Implement actions badge svgs (#28102)

replace #27187 
close #23688
The badge has two parts: label(workflow name) and message(action
status). 5 colors are provided with 7 statuses.
Color mapping:
```go
var statusColorMap = map[actions_model.Status]string{
	actions_model.StatusSuccess:   "#4c1",    // Green
	actions_model.StatusSkipped:   "#dfb317", // Yellow
	actions_model.StatusUnknown:   "#97ca00", // Light Green
	actions_model.StatusFailure:   "#e05d44", // Red
	actions_model.StatusCancelled: "#fe7d37", // Orange
	actions_model.StatusWaiting:   "#dfb317", // Yellow
	actions_model.StatusRunning:   "#dfb317", // Yellow
	actions_model.StatusBlocked:   "#dfb317", // Yellow
}
```
preview:

![1](https://github.com/go-gitea/gitea/assets/70063547/5465cbaf-23cd-4437-9848-2738c3cb8985)

![2](https://github.com/go-gitea/gitea/assets/70063547/ec393d26-c6e6-4d38-b72c-51f2494c5e71)

![3](https://github.com/go-gitea/gitea/assets/70063547/3edb4fdf-1b08-4a02-ab2a-6bdd7f532fb2)

![4](https://github.com/go-gitea/gitea/assets/70063547/8c189de2-2169-4251-b115-0e39a52f3df8)

![5](https://github.com/go-gitea/gitea/assets/70063547/3fe22c73-c2d7-4fec-9ea4-c501a1e4e3bd)

---------

Co-authored-by: Lunny Xiao <xiaolunwen@gmail.com>
Co-authored-by: Giteabot <teabot@gitea.io>
Co-authored-by: delvh <dev.lh@web.de>

6 files changed, 242 insertions, 0 deletions

diff --git a/docs/content/usage/badge.en-us.md b/docs/content/usage/badge.en-us.md
new file mode 100644
index 0000000000..212134e01c
--- /dev/null
+++ b/docs/content/usage/badge.en-us.md
@@ -0,0 +1,37 @@
+---
+date: "2023-02-25T00:00:00+00:00"
+title: "Badge"
+slug: "badge"
+sidebar_position: 11
+toc: false
+draft: false
+aliases:
+  - /en-us/badge
+menu:
+  sidebar:
+    parent: "usage"
+    name: "Badge"
+    sidebar_position: 11
+    identifier: "Badge"
+---
+
+# Badge
+
+Gitea has its builtin Badge system which allows you to display the status of your repository in other places. You can use the following badges:
+
+## Workflow Badge
+
+The Gitea Actions workflow badge is a badge that shows the status of the latest workflow run.
+It is designed to be compatible with [GitHub Actions workflow badge](https://docs.github.com/en/actions/monitoring-and-troubleshooting-workflows/adding-a-workflow-status-badge).
+
+You can use the following URL to get the badge:
+
+```
+https://your-gitea-instance.com/{owner}/{repo}/actions/workflows/{workflow_file}?branch={branch}&event={event}
+```
+
+- `{owner}`: The owner of the repository.
+- `{repo}`: The name of the repository.
+- `{workflow_file}`: The name of the workflow file.
+- `{branch}`: Optional. The branch of the workflow. Default to your repository's default branch.
+- `{event}`: Optional. The event of the workflow. Default to none.
diff --git a/models/actions/run.go b/models/actions/run.go
index fcac58d515..7b3125949b 100644
--- a/models/actions/run.go
+++ b/models/actions/run.go
@@ -339,6 +339,23 @@ func GetRunByIndex(ctx context.Context, repoID, index int64) (*ActionRun, error)
 	return run, nil
 }
 
