Add API to get/edit wiki (#17278)

* Add API to get/edit wiki

* Add swagger docs, various improvements

* fmt

* Fix lint and rm comment

* Add page parameter

* Add pagination to pages

* Add tests

* fmt

* Update func names

* Update error handling

* Update type name

* Fix lint

* Don't delete Home

* Update func name

* Update routers/api/v1/repo/wiki.go

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

* Remove unnecessary check

* Fix lint

* Use English strings

* Update integrations/api_wiki_test.go

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

* Update func and test names

* Remove unsed check and avoid duplicated error reports

* Improve error handling

* Return after error

* Document 404 error

* Update swagger

* Fix lint

* Apply suggestions from code review

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

* Document file encoding

* fmt

* Apply suggestions

* Use convert

* Fix integration test

* simplify permissions

* unify duplicate key Title/Name

* improve types & return UTC timestamps

* improve types pt.2

- add WikiPageMetaData.LastCommit
- add WikiPageMetaData.HTMLURL
- replace WikiPageMetaData.Updated with .LastCommit.Committer.Created

also delete convert.ToWikiPage(), as it received too many arguments and
only had one callsite anyway. sorry for bad advice earlier 🙃

* WikiPage.Content is base64 encoded

* simplify error handling in wikiContentsByName()

* update swagger

* fix & DRY findWikiRepoCommit() error handling

ListWikiPages() previously wrote error twice when repo wiki didn't exist

* rename Content -> ContentBase64

* Fix test

* Fix tests

* Update var name

* suburl -> sub_url

Co-authored-by: delvh <dev.lh@web.de>
Co-authored-by: Norwin <git@nroo.de>
Co-authored-by: 6543 <6543@obermui.de>
Co-authored-by: zeripath <art27@cantab.net>
Co-authored-by: wxiaoguang <wxiaoguang@gmail.com>

modules/convert/wiki.go

@@ -0,0 +1,60 @@
+// 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 convert
+
+import (
+	"time"
+
+	"code.gitea.io/gitea/models"
+	"code.gitea.io/gitea/modules/git"
+	api "code.gitea.io/gitea/modules/structs"
+	"code.gitea.io/gitea/modules/util"
+	wiki_service "code.gitea.io/gitea/services/wiki"
+)
+
+// ToWikiCommit convert a git commit into a WikiCommit
+func ToWikiCommit(commit *git.Commit) *api.WikiCommit {
+	return &api.WikiCommit{
+		ID: commit.ID.String(),
+		Author: &api.CommitUser{
+			Identity: api.Identity{
+				Name:  commit.Author.Name,
+				Email: commit.Author.Email,
+			},
+			Date: commit.Author.When.UTC().Format(time.RFC3339),
+		},
+		Committer: &api.CommitUser{
+			Identity: api.Identity{
+				Name:  commit.Committer.Name,
+				Email: commit.Committer.Email,
+			},
+			Date: commit.Committer.When.UTC().Format(time.RFC3339),
+		},
+		Message: commit.CommitMessage,
+	}
+}
+
+// ToWikiCommitList convert a list of git commits into a WikiCommitList
+func ToWikiCommitList(commits []*git.Commit, total int64) *api.WikiCommitList {
+	result := make([]*api.WikiCommit, len(commits))
+	for i := range commits {
+		result[i] = ToWikiCommit(commits[i])
+	}
+	return &api.WikiCommitList{
+		WikiCommits: result,
+		Count:       total,
+	}
+}
+
+// ToWikiPageMetaData converts meta information to a WikiPageMetaData
+func ToWikiPageMetaData(title string, lastCommit *git.Commit, repo *models.Repository) *api.WikiPageMetaData {
+	suburl := wiki_service.NameToSubURL(title)
+	return &api.WikiPageMetaData{
+		Title:      title,
+		HTMLURL:    util.URLJoin(repo.HTMLURL(), "wiki", suburl),
+		SubURL:     suburl,
+		LastCommit: ToWikiCommit(lastCommit),
+	}
+}