feat: support evaluation of concurrency clauses in runner (#827)

Pre-req for support `concurrency` clauses for Gitea Actions, later added to Gitea in PR: https://github.com/go-gitea/gitea/pull/32751. Unit tests added in this PR relative to upstream.

Squashes PRs https://gitea.com/gitea/act/pulls/124 & https://gitea.com/gitea/act/pulls/139, as noted in https://code.forgejo.org/forgejo/runner/issues/678

Reviewed-on: https://gitea.com/gitea/act/pulls/124
Reviewed-by: Lunny Xiao <lunny@noreply.gitea.com>
Co-authored-by: Zettat123 <zettat123@gmail.com>
Co-committed-by: Zettat123 <zettat123@gmail.com>
Reviewed-on: https://gitea.com/gitea/act/pulls/139
Reviewed-by: Zettat123 <zettat123@noreply.gitea.com>
Reviewed-by: Lunny Xiao <xiaolunwen@gmail.com>
Co-authored-by: ChristopherHX <christopher.homberger@web.de>
Co-committed-by: ChristopherHX <christopher.homberger@web.de>

<!--start release-notes-assistant-->
<!--URL:https://code.forgejo.org/forgejo/runner-->
- features
  - [PR](https://code.forgejo.org/forgejo/runner/pulls/827): <!--number 827 --><!--line 0 --><!--description ZmVhdDogc3VwcG9ydCBldmFsdWF0aW9uIG9mIGNvbmN1cnJlbmN5IGNsYXVzZXMgaW4gcnVubmVy-->feat: support evaluation of concurrency clauses in runner<!--description-->
<!--end release-notes-assistant-->

Reviewed-on: https://code.forgejo.org/forgejo/runner/pulls/827
Reviewed-by: earl-warren <earl-warren@noreply.code.forgejo.org>
Co-authored-by: Mathieu Fenniak <mathieu@fenniak.net>
Co-committed-by: Mathieu Fenniak <mathieu@fenniak.net>

act/jobparser/model.go

@@ -1,6 +1,7 @@
 package jobparser
 
 import (
+	"bytes"
 	"fmt"
 
 	"code.forgejo.org/forgejo/runner/v9/act/model"
@@ -82,6 +83,7 @@ type Job struct {
 	Uses           string                    `yaml:"uses,omitempty"`
 	With           map[string]interface{}    `yaml:"with,omitempty"`
 	RawSecrets     yaml.Node                 `yaml:"secrets,omitempty"`
+	RawConcurrency *model.RawConcurrency     `yaml:"concurrency,omitempty"`
 }
 
 func (j *Job) Clone() *Job {
@@ -104,6 +106,7 @@ func (j *Job) Clone() *Job {
 		Uses:           j.Uses,
 		With:           j.With,
 		RawSecrets:     j.RawSecrets,
+		RawConcurrency: j.RawConcurrency,
 	}
 }
 
@@ -190,6 +193,85 @@ func (evt *Event) Schedules() []map[string]string {
 	return evt.schedules
 }
 
+func ReadWorkflowRawConcurrency(content []byte) (*model.RawConcurrency, error) {
+	w := new(model.Workflow)
+	err := yaml.NewDecoder(bytes.NewReader(content)).Decode(w)
+	return w.RawConcurrency, err
+}
+
+func EvaluateConcurrency(rc *model.RawConcurrency, jobID string, job *Job, gitCtx map[string]any, results map[string]*JobResult, vars map[string]string, inputs map[string]any) (string, bool, error) {
+	actJob := &model.Job{}
+	if job != nil {
+		actJob.Strategy = &model.Strategy{
+			FailFastString:    job.Strategy.FailFastString,
+			MaxParallelString: job.Strategy.MaxParallelString,
+			RawMatrix:         job.Strategy.RawMatrix,
+		}
+		actJob.Strategy.FailFast = actJob.Strategy.GetFailFast()
+		actJob.Strategy.MaxParallel = actJob.Strategy.GetMaxParallel()
+	}
+
+	matrix := make(map[string]any)
+	matrixes, err := actJob.GetMatrixes()
+	if err != nil {
+		return "", false, err
+	}
+	if len(matrixes) > 0 {
+		matrix = matrixes[0]
+	}
+
+	evaluator := NewExpressionEvaluator(NewInterpeter(jobID, actJob, matrix, toGitContext(gitCtx), results, vars, inputs))
+	var node yaml.Node
+	if err := node.Encode(rc); err != nil {
+		return "", false, fmt.Errorf("failed to encode concurrency: %w", err)
+	}
+	if err := evaluator.EvaluateYamlNode(&node); err != nil {
+		return "", false, fmt.Errorf("failed to evaluate concurrency: %w", err)
+	}
+	var evaluated model.RawConcurrency
+	if err := node.Decode(&evaluated); err != nil {
+		return "", false, fmt.Errorf("failed to unmarshal evaluated concurrency: %w", err)
+	}
+	if evaluated.RawExpression != "" {
+		return evaluated.RawExpression, false, nil
+	}
+	return evaluated.Group, evaluated.CancelInProgress == "true", nil
+}
+
+func toGitContext(input map[string]any) *model.GithubContext {
+	gitContext := &model.GithubContext{
+		EventPath:        asString(input["event_path"]),
+		Workflow:         asString(input["workflow"]),
+		RunID:            asString(input["run_id"]),
+		RunNumber:        asString(input["run_number"]),
+		Actor:            asString(input["actor"]),
+		Repository:       asString(input["repository"]),
+		EventName:        asString(input["event_name"]),
+		Sha:              asString(input["sha"]),
+		Ref:              asString(input["ref"]),
+		RefName:          asString(input["ref_name"]),
+		RefType:          asString(input["ref_type"]),
+		HeadRef:          asString(input["head_ref"]),
+		BaseRef:          asString(input["base_ref"]),
+		Token:            asString(input["token"]),
+		Workspace:        asString(input["workspace"]),
+		Action:           asString(input["action"]),
+		ActionPath:       asString(input["action_path"]),
+		ActionRef:        asString(input["action_ref"]),
+		ActionRepository: asString(input["action_repository"]),
+		Job:              asString(input["job"]),
+		RepositoryOwner:  asString(input["repository_owner"]),
+		RetentionDays:    asString(input["retention_days"]),
+	}
+
+	event, ok := input["event"].(map[string]any)
+	if ok {
+		gitContext.Event = event
+	}
+
+	return gitContext
+}
+
 func ParseRawOn(rawOn *yaml.Node) ([]*Event, error) {
 	switch rawOn.Kind {
 	case yaml.ScalarNode:
@@ -348,3 +430,12 @@ func parseMappingNode[T any](node *yaml.Node) ([]string, []T, error) {
 
 	return scalars, datas, nil
 }
+
+func asString(v interface{}) string {
+	if v == nil {
+		return ""
+	} else if s, ok := v.(string); ok {
+		return s
+	}
+	return ""
+}