Add agit flow support in gitea (#14295)

* feature: add agit flow support

ref: https://git-repo.info/en/2020/03/agit-flow-and-git-repo/

example:

```Bash
git checkout -b test
echo "test" >> README.md
git commit -m "test"
git push origin HEAD:refs/for/master -o topic=test
```

Signed-off-by: a1012112796 <1012112796@qq.com>

* fix lint

* simplify code add fix some nits

* update merge help message

* Apply suggestions from code review. Thanks @jiangxin

* add forced-update message

* fix lint

* splite writePktLine

* add refs/for/<target-branch>/<topic-branch> support also

* Add test code add fix api

* fix lint

* fix test

* skip test if git version < 2.29

* try test with git 2.30.1

* fix permission check bug

* fix some nit

* logic implify and test code update

* fix bug

* apply suggestions from code review

* prepare for merge

Signed-off-by: Andrew Thornton <art27@cantab.net>

* fix permission check bug

- test code update
- apply suggestions from code review @zeripath

Signed-off-by: a1012112796 <1012112796@qq.com>

* fix bug when target branch isn't exist

* prevent some special push and fix some nits

* fix lint

* try splite

* Apply suggestions from code review

- fix permission check
- handle user rename

* fix version negotiation

* remane

* fix template

* handle empty repo

* ui: fix  branch link under the title

* fix nits

Co-authored-by: Andrew Thornton <art27@cantab.net>
Co-authored-by: 6543 <6543@obermui.de>
Co-authored-by: Lunny Xiao <xiaolunwen@gmail.com>

5 files changed, 65 insertions, 8 deletions

diff --git a/models/migrations/migrations.go b/models/migrations/migrations.go
index fed7b909c1..9b04a364ca 100644
--- a/models/migrations/migrations.go
+++ b/models/migrations/migrations.go
@@ -329,6 +329,8 @@ var migrations = []Migration{
 	NewMigration("Add key is verified to gpg key", addKeyIsVerified),
 	// v189 -> v190
 	NewMigration("Unwrap ldap.Sources", unwrapLDAPSourceCfg),
+	// v190 -> v191
+	NewMigration("Add agit flow pull request support", addAgitFlowPullRequest),
 }
 
 // GetCurrentDBVersion returns the current db version
diff --git a/models/migrations/v190.go b/models/migrations/v190.go
new file mode 100644
index 0000000000..8d1fba8373
--- /dev/null
+++ b/models/migrations/v190.go
@@ -0,0 +1,24 @@
+// 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 migrations
+
+import (
+	"fmt"
+
+	"xorm.io/xorm"
+)
+
+func addAgitFlowPullRequest(x *xorm.Engine) error {
+	type PullRequestFlow int
+
+	type PullRequest struct {
+		Flow PullRequestFlow `xorm:"NOT NULL DEFAULT 0"`
+	}
+
+	if err := x.Sync2(new(PullRequest)); err != nil {
+		return fmt.Errorf("sync2: %v", err)
+	}
+	return nil
+}
diff --git a/models/pull.go b/models/pull.go
index 3717878f42..e8e815385d 100644
--- a/models/pull.go
+++ b/models/pull.go
@@ -38,6 +38,16 @@ const (
 	PullRequestStatusEmpty
 )
 
+// PullRequestFlow the flow of pull request
+type PullRequestFlow int
+
+const (
+	// PullRequestFlowGithub github flow from head branch to base branch
+	PullRequestFlowGithub PullRequestFlow = iota
+	// PullRequestFlowAGit Agit flow pull request, head branch is not exist
+	PullRequestFlowAGit
+)
+
 // PullRequest represents relation between pull request and repositories.
 type PullRequest struct {
 	ID              int64 `xorm:"pk autoincr"`
@@ -58,6 +68,7 @@ type PullRequest struct {
 	BaseRepoID      int64       `xorm:"INDEX"`
 	BaseRepo        *Repository `xorm:"-"`
 	HeadBranch      string
+	HeadCommitID    string `xorm:"-"`
 	BaseBranch      string
 	ProtectedBranch *ProtectedBranch `xorm:"-"`
 	MergeBase       string           `xorm:"VARCHAR(40)"`
@@ -69,6 +80,8 @@ type PullRequest struct {
 	MergedUnix     timeutil.TimeStamp `xorm:"updated INDEX"`
 
 	isHeadRepoLoaded bool `xorm:"-"`
+
+	Flow PullRequestFlow `xorm:"NOT NULL DEFAULT 0"`
 }
 
 // MustHeadUserName returns the HeadRepo's username if failed return blank
@@ -470,11 +483,11 @@ func NewPullRequest(repo *Repository, issue *Issue, labelIDs []int64, uuids []st
 
