Implement actions (#21937)

Close #13539.

Co-authored by: @lunny @appleboy @fuxiaohei and others.

Related projects:
- https://gitea.com/gitea/actions-proto-def
- https://gitea.com/gitea/actions-proto-go
- https://gitea.com/gitea/act
- https://gitea.com/gitea/act_runner

### Summary

The target of this PR is to bring a basic implementation of "Actions",
an internal CI/CD system of Gitea. That means even though it has been
merged, the state of the feature is **EXPERIMENTAL**, and please note
that:

- It is disabled by default;
- It shouldn't be used in a production environment currently;
- It shouldn't be used in a public Gitea instance currently;
- Breaking changes may be made before it's stable.

**Please comment on #13539 if you have any different product design
ideas**, all decisions reached there will be adopted here. But in this
PR, we don't talk about **naming, feature-creep or alternatives**.

### ⚠️ Breaking

`gitea-actions` will become a reserved user name. If a user with the
name already exists in the database, it is recommended to rename it.

### Some important reviews

- What is `DEFAULT_ACTIONS_URL` in `app.ini` for?
  - https://github.com/go-gitea/gitea/pull/21937#discussion_r1055954954
- Why the api for runners is not under the normal `/api/v1` prefix?
  - https://github.com/go-gitea/gitea/pull/21937#discussion_r1061173592
- Why DBFS?
  - https://github.com/go-gitea/gitea/pull/21937#discussion_r1061301178
- Why ignore events triggered by `gitea-actions` bot?
  - https://github.com/go-gitea/gitea/pull/21937#discussion_r1063254103
- Why there's no permission control for actions?
  - https://github.com/go-gitea/gitea/pull/21937#discussion_r1090229868

### What it looks like

<details>

#### Manage runners

<img width="1792" alt="image"
src="https://user-images.githubusercontent.com/9418365/205870657-c72f590e-2e08-4cd4-be7f-2e0abb299bbf.png">

#### List runs

<img width="1792" alt="image"
src="https://user-images.githubusercontent.com/9418365/205872794-50fde990-2b45-48c1-a178-908e4ec5b627.png">


#### View logs

<img width="1792" alt="image"
src="https://user-images.githubusercontent.com/9418365/205872501-9b7b9000-9542-4991-8f55-18ccdada77c3.png">



</details>

### How to try it

<details>

#### 1. Start Gitea

Clone this branch and [install from
source](https://docs.gitea.io/en-us/install-from-source).

Add additional configurations in `app.ini` to enable Actions:

```ini
[actions]
ENABLED = true
```

Start it.

If all is well, you'll see the management page of runners:

<img width="1792" alt="image"
src="https://user-images.githubusercontent.com/9418365/205877365-8e30a780-9b10-4154-b3e8-ee6c3cb35a59.png">


#### 2. Start runner

Clone the [act_runner](https://gitea.com/gitea/act_runner), and follow
the
[README](https://gitea.com/gitea/act_runner/src/branch/main/README.md)
to start it.

If all is well, you'll see a new runner has been added:

<img width="1792" alt="image"
src="https://user-images.githubusercontent.com/9418365/205878000-216f5937-e696-470d-b66c-8473987d91c3.png">

#### 3. Enable actions for a repo

Create a new repo or open an existing one, check the `Actions` checkbox
in settings and submit.

<img width="1792" alt="image"
src="https://user-images.githubusercontent.com/9418365/205879705-53e09208-73c0-4b3e-a123-2dcf9aba4b9c.png">
<img width="1792" alt="image"
src="https://user-images.githubusercontent.com/9418365/205879383-23f3d08f-1a85-41dd-a8b3-54e2ee6453e8.png">

If all is well, you'll see a new tab "Actions":

<img width="1792" alt="image"
src="https://user-images.githubusercontent.com/9418365/205881648-a8072d8c-5803-4d76-b8a8-9b2fb49516c1.png">

