package runner

import (
	"archive/tar"
	"context"
	"errors"
	"fmt"
	"io"
	"os"
	"path"
	"path/filepath"
	"regexp"
	"strings"

	gogit "github.com/go-git/go-git/v5"

	"github.com/nektos/act/pkg/common"
	"github.com/nektos/act/pkg/common/git"
	"github.com/nektos/act/pkg/model"
)

type stepActionRemote struct {
	Step                *model.Step
	RunContext          *RunContext
	compositeRunContext *RunContext
	compositeSteps      *compositeSteps
	readAction          readAction
	runAction           runAction
	action              *model.Action
	env                 map[string]string
	remoteAction        *remoteAction
	cacheDir            string
	resolvedSha         string
}

var stepActionRemoteNewCloneExecutor = git.NewGitCloneExecutor

func (sar *stepActionRemote) prepareActionExecutor() common.Executor {
	return func(ctx context.Context) error {
		if sar.remoteAction != nil && sar.action != nil {
			// we are already good to run
			return nil
		}

		// For gitea:
		// Since actions can specify the download source via a url prefix.
		// The prefix may contain some sensitive information that needs to be stored in secrets,
		// so we need to interpolate the expression value for uses first.
		sar.Step.Uses = sar.RunContext.NewExpressionEvaluator(ctx).Interpolate(ctx, sar.Step.Uses)

		sar.remoteAction = newRemoteAction(sar.Step.Uses)
		if sar.remoteAction == nil {
			return fmt.Errorf("Expected format {org}/{repo}[/path]@ref. Actual '%s' Input string was not in a correct format", sar.Step.Uses)
		}

		github := sar.getGithubContext(ctx)
		if sar.remoteAction.IsCheckout() && isLocalCheckout(github, sar.Step) && !sar.RunContext.Config.NoSkipCheckout {
			common.Logger(ctx).Debugf("Skipping local actions/checkout because workdir was already copied")
			return nil
		}

		for _, action := range sar.RunContext.Config.ReplaceGheActionWithGithubCom {
			if strings.EqualFold(fmt.Sprintf("%s/%s", sar.remoteAction.Org, sar.remoteAction.Repo), action) {
				sar.remoteAction.URL = "https://github.com"
				github.Token = sar.RunContext.Config.ReplaceGheActionTokenWithGithubCom
			}
		}
		if sar.RunContext.Config.ActionCache != nil {
			cache := sar.RunContext.Config.ActionCache

			var err error
			sar.cacheDir = fmt.Sprintf("%s/%s", sar.remoteAction.Org, sar.remoteAction.Repo)
			repoURL := sar.remoteAction.URL + "/" + sar.cacheDir
			repoRef := sar.remoteAction.Ref
			sar.resolvedSha, err = cache.Fetch(ctx, sar.cacheDir, repoURL, repoRef, github.Token)
			if err != nil {
				return fmt.Errorf("failed to fetch \"%s\" version \"%s\": %w", repoURL, repoRef, err)
			}

			remoteReader := func(ctx context.Context) actionYamlReader {
				return func(filename string) (io.Reader, io.Closer, error) {
					spath := path.Join(sar.remoteAction.Path, filename)
					for i := 0; i < maxSymlinkDepth; i++ {
						tars, err := cache.GetTarArchive(ctx, sar.cacheDir, sar.resolvedSha, spath)
						if err != nil {
							return nil, nil, os.ErrNotExist
						}
						treader := tar.NewReader(tars)
						header, err := treader.Next()
						if err != nil {
							return nil, nil, os.ErrNotExist
						}
						if header.FileInfo().Mode()&os.ModeSymlink == os.ModeSymlink {
							spath, err = symlinkJoin(spath, header.Linkname, ".")
							if err != nil {
								return nil, nil, err
							}
						} else {
							return treader, tars, nil
						}
					}
					return nil, nil, fmt.Errorf("max depth %d of symlinks exceeded while reading %s", maxSymlinkDepth, spath)
				}
			}

			actionModel, err := sar.readAction(ctx, sar.Step, sar.resolvedSha, sar.remoteAction.Path, remoteReader(ctx), os.WriteFile)
			sar.action = actionModel
			return err
		}

		actionDir := fmt.Sprintf("%s/%s", sar.RunContext.ActionCacheDir(), safeFilename(sar.Step.Uses))
		gitClone := stepActionRemoteNewCloneExecutor(git.NewGitCloneExecutorInput{
			URL:   sar.remoteAction.CloneURL(sar.RunContext.Config.DefaultActionInstance),
			Ref:   sar.remoteAction.Ref,
			Dir:   actionDir,
			Token: "", /*
				Shouldn't provide token when cloning actions,
				the token comes from the instance which triggered the task,
				however, it might be not the same instance which provides actions.
				For GitHub, they are the same, always github.com.
				But for Gitea, tasks triggered by a.com can clone actions from b.com.
			*/
			OfflineMode: sar.RunContext.Config.ActionOfflineMode,

