjectRequest{
		Bucket: oss.Ptr(s.cfg.Bucket),
		Key:    oss.Ptr(objectKey),
		Body:   reader,
	}
	if contentType != "" {
		request.ContentType = oss.Ptr(contentType)
	}

	if _, err := s.newClient().PutObject(context.TODO(), request); err != nil {
		return fmt.Errorf("上传现场图片失败: %w", err)
	}

	return nil
}

func (s OSSService) validateConfig() error {
	if strings.TrimSpace(s.cfg.Endpoint) == "" ||
		strings.TrimSpace(s.cfg.Bucket) == "" ||
		strings.TrimSpace(s.cfg.AccessKeyID) == "" ||
		strings.TrimSpace(s.cfg.AccessKeySecret) == "" {
		return fmt.Errorf("OSS 配置未完整，请检查 endpoint、bucket、access_key_id、access_key_secret")
	}
	return nil
}

func (s OSSService) publicURL(objectKey string) string {
	if base := strings.TrimRight(strings.TrimSpace(s.cfg.PublicBaseURL), "/"); base != "" {
		return base + "/" + objectKey
	}
	endpoint := normalizeOSSEndpoint(s.cfg.Endpoint)
	u, err := url.Parse(endpoint)
	if err != nil || u.Host == "" {
		return fmt.Sprintf("https://%s.%s/%s", s.cfg.Bucket, strings.TrimPrefix(endpoint, "https://"), objectKey)
	}
	return fmt.Sprintf("%s://%s.%s/%s", u.Scheme, s.cfg.Bucket, u.Host, objectKey)
}

func (s OSSService) AccessURL(objectRef string) string {
	objectKey := s.objectKeyFromRef(objectRef)
	if objectKey == "" {
		return objectRef
	}
	if strings.TrimSpace(s.cfg.PublicBaseURL) != "" {
		return s.publicURL(objectKey)
	}
	url, err := s.SignedURL(objectKey)
	if err != nil {
		return s.publicURL(objectKey)
	}
	return url
}

func (s OSSService) SignedURL(objectKey string) (string, error) {
	if err := s.validateConfig(); err != nil {
		return "", err
	}
	expires := s.cfg.SignedURLExpire
	if expires <= 0 {
		expires = 3600
	}
	result, err := s.newClient().Presign(
		context.TODO(),
		&oss.GetObjectRequest{
			Bucket: oss.Ptr(s.cfg.Bucket),
			Key:    oss.Ptr(objectKey),
		},
		oss.PresignExpires(time.Duration(expires)*time.Second),
	)
	if err != nil {
		return "", fmt.Errorf("生成 OSS 签名 URL 失败: %w", err)
	}
	return result.URL, nil
}

func (s OSSService) objectKeyFromRef(objectRef string) string {
	objectRef = strings.TrimSpace(objectRef)
	if objectRef == "" {
		return ""
	}
	if !strings.HasPrefix(objectRef, "http://") && !strings.HasPrefix(objectRef, "https://") {
		return strings.TrimLeft(objectRef, "/")
	}
	u, err := url.Parse(objectRef)
	if err != nil {
		return ""
	}
	host := strings.ToLower(u.Host)
	bucketHostPrefix := strings.ToLower(s.cfg.Bucket) + "."
	if strings.HasPrefix(host, bucketHostPrefix) {
		return strings.TrimLeft(u.Path, "/")
	}
	if base := strings.TrimSpace(s.cfg.PublicBaseURL); base != "" {
		baseURL, err := url.Parse(base)
		if err == nil && strings.EqualFold(baseURL.Host, u.Host) {
			return strings.TrimLeft(strings.TrimPrefix(u.Path, baseURL.Path), "/")
		}
	}
	return ""
}

func normalizeOSSEndpoint(endpoint string) string {
	endpoint = strings.TrimSpace(endpoint)
	if endpoint == "" {
		return endpoint
	}
	if strings.HasPrefix(endpoint, "http://") || strings.HasPrefix(endpoint, "https://") {
		return endpoint
	}
	return "https://" + endpoint
}

func (s OSSService) newClient() *oss.Client {
	cfg := oss.LoadDefaultConfig().
		WithCredentialsProvider(credentials.NewStaticCredentialsProvider(
			s.cfg.AccessKeyID,
			s.cfg.AccessKeySecret,
		)).
		WithRegion(strings.TrimSpace(s.cfg.Region)).
		WithEndpoint(strings.TrimPrefix(strings.TrimPrefix(normalizeOSSEndpoint(s.cfg.Endpoint), "https://"), "http://"))
	return oss.NewClient(cfg)
}