+func GetWorkflowLatestRun(ctx context.Context, repoID int64, workflowFile, branch, event string) (*ActionRun, error) {
+	var run ActionRun
+	q := db.GetEngine(ctx).Where("repo_id=?", repoID).
+		And("ref = ?", branch).
+		And("workflow_id = ?", workflowFile)
+	if event != "" {
+		q.And("event = ?", event)
+	}
+	has, err := q.Desc("id").Get(&run)
+	if err != nil {
+		return nil, err
+	} else if !has {
+		return nil, util.NewNotExistErrorf("run with repo_id %d, ref %s, workflow_id %s", repoID, branch, workflowFile)
+	}
+	return &run, nil
+}
+
 // UpdateRun updates a run.
 // It requires the inputted run has Version set.
 // It will return error if the version is not matched (it means the run has been changed after loaded).
diff --git a/modules/badge/badge.go b/modules/badge/badge.go
new file mode 100644
index 0000000000..b30d0b4729
--- /dev/null
+++ b/modules/badge/badge.go
@@ -0,0 +1,104 @@
+// Copyright 2024 The Gitea Authors. All rights reserved.
+// SPDX-License-Identifier: MIT
+
+package badge
+
+import (
+	actions_model "code.gitea.io/gitea/models/actions"
+)
+
+// The Badge layout: |offset|label|message|
+// We use 10x scale to calculate more precisely
+// Then scale down to normal size in tmpl file
+
+type Label struct {
+	text  string
+	width int
+}
+
+func (l Label) Text() string {
+	return l.text
+}
+
+func (l Label) Width() int {
+	return l.width
+}
+
+func (l Label) TextLength() int {
+	return int(float64(l.width-defaultOffset) * 9.5)
+}
+
+func (l Label) X() int {
+	return l.width*5 + 10
+}
+
+type Message struct {
+	text  string
+	width int
+	x     int
+}
+
+func (m Message) Text() string {
+	return m.text
+}
+
+func (m Message) Width() int {
+	return m.width
+}
+
+func (m Message) X() int {
+	return m.x
+}
+
+func (m Message) TextLength() int {
+	return int(float64(m.width-defaultOffset) * 9.5)
+}
+
+type Badge struct {
+	Color    string
+	FontSize int
+	Label    Label
+	Message  Message
+}
+
+func (b Badge) Width() int {
+	return b.Label.width + b.Message.width
+}
+
+const (
+	defaultOffset    = 9
+	defaultFontSize  = 11
+	DefaultColor     = "#9f9f9f" // Grey
+	defaultFontWidth = 7         // approximate speculation
+)
+
+var StatusColorMap = map[actions_model.Status]string{
+	actions_model.StatusSuccess:   "#4c1",    // Green
+	actions_model.StatusSkipped:   "#dfb317", // Yellow
+	actions_model.StatusUnknown:   "#97ca00", // Light Green
+	actions_model.StatusFailure:   "#e05d44", // Red
+	actions_model.StatusCancelled: "#fe7d37", // Orange
+	actions_model.StatusWaiting:   "#dfb317", // Yellow
+	actions_model.StatusRunning:   "#dfb317", // Yellow
+	actions_model.StatusBlocked:   "#dfb317", // Yellow
+}
+
+// GenerateBadge generates badge with given template
+func GenerateBadge(label, message, color string) Badge {
+	lw := defaultFontWidth*len(label) + defaultOffset
+	mw := defaultFontWidth*len(message) + defaultOffset
+	x := lw*10 + mw*5 - 10
+	return Badge{
+		Label: Label{
+			text:  label,
+			width: lw,
+		},
+		Message: Message{
+			text:  message,
+			width: mw,
+			x:     x,
+		},
+		FontSize: defaultFontSize * 10,
+		Color:    color,
+	}
+}
diff --git a/routers/web/repo/actions/badge.go b/routers/web/repo/actions/badge.go
new file mode 100644
index 0000000000..6fa951826c
--- /dev/null
+++ b/routers/web/repo/actions/badge.go
@@ -0,0 +1,56 @@
+// Copyright 2024 The Gitea Authors. All rights reserved.
+// SPDX-License-Identifier: MIT
+
+package actions
+
+import (
+	"errors"
+	"fmt"
+	"net/http"
+	"path/filepath"
+	"strings"
+
+	actions_model "code.gitea.io/gitea/models/actions"
+	"code.gitea.io/gitea/modules/badge"
+	"code.gitea.io/gitea/modules/util"
+	"code.gitea.io/gitea/services/context"
+)
+
+func GetWorkflowBadge(ctx *context.Context) {
+	workflowFile := ctx.Params("workflow_name")
+	branch := ctx.Req.URL.Query().Get("branch")
+	if branch == "" {
+		branch = ctx.Repo.Repository.DefaultBranch
+	}
+	branchRef := fmt.Sprintf("refs/heads/%s", branch)
+	event := ctx.Req.URL.Query().Get("event")
+
+	badge, err := getWorkflowBadge(ctx, workflowFile, branchRef, event)
+	if err != nil {
+		ctx.ServerError("GetWorkflowBadge", err)
+		return
+	}
+
+	ctx.Data["Badge"] = badge
+	ctx.RespHeader().Set("Content-Type", "image/svg+xml")
+	ctx.HTML(http.StatusOK, "shared/actions/runner_badge")
+}
+
+func getWorkflowBadge(ctx *context.Context, workflowFile, branchName, event string) (badge.Badge, error) {
+	extension := filepath.Ext(workflowFile)
+	workflowName := strings.TrimSuffix(workflowFile, extension)
+
+	run, err := actions_model.GetWorkflowLatestRun(ctx, ctx.Repo.Repository.ID, workflowFile, branchName, event)
+	if err != nil {
+		if errors.Is(err, util.ErrNotExist) {
+			return badge.GenerateBadge(workflowName, "no status", badge.DefaultColor), nil
+		}
+		return badge.Badge{}, err
+	}
+
+	color, ok := badge.StatusColorMap[run.Status]
+	if !ok {
+		return badge.GenerateBadge(workflowName, "unknown status", badge.DefaultColor), nil
+	}
+	return badge.GenerateBadge(workflowName, run.Status.String(), color), nil
+}
diff --git a/routers/web/web.go b/routers/web/web.go
index 452998703a..b6dd9500c8 100644
--- a/routers/web/web.go
+++ b/routers/web/web.go
@@ -1371,6 +1371,9 @@ func registerRoutes(m *web.Route) {
 				m.Delete("/artifacts/{artifact_name}", actions.ArtifactsDeleteView)
 				m.Post("/rerun", reqRepoActionsWriter, actions.Rerun)
 			})
+			m.Group("/workflows/{workflow_name}", func() {
+				m.Get("/badge.svg", actions.GetWorkflowBadge)
+			})
 		}, reqRepoActionsReader, actions.MustEnableActions)
 
