package worker

import (
	"context"
	"crypto/sha256"
	"encoding/hex"
	"encoding/json"
	"fmt"
	"io"
	"log/slog"
	"os"
	"os/exec"
	"path/filepath"
	"runtime"
	"sort"
	"strings"
	"sync"
	"time"

	"github.com/jfraeys/fetch_ml/internal/container"
	"github.com/jfraeys/fetch_ml/internal/errtypes"
	"github.com/jfraeys/fetch_ml/internal/experiment"
	"github.com/jfraeys/fetch_ml/internal/logging"
	"github.com/jfraeys/fetch_ml/internal/metrics"
	"github.com/jfraeys/fetch_ml/internal/queue"
)

// NEW: Fetch datasets using data_manager.
func (w *Worker) fetchDatasets(ctx context.Context, task *queue.Task) error {
	logger := w.logger.Job(ctx, task.JobName, task.ID)
	logger.Info("fetching datasets",
		"worker_id", w.id,
		"dataset_count", len(task.Datasets))

	for _, dataset := range task.Datasets {
		if w.datasetIsFresh(dataset) {
			logger.Debug("skipping cached dataset",
				"dataset", dataset)
			continue
		}
		// Check for cancellation before each dataset fetch
		select {
		case <-ctx.Done():
			return fmt.Errorf("dataset fetch cancelled: %w", ctx.Err())
		default:
		}

		logger.Info("fetching dataset",
			"worker_id", w.id,
			"dataset", dataset)

		// Create command with context for cancellation support
		cmdCtx, cancel := context.WithTimeout(ctx, 30*time.Minute)
		// Validate inputs to prevent command injection
		if !isValidName(task.JobName) || !isValidName(dataset) {
			cancel()
			return fmt.Errorf("invalid input: jobName or dataset contains unsafe characters")
		}
		//nolint:gosec // G204: Subprocess launched with potential tainted input - input is validated
		cmd := exec.CommandContext(cmdCtx,
			w.config.DataManagerPath,
			"fetch",
			task.JobName,
			dataset,
		)

		output, err := cmd.CombinedOutput()
		cancel() // Clean up context

		if err != nil {
			return &errtypes.DataFetchError{
				Dataset: dataset,
				JobName: task.JobName,
				Err:     fmt.Errorf("command failed: %w, output: %s", err, output),
			}
		}

		logger.Info("dataset ready",
			"worker_id", w.id,
			"dataset", dataset)
		w.markDatasetFetched(dataset)
	}

	return nil
}

func resolveDatasets(task *queue.Task) []string {
	if task == nil {
		return nil
	}
	if len(task.DatasetSpecs) > 0 {
		out := make([]string, 0, len(task.DatasetSpecs))
		for _, ds := range task.DatasetSpecs {
			if ds.Name != "" {
				out = append(out, ds.Name)
			}
		}
		if len(out) > 0 {
			return out
		}
	}
	if len(task.Datasets) > 0 {
		return task.Datasets
	}
	return parseDatasets(task.Args)
}

func parseDatasets(args string) []string {
	if !strings.Contains(args, "--datasets") {
		return nil
	}

	parts := strings.Fields(args)
	for i, part := range parts {
		if part == "--datasets" && i+1 < len(parts) {
			return strings.Split(parts[i+1], ",")
		}
	}

	return nil
}

func (w *Worker) datasetIsFresh(dataset string) bool {
	w.datasetCacheMu.RLock()
	defer w.datasetCacheMu.RUnlock()
	expires, ok := w.datasetCache[dataset]
	return ok && time.Now().Before(expires)
}

func (w *Worker) markDatasetFetched(dataset string) {
	expires := time.Now().Add(w.datasetCacheTTL)
	w.datasetCacheMu.Lock()
	w.datasetCache[dataset] = expires
	w.datasetCacheMu.Unlock()
}

func (w *Worker) cancelPrewarmLocked() {
	if w.prewarmCancel != nil {
		w.prewarmCancel()
		w.prewarmCancel = nil
	}
	w.prewarmTargetID = ""
}

func (w *Worker) prewarmNextLoop() {
	if w == nil || w.config == nil || !w.config.PrewarmEnabled {
		return
	}
	if w.ctx == nil || w.queue == nil || w.metrics == nil {
		return
	}
	// Phase 1: Best-effort prewarm of the next queued task.
	// This must never be required for correctness.
	runOnce := func() {
		_, err := w.PrewarmNextOnce(w.ctx)
		if err != nil {
			w.logger.Warn("prewarm next task failed", "worker_id", w.id, "error", err)
		}
	}

