Auto merge pull requests when all checks succeeded via API (#9307)

* Fix indention

Signed-off-by: kolaente <k@knt.li>

* Add option to merge a pr right now without waiting for the checks to succeed

Signed-off-by: kolaente <k@knt.li>

* Fix lint

Signed-off-by: kolaente <k@knt.li>

* Add scheduled pr merge to tables used for testing

Signed-off-by: kolaente <k@knt.li>

* Add status param to make GetPullRequestByHeadBranch reusable

Signed-off-by: kolaente <k@knt.li>

* Move "Merge now" to a seperate button to make the ui clearer

Signed-off-by: kolaente <k@knt.li>

* Update models/scheduled_pull_request_merge.go

Co-authored-by: 赵智超 <1012112796@qq.com>

* Update web_src/js/index.js

Co-authored-by: 赵智超 <1012112796@qq.com>

* Update web_src/js/index.js

Co-authored-by: 赵智超 <1012112796@qq.com>

* Re-add migration after merge

* Fix frontend lint

* Fix version compare

* Add vendored dependencies

* Add basic tets

* Make sure the api route is capable of scheduling PRs for merging

* Fix comparing version

* make vendor

* adopt refactor

* apply suggestion: User -> Doer

* init var once

* Fix Test

* Update templates/repo/issue/view_content/comments.tmpl

* adopt

* nits

* next

* code format

* lint

* use same name schema; rm CreateUnScheduledPRToAutoMergeComment

* API: can not create schedule twice

* Add TestGetBranchNamesForSha

* nits

* new go routine for each pull to merge

* Update models/pull.go

Co-authored-by: a1012112796 <1012112796@qq.com>

* Update models/scheduled_pull_request_merge.go

Co-authored-by: a1012112796 <1012112796@qq.com>

* fix & add renaming sugestions

* Update services/automerge/pull_auto_merge.go

Co-authored-by: a1012112796 <1012112796@qq.com>

* fix conflict relicts

* apply latest refactors

* fix: migration after merge

* Update models/error.go

Co-authored-by: delvh <dev.lh@web.de>

* Update options/locale/locale_en-US.ini

Co-authored-by: delvh <dev.lh@web.de>

* Update options/locale/locale_en-US.ini

Co-authored-by: delvh <dev.lh@web.de>

* adapt latest refactors

* fix test

* use more context

* skip potential edgecases

* document func usage

* GetBranchNamesForSha() -> GetRefsBySha()

* start refactoring

* ajust to new changes

* nit

* docu nit

* the great check move

* move checks for branchprotection into own package

* resolve todo now ...

* move & rename

* unexport if posible

* fix

* check if merge is allowed before merge on scheduled pull

* debugg

* wording

* improve SetDefaults & nits

* NotAllowedToMerge -> DisallowedToMerge

* fix test

* merge files

* use package "errors"

* merge files

* add string names

* other implementation for gogit

* adapt refactor

* more context for models/pull.go

* GetUserRepoPermission use context

* more ctx

* use context for loading pull head/base-repo

* more ctx

* more ctx

* models.LoadIssueCtx()

* models.LoadIssueCtx()

* Handle pull_service.Merge in one DB transaction

* add TODOs

* next

* next

* next

* more ctx

* more ctx

* Start refactoring structure of old pull code ...

* move code into new packages

* shorter names ... and finish **restructure**

* Update models/branches.go

Co-authored-by: zeripath <art27@cantab.net>

* finish UpdateProtectBranch

* more and fix

* update datum

* template: use "svg" helper

* rename prQueue 2 prPatchCheckerQueue

* handle automerge in queue

* lock pull on git&db actions ...

* lock pull on git&db actions ...

* add TODO notes

* the regex

* transaction in tests

* GetRepositoryByIDCtx

* shorter table name and lint fix

* close transaction bevore notify

* Update models/pull.go

* next

* CheckPullMergable check all branch protections!

* Update routers/web/repo/pull.go

* CheckPullMergable check all branch protections!

* Revert "PullService lock via pullID (#19520)" (for now...)

This reverts commit 6cde7c9159a5ea75a10356feb7b8c7ad4c434a9a.

