package service

import (
	"bytes"
	"context"
	"crypto/hmac"
	"crypto/sha1"
	"encoding/base64"
	"fmt"
	"net/url"
	"path/filepath"
	"strings"
	"time"

	"gen2d/internal/config"
	"gen2d/internal/logger"

	"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) {
	l := logger.FromCtx(ctx)

	putPolicy, err := uptoken.NewPutPolicy(s.bucket, time.Now().Add(1*time.Hour))
	if err != nil {
		l.Error("qiniu put policy failed", "key", key, "error", err)
		return "", fmt.Errorf("qiniu put policy: %w", err)
	}
	upToken := uptoken.NewSigner(putPolicy, s.creds)

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

	l.Info("uploading to qiniu", "key", key, "size", len(data))
	err = uploadMgr.UploadReader(ctx, bytes.NewReader(data), &uploader.ObjectOptions{
		BucketName: s.bucket,
		ObjectName: &key,
		FileName:   filepath.Base(key),
	}, nil)
	if err != nil {
		l.Error("qiniu upload failed", "key", key, "error", err)
		return "", fmt.Errorf("qiniu upload: %w", err)
	}

	cdnURL := s.buildBaseURL(key)
	l.Info("upload succeeded", "key", key, "url", cdnURL)
	return cdnURL, nil
}

// GetDownloadURL 生成素材的下载 URL。
// 私有 bucket 生成带签名和过期时间的临时 URL。
func (s *StorageService) GetDownloadURL(_ context.Context, key string) (string, error) {
	return s.signDownloadURL(key), nil
}

// GetSignedURL 获取私有资源签名 URL（公开方法，供 handler 层使用）。
func (s *StorageService) GetSignedURL(key string) string {
	return s.signDownloadURL(key)
}

// signDownloadURL 生成七牛云私有资源下载签名 URL。
// 格式：http://<domain>/<key>?e=<deadline>&token=<downloadToken>
func (s *StorageService) signDownloadURL(key string) string {
	baseURL := s.buildBaseURL(key)

	expire := s.cfg.URLExpire
	if expire <= 0 {
		expire = 3600
	}
	deadline := time.Now().Unix() + expire

	signStr := fmt.Sprintf("%s?e=%d", baseURL, deadline)

	mac := hmac.New(sha1.New, []byte(s.cfg.SecretKey))
	mac.Write([]byte(signStr))
	signature := mac.Sum(nil)

	encodedSign := base64.URLEncoding.EncodeToString(signature)
	token := fmt.Sprintf("%s:%s", s.cfg.AccessKey, encodedSign)

	return fmt.Sprintf("%s?e=%d&token=%s", baseURL, deadline, token)
}

// Delete 从七牛云删除指定对象。
func (s *StorageService) Delete(ctx context.Context, key string) error {
	l := logger.FromCtx(ctx)

	bucket := s.objectsMgr.Bucket(s.bucket)
	err := bucket.Object(key).Delete().Call(ctx)
	if err != nil {
		l.Error("qiniu delete failed", "key", key, "error", err)
		return err
	}

	l.Info("delete succeeded", "key", key)
	return nil
}

// buildBaseURL 根据配置构建完整的基础 CDN URL（不含签名参数）。
func (s *StorageService) buildBaseURL(key string) string {
	host := strings.TrimRight(s.cfg.CDNHost, "/")
	scheme := "http"
	if s.cfg.UseHTTPS {
		scheme = "https"
	}
	// 如果 host 已经包含 scheme，直接使用；否则添加
	if !strings.HasPrefix(host, "http://") && !strings.HasPrefix(host, "https://") {
		host = scheme + "://" + host
	}
	segments := strings.Split(key, "/")
	for i, seg := range segments {
		segments[i] = url.PathEscape(seg)
	}
	return fmt.Sprintf("%s/%s", host, strings.Join(segments, "/"))
}