Implement git refs API for listing references (branches, tags and other) (#5354)

* Inital routes to git refs api

* Git refs API implementation

* Update swagger

* Fix copyright

* Make swagger happy add basic test

* Fix test

* Fix test again :)

vendor/code.gitea.io/sdk/gitea/repo_refs.go

@@ -0,0 +1,69 @@
+// Copyright 2018 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 gitea
+
+import (
+	"encoding/json"
+	"errors"
+	"fmt"
+	"strings"
+)
+
+// Reference represents a Git reference.
+type Reference struct {
+	Ref    string     `json:"ref"`
+	URL    string     `json:"url"`
+	Object *GitObject `json:"object"`
+}
+
+// GitObject represents a Git object.
+type GitObject struct {
+	Type string `json:"type"`
+	SHA  string `json:"sha"`
+	URL  string `json:"url"`
+}
+
+// GetRepoRef get one ref's information of one repository
+func (c *Client) GetRepoRef(user, repo, ref string) (*Reference, error) {
+	ref = strings.TrimPrefix(ref, "refs/")
+	r := new(Reference)
+	err := c.getParsedResponse("GET", fmt.Sprintf("/repos/%s/%s/git/refs/%s", user, repo, ref), nil, nil, &r)
+	if _, ok := err.(*json.UnmarshalTypeError); ok {
+		// Multiple refs
+		return nil, errors.New("no exact match found for this ref")
+	} else if err != nil {
+		return nil, err
+	}
+
+	return r, nil
+}
+
+// GetRepoRefs get list of ref's information of one repository
+func (c *Client) GetRepoRefs(user, repo, ref string) ([]*Reference, error) {
+	ref = strings.TrimPrefix(ref, "refs/")
+	resp, err := c.getResponse("GET", fmt.Sprintf("/repos/%s/%s/git/refs/%s", user, repo, ref), nil, nil)
+	if err != nil {
+		return nil, err
+	}
+
+	// Attempt to unmarshal single returned ref.
+	r := new(Reference)
+	refErr := json.Unmarshal(resp, r)
+	if refErr == nil {
+		return []*Reference{r}, nil
+	}
+
+	// Attempt to unmarshal multiple refs.
+	var rs []*Reference
+	refsErr := json.Unmarshal(resp, &rs)
+	if refsErr == nil {
+		if len(rs) == 0 {
+			return nil, errors.New("unexpected response: an array of refs with length 0")
+		}
+		return rs, nil
+	}
+
+	return nil, fmt.Errorf("unmarshalling failed for both single and multiple refs: %s and %s", refErr, refsErr)
+}