wip: file download

internal/api/api.go

@@ -34,6 +34,8 @@ func Init(ctx context.Context) error {
 	register("/api/bucket/files", handler.BucketFiles)
 	register("/api/bucket/create", handler.BucketCreate)
 	register("/api/file/upload", handler.FileUpload)
+	register("/api/file/info", handler.FileInfo)
+	register("/api/file/get", handler.FileGet)
 
 	return nil
 }

internal/handler/file.go

@@ -86,3 +86,61 @@ func FileUpload(c *ndh.Ctx) error {
 
 	return c.Send200(req)
 }
+
+func FileInfo(c *ndh.Ctx) error {
+	type Req struct {
+		ConnId uint64 `json:"conn_id"`
+		Bucket string `json:"bucket"`
+		Key    string `json:"key"`
+	}
+
+	var (
+		err    error
+		req    = new(Req)
+		client *s3.Client
+		info   *s3.ObjectInfo
+	)
+
+	if err = c.ReqParse(req); err != nil {
+		return c.Send400(err.Error())
+	}
+
+	if _, client, err = manager.Manager.Use(req.ConnId); err != nil {
+		return c.Send500(err.Error())
+	}
+
+	if info, err = client.GetObjectInfo(c.Context(), req.Bucket, req.Key); err != nil {
+		return c.Send500(err.Error())
+	}
+
+	return c.Send200(info)
+}
+
+func FileGet(c *ndh.Ctx) error {
+	type Req struct {
+		ConnId uint64 `json:"conn_id"`
+		Bucket string `json:"bucket"`
+		Key    string `json:"key"`
+	}
+
+	var (
+		err    error
+		req    = new(Req)
+		client *s3.Client
+		link   *s3.ObjectEntry
+	)
+
+	if err = c.ReqParse(req); err != nil {
+		return c.Send400(err.Error())
+	}
+
+	if _, client, err = manager.Manager.Use(req.ConnId); err != nil {
+		return c.Send500(err.Error())
+	}
+
+	if link, err = client.GetObject(c.Context(), req.Bucket, req.Key); err != nil {
+		return c.Send500(err.Error())
+	}
+
+	return c.Send200(link)
+}

internal/s3/get.go

@@ -0,0 +1,90 @@
+package s3
+
+import (
+	"context"
+	"github.com/aws/aws-sdk-go-v2/aws"
+	v4 "github.com/aws/aws-sdk-go-v2/aws/signer/v4"
+	"github.com/aws/aws-sdk-go-v2/service/s3"
+	"github.com/labstack/gommon/log"
+	"net/http"
+	"time"
+)
+
+type ObjectInfo struct {
+	Bucket      string
+	Key         string
+	ContentType string
+	Expire      int64
+}
+
+func (c *Client) GetObjectInfo(ctx context.Context, bucket string, key string) (*ObjectInfo, error) {
+	var (
+		err   error
+		input = &s3.HeadObjectInput{
+			Bucket: aws.String(bucket),
+			Key:    aws.String(key),
+		}
+		output *s3.HeadObjectOutput
+	)
+
+	if output, err = c.client.HeadObject(ctx, input); err != nil {
+		return nil, err
+	}
+
+	return &ObjectInfo{
+		Bucket:      bucket,
+		Key:         key,
+		ContentType: aws.ToString(output.ContentType),
+		Expire:      aws.ToTime(output.Expires).UnixMilli(),
+	}, nil
+}
+
+// GetObject
+// https://docs.aws.amazon.com/AmazonS3/latest/userguide/example_s3_Scenario_PresignedUrl_section.html
+
+type Presigner struct {
+	PresignClient *s3.PresignClient
+}
+
+func (presigner *Presigner) GetObject(ctx context.Context, bucketName string, objectKey string, lifetimeSecs int64) (*v4.PresignedHTTPRequest, error) {
+	request, err := presigner.PresignClient.PresignGetObject(ctx, &s3.GetObjectInput{
+		Bucket: aws.String(bucketName),
+		Key:    aws.String(objectKey),
+	}, func(opts *s3.PresignOptions) {
+		opts.Expires = time.Duration(lifetimeSecs * int64(time.Second))
+	})
+	if err != nil {
+		log.Error("Presigner: couldn't get a presigned request to get %v:%v. Here's why: %v\n",
+			bucketName, objectKey, err)
+	}
+	return request, err
+}
+
+type ObjectEntry struct {
+	URL    string
+	Method string
+	Header http.Header
+}
+
+func (c *Client) GetObject(ctx context.Context, bucket string, key string, lifetimes ...int64) (*ObjectEntry, error) {
+	var (
+		err      error
+		lifetime int64 = 5 * 60
+		pc             = &Presigner{PresignClient: s3.NewPresignClient(c.client)}
+		output   *v4.PresignedHTTPRequest
+	)
+
+	if len(lifetimes) > 0 && lifetimes[0] > 0 {
+		lifetime = lifetimes[0]
+	}
+
+	if output, err = pc.GetObject(ctx, bucket, key, lifetime); err != nil {
+		return nil, err
+	}
+
+	return &ObjectEntry{
+		URL:    output.URL,
+		Method: output.Method,
+		Header: output.SignedHeader,
+	}, nil
+}