* Update services/pull/check.go

* Use for a repo action one database transaction

* Apply suggestions from code review

* Apply suggestions from code review

Co-authored-by: delvh <dev.lh@web.de>

* Update services/issue/status.go

Co-authored-by: delvh <dev.lh@web.de>

* Update services/issue/status.go

Co-authored-by: delvh <dev.lh@web.de>

* use db.WithTx()

* gofmt

* make pr.GetDefaultMergeMessage() context aware

* make MergePullRequestForm.SetDefaults context aware

* use db.WithTx()

* pull.SetMerged only with context

* fix deadlock in `test-sqlite\#TestAPIBranchProtection`

* dont forget templates

* db.WithTx allow to set the parentCtx

* handle db transaction in service packages but not router

* issue_service.ChangeStatus just had caused another deadlock :/
it has to do something with how notification package is handled

* if we merge a pull in one database transaktion, we get a lock, because merge infoce internal api that cant handle open db sessions to the same repo

* ajust to current master

* Apply suggestions from code review

Co-authored-by: delvh <dev.lh@web.de>

* dont open db transaction in router

* make generate-swagger

* one _success less

* wording nit

* rm

* adapt

* remove not needed test files

* rm less diff & use attr in JS

* ...

* Update services/repository/files/commit.go

Co-authored-by: wxiaoguang <wxiaoguang@gmail.com>

* ajust db schema for PullAutoMerge

* skip broken pull refs

* more context in error messages

* remove webUI part for another pull

* remove more WebUI only parts

* API: add CancleAutoMergePR

* Apply suggestions from code review

Co-authored-by: wxiaoguang <wxiaoguang@gmail.com>

* fix lint

* Apply suggestions from code review

* cancle -> cancel

Co-authored-by: delvh <dev.lh@web.de>

* change queue identifyer

* fix swagger

* prevent nil issue

* fix and dont drop error

* as per @zeripath

* Update integrations/git_test.go

Co-authored-by: delvh <dev.lh@web.de>

* Update integrations/git_test.go

Co-authored-by: delvh <dev.lh@web.de>

* more declarative integration tests (dedup code)

* use assert.False/True helper

Co-authored-by: 赵智超 <1012112796@qq.com>
Co-authored-by: 6543 <6543@obermui.de>
Co-authored-by: delvh <dev.lh@web.de>
Co-authored-by: zeripath <art27@cantab.net>
Co-authored-by: wxiaoguang <wxiaoguang@gmail.com>

5 files changed, 188 insertions, 0 deletions

diff --git a/models/issue_comment.go b/models/issue_comment.go
index ceea878662..13b2c62546 100644
--- a/models/issue_comment.go
+++ b/models/issue_comment.go
@@ -110,6 +110,10 @@ const (
 	CommentTypeDismissReview
 	// 33 Change issue ref
 	CommentTypeChangeIssueRef
+	// 34 pr was scheduled to auto merge when checks succeed
+	CommentTypePRScheduledToAutoMerge
+	// 35 pr was un scheduled to auto merge when checks succeed
+	CommentTypePRUnScheduledToAutoMerge
 )
 
 var commentStrings = []string{
@@ -147,6 +151,8 @@ var commentStrings = []string{
 	"project_board",
 	"dismiss_review",
 	"change_issue_ref",
+	"pull_scheduled_merge",
+	"pull_cancel_scheduled_merge",
 }
 
 func (t CommentType) String() string {
diff --git a/models/migrations/migrations.go b/models/migrations/migrations.go
index 9e46791ec6..817ba3bfac 100644
--- a/models/migrations/migrations.go
+++ b/models/migrations/migrations.go
@@ -383,6 +383,8 @@ var migrations = []Migration{
 	NewMigration("Add package tables", addPackageTables),
 	// v213 -> v214
 	NewMigration("Add allow edits from maintainers to PullRequest table", addAllowMaintainerEdit),
+	// v214 -> v215
+	NewMigration("Add auto merge table", addAutoMergeTable),
 }
 
