refactor: move act/model and act/exprparser to actions-proto-go

Gitea needs the workflow model and the expression evaluator to parse
workflows and to build the task payload this runner consumes, so it had
to depend on gitea.com/gitea/runner for it. Both packages now live in
gitea.dev/actions-proto-go, the module both sides already share, and this
repository consumes them from there.

The GithubContext helpers that need a git checkout on disk (SetRef,
SetSha and SetRepositoryAndOwner) are not moved: they are runner only and
would drag a git client and the act context logger into the shared
module. They become functions of the new act/ghcontext package, together
with their tests.

act/common.CartesianProduct moved to the shared model package as well,
act/model was its only user. act/model/testdata/container-volumes is now
act/runner/testdata/container-volumes, its only user is runner_test.go.

The x-runner-uuid and x-runner-token header names come from
actions-proto-go too, so the runner and Gitea cannot drift apart.

Signed-off-by: Lunny Xiao <xiaolunwen@gmail.com>

act/ghcontext/github_context.go

@@ -0,0 +1,138 @@
+// Copyright 2022 The Gitea Authors. All rights reserved.
+// Copyright 2021 The nektos/act Authors. All rights reserved.
+// SPDX-License-Identifier: MIT
+
+// Package ghcontext fills a model.GithubContext from the local git checkout.
+// The pure data parts of the context live in the shared
+// gitea.dev/actions-proto-go/pkg/model package, only the helpers that need a
+// git repository on disk are kept here.
+package ghcontext
+
+import (
+	"context"
+	"fmt"
+	"strings"
+
+	"gitea.com/gitea/runner/act/common"
+	"gitea.com/gitea/runner/act/common/git"
+
+	"gitea.dev/actions-proto-go/pkg/model"
+)
+
+var (
+	findGitRef      = git.FindGitRef
+	findGitRevision = git.FindGitRevision
+	findGithubRepo  = git.FindGithubRepo
+)
+
+func withDefaultBranch(ctx context.Context, b string, event map[string]any) map[string]any {
+	repoI, ok := event["repository"]
+	if !ok {
+		repoI = make(map[string]any)
+	}
+
+	repo, ok := repoI.(map[string]any)
+	if !ok {
+		common.Logger(ctx).Warnf("unable to set default branch to %v", b)
+		return event
+	}
+
+	// if the branch is already there return with no changes
+	if _, ok = repo["default_branch"]; ok {
+		return event
+	}
+
+	repo["default_branch"] = b
+	event["repository"] = repo
+
+	return event
+}
+
+// SetRef resolves the ref of the context from its event payload, falling back
+// to the ref checked out in repoPath.
+func SetRef(ctx context.Context, ghc *model.GithubContext, defaultBranch, repoPath string) {
+	logger := common.Logger(ctx)
+
+	// https://docs.github.com/en/actions/learn-github-actions/events-that-trigger-workflows
+	// https://docs.github.com/en/developers/webhooks-and-events/webhooks/webhook-events-and-payloads
+	switch ghc.EventName {
+	case "pull_request_target":
+		ghc.Ref = "refs/heads/" + ghc.BaseRef
+	case "pull_request", "pull_request_review", "pull_request_review_comment":
+		ghc.Ref = fmt.Sprintf("refs/pull/%.0f/merge", ghc.Event["number"])
+	case "deployment", "deployment_status":
+		ghc.Ref = model.AsString(model.NestedMapLookup(ghc.Event, "deployment", "ref"))
+	case "release":
+		ghc.Ref = "refs/tags/" + model.AsString(model.NestedMapLookup(ghc.Event, "release", "tag_name"))
+	case "push", "create", "workflow_dispatch":
+		ghc.Ref = model.AsString(ghc.Event["ref"])
+	default:
+		defaultBranch := model.AsString(model.NestedMapLookup(ghc.Event, "repository", "default_branch"))
+		if defaultBranch != "" {
+			ghc.Ref = "refs/heads/" + defaultBranch
+		}
+	}
+
+	if ghc.Ref == "" {
+		ref, err := findGitRef(ctx, repoPath)
+		if err != nil {
+			logger.Warningf("unable to get git ref: %v", err)
+		} else {
+			logger.Debugf("using github ref: %s", ref)
+			ghc.Ref = ref
+		}
+
+		// set the branch in the event data
+		if defaultBranch != "" {
+			ghc.Event = withDefaultBranch(ctx, defaultBranch, ghc.Event)
+		} else {
+			ghc.Event = withDefaultBranch(ctx, "master", ghc.Event)
+		}
+
+		if ghc.Ref == "" {
+			ghc.Ref = "refs/heads/" + model.AsString(model.NestedMapLookup(ghc.Event, "repository", "default_branch"))
+		}
+	}
+}
+
+// SetSha resolves the commit of the context from its event payload, falling
+// back to the revision checked out in repoPath.
+func SetSha(ctx context.Context, ghc *model.GithubContext, repoPath string) {
+	logger := common.Logger(ctx)
+
+	// https://docs.github.com/en/actions/learn-github-actions/events-that-trigger-workflows
+	// https://docs.github.com/en/developers/webhooks-and-events/webhooks/webhook-events-and-payloads
+	switch ghc.EventName {
+	case "pull_request_target":
+		ghc.Sha = model.AsString(model.NestedMapLookup(ghc.Event, "pull_request", "base", "sha"))
+	case "deployment", "deployment_status":
+		ghc.Sha = model.AsString(model.NestedMapLookup(ghc.Event, "deployment", "sha"))
+	case "push", "create", "workflow_dispatch":
+		if deleted, ok := ghc.Event["deleted"].(bool); ok && !deleted {
+			ghc.Sha = model.AsString(ghc.Event["after"])
+		}
+	}
+
+	if ghc.Sha == "" {
+		_, sha, err := findGitRevision(ctx, repoPath)
+		if err != nil {
+			logger.Warningf("unable to get git revision: %v", err)
+		} else {
+			ghc.Sha = sha
+		}
+	}
+}
+
+// SetRepositoryAndOwner resolves the repository of the context from the git
+// remote in repoPath when it is not set yet, and derives its owner.
+func SetRepositoryAndOwner(ctx context.Context, ghc *model.GithubContext, githubInstance, remoteName, repoPath string) {
+	if ghc.Repository == "" {
+		repo, err := findGithubRepo(ctx, repoPath, githubInstance, remoteName)
+		if err != nil {
+			common.Logger(ctx).Warningf("unable to get git repo (githubInstance: %v; remoteName: %v, repoPath: %v): %v", githubInstance, remoteName, repoPath, err)
+			return
+		}
+		ghc.Repository = repo
+	}
+	ghc.RepositoryOwner = strings.Split(ghc.Repository, "/")[0]
+}