			InsecureSkipTLS: sar.cloneSkipTLS(), // For Gitea
		})
		var ntErr common.Executor
		if err := gitClone(ctx); err != nil {
			if errors.Is(err, git.ErrShortRef) {
				return fmt.Errorf("Unable to resolve action `%s`, the provided ref `%s` is the shortened version of a commit SHA, which is not supported. Please use the full commit SHA `%s` instead",
					sar.Step.Uses, sar.remoteAction.Ref, err.(*git.Error).Commit())
			} else if errors.Is(err, gogit.ErrForceNeeded) { // TODO: figure out if it will be easy to shadow/alias go-git err's
				ntErr = common.NewInfoExecutor("Non-terminating error while running 'git clone': %v", err)
			} else {
				return err
			}
		}

		remoteReader := func(ctx context.Context) actionYamlReader {
			return func(filename string) (io.Reader, io.Closer, error) {
				f, err := os.Open(filepath.Join(actionDir, sar.remoteAction.Path, filename))
				return f, f, err
			}
		}

		return common.NewPipelineExecutor(
			ntErr,
			func(ctx context.Context) error {
				actionModel, err := sar.readAction(ctx, sar.Step, actionDir, sar.remoteAction.Path, remoteReader(ctx), os.WriteFile)
				sar.action = actionModel
				return err
			},
		)(ctx)
	}
}

func (sar *stepActionRemote) pre() common.Executor {
	sar.env = map[string]string{}

	return common.NewPipelineExecutor(
		sar.prepareActionExecutor(),
		runStepExecutor(sar, stepStagePre, runPreStep(sar)).If(hasPreStep(sar)).If(shouldRunPreStep(sar)))
}

func (sar *stepActionRemote) main() common.Executor {
	return common.NewPipelineExecutor(
		sar.prepareActionExecutor(),
		runStepExecutor(sar, stepStageMain, func(ctx context.Context) error {
			github := sar.getGithubContext(ctx)
			if sar.remoteAction.IsCheckout() && isLocalCheckout(github, sar.Step) && !sar.RunContext.Config.NoSkipCheckout {
				if sar.RunContext.Config.BindWorkdir {
					common.Logger(ctx).Debugf("Skipping local actions/checkout because you bound your workspace")
					return nil
				}
				eval := sar.RunContext.NewExpressionEvaluator(ctx)
				copyToPath := path.Join(sar.RunContext.JobContainer.ToContainerPath(sar.RunContext.Config.Workdir), eval.Interpolate(ctx, sar.Step.With["path"]))
				return sar.RunContext.JobContainer.CopyDir(copyToPath, sar.RunContext.Config.Workdir+string(filepath.Separator)+".", sar.RunContext.Config.UseGitIgnore)(ctx)
			}

			actionDir := fmt.Sprintf("%s/%s", sar.RunContext.ActionCacheDir(), safeFilename(sar.Step.Uses))

			return sar.runAction(sar, actionDir, sar.remoteAction)(ctx)
		}),
	)
}

func (sar *stepActionRemote) post() common.Executor {
	return runStepExecutor(sar, stepStagePost, runPostStep(sar)).If(hasPostStep(sar)).If(shouldRunPostStep(sar))
}

func (sar *stepActionRemote) getRunContext() *RunContext {
	return sar.RunContext
}

func (sar *stepActionRemote) getGithubContext(ctx context.Context) *model.GithubContext {
	ghc := sar.getRunContext().getGithubContext(ctx)

	// extend github context if we already have an initialized remoteAction
	remoteAction := sar.remoteAction
	if remoteAction != nil {
		ghc.ActionRepository = fmt.Sprintf("%s/%s", remoteAction.Org, remoteAction.Repo)
		ghc.ActionRef = remoteAction.Ref
	}

	return ghc
}

func (sar *stepActionRemote) getStepModel() *model.Step {
	return sar.Step
}

func (sar *stepActionRemote) getEnv() *map[string]string {
	return &sar.env
}

func (sar *stepActionRemote) getIfExpression(ctx context.Context, stage stepStage) string {
	switch stage {
	case stepStagePre:
		github := sar.getGithubContext(ctx)
		if sar.remoteAction.IsCheckout() && isLocalCheckout(github, sar.Step) && !sar.RunContext.Config.NoSkipCheckout {
			// skip local checkout pre step
			return "false"
		}
		return sar.action.Runs.PreIf
	case stepStageMain:
		return sar.Step.If.Value
	case stepStagePost:
		return sar.action.Runs.PostIf
	}
	return ""
}

