1 files changed, 129 insertions, 0 deletions
diff --git a/modules/lfs/http_client.go b/modules/lfs/http_client.go
new file mode 100644
index 0000000000..fb45defda1
--- /dev/null
+++ b/modules/lfs/http_client.go
@@ -0,0 +1,129 @@
+// Copyright 2021 The Gitea Authors. All rights reserved.
+// Use of this source code is governed by a MIT-style
+// license that can be found in the LICENSE file.
+
+package lfs
+
+import (
+	"bytes"
+	"context"
+	"encoding/json"
+	"errors"
+	"fmt"
+	"io"
+	"net/http"
+	"net/url"
+	"strings"
+
+	"code.gitea.io/gitea/modules/log"
+)
+
+// HTTPClient is used to communicate with the LFS server
+// https://github.com/git-lfs/git-lfs/blob/main/docs/api/batch.md
+type HTTPClient struct {
+	client    *http.Client
+	endpoint  string
+	transfers map[string]TransferAdapter
+}
+
+func newHTTPClient(endpoint *url.URL) *HTTPClient {
+	hc := &http.Client{}
+
+	client := &HTTPClient{
+		client:    hc,
+		endpoint:  strings.TrimSuffix(endpoint.String(), "/"),
+		transfers: make(map[string]TransferAdapter),
+	}
+
+	basic := &BasicTransferAdapter{hc}
+
+	client.transfers[basic.Name()] = basic
+
+	return client
+}
+
+func (c *HTTPClient) transferNames() []string {
+	keys := make([]string, len(c.transfers))
+
+	i := 0
+	for k := range c.transfers {
+		keys[i] = k
+		i++
+	}
+
+	return keys
+}
+
+func (c *HTTPClient) batch(ctx context.Context, operation string, objects []Pointer) (*BatchResponse, error) {
+	url := fmt.Sprintf("%s/objects/batch", c.endpoint)
+
+	request := &BatchRequest{operation, c.transferNames(), nil, objects}
+
+	payload := new(bytes.Buffer)
+	err := json.NewEncoder(payload).Encode(request)
+	if err != nil {
+		return nil, fmt.Errorf("lfs.HTTPClient.batch json.Encode: %w", err)
+	}
+
+	log.Trace("lfs.HTTPClient.batch NewRequestWithContext: %s", url)
+
+	req, err := http.NewRequestWithContext(ctx, "POST", url, payload)
+	if err != nil {
+		return nil, fmt.Errorf("lfs.HTTPClient.batch http.NewRequestWithContext: %w", err)
+	}
+	req.Header.Set("Content-type", MediaType)
+	req.Header.Set("Accept", MediaType)
+
+	res, err := c.client.Do(req)
+	if err != nil {
+		select {
+		case <-ctx.Done():
+			return nil, ctx.Err()
+		default:
+		}
+		return nil, fmt.Errorf("lfs.HTTPClient.batch http.Do: %w", err)
+	}
+	defer res.Body.Close()
+
+	if res.StatusCode != http.StatusOK {
+		return nil, fmt.Errorf("lfs.HTTPClient.batch: Unexpected servers response: %s", res.Status)
+	}
+
+	var response BatchResponse
+	err = json.NewDecoder(res.Body).Decode(&response)
+	if err != nil {
+		return nil, fmt.Errorf("lfs.HTTPClient.batch json.Decode: %w", err)
+	}
+
+	if len(response.Transfer) == 0 {
+		response.Transfer = "basic"
+	}
+
+	return &response, nil
+}
+
+// Download reads the specific LFS object from the LFS server
+func (c *HTTPClient) Download(ctx context.Context, oid string, size int64) (io.ReadCloser, error) {
+	var objects []Pointer
+	objects = append(objects, Pointer{oid, size})
+
+	result, err := c.batch(ctx, "download", objects)
+	if err != nil {
+		return nil, err
+	}
+
+	transferAdapter, ok := c.transfers[result.Transfer]
+	if !ok {
+		return nil, fmt.Errorf("lfs.HTTPClient.Download Transferadapter not found: %s", result.Transfer)
+	}
+
+	if len(result.Objects) == 0 {
+		return nil, errors.New("lfs.HTTPClient.Download: No objects in result")
+	}
+
+	content, err := transferAdapter.Download(ctx, result.Objects[0])
+	if err != nil {
+		return nil, err
+	}
+	return content, nil
+}