Move `convert` package to services (#22264)

Addition to #22256

The `convert` package relies heavily on different models which is
[disallowed by our definition of
modules](https://github.com/go-gitea/gitea/blob/main/CONTRIBUTING.md#design-guideline).
This helps to prevent possible import cycles.

Co-authored-by: Lunny Xiao <xiaolunwen@gmail.com>

1 files changed, 204 insertions, 0 deletions

diff --git a/services/convert/pull.go b/services/convert/pull.go
new file mode 100644
index 0000000000..db0add6cde
--- /dev/null
+++ b/services/convert/pull.go
@@ -0,0 +1,204 @@
+// Copyright 2020 The Gitea Authors. All rights reserved.
+// SPDX-License-Identifier: MIT
+
+package convert
+
+import (
+	"context"
+	"fmt"
+
+	issues_model "code.gitea.io/gitea/models/issues"
+	"code.gitea.io/gitea/models/perm"
+	access_model "code.gitea.io/gitea/models/perm/access"
+	user_model "code.gitea.io/gitea/models/user"
+	"code.gitea.io/gitea/modules/git"
+	"code.gitea.io/gitea/modules/log"
+	api "code.gitea.io/gitea/modules/structs"
+)
+
+// ToAPIPullRequest assumes following fields have been assigned with valid values:
+// Required - Issue
+// Optional - Merger
+func ToAPIPullRequest(ctx context.Context, pr *issues_model.PullRequest, doer *user_model.User) *api.PullRequest {
+	var (
+		baseBranch *git.Branch
+		headBranch *git.Branch
+		baseCommit *git.Commit
+		err        error
+	)
+
+	if err = pr.Issue.LoadRepo(ctx); err != nil {
+		log.Error("pr.Issue.LoadRepo[%d]: %v", pr.ID, err)
+		return nil
+	}
+
+	apiIssue := ToAPIIssue(ctx, pr.Issue)
+	if err := pr.LoadBaseRepo(ctx); err != nil {
+		log.Error("GetRepositoryById[%d]: %v", pr.ID, err)
+		return nil
+	}
+
+	if err := pr.LoadHeadRepo(ctx); err != nil {
+		log.Error("GetRepositoryById[%d]: %v", pr.ID, err)
+		return nil
+	}
+
+	p, err := access_model.GetUserRepoPermission(ctx, pr.BaseRepo, doer)
+	if err != nil {
+		log.Error("GetUserRepoPermission[%d]: %v", pr.BaseRepoID, err)
+		p.AccessMode = perm.AccessModeNone
+	}
+
+	apiPullRequest := &api.PullRequest{
+		ID:        pr.ID,
+		URL:       pr.Issue.HTMLURL(),
+		Index:     pr.Index,
+		Poster:    apiIssue.Poster,
+		Title:     apiIssue.Title,
+		Body:      apiIssue.Body,
+		Labels:    apiIssue.Labels,
+		Milestone: apiIssue.Milestone,
+		Assignee:  apiIssue.Assignee,
+		Assignees: apiIssue.Assignees,
+		State:     apiIssue.State,
+		IsLocked:  apiIssue.IsLocked,
+		Comments:  apiIssue.Comments,
+		HTMLURL:   pr.Issue.HTMLURL(),
+		DiffURL:   pr.Issue.DiffURL(),
+		PatchURL:  pr.Issue.PatchURL(),
+		HasMerged: pr.HasMerged,
+		MergeBase: pr.MergeBase,
+		Mergeable: pr.Mergeable(),
+		Deadline:  apiIssue.Deadline,
+		Created:   pr.Issue.CreatedUnix.AsTimePtr(),
+		Updated:   pr.Issue.UpdatedUnix.AsTimePtr(),
+
+		AllowMaintainerEdit: pr.AllowMaintainerEdit,
+
+		Base: &api.PRBranchInfo{
+			Name:       pr.BaseBranch,
+			Ref:        pr.BaseBranch,
+			RepoID:     pr.BaseRepoID,
+			Repository: ToRepo(ctx, pr.BaseRepo, p.AccessMode),
+		},
+		Head: &api.PRBranchInfo{
+			Name:   pr.HeadBranch,
+			Ref:    fmt.Sprintf("%s%d/head", git.PullPrefix, pr.Index),
+			RepoID: -1,
+		},
+	}
+
+	gitRepo, err := git.OpenRepository(ctx, pr.BaseRepo.RepoPath())
+	if err != nil {
+		log.Error("OpenRepository[%s]: %v", pr.BaseRepo.RepoPath(), err)
+		return nil
+	}