	// Run once immediately so prewarm doesn't lag behind the worker loop.
	runOnce()

	ticker := time.NewTicker(500 * time.Millisecond)
	defer ticker.Stop()

	for {
		select {
		case <-w.ctx.Done():
			w.prewarmMu.Lock()
			w.cancelPrewarmLocked()
			w.prewarmMu.Unlock()
			return
		case <-ticker.C:
		}
		runOnce()
	}
}

func (w *Worker) PrewarmNextOnce(ctx context.Context) (bool, error) {
	if w == nil || w.config == nil || !w.config.PrewarmEnabled {
		return false, nil
	}
	if ctx == nil || w.queue == nil || w.metrics == nil {
		return false, nil
	}

	next, err := w.queue.PeekNextTask()
	if err != nil {
		return false, err
	}
	if next == nil {
		w.prewarmMu.Lock()
		w.cancelPrewarmLocked()
		w.prewarmMu.Unlock()
		return false, nil
	}

	return w.prewarmTaskOnce(ctx, next)
}

func (w *Worker) prewarmTaskOnce(ctx context.Context, next *queue.Task) (bool, error) {
	if w == nil || w.config == nil || !w.config.PrewarmEnabled {
		return false, nil
	}
	if ctx == nil || w.queue == nil || w.metrics == nil {
		return false, nil
	}
	if next == nil {
		return false, nil
	}

	w.prewarmMu.Lock()
	if w.prewarmTargetID == next.ID {
		w.prewarmMu.Unlock()
		return false, nil
	}
	w.cancelPrewarmLocked()
	prewarmCtx, cancel := context.WithCancel(ctx)
	w.prewarmCancel = cancel
	w.prewarmTargetID = next.ID
	w.prewarmStartedAt = time.Now()
	startedAt := w.prewarmStartedAt.UTC().Format(time.RFC3339Nano)
	phase := "datasets"
	dsCnt := len(resolveDatasets(next))
	snapID := next.SnapshotID
	if strings.TrimSpace(snapID) != "" {
		phase = "snapshot"
	} else if dsCnt == 0 {
		phase = "env"
	}
	_ = w.queue.SetWorkerPrewarmState(queue.PrewarmState{
		WorkerID:   w.id,
		TaskID:     next.ID,
		SnapshotID: snapID,
		StartedAt:  startedAt,
		UpdatedAt:  time.Now().UTC().Format(time.RFC3339Nano),
		Phase:      phase,
		DatasetCnt: dsCnt,
		EnvHit:     w.metrics.PrewarmEnvHit.Load(),
		EnvMiss:    w.metrics.PrewarmEnvMiss.Load(),
		EnvBuilt:   w.metrics.PrewarmEnvBuilt.Load(),
		EnvTimeNs:  w.metrics.PrewarmEnvTime.Load(),
	})
	w.prewarmMu.Unlock()

	w.logger.Info("prewarm started",
		"worker_id", w.id,
		"task_id", next.ID,
		"snapshot_id", snapID,
		"phase", phase,
	)

	local := *next
	local.Datasets = resolveDatasets(&local)

	hasSnapshot := strings.TrimSpace(local.SnapshotID) != ""
	hasDatasets := w.config.AutoFetchData && len(local.Datasets) > 0
	hasEnv := false
	if w.envPool != nil && !w.config.LocalMode && strings.TrimSpace(w.config.PodmanImage) != "" {
		if local.Metadata != nil {
			depsSHA := strings.TrimSpace(local.Metadata["deps_manifest_sha256"])
			commitID := strings.TrimSpace(local.Metadata["commit_id"])
			if depsSHA != "" && commitID != "" {
				expMgr := experiment.NewManager(w.config.BasePath)
				hostWorkspace := expMgr.GetFilesPath(commitID)
				if name, err := selectDependencyManifest(hostWorkspace); err == nil && name != "" {
					if tag, err := w.envPool.WarmImageTag(depsSHA); err == nil && strings.TrimSpace(tag) != "" {
						hasEnv = true
					}
				}
			}
		}
	}
	if !hasSnapshot && !hasDatasets && !hasEnv {
		_ = w.queue.ClearWorkerPrewarmState(w.id)
		return false, nil
	}