 // GetCurrentDBVersion returns the current db version
diff --git a/models/migrations/v214.go b/models/migrations/v214.go
new file mode 100644
index 0000000000..dfe5d776a0
--- /dev/null
+++ b/models/migrations/v214.go
@@ -0,0 +1,23 @@
+// Copyright 2022 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 (
+	"xorm.io/xorm"
+)
+
+func addAutoMergeTable(x *xorm.Engine) error {
+	type MergeStyle string
+	type PullAutoMerge struct {
+		ID          int64      `xorm:"pk autoincr"`
+		PullID      int64      `xorm:"UNIQUE"`
+		DoerID      int64      `xorm:"NOT NULL"`
+		MergeStyle  MergeStyle `xorm:"varchar(30)"`
+		Message     string     `xorm:"LONGTEXT"`
+		CreatedUnix int64      `xorm:"created"`
+	}
+
+	return x.Sync2(&PullAutoMerge{})
+}
diff --git a/models/pull.go b/models/pull.go
index d056888130..0fa3bdf14f 100644
--- a/models/pull.go
+++ b/models/pull.go
@@ -20,6 +20,8 @@ import (
 	"code.gitea.io/gitea/modules/setting"
 	"code.gitea.io/gitea/modules/timeutil"
 	"code.gitea.io/gitea/modules/util"
+
+	"xorm.io/builder"
 )
 
 // PullRequestType defines pull request type
@@ -675,6 +677,18 @@ func (pr *PullRequest) IsSameRepo() bool {
 	return pr.BaseRepoID == pr.HeadRepoID
 }
 