+	defer gitRepo.Close()
+
+	baseBranch, err = gitRepo.GetBranch(pr.BaseBranch)
+	if err != nil && !git.IsErrBranchNotExist(err) {
+		log.Error("GetBranch[%s]: %v", pr.BaseBranch, err)
+		return nil
+	}
+
+	if err == nil {
+		baseCommit, err = baseBranch.GetCommit()
+		if err != nil && !git.IsErrNotExist(err) {
+			log.Error("GetCommit[%s]: %v", baseBranch.Name, err)
+			return nil
+		}
+
+		if err == nil {
+			apiPullRequest.Base.Sha = baseCommit.ID.String()
+		}
+	}
+
+	if pr.Flow == issues_model.PullRequestFlowAGit {
+		gitRepo, err := git.OpenRepository(ctx, pr.BaseRepo.RepoPath())
+		if err != nil {
+			log.Error("OpenRepository[%s]: %v", pr.GetGitRefName(), err)
+			return nil
+		}
+		defer gitRepo.Close()
+
+		apiPullRequest.Head.Sha, err = gitRepo.GetRefCommitID(pr.GetGitRefName())
+		if err != nil {
+			log.Error("GetRefCommitID[%s]: %v", pr.GetGitRefName(), err)
+			return nil
+		}
+		apiPullRequest.Head.RepoID = pr.BaseRepoID
+		apiPullRequest.Head.Repository = apiPullRequest.Base.Repository
+		apiPullRequest.Head.Name = ""
+	}
+
+	if pr.HeadRepo != nil && pr.Flow == issues_model.PullRequestFlowGithub {
+		p, err := access_model.GetUserRepoPermission(ctx, pr.HeadRepo, doer)
+		if err != nil {
+			log.Error("GetUserRepoPermission[%d]: %v", pr.HeadRepoID, err)
+			p.AccessMode = perm.AccessModeNone
+		}
+
+		apiPullRequest.Head.RepoID = pr.HeadRepo.ID
+		apiPullRequest.Head.Repository = ToRepo(ctx, pr.HeadRepo, p.AccessMode)
+
+		headGitRepo, err := git.OpenRepository(ctx, pr.HeadRepo.RepoPath())
+		if err != nil {
+			log.Error("OpenRepository[%s]: %v", pr.HeadRepo.RepoPath(), err)
+			return nil
+		}
+		defer headGitRepo.Close()
+
+		headBranch, err = headGitRepo.GetBranch(pr.HeadBranch)
+		if err != nil && !git.IsErrBranchNotExist(err) {
+			log.Error("GetBranch[%s]: %v", pr.HeadBranch, err)
+			return nil
+		}
+
+		if git.IsErrBranchNotExist(err) {
+			headCommitID, err := headGitRepo.GetRefCommitID(apiPullRequest.Head.Ref)
+			if err != nil && !git.IsErrNotExist(err) {
+				log.Error("GetCommit[%s]: %v", pr.HeadBranch, err)
+				return nil
+			}
+			if err == nil {
+				apiPullRequest.Head.Sha = headCommitID
+			}
+		} else {
+			commit, err := headBranch.GetCommit()
+			if err != nil && !git.IsErrNotExist(err) {
+				log.Error("GetCommit[%s]: %v", headBranch.Name, err)
+				return nil
+			}
+			if err == nil {
+				apiPullRequest.Head.Ref = pr.HeadBranch
+				apiPullRequest.Head.Sha = commit.ID.String()
+			}
+		}
+	}
+
+	if len(apiPullRequest.Head.Sha) == 0 && len(apiPullRequest.Head.Ref) != 0 {
+		baseGitRepo, err := git.OpenRepository(ctx, pr.BaseRepo.RepoPath())
+		if err != nil {
+			log.Error("OpenRepository[%s]: %v", pr.BaseRepo.RepoPath(), err)
+			return nil
+		}
+		defer baseGitRepo.Close()
+		refs, err := baseGitRepo.GetRefsFiltered(apiPullRequest.Head.Ref)
+		if err != nil {
+			log.Error("GetRefsFiltered[%s]: %v", apiPullRequest.Head.Ref, err)
+			return nil
+		} else if len(refs) == 0 {
+			log.Error("unable to resolve PR head ref")
+		} else {
+			apiPullRequest.Head.Sha = refs[0].Object.String()
+		}
+	}
+
+	if pr.HasMerged {
+		apiPullRequest.Merged = pr.MergedUnix.AsTimePtr()
+		apiPullRequest.MergedCommitID = &pr.MergedCommitID
+		apiPullRequest.MergedBy = ToUser(pr.Merger, nil)
+	}
+
+	return apiPullRequest
+}