	if hasSnapshot {
		want := ""
		if local.Metadata != nil {
			want = local.Metadata["snapshot_sha256"]
		}
		start := time.Now()
		src, err := ResolveSnapshot(
			prewarmCtx,
			w.config.DataDir,
			&w.config.SnapshotStore,
			local.SnapshotID,
			want,
			nil,
		)
		if err != nil {
			return true, err
		}
		dst := filepath.Join(w.config.BasePath, ".prewarm", "snapshots", local.ID)
		_ = os.RemoveAll(dst)
		if err := copyDir(src, dst); err != nil {
			return true, err
		}
		w.metrics.RecordPrewarmSnapshotBuilt(time.Since(start))
	}

	if hasDatasets {
		if err := w.fetchDatasets(prewarmCtx, &local); err != nil {
			return true, err
		}
	}

	_ = w.queue.SetWorkerPrewarmState(queue.PrewarmState{
		WorkerID:   w.id,
		TaskID:     local.ID,
		SnapshotID: local.SnapshotID,
		StartedAt:  startedAt,
		UpdatedAt:  time.Now().UTC().Format(time.RFC3339Nano),
		Phase:      "ready",
		DatasetCnt: len(local.Datasets),
		EnvHit:     w.metrics.PrewarmEnvHit.Load(),
		EnvMiss:    w.metrics.PrewarmEnvMiss.Load(),
		EnvBuilt:   w.metrics.PrewarmEnvBuilt.Load(),
		EnvTimeNs:  w.metrics.PrewarmEnvTime.Load(),
	})

	w.logger.Info("prewarm ready",
		"worker_id", w.id,
		"task_id", local.ID,
		"snapshot_id", local.SnapshotID,
	)

	return true, nil
}

func (w *Worker) verifySnapshot(ctx context.Context, task *queue.Task) error {
	if task == nil {
		return fmt.Errorf("task is nil")
	}
	if task.SnapshotID == "" {
		return nil
	}
	if err := container.ValidateJobName(task.SnapshotID); err != nil {
		return fmt.Errorf("snapshot %q: invalid snapshot_id: %w", task.SnapshotID, err)
	}
	if task.Metadata == nil {
		return fmt.Errorf("snapshot %q: missing snapshot_sha256 metadata", task.SnapshotID)
	}
	want, err := normalizeSHA256ChecksumHex(task.Metadata["snapshot_sha256"])
	if err != nil {
		return fmt.Errorf("snapshot %q: invalid snapshot_sha256: %w", task.SnapshotID, err)
	}
	if want == "" {
		return fmt.Errorf("snapshot %q: missing snapshot_sha256 metadata", task.SnapshotID)
	}
	path, err := ResolveSnapshot(
		ctx,
		w.config.DataDir,
		&w.config.SnapshotStore,
		task.SnapshotID,
		want,
		nil,
	)
	if err != nil {
		return fmt.Errorf("snapshot %q: resolve failed: %w", task.SnapshotID, err)
	}
	got, err := dirOverallSHA256Hex(path)
	if err != nil {
		return fmt.Errorf("snapshot %q: checksum verification failed: %w", task.SnapshotID, err)
	}
	if got != want {
		return fmt.Errorf(
			"snapshot %q: checksum mismatch: expected %s, got %s",
			task.SnapshotID,
			want,
			got,
		)
	}
	w.logger.Job(
		ctx,
		task.JobName,
		task.ID,
	).Info("snapshot checksum verified", "snapshot_id", task.SnapshotID)
	return nil
}