 		m.Group("/wiki", func() {
diff --git a/templates/shared/actions/runner_badge.tmpl b/templates/shared/actions/runner_badge.tmpl
new file mode 100644
index 0000000000..816e87e177
--- /dev/null
+++ b/templates/shared/actions/runner_badge.tmpl
@@ -0,0 +1,25 @@
+<svg xmlns="http://www.w3.org/2000/svg" xmlns:xlink="http://www.w3.org/1999/xlink" width="{{.Badge.Width}}" height="18"
+	role="img" aria-label="{{.Badge.Label.Text}}: {{.Badge.Message.Text}}">
+	<title>{{.Badge.Label.Text}}: {{.Badge.Message.Text}}</title>
+	<linearGradient id="s" x2="0" y2="100%">
+		<stop offset="0" stop-color="#fff" stop-opacity=".7" />
+		<stop offset=".1" stop-color="#aaa" stop-opacity=".1" />
+		<stop offset=".9" stop-color="#000" stop-opacity=".3" />
+		<stop offset="1" stop-color="#000" stop-opacity=".5" />
+	</linearGradient>
+	<clipPath id="r">
+		<rect width="{{.Badge.Width}}" height="18" rx="4" fill="#fff" />
+	</clipPath>
+	<g clip-path="url(#r)">
+		<rect width="{{.Badge.Label.Width}}" height="18" fill="#555" />
+		<rect x="{{.Badge.Label.Width}}" width="{{.Badge.Message.Width}}" height="18" fill="{{.Badge.Color}}" />
+		<rect width="{{.Badge.Width}}" height="18" fill="url(#s)" />
+	</g>
+	<g fill="#fff" text-anchor="middle" font-family="Geneva,DejaVu Sans,sans-serif" text-rendering="geometricPrecision"
+		font-size="{{.Badge.FontSize}}"><text aria-hidden="true" x="{{.Badge.Label.X}}" y="140" fill="#010101" fill-opacity=".3"
+			transform="scale(.1)" textLength="{{.Badge.Label.TextLength}}">{{.Badge.Label.Text}}</text><text x="{{.Badge.Label.X}}" y="130"
+			transform="scale(.1)" fill="#fff" textLength="{{.Badge.Label.TextLength}}">{{.Badge.Label.Text}}</text><text aria-hidden="true"
+			x="{{.Badge.Message.X}}" y="140" fill="#010101" fill-opacity=".3" transform="scale(.1)"
+			textLength="{{.Badge.Message.TextLength}}">{{.Badge.Message.Text}}</text><text x="{{.Badge.Message.X}}" y="130" transform="scale(.1)"
+			fill="#fff" textLength="{{.Badge.Message.TextLength}}">{{.Badge.Message.Text}}</text></g>
+</svg>