package pull

import (
	"archive/zip"
	"context"
	"fmt"
	"io"
	"os"
	"path/filepath"
	"strconv"
	"strings"

	"code.geekeey.de/actions/sdk"
	"code.geekeey.de/actions/sdk/artifact"
)

type Action struct {
	*sdk.Action
}

func New(action *sdk.Action) *Action {
	return &Action{Action: action}
}

type config struct {
	Name       string
	Path       string
	Repository string
	RunID      string
	Token      string
}

func parseConfig(get func(string) string) (*config, error) {
	name := get("name")
	if len(name) == 0 {
		return nil, fmt.Errorf("input 'name': is empty")
	}

	path := get("path")
	if len(path) == 0 {
		path = "."
	}
	return &config{
		Name:       name,
		Path:       path,
		Repository: get("repository"),
		RunID:      get("run-id"),
		Token:      get("github-token"),
	}, nil
}

func (a *Action) Run(ctx context.Context) error {
	cfg, err := parseConfig(a.GetInput)
	if err != nil {
		return err
	}

	// Only use the repository API when the artifact lives in another repository
	// or another run. For the current run the results service is used instead.
	if useRepositoryAPI(cfg, a.Context()) {
		return a.pullFromRepository(ctx, cfg)
	}

	run, job, err := artifact.JobInfo()
	if err != nil {
		return fmt.Errorf("unable to get job info: %v", err)
	}

	client := artifact.NewClientFromEnv(os.Getenv)

	signed, err := client.GetSignedArtifactURL(ctx, artifact.GetSignedArtifactURLRequest{
		RunID:    run,
		JobRunID: job,
		Name:     cfg.Name,
	})
	if err != nil {
		return fmt.Errorf("cannot get signed artifact URL: %w", err)
	}
	if signed.SignedUrl == "" {
		return fmt.Errorf("no signed URL for artifact %q", cfg.Name)
	}

	tmp, err := os.CreateTemp("", "artifact-*.zip")
	if err != nil {
		return fmt.Errorf("cannot create temporary file: %w", err)
	}
	defer os.Remove(tmp.Name())
	defer tmp.Close()

	res, err := artifact.PullBlob(ctx, nil, tmp, signed.SignedUrl)
	if err != nil {
		return fmt.Errorf("cannot download artifact: %w", err)
	}

	if err := extractArchive(tmp.Name(), cfg.Path); err != nil {
		return fmt.Errorf("cannot extract artifact: %w", err)
	}

	a.SetOutput("download-path", downloadPath(cfg.Path))
	a.Noticef("downloaded artifact %s (%d bytes)", cfg.Name, res.Size)
	return nil
}

// useRepositoryAPI reports whether the configured repository/run differs from
// the current one and therefore has to be resolved through the repository API.
// Empty values mean "current".
func useRepositoryAPI(cfg *config, gh *sdk.GitHubContext) bool {
	if cfg.Repository != "" && cfg.Repository != gh.Repository {
		return true
	}
	if cfg.RunID != "" && cfg.RunID != gh.RunID {
		return true
	}
	return false
}

// pullFromRepository downloads an artifact from a specific repository run using
// the repository-scoped actions API, so it works across runs and repositories.
func (a *Action) pullFromRepository(ctx context.Context, cfg *config) error {
	gh := a.Context()

	repository := cfg.Repository
	if repository == "" {
		repository = gh.Repository
	}
	owner, repo, ok := strings.Cut(repository, "/")
	if !ok || owner == "" || repo == "" {
		return fmt.Errorf("input 'repository': %q must be <owner>/<repo>", repository)
	}

	runID := cfg.RunID
	if runID == "" {
		runID = gh.RunID
	}
	id, err := strconv.ParseInt(runID, 10, 64)
	if err != nil {
		return fmt.Errorf("input 'run-id': %q is not a number", runID)
	}

	token := cfg.Token
	if token == "" {
		token = gh.Token
	}

	client := artifact.NewRepositoryClient(gh.APIURL, token)
	list, err := client.ListRunArtifacts(ctx, owner, repo, id)
	if err != nil {
		return fmt.Errorf("cannot list artifacts: %w", err)
	}

	var found *artifact.RepositoryArtifact
	for i := range list.Artifacts {
		if list.Artifacts[i].Name == cfg.Name {
			found = &list.Artifacts[i]
			break
		}
	}
	if found == nil {
		return fmt.Errorf("artifact %q not found in %s run %s", cfg.Name, repository, runID)
	}
	if found.Expired {
		return fmt.Errorf("artifact %q is expired", cfg.Name)
	}

	body, err := client.DownloadArtifact(ctx, owner, repo, found.Id)
	if err != nil {
		return fmt.Errorf("cannot download artifact: %w", err)
	}
	defer body.Close()

	tmp, err := os.CreateTemp("", "artifact-*.zip")
	if err != nil {
		return fmt.Errorf("cannot create temporary file: %w", err)
	}
	defer os.Remove(tmp.Name())

	if _, err := io.Copy(tmp, body); err != nil {
		tmp.Close()
		return fmt.Errorf("cannot download artifact: %w", err)
	}
	if err := tmp.Close(); err != nil {
		return err
	}

	if err := extractArchive(tmp.Name(), cfg.Path); err != nil {
		return fmt.Errorf("cannot extract artifact: %w", err)
	}

	a.SetOutput("download-path", downloadPath(cfg.Path))
	a.Noticef("downloaded artifact %s from %s run %s", cfg.Name, repository, runID)
	return nil
}

// downloadPath returns the absolute path of the directory the artifact was
// extracted into.
func downloadPath(dest string) string {
	abs, err := filepath.Abs(dest)
	if err != nil {
		return dest
	}
	return abs
}

// extractArchive extracts the zip file at zipPath into dest. Entries that would
// escape dest are rejected.
func extractArchive(zipPath, dest string) error {
	r, err := zip.OpenReader(zipPath)
	if err != nil {
		return err
	}
	defer r.Close()

	for _, f := range r.File {
		if err := extractFile(f, dest); err != nil {
			return err
		}
	}
	return nil
}

func extractFile(f *zip.File, dest string) error {
	cleanDest := filepath.Clean(dest)
	target := filepath.Join(cleanDest, f.Name)
	if target != cleanDest && !strings.HasPrefix(target, cleanDest+string(os.PathSeparator)) {
		return fmt.Errorf("illegal file path %q", f.Name)
	}

	if f.FileInfo().IsDir() {
		return os.MkdirAll(target, 0o755)
	}

	if err := os.MkdirAll(filepath.Dir(target), 0o755); err != nil {
		return err
	}

	rc, err := f.Open()
	if err != nil {
		return err
	}
	defer rc.Close()

	out, err := os.OpenFile(target, os.O_WRONLY|os.O_CREATE|os.O_TRUNC, f.Mode())
	if err != nil {
		return err
	}
	defer out.Close()

	_, err = io.Copy(out, rc)
	return err
}