Give user a link to create PR after push (#4716)

* Give user a link to create PR after push

* Forks now create PR in the base repository + make sure PR creation is allowed

* fix code style

routers/private/internal.go

@@ -44,5 +44,7 @@ func RegisterRoutes(m *macaron.Macaron) {
 		m.Post("/push/update", PushUpdate)
 		m.Get("/protectedbranch/:pbid/:userid", CanUserPush)
 		m.Get("/branch/:id/*", GetProtectedBranchBy)
+		m.Get("/repository/:rid", GetRepository)
+		m.Get("/active-pull-request", GetActivePullRequest)
 	}, CheckInternalToken)
 }

routers/private/repository.go

@@ -0,0 +1,84 @@
+// 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 private
+
+import (
+	"net/http"
+	"net/url"
+
+	"code.gitea.io/gitea/models"
+
+	macaron "gopkg.in/macaron.v1"
+)
+
+// GetRepository return the default branch of a repository
+func GetRepository(ctx *macaron.Context) {
+	repoID := ctx.ParamsInt64(":rid")
+	repository, err := models.GetRepositoryByID(repoID)
+	repository.MustOwnerName()
+	allowPulls := repository.AllowsPulls()
+	// put it back to nil because json unmarshal can't unmarshal it
+	repository.Units = nil
+
+	if err != nil {
+		ctx.JSON(http.StatusInternalServerError, map[string]interface{}{
+			"err": err.Error(),
+		})
+		return
+	}
+
+	if repository.IsFork {
+		repository.GetBaseRepo()
+		if err != nil {
+			ctx.JSON(http.StatusInternalServerError, map[string]interface{}{
+				"err": err.Error(),
+			})
+			return
+		}
+		repository.BaseRepo.MustOwnerName()
+		allowPulls = repository.BaseRepo.AllowsPulls()
+		// put it back to nil because json unmarshal can't unmarshal it
+		repository.BaseRepo.Units = nil
+	}
+
+	ctx.JSON(http.StatusOK, struct {
+		Repository       *models.Repository
+		AllowPullRequest bool
+	}{
+		Repository:       repository,
+		AllowPullRequest: allowPulls,
+	})
+}
+
+// GetActivePullRequest return an active pull request when it exists or an empty object
+func GetActivePullRequest(ctx *macaron.Context) {
+	baseRepoID := ctx.QueryInt64("baseRepoID")
+	headRepoID := ctx.QueryInt64("headRepoID")
+	baseBranch, err := url.QueryUnescape(ctx.QueryTrim("baseBranch"))
+	if err != nil {
+		ctx.JSON(http.StatusInternalServerError, map[string]interface{}{
+			"err": err.Error(),
+		})
+		return
+	}
+
+	headBranch, err := url.QueryUnescape(ctx.QueryTrim("headBranch"))
+	if err != nil {
+		ctx.JSON(http.StatusInternalServerError, map[string]interface{}{
+			"err": err.Error(),
+		})
+		return
+	}
+
+	pr, err := models.GetUnmergedPullRequest(headRepoID, baseRepoID, headBranch, baseBranch)
+	if err != nil && !models.IsErrPullRequestNotExist(err) {
+		ctx.JSON(http.StatusInternalServerError, map[string]interface{}{
+			"err": err.Error(),
+		})
+		return
+	}
+
+	ctx.JSON(http.StatusOK, pr)
+}