+// GetPullRequestsByHeadBranch returns all prs by head branch
+// Since there could be multiple prs with the same head branch, this function returns a slice of prs
+func GetPullRequestsByHeadBranch(ctx context.Context, headBranch string, headRepoID int64) ([]*PullRequest, error) {
+	log.Trace("GetPullRequestsByHeadBranch: headBranch: '%s', headRepoID: '%d'", headBranch, headRepoID)
+	prs := make([]*PullRequest, 0, 2)
+	if err := db.GetEngine(ctx).Where(builder.Eq{"head_branch": headBranch, "head_repo_id": headRepoID}).
+		Find(&prs); err != nil {
+		return nil, err
+	}
+	return prs, nil
+}
+
 // GetBaseBranchHTMLURL returns the HTML URL of the base branch
 func (pr *PullRequest) GetBaseBranchHTMLURL() string {
 	if err := pr.LoadBaseRepo(); err != nil {
diff --git a/models/pull/automerge.go b/models/pull/automerge.go
new file mode 100644
index 0000000000..fd73f2b0fb
--- /dev/null
+++ b/models/pull/automerge.go
@@ -0,0 +1,143 @@
+// Copyright 2022 Gitea. All rights reserved.
+// Use of this source code is governed by a MIT-style
+// license that can be found in the LICENSE file.
+
+package pull
+
+import (
+	"context"
+	"fmt"
+
+	"code.gitea.io/gitea/models"
+	"code.gitea.io/gitea/models/db"
+	repo_model "code.gitea.io/gitea/models/repo"
+	user_model "code.gitea.io/gitea/models/user"
+	"code.gitea.io/gitea/modules/timeutil"
+)
+
+// AutoMerge represents a pull request scheduled for merging when checks succeed
+type AutoMerge struct {
+	ID          int64                 `xorm:"pk autoincr"`
+	PullID      int64                 `xorm:"UNIQUE"`
+	DoerID      int64                 `xorm:"NOT NULL"`
+	Doer        *user_model.User      `xorm:"-"`
+	MergeStyle  repo_model.MergeStyle `xorm:"varchar(30)"`
+	Message     string                `xorm:"LONGTEXT"`
+	CreatedUnix timeutil.TimeStamp    `xorm:"created"`
+}
+
+// TableName return database table name for xorm
+func (AutoMerge) TableName() string {
+	return "pull_auto_merge"
+}
+
+func init() {
+	db.RegisterModel(new(AutoMerge))
+}
+
+// ErrAlreadyScheduledToAutoMerge represents a "PullRequestHasMerged"-error
+type ErrAlreadyScheduledToAutoMerge struct {
+	PullID int64
+}
+
+func (err ErrAlreadyScheduledToAutoMerge) Error() string {
+	return fmt.Sprintf("pull request is already scheduled to auto merge when checks succeed [pull_id: %d]", err.PullID)
+}
+
+// IsErrAlreadyScheduledToAutoMerge checks if an error is a ErrAlreadyScheduledToAutoMerge.
+func IsErrAlreadyScheduledToAutoMerge(err error) bool {
+	_, ok := err.(ErrAlreadyScheduledToAutoMerge)
+	return ok
+}
+
+// ScheduleAutoMerge schedules a pull request to be merged when all checks succeed
+func ScheduleAutoMerge(ctx context.Context, doer *user_model.User, pullID int64, style repo_model.MergeStyle, message string) error {
+	// Check if we already have a merge scheduled for that pull request
+	if exists, _, err := GetScheduledMergeByPullID(ctx, pullID); err != nil {
+		return err
+	} else if exists {
+		return ErrAlreadyScheduledToAutoMerge{PullID: pullID}
+	}
+
+	if _, err := db.GetEngine(ctx).Insert(&AutoMerge{
+		DoerID:     doer.ID,
+		PullID:     pullID,
+		MergeStyle: style,
+		Message:    message,
+	}); err != nil {
+		return err
+	}
+
+	pr, err := models.GetPullRequestByID(ctx, pullID)
+	if err != nil {
+		return err
+	}
+
+	_, err = createAutoMergeComment(ctx, models.CommentTypePRScheduledToAutoMerge, pr, doer)
+	return err
+}
+
+// GetScheduledMergeByPullID gets a scheduled pull request merge by pull request id
+func GetScheduledMergeByPullID(ctx context.Context, pullID int64) (bool, *AutoMerge, error) {
+	scheduledPRM := &AutoMerge{}
+	exists, err := db.GetEngine(ctx).Where("pull_id = ?", pullID).Get(scheduledPRM)
+	if err != nil || !exists {
+		return false, nil, err
+	}
+
+	doer, err := user_model.GetUserByIDCtx(ctx, scheduledPRM.DoerID)
+	if err != nil {
+		return false, nil, err
+	}
+
+	scheduledPRM.Doer = doer
+	return true, scheduledPRM, nil
+}
+
+// RemoveScheduledAutoMerge cancels a previously scheduled pull request
+func RemoveScheduledAutoMerge(ctx context.Context, doer *user_model.User, pullID int64, comment bool) error {
+	return db.WithTx(func(ctx context.Context) error {
+		exist, scheduledPRM, err := GetScheduledMergeByPullID(ctx, pullID)
+		if err != nil {
+			return err
+		} else if !exist {
+			return models.ErrNotExist{ID: pullID}
+		}
+
+		if _, err := db.GetEngine(ctx).ID(scheduledPRM.ID).Delete(&AutoMerge{}); err != nil {
+			return err
+		}
+
+		// if pull got merged we don't need to add "auto-merge canceled comment"
+		if !comment || doer == nil {
+			return nil
+		}
+
+		pr, err := models.GetPullRequestByID(ctx, pullID)
+		if err != nil {
+			return err
+		}
+
+		_, err = createAutoMergeComment(ctx, models.CommentTypePRUnScheduledToAutoMerge, pr, doer)
+		return err
+	}, ctx)
+}
+
+// createAutoMergeComment is a internal function, only use it for CommentTypePRScheduledToAutoMerge and CommentTypePRUnScheduledToAutoMerge CommentTypes
+func createAutoMergeComment(ctx context.Context, typ models.CommentType, pr *models.PullRequest, doer *user_model.User) (comment *models.Comment, err error) {
+	if err = pr.LoadIssueCtx(ctx); err != nil {
+		return
+	}
+
+	if err = pr.LoadBaseRepoCtx(ctx); err != nil {
+		return
+	}
+
+	comment, err = models.CreateCommentCtx(ctx, &models.CreateCommentOptions{
+		Type:  typ,
+		Doer:  doer,
+		Repo:  pr.BaseRepo,
+		Issue: pr.Issue,
+	})
+	return
+}