#### 4. Upload workflow files

Upload some workflow files to `.gitea/workflows/xxx.yaml`, you can
follow the [quickstart](https://docs.github.com/en/actions/quickstart)
of GitHub Actions. Yes, Gitea Actions is compatible with GitHub Actions
in most cases, you can use the same demo:

```yaml
name: GitHub Actions Demo
run-name: ${{ github.actor }} is testing out GitHub Actions 🚀
on: [push]
jobs:
  Explore-GitHub-Actions:
    runs-on: ubuntu-latest
    steps:
      - run: echo "🎉 The job was automatically triggered by a ${{ github.event_name }} event."
      - run: echo "🐧 This job is now running on a ${{ runner.os }} server hosted by GitHub!"
      - run: echo "🔎 The name of your branch is ${{ github.ref }} and your repository is ${{ github.repository }}."
      - name: Check out repository code
        uses: actions/checkout@v3
      - run: echo "💡 The ${{ github.repository }} repository has been cloned to the runner."
      - run: echo "🖥️ The workflow is now ready to test your code on the runner."
      - name: List files in the repository
        run: |
          ls ${{ github.workspace }}
      - run: echo "🍏 This job's status is ${{ job.status }}."
```

If all is well, you'll see a new run in `Actions` tab:

<img width="1792" alt="image"
src="https://user-images.githubusercontent.com/9418365/205884473-79a874bc-171b-4aaf-acd5-0241a45c3b53.png">

#### 5. Check the logs of jobs

Click a run and you'll see the logs:

<img width="1792" alt="image"
src="https://user-images.githubusercontent.com/9418365/205884800-994b0374-67f7-48ff-be9a-4c53f3141547.png">

#### 6. Go on

You can try more examples in [the
documents](https://docs.github.com/en/actions/using-workflows/workflow-syntax-for-github-actions)
of GitHub Actions, then you might find a lot of bugs.

Come on, PRs are welcome.

</details>

See also: [Feature Preview: Gitea
Actions](https://blog.gitea.io/2022/12/feature-preview-gitea-actions/)

---------

Co-authored-by: a1012112796 <1012112796@qq.com>
Co-authored-by: Lunny Xiao <xiaolunwen@gmail.com>
Co-authored-by: delvh <dev.lh@web.de>
Co-authored-by: ChristopherHX <christopher.homberger@web.de>
Co-authored-by: John Olheiser <john.olheiser@gmail.com>

6 files changed, 38 insertions, 37 deletions

diff --git a/models/issues/comment.go b/models/issues/comment.go
index 91dc128277..9ad538fcc6 100644
--- a/models/issues/comment.go
+++ b/models/issues/comment.go
@@ -355,7 +355,7 @@ func (c *Comment) LoadPoster(ctx context.Context) (err error) {
 		return nil
 	}
 
-	c.Poster, err = user_model.GetUserByID(ctx, c.PosterID)
+	c.Poster, err = user_model.GetPossibleUserByID(ctx, c.PosterID)
 	if err != nil {
 		if user_model.IsErrUserNotExist(err) {
 			c.PosterID = -1
diff --git a/models/issues/comment_list.go b/models/issues/comment_list.go
index 2b55bc212f..0411d44531 100644
--- a/models/issues/comment_list.go
+++ b/models/issues/comment_list.go
@@ -29,32 +29,13 @@ func (comments CommentList) LoadPosters(ctx context.Context) error {
 		return nil
 	}
 
-	posterIDs := comments.getPosterIDs()
-	posterMaps := make(map[int64]*user_model.User, len(posterIDs))
-	left := len(posterIDs)
-	for left > 0 {
-		limit := db.DefaultMaxInSize
-		if left < limit {
-			limit = left
-		}
-		err := db.GetEngine(ctx).
-			In("id", posterIDs[:limit]).
-			Find(&posterMaps)
-		if err != nil {
-			return err
-		}
-		left -= limit
-		posterIDs = posterIDs[limit:]
+	posterMaps, err := getPosters(ctx, comments.getPosterIDs())
+	if err != nil {
+		return err
 	}
 