func (sar *stepActionRemote) getActionModel() *model.Action {
	return sar.action
}

func (sar *stepActionRemote) getCompositeRunContext(ctx context.Context) *RunContext {
	if sar.compositeRunContext == nil {
		actionDir := fmt.Sprintf("%s/%s", sar.RunContext.ActionCacheDir(), safeFilename(sar.Step.Uses))
		actionLocation := path.Join(actionDir, sar.remoteAction.Path)
		_, containerActionDir := getContainerActionPaths(sar.getStepModel(), actionLocation, sar.RunContext)

		sar.compositeRunContext = newCompositeRunContext(ctx, sar.RunContext, sar, containerActionDir)
		sar.compositeSteps = sar.compositeRunContext.compositeExecutor(sar.action)
	} else {
		// Re-evaluate environment here. For remote actions the environment
		// need to be re-created for every stage (pre, main, post) as there
		// might be required context changes (inputs/outputs) while the action
		// stages are executed. (e.g. the output of another action is the
		// input for this action during the main stage, but the env
		// was already created during the pre stage)
		env := evaluateCompositeInputAndEnv(ctx, sar.RunContext, sar)
		sar.compositeRunContext.Env = env
		sar.compositeRunContext.ExtraPath = sar.RunContext.ExtraPath
	}
	return sar.compositeRunContext
}

func (sar *stepActionRemote) getCompositeSteps() *compositeSteps {
	return sar.compositeSteps
}

// For Gitea
// cloneSkipTLS returns true if the runner can clone an action from the Gitea instance
func (sar *stepActionRemote) cloneSkipTLS() bool {
	if !sar.RunContext.Config.InsecureSkipTLS {
		// Return false if the Gitea instance is not an insecure instance
		return false
	}
	if sar.remoteAction.URL == "" {
		// Empty URL means the default action instance should be used
		// Return true if the URL of the Gitea instance is the same as the URL of the default action instance
		return sar.RunContext.Config.DefaultActionInstance == sar.RunContext.Config.GitHubInstance
	}
	// Return true if the URL of the remote action is the same as the URL of the Gitea instance
	return sar.remoteAction.URL == sar.RunContext.Config.GitHubInstance
}

type remoteAction struct {
	URL  string
	Org  string
	Repo string
	Path string
	Ref  string
}

func (ra *remoteAction) CloneURL(u string) string {
	if ra.URL == "" {
		if !strings.HasPrefix(u, "http://") && !strings.HasPrefix(u, "https://") {
			u = "https://" + u
		}
	} else {
		u = ra.URL
	}

	return fmt.Sprintf("%s/%s/%s", u, ra.Org, ra.Repo)
}

func (ra *remoteAction) IsCheckout() bool {
	if ra.Org == "actions" && ra.Repo == "checkout" {
		return true
	}
	return false
}

func newRemoteAction(action string) *remoteAction {
	// support http(s)://host/owner/repo@v3
	for _, schema := range []string{"https://", "http://"} {
		if strings.HasPrefix(action, schema) {
			splits := strings.SplitN(strings.TrimPrefix(action, schema), "/", 2)
			if len(splits) != 2 {
				return nil
			}
			ret := parseAction(splits[1])
			if ret == nil {
				return nil
			}
			ret.URL = schema + splits[0]
			return ret
		}
	}

	return parseAction(action)
}

func parseAction(action string) *remoteAction {
	// GitHub's document[^] describes:
	// > We strongly recommend that you include the version of
	// > the action you are using by specifying a Git ref, SHA, or Docker tag number.
	// Actually, the workflow stops if there is the uses directive that hasn't @ref.
	// [^]: https://docs.github.com/en/actions/reference/workflow-syntax-for-github-actions
	r := regexp.MustCompile(`^([^/@]+)/([^/@]+)(/([^@]*))?(@(.*))?$`)
	matches := r.FindStringSubmatch(action)
	if len(matches) < 7 || matches[6] == "" {
		return nil
	}
	return &remoteAction{
		Org:  matches[1],
		Repo: matches[2],
		Path: matches[4],
		Ref:  matches[6],
		URL:  "",
	}
}

func safeFilename(s string) string {
	return strings.NewReplacer(
		`<`, "-",
		`>`, "-",
		`:`, "-",
		`"`, "-",
		`/`, "-",
		`\`, "-",
		`|`, "-",
		`?`, "-",
		`*`, "-",
	).Replace(s)
}