func fileSHA256Hex(path string) (string, error) {
	f, err := os.Open(filepath.Clean(path))
	if err != nil {
		return "", err
	}
	defer func() { _ = f.Close() }()

	h := sha256.New()
	if _, err := io.Copy(h, f); err != nil {
		return "", err
	}
	return fmt.Sprintf("%x", h.Sum(nil)), nil
}

func normalizeSHA256ChecksumHex(checksum string) (string, error) {
	checksum = strings.TrimSpace(checksum)
	checksum = strings.TrimPrefix(checksum, "sha256:")
	checksum = strings.TrimPrefix(checksum, "SHA256:")
	checksum = strings.TrimSpace(checksum)
	if checksum == "" {
		return "", nil
	}
	if len(checksum) != 64 {
		return "", fmt.Errorf("expected sha256 hex length 64, got %d", len(checksum))
	}
	if _, err := hex.DecodeString(checksum); err != nil {
		return "", fmt.Errorf("invalid sha256 hex: %w", err)
	}
	return strings.ToLower(checksum), nil
}

func dirOverallSHA256HexGo(root string) (string, error) {
	root = filepath.Clean(root)
	info, err := os.Stat(root)
	if err != nil {
		return "", err
	}
	if !info.IsDir() {
		return "", fmt.Errorf("not a directory")
	}

	var files []string
	err = filepath.WalkDir(root, func(path string, d os.DirEntry, walkErr error) error {
		if walkErr != nil {
			return walkErr
		}
		if d.IsDir() {
			return nil
		}
		rel, err := filepath.Rel(root, path)
		if err != nil {
			return err
		}
		files = append(files, rel)
		return nil
	})
	if err != nil {
		return "", err
	}

	// Deterministic order.
	for i := 0; i < len(files); i++ {
		for j := i + 1; j < len(files); j++ {
			if files[i] > files[j] {
				files[i], files[j] = files[j], files[i]
			}
		}
	}

	// Hash file hashes to avoid holding all bytes.
	overall := sha256.New()
	for _, rel := range files {
		p := filepath.Join(root, rel)
		sum, err := fileSHA256Hex(p)
		if err != nil {
			return "", err
		}
		overall.Write([]byte(sum))
	}
	return fmt.Sprintf("%x", overall.Sum(nil)), nil
}

// dirOverallSHA256HexParallel is a parallel Go implementation for baseline comparison.
// This demonstrates best-effort Go performance before C++ optimization.
// Uses worker pool to hash files in parallel, then combines deterministically.
func dirOverallSHA256HexParallel(root string) (string, error) {
	root = filepath.Clean(root)
	info, err := os.Stat(root)
	if err != nil {
		return "", err
	}
	if !info.IsDir() {
		return "", fmt.Errorf("not a directory")
	}

	// Collect all files first
	var files []string
	err = filepath.WalkDir(root, func(path string, d os.DirEntry, walkErr error) error {
		if walkErr != nil {
			return walkErr
		}
		if d.IsDir() {
			return nil
		}
		rel, err := filepath.Rel(root, path)
		if err != nil {
			return err
		}
		files = append(files, rel)
		return nil
	})
	if err != nil {
		return "", err
	}

	// Sort for deterministic order
	sort.Strings(files)

	// Parallel hashing with worker pool
	numWorkers := runtime.NumCPU()
	if numWorkers > 8 {
		numWorkers = 8 // Cap at 8 workers
	}

	type result struct {
		index int
		hash  string
		err   error
	}

	workCh := make(chan int, len(files))
	resultCh := make(chan result, len(files))

	// Start workers
	var wg sync.WaitGroup
	for i := 0; i < numWorkers; i++ {
		wg.Add(1)
		go func() {
			defer wg.Done()
			for idx := range workCh {
				rel := files[idx]
				p := filepath.Join(root, rel)
				hash, err := fileSHA256Hex(p)
				resultCh <- result{index: idx, hash: hash, err: err}
			}
		}()
	}

	// Send work
	go func() {
		for i := range files {
			workCh <- i
		}
		close(workCh)
	}()

