init: 提交 files 服务初始代码

Co-authored-by: Cursor <cursoragent@cursor.com>

internal/storage/presign.go

@@ -0,0 +1,43 @@
+package storage
+
+import (
+	"context"
+	"fmt"
+	"strings"
+	"time"
+
+	"github.com/aliyun/alibabacloud-oss-go-sdk-v2/oss"
+)
+
+type UploadInstruction struct {
+	Method    string            `json:"method"`
+	URL       string            `json:"url"`
+	Headers   map[string]string `json:"headers"`
+	ExpiresAt time.Time         `json:"expires_at"`
+}
+
+func (c *Client) PresignPut(ctx context.Context, objectKey, contentType string) (UploadInstruction, error) {
+	if strings.TrimSpace(objectKey) == "" {
+		return UploadInstruction{}, fmt.Errorf("对象键不能为空")
+	}
+	if strings.TrimSpace(contentType) == "" {
+		return UploadInstruction{}, fmt.Errorf("内容类型不能为空")
+	}
+
+	result, err := c.client.Presign(ctx, &oss.PutObjectRequest{
+		Bucket:          oss.Ptr(c.bucket),
+		Key:             oss.Ptr(objectKey),
+		ContentType:     oss.Ptr(contentType),
+		ForbidOverwrite: oss.Ptr("true"),
+	}, oss.PresignExpires(c.presignTTL))
+	if err != nil {
+		return UploadInstruction{}, fmt.Errorf("生成上传预签名: %w", err)
+	}
+
+	return UploadInstruction{
+		Method:    result.Method,
+		URL:       result.URL,
+		Headers:   result.SignedHeaders,
+		ExpiresAt: result.Expiration,
+	}, nil
+}