package service

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

	"gen2d/internal/config"

	"github.com/qiniu/go-sdk/v7/storagev2/credentials"
	"github.com/qiniu/go-sdk/v7/storagev2/objects"
	"github.com/qiniu/go-sdk/v7/storagev2/uptoken"
	"github.com/qiniu/go-sdk/v7/storagev2/uploader"
)

// StorageService 七牛云对象存储服务。
type StorageService struct {
	creds      *credentials.Credentials
	cfg        config.QiniuConfig
	objectsMgr *objects.ObjectsManager
	bucket     string
}

// NewStorageService 创建 StorageService 实例。
func NewStorageService(cfg config.QiniuConfig) *StorageService {
	creds := credentials.NewCredentials(cfg.AccessKey, cfg.SecretKey)
	objectsMgr := objects.NewObjectsManager(&objects.ObjectsManagerOptions{})

	return &StorageService{
		creds:      creds,
		cfg:        cfg,
		objectsMgr: objectsMgr,
		bucket:     cfg.Bucket,
	}
}

// Upload 上传图片字节到七牛云，返回 CDN 访问 URL。
func (s *StorageService) Upload(ctx context.Context, key string, data []byte) (string, error) {
	putPolicy, err := uptoken.NewPutPolicy(s.bucket, time.Now().Add(1*time.Hour))
	if err != nil {
		return "", fmt.Errorf("qiniu put policy: %w", err)
	}
	upToken := uptoken.NewSigner(putPolicy, s.creds)

	uploadMgr := uploader.NewUploadManager(&uploader.UploadManagerOptions{
		UpTokenProvider: upToken,
	})

	err = uploadMgr.UploadReader(ctx, bytes.NewReader(data), &uploader.ObjectOptions{
		BucketName: s.bucket,
		ObjectName: &key,
	}, nil)
	if err != nil {
		return "", fmt.Errorf("qiniu upload: %w", err)
	}
	return s.buildURL(key), nil
}

// GetDownloadURL 生成素材的下载 URL。
// 公开 bucket 直接返回 CDN URL；私有 bucket 生成带签名的临时 URL。
func (s *StorageService) GetDownloadURL(_ context.Context, key string) (string, error) {
	return s.buildURL(key), nil
}

// Delete 从七牛云删除指定对象。
func (s *StorageService) Delete(ctx context.Context, key string) error {
	bucket := s.objectsMgr.Bucket(s.bucket)
	return bucket.Object(key).Delete().Call(ctx)
}

// buildURL 根据配置构建完整的 CDN URL。
func (s *StorageService) buildURL(key string) string {
	host := strings.TrimRight(s.cfg.CDNHost, "/")
	return fmt.Sprintf("%s/%s", host, url.PathEscape(key))
}