	// Collect results
	go func() {
		wg.Wait()
		close(resultCh)
	}()

	hashes := make([]string, len(files))
	for r := range resultCh {
		if r.err != nil {
			return "", r.err
		}
		hashes[r.index] = r.hash
	}

	// Combine hashes deterministically
	overall := sha256.New()
	for _, h := range hashes {
		overall.Write([]byte(h))
	}
	return fmt.Sprintf("%x", overall.Sum(nil)), nil
}

func (w *Worker) verifyDatasetSpecs(ctx context.Context, task *queue.Task) error {
	if task == nil {
		return fmt.Errorf("task is nil")
	}
	if len(task.DatasetSpecs) == 0 {
		return nil
	}

	logger := w.logger.Job(ctx, task.JobName, task.ID)
	for _, ds := range task.DatasetSpecs {
		want, err := normalizeSHA256ChecksumHex(ds.Checksum)
		if err != nil {
			return fmt.Errorf("dataset %q: invalid checksum: %w", ds.Name, err)
		}
		if want == "" {
			continue
		}
		if err := container.ValidateJobName(ds.Name); err != nil {
			return fmt.Errorf("dataset %q: invalid name: %w", ds.Name, err)
		}
		path := filepath.Join(w.config.DataDir, ds.Name)
		got, err := dirOverallSHA256HexGo(path)
		if err != nil {
			return fmt.Errorf("dataset %q: checksum verification failed: %w", ds.Name, err)
		}
		if got != want {
			return fmt.Errorf("dataset %q: checksum mismatch: expected %s, got %s", ds.Name, want, got)
		}
		logger.Info("dataset checksum verified", "dataset", ds.Name)
	}
	return nil
}

func computeTaskProvenance(basePath string, task *queue.Task) (map[string]string, error) {
	if task == nil {
		return nil, fmt.Errorf("task is nil")
	}
	out := map[string]string{}

	if task.SnapshotID != "" {
		out["snapshot_id"] = task.SnapshotID
	}

	datasets := resolveDatasets(task)
	if len(datasets) > 0 {
		out["datasets"] = strings.Join(datasets, ",")
	}
	if len(task.DatasetSpecs) > 0 {
		b, err := json.Marshal(task.DatasetSpecs)
		if err != nil {
			return nil, fmt.Errorf("marshal dataset_specs: %w", err)
		}
		out["dataset_specs"] = string(b)
	}

	if task.Metadata == nil {
		return out, nil
	}
	commitID := task.Metadata["commit_id"]
	if commitID == "" {
		return out, nil
	}

	expMgr := experiment.NewManager(basePath)
	manifest, err := expMgr.ReadManifest(commitID)
	if err == nil && manifest != nil && manifest.OverallSHA != "" {
		out["experiment_manifest_overall_sha"] = manifest.OverallSHA
	}

	filesPath := expMgr.GetFilesPath(commitID)
	depName, err := selectDependencyManifest(filesPath)
	if err == nil && depName != "" {
		depPath := filepath.Join(filesPath, depName)
		sha, err := fileSHA256Hex(depPath)
		if err == nil && sha != "" {
			out["deps_manifest_name"] = depName
			out["deps_manifest_sha256"] = sha
		}
	}

	return out, nil
}

func (w *Worker) recordTaskProvenance(ctx context.Context, task *queue.Task) {
	if task == nil {
		return
	}
	prov, err := computeTaskProvenance(w.config.BasePath, task)
	if err != nil {
		w.logger.Job(ctx, task.JobName, task.ID).Debug("provenance compute failed", "error", err)
		return
	}
	if len(prov) == 0 {
		return
	}
	if task.Metadata == nil {
		task.Metadata = map[string]string{}
	}
	for k, v := range prov {
		if v == "" {
			continue
		}
		// Phase 1: best-effort only; do not error if overwriting.
		task.Metadata[k] = v
	}
}

func (w *Worker) enforceTaskProvenance(ctx context.Context, task *queue.Task) error {
	if task == nil {
		return fmt.Errorf("task is nil")
	}
	if task.Metadata == nil {
		return fmt.Errorf("missing task metadata")
	}
	commitID := task.Metadata["commit_id"]
	if commitID == "" {
		return fmt.Errorf("missing commit_id")
	}