 	for _, comment := range comments {
-		if comment.PosterID <= 0 {
-			continue
-		}
-		var ok bool
-		if comment.Poster, ok = posterMaps[comment.PosterID]; !ok {
-			comment.Poster = user_model.NewGhostUser()
-		}
+		comment.Poster = getPoster(comment.PosterID, posterMaps)
 	}
 	return nil
 }
diff --git a/models/issues/issue.go b/models/issues/issue.go
index 50c9b77119..78cac90052 100644
--- a/models/issues/issue.go
+++ b/models/issues/issue.go
@@ -235,7 +235,7 @@ func (issue *Issue) LoadLabels(ctx context.Context) (err error) {
 // LoadPoster loads poster
 func (issue *Issue) LoadPoster(ctx context.Context) (err error) {
 	if issue.Poster == nil {
-		issue.Poster, err = user_model.GetUserByID(ctx, issue.PosterID)
+		issue.Poster, err = user_model.GetPossibleUserByID(ctx, issue.PosterID)
 		if err != nil {
 			issue.PosterID = -1
 			issue.Poster = user_model.NewGhostUser()
diff --git a/models/issues/issue_list.go b/models/issues/issue_list.go
index e22e48c0bb..6ddadd27ed 100644
--- a/models/issues/issue_list.go
+++ b/models/issues/issue_list.go
@@ -86,7 +86,18 @@ func (issues IssueList) loadPosters(ctx context.Context) error {
 		return nil
 	}
 
-	posterIDs := issues.getPosterIDs()
+	posterMaps, err := getPosters(ctx, issues.getPosterIDs())
+	if err != nil {
+		return err
+	}
+
+	for _, issue := range issues {
+		issue.Poster = getPoster(issue.PosterID, posterMaps)
+	}
+	return nil
+}
+
+func getPosters(ctx context.Context, posterIDs []int64) (map[int64]*user_model.User, error) {
 	posterMaps := make(map[int64]*user_model.User, len(posterIDs))
 	left := len(posterIDs)
 	for left > 0 {
@@ -98,22 +109,26 @@ func (issues IssueList) loadPosters(ctx context.Context) error {
 			In("id", posterIDs[:limit]).
 			Find(&posterMaps)
 		if err != nil {
-			return err
+			return nil, err
 		}
 		left -= limit
 		posterIDs = posterIDs[limit:]
 	}
+	return posterMaps, nil
+}
 
-	for _, issue := range issues {
-		if issue.PosterID <= 0 {
-			continue
-		}
-		var ok bool
-		if issue.Poster, ok = posterMaps[issue.PosterID]; !ok {
-			issue.Poster = user_model.NewGhostUser()
-		}
+func getPoster(posterID int64, posterMaps map[int64]*user_model.User) *user_model.User {
+	if posterID == user_model.ActionsUserID {
+		return user_model.NewActionsUser()
 	}
-	return nil
+	if posterID <= 0 {
+		return nil
+	}
+	poster, ok := posterMaps[posterID]
+	if !ok {
+		return user_model.NewGhostUser()
+	}
+	return poster
 }
 
 func (issues IssueList) getIssueIDs() []int64 {
diff --git a/models/issues/pull.go b/models/issues/pull.go
index 93b227f3fd..6ff6502e4e 100644
--- a/models/issues/pull.go
+++ b/models/issues/pull.go
@@ -394,6 +394,11 @@ func (pr *PullRequest) IsAncestor() bool {
 	return pr.Status == PullRequestStatusAncestor
 }
 
+// IsFromFork return true if this PR is from a fork.
+func (pr *PullRequest) IsFromFork() bool {
+	return pr.HeadRepoID != pr.BaseRepoID
+}
+
 // SetMerged sets a pull request to merged and closes the corresponding issue
 func (pr *PullRequest) SetMerged(ctx context.Context) (bool, error) {
 	if pr.HasMerged {
diff --git a/models/issues/review.go b/models/issues/review.go
index 7e1a39bb5b..fe123d7398 100644
--- a/models/issues/review.go
+++ b/models/issues/review.go
@@ -158,7 +158,7 @@ func (r *Review) LoadReviewer(ctx context.Context) (err error) {
 	if r.ReviewerID == 0 || r.Reviewer != nil {
 		return
 	}
-	r.Reviewer, err = user_model.GetUserByID(ctx, r.ReviewerID)
+	r.Reviewer, err = user_model.GetPossibleUserByID(ctx, r.ReviewerID)
 	return err
 }