 // GetUnmergedPullRequest returns a pull request that is open and has not been merged
 // by given head/base and repo/branch.
-func GetUnmergedPullRequest(headRepoID, baseRepoID int64, headBranch, baseBranch string) (*PullRequest, error) {
+func GetUnmergedPullRequest(headRepoID, baseRepoID int64, headBranch, baseBranch string, flow PullRequestFlow) (*PullRequest, error) {
 	pr := new(PullRequest)
 	has, err := x.
-		Where("head_repo_id=? AND head_branch=? AND base_repo_id=? AND base_branch=? AND has_merged=? AND issue.is_closed=?",
-			headRepoID, headBranch, baseRepoID, baseBranch, false, false).
+		Where("head_repo_id=? AND head_branch=? AND base_repo_id=? AND base_branch=? AND has_merged=? AND flow = ? AND issue.is_closed=?",
+			headRepoID, headBranch, baseRepoID, baseBranch, false, flow, false).
 		Join("INNER", "issue", "issue.id=pull_request.issue_id").
 		Get(pr)
 	if err != nil {
@@ -491,7 +504,7 @@ func GetUnmergedPullRequest(headRepoID, baseRepoID int64, headBranch, baseBranch
 func GetLatestPullRequestByHeadInfo(repoID int64, branch string) (*PullRequest, error) {
 	pr := new(PullRequest)
 	has, err := x.
-		Where("head_repo_id = ? AND head_branch = ?", repoID, branch).
+		Where("head_repo_id = ? AND head_branch = ? AND flow = ?", repoID, branch, PullRequestFlowGithub).
 		OrderBy("id DESC").
 		Get(pr)
 	if !has {
@@ -566,6 +579,20 @@ func getPullRequestByIssueID(e Engine, issueID int64) (*PullRequest, error) {
 	return pr, pr.loadAttributes(e)
 }
 
+// GetAllUnmergedAgitPullRequestByPoster get all unmerged agit flow pull request
+// By poster id.
+func GetAllUnmergedAgitPullRequestByPoster(uid int64) ([]*PullRequest, error) {
+	pulls := make([]*PullRequest, 0, 10)
+
+	err := x.
+		Where("has_merged=? AND flow = ? AND issue.is_closed=? AND issue.poster_id=?",
+			false, PullRequestFlowAGit, false, uid).
+		Join("INNER", "issue", "issue.id=pull_request.issue_id").
+		Find(&pulls)
+
+	return pulls, err
+}
+
 // GetPullRequestByIssueID returns pull request by given issue ID.
 func GetPullRequestByIssueID(issueID int64) (*PullRequest, error) {
 	return getPullRequestByIssueID(x, issueID)
@@ -663,6 +690,10 @@ func (pr *PullRequest) GetBaseBranchHTMLURL() string {
 
 // GetHeadBranchHTMLURL returns the HTML URL of the head branch
 func (pr *PullRequest) GetHeadBranchHTMLURL() string {
+	if pr.Flow == PullRequestFlowAGit {
+		return ""
+	}
+
 	if err := pr.LoadHeadRepo(); err != nil {
 		log.Error("LoadHeadRepo: %v", err)
 		return ""
diff --git a/models/pull_list.go b/models/pull_list.go
index 989de46891..2f685e19f5 100644
--- a/models/pull_list.go
+++ b/models/pull_list.go
@@ -51,8 +51,8 @@ func listPullRequestStatement(baseRepoID int64, opts *PullRequestsOptions) (*xor
 func GetUnmergedPullRequestsByHeadInfo(repoID int64, branch string) ([]*PullRequest, error) {
 	prs := make([]*PullRequest, 0, 2)
 	return prs, x.
-		Where("head_repo_id = ? AND head_branch = ? AND has_merged = ? AND issue.is_closed = ?",
-			repoID, branch, false, false).
+		Where("head_repo_id = ? AND head_branch = ? AND has_merged = ? AND issue.is_closed = ? AND flow = ?",
+			repoID, branch, false, false, PullRequestFlowGithub).
 		Join("INNER", "issue", "issue.id = pull_request.issue_id").
 		Find(&prs)
 }
diff --git a/models/pull_test.go b/models/pull_test.go
index 5eaeb60e67..07216da324 100644
--- a/models/pull_test.go
+++ b/models/pull_test.go
@@ -92,11 +92,11 @@ func TestPullRequestsOldest(t *testing.T) {
 
 func TestGetUnmergedPullRequest(t *testing.T) {
 	assert.NoError(t, PrepareTestDatabase())
-	pr, err := GetUnmergedPullRequest(1, 1, "branch2", "master")
+	pr, err := GetUnmergedPullRequest(1, 1, "branch2", "master", PullRequestFlowGithub)
 	assert.NoError(t, err)
 	assert.Equal(t, int64(2), pr.ID)
 
-	_, err = GetUnmergedPullRequest(1, 9223372036854775807, "branch1", "master")
+	_, err = GetUnmergedPullRequest(1, 9223372036854775807, "branch1", "master", PullRequestFlowGithub)
 	assert.Error(t, err)
 	assert.True(t, IsErrPullRequestNotExist(err))
 }