	current, err := computeTaskProvenance(w.config.BasePath, task)
	if err != nil {
		return err
	}

	snapshotCur := ""
	if task.SnapshotID != "" {
		want := ""
		if task.Metadata != nil {
			want = task.Metadata["snapshot_sha256"]
		}
		wantNorm, nerr := normalizeSHA256ChecksumHex(want)
		if nerr != nil {
			if w.config != nil && w.config.ProvenanceBestEffort {
				w.logger.Warn("invalid snapshot_sha256; unable to compute current snapshot provenance",
					"snapshot_id", task.SnapshotID,
					"error", nerr)
			} else {
				return fmt.Errorf("snapshot %q: invalid snapshot_sha256: %w", task.SnapshotID, nerr)
			}
		} else if wantNorm != "" {
			resolved, err := ResolveSnapshot(
				ctx, w.config.DataDir,
				&w.config.SnapshotStore,
				task.SnapshotID,
				wantNorm,
				nil,
			)
			if err != nil {
				if w.config != nil && w.config.ProvenanceBestEffort {
					w.logger.Warn("snapshot resolve failed; unable to compute current snapshot provenance",
						"snapshot_id", task.SnapshotID,
						"error", err)
				} else {
					return fmt.Errorf("snapshot %q: resolve failed: %w", task.SnapshotID, err)
				}
			} else {
				sha, err := dirOverallSHA256HexGo(resolved)
				if err == nil {
					snapshotCur = sha
				} else if w.config != nil && w.config.ProvenanceBestEffort {
					w.logger.Warn("snapshot hash failed; unable to compute current snapshot provenance",
						"snapshot_id", task.SnapshotID,
						"error", err)
				} else {
					return fmt.Errorf("snapshot %q: checksum computation failed: %w", task.SnapshotID, err)
				}
			}
		}
		if snapshotCur == "" && w.config != nil && w.config.ProvenanceBestEffort {
			// Best-effort fallback: if the caller didn't provide snapshot_sha256,
			// compute from the local snapshot directory if it exists.
			localPath := filepath.Join(w.config.DataDir, "snapshots", strings.TrimSpace(task.SnapshotID))
			if sha, err := dirOverallSHA256HexGo(localPath); err == nil {
				snapshotCur = sha
			}
		}
	}

	logger := w.logger.Job(ctx, task.JobName, task.ID)

	type requiredField struct {
		Key string
		Cur string
	}
	required := []requiredField{
		{Key: "experiment_manifest_overall_sha", Cur: current["experiment_manifest_overall_sha"]},
		{Key: "deps_manifest_name", Cur: current["deps_manifest_name"]},
		{Key: "deps_manifest_sha256", Cur: current["deps_manifest_sha256"]},
	}
	if task.SnapshotID != "" {
		required = append(required, requiredField{Key: "snapshot_sha256", Cur: snapshotCur})
	}

	for _, f := range required {
		want := strings.TrimSpace(task.Metadata[f.Key])
		if f.Key == "snapshot_sha256" {
			norm, nerr := normalizeSHA256ChecksumHex(want)
			if nerr != nil {
				if w.config != nil && w.config.ProvenanceBestEffort {
					logger.Warn("invalid snapshot_sha256; continuing due to best-effort mode",
						"snapshot_id", task.SnapshotID,
						"error", nerr)
					want = ""
				} else {
					return fmt.Errorf("snapshot %q: invalid snapshot_sha256: %w", task.SnapshotID, nerr)
				}
			} else {
				want = norm
			}
		}
		if want == "" {
			if w.config != nil && w.config.ProvenanceBestEffort {
				logger.Warn("missing provenance field; continuing due to best-effort mode",
					"field", f.Key)
				if f.Cur != "" {
					if f.Key == "snapshot_sha256" {
						task.Metadata[f.Key] = "sha256:" + f.Cur
					} else {
						task.Metadata[f.Key] = f.Cur
					}
				}
				continue
			}
			return fmt.Errorf("missing provenance field: %s", f.Key)
		}
		if f.Cur == "" {
			if w.config != nil && w.config.ProvenanceBestEffort {
				logger.Warn("unable to compute provenance field; continuing due to best-effort mode",
					"field", f.Key)
				continue
			}
			return fmt.Errorf("unable to compute provenance field: %s", f.Key)
		}
		if want != f.Cur {
			if w.config != nil && w.config.ProvenanceBestEffort {
				logger.Warn("provenance mismatch; continuing due to best-effort mode",
					"field", f.Key,
					"expected", want,
					"current", f.Cur)
				if f.Key == "snapshot_sha256" {
					task.Metadata[f.Key] = "sha256:" + f.Cur
				} else {
					task.Metadata[f.Key] = f.Cur
				}
				continue
			}
			return fmt.Errorf("provenance mismatch for %s: expected %s, got %s", f.Key, want, f.Cur)
		}
	}

