Fix bug when creating pull request (#36166)

Extract from #36105 

Fix #36116
Fix #35912
Fix #20906

routers/api/v1/repo/pull.go

@@ -30,6 +30,7 @@ import (
 	"code.gitea.io/gitea/modules/timeutil"
 	"code.gitea.io/gitea/modules/web"
 	"code.gitea.io/gitea/routers/api/v1/utils"
+	"code.gitea.io/gitea/routers/common"
 	asymkey_service "code.gitea.io/gitea/services/asymkey"
 	"code.gitea.io/gitea/services/automerge"
 	"code.gitea.io/gitea/services/context"
@@ -1082,7 +1083,7 @@ func parseCompareInfo(ctx *context.APIContext, form api.CreatePullRequestOption)
 	} else if len(headInfos) == 2 {
 		// There is a head repository (the head repository could also be the same base repo)
 		headRefToGuess = headInfos[1]
-		headUser, err = user_model.GetUserByName(ctx, headInfos[0])
+		headUser, err = user_model.GetUserOrOrgByName(ctx, headInfos[0])
 		if err != nil {
 			if user_model.IsErrUserNotExist(err) {
 				ctx.APIErrorNotFound("GetUserByName")
@@ -1098,28 +1099,23 @@ func parseCompareInfo(ctx *context.APIContext, form api.CreatePullRequestOption)
 
 	isSameRepo := ctx.Repo.Owner.ID == headUser.ID
 
-	// Check if current user has fork of repository or in the same repository.
-	headRepo := repo_model.GetForkedRepo(ctx, headUser.ID, baseRepo.ID)
-	if headRepo == nil && !isSameRepo {
-		err = baseRepo.GetBaseRepo(ctx)
+	var headRepo *repo_model.Repository
+	if isSameRepo {
+		headRepo = baseRepo
+	} else {
+		headRepo, err = common.FindHeadRepo(ctx, baseRepo, headUser.ID)
 		if err != nil {
 			ctx.APIErrorInternal(err)
 			return nil, nil
 		}
-
-		// Check if baseRepo's base repository is the same as headUser's repository.
-		if baseRepo.BaseRepo == nil || baseRepo.BaseRepo.OwnerID != headUser.ID {
-			log.Trace("parseCompareInfo[%d]: does not have fork or in same repository", baseRepo.ID)
-			ctx.APIErrorNotFound("GetBaseRepo")
+		if headRepo == nil {
+			ctx.APIErrorNotFound("head repository not found")
 			return nil, nil
 		}
-		// Assign headRepo so it can be used below.
-		headRepo = baseRepo.BaseRepo
 	}
 
 	var headGitRepo *git.Repository
 	if isSameRepo {
-		headRepo = ctx.Repo.Repository
 		headGitRepo = ctx.Repo.GitRepo
 		closer = func() {} // no need to close the head repo because it shares the base repo
 	} else {
@@ -1143,7 +1139,7 @@ func parseCompareInfo(ctx *context.APIContext, form api.CreatePullRequestOption)
 		return nil, nil
 	}
 
-	if !permBase.CanReadIssuesOrPulls(true) || !permBase.CanRead(unit.TypeCode) {
+	if !permBase.CanRead(unit.TypeCode) {
 		log.Trace("Permission Denied: User %-v cannot create/read pull requests or cannot read code in Repo %-v\nUser in baseRepo has Permissions: %-+v", ctx.Doer, baseRepo, permBase)
 		ctx.APIErrorNotFound("Can't read pulls or can't read UnitTypeCode")
 		return nil, nil

routers/common/compare.go

@@ -4,6 +4,8 @@
 package common
 
 import (
+	"context"
+
 	repo_model "code.gitea.io/gitea/models/repo"
 	user_model "code.gitea.io/gitea/models/user"
 	"code.gitea.io/gitea/modules/git"
@@ -20,3 +22,54 @@ type CompareInfo struct {
 	HeadBranch       string
 	DirectComparison bool
 }
+
+// maxForkTraverseLevel defines the maximum levels to traverse when searching for the head repository.
+const maxForkTraverseLevel = 10
+
+// FindHeadRepo tries to find the head repository based on the base repository and head user ID.
+func FindHeadRepo(ctx context.Context, baseRepo *repo_model.Repository, headUserID int64) (*repo_model.Repository, error) {
+	if baseRepo.IsFork {
+		curRepo := baseRepo
+		for curRepo.OwnerID != headUserID { // We assume the fork deepth is not too deep.
+			if err := curRepo.GetBaseRepo(ctx); err != nil {
+				return nil, err
+			}
+			if curRepo.BaseRepo == nil {
+				return findHeadRepoFromRootBase(ctx, curRepo, headUserID, maxForkTraverseLevel)
+			}
+			curRepo = curRepo.BaseRepo
+		}
+		return curRepo, nil
+	}
+
+	return findHeadRepoFromRootBase(ctx, baseRepo, headUserID, maxForkTraverseLevel)
+}
+
+func findHeadRepoFromRootBase(ctx context.Context, baseRepo *repo_model.Repository, headUserID int64, traverseLevel int) (*repo_model.Repository, error) {
+	if traverseLevel == 0 {
+		return nil, nil
+	}
+	// test if we are lucky
+	repo, err := repo_model.GetUserFork(ctx, baseRepo.ID, headUserID)
+	if err != nil {
+		return nil, err
+	}
+	if repo != nil {
+		return repo, nil
+	}
+
+	firstLevelForkedRepos, err := repo_model.GetRepositoriesByForkID(ctx, baseRepo.ID)
+	if err != nil {
+		return nil, err
+	}
+	for _, repo := range firstLevelForkedRepos {
+		forked, err := findHeadRepoFromRootBase(ctx, repo, headUserID, traverseLevel-1)
+		if err != nil {
+			return nil, err
+		}
+		if forked != nil {
+			return forked, nil
+		}
+	}
+	return nil, nil
+}

routers/web/repo/compare.go

@@ -259,7 +259,7 @@ func ParseCompareInfo(ctx *context.Context) *common.CompareInfo {
 	} else if len(headInfos) == 2 {
 		headInfosSplit := strings.Split(headInfos[0], "/")
 		if len(headInfosSplit) == 1 {
-			ci.HeadUser, err = user_model.GetUserByName(ctx, headInfos[0])
+			ci.HeadUser, err = user_model.GetUserOrOrgByName(ctx, headInfos[0])
 			if err != nil {
 				if user_model.IsErrUserNotExist(err) {
 					ctx.NotFound(nil)

routers/web/repo/pull.go

@@ -1340,6 +1340,17 @@ func CompareAndPullRequestPost(ctx *context.Context) {
 		return
 	}
 
+	// Check if a pull request already exists with the same head and base branch.
+	pr, err := issues_model.GetUnmergedPullRequest(ctx, ci.HeadRepo.ID, repo.ID, ci.HeadBranch, ci.BaseBranch, issues_model.PullRequestFlowGithub)
+	if err != nil && !issues_model.IsErrPullRequestNotExist(err) {
+		ctx.ServerError("GetUnmergedPullRequest", err)
+		return
+	}
+	if pr != nil {
+		ctx.JSONError(ctx.Tr("repo.pulls.new.already_existed"))
+		return
+	}
+
 	content := form.Content
 	if filename := ctx.Req.Form.Get("template-file"); filename != "" {
 		if template, err := issue_template.UnmarshalFromRepo(ctx.Repo.GitRepo, ctx.Repo.Repository.DefaultBranch, filename); err == nil {