	return nil
}

func selectDependencyManifest(filesPath string) (string, error) {
	if filesPath == "" {
		return "", fmt.Errorf("missing files path")
	}
	candidates := []string{
		"environment.yml",
		"environment.yaml",
		"poetry.lock",
		"pyproject.toml",
		"requirements.txt",
	}
	for _, name := range candidates {
		p := filepath.Join(filesPath, name)
		if _, err := os.Stat(p); err == nil {
			if name == "poetry.lock" {
				pyprojectPath := filepath.Join(filesPath, "pyproject.toml")
				if _, err := os.Stat(pyprojectPath); err != nil {
					return "", fmt.Errorf(
						"poetry.lock found but pyproject.toml missing (required for Poetry projects)")
				}
			}
			return name, nil
		}
	}
	return "", fmt.Errorf(
		"missing dependency manifest (supported: environment.yml, environment.yaml, " +
			"poetry.lock, pyproject.toml, requirements.txt)")
}

// Exported wrappers for tests under tests/.

func ResolveDatasets(task *queue.Task) []string { return resolveDatasets(task) }

func SelectDependencyManifest(filesPath string) (string, error) {
	return selectDependencyManifest(filesPath)
}

func NormalizeSHA256ChecksumHex(checksum string) (string, error) {
	return normalizeSHA256ChecksumHex(checksum)
}

func DirOverallSHA256Hex(root string) (string, error) { return dirOverallSHA256Hex(root) }

// DirOverallSHA256HexParallel is an exported wrapper for testing/benchmarking.
func DirOverallSHA256HexParallel(root string) (string, error) {
	return dirOverallSHA256HexParallel(root)
}

func ComputeTaskProvenance(basePath string, task *queue.Task) (map[string]string, error) {
	return computeTaskProvenance(basePath, task)
}

func (w *Worker) EnforceTaskProvenance(ctx context.Context, task *queue.Task) error {
	return w.enforceTaskProvenance(ctx, task)
}

func (w *Worker) VerifyDatasetSpecs(ctx context.Context, task *queue.Task) error {
	return w.verifyDatasetSpecs(ctx, task)
}

func (w *Worker) VerifySnapshot(ctx context.Context, task *queue.Task) error {
	return w.verifySnapshot(ctx, task)
}

func NewTestWorker(cfg *Config) *Worker {
	baseLogger := logging.NewLogger(slog.LevelInfo, false)
	ctx := logging.EnsureTrace(context.Background())
	logger := baseLogger.Component(ctx, "worker")
	if cfg == nil {
		cfg = &Config{}
	}
	if cfg.DatasetCacheTTL == 0 {
		cfg.DatasetCacheTTL = datasetCacheDefaultTTL
	}
	return &Worker{
		id:              cfg.WorkerID,
		config:          cfg,
		logger:          logger,
		datasetCache:    make(map[string]time.Time),
		datasetCacheTTL: cfg.DatasetCacheTTL,
	}
}

func NewTestWorkerWithQueue(cfg *Config, tq queue.Backend) *Worker {
	baseLogger := logging.NewLogger(slog.LevelInfo, false)
	ctx := logging.EnsureTrace(context.Background())
	ctx, cancel := context.WithCancel(ctx)
	logger := baseLogger.Component(ctx, "worker")
	if cfg == nil {
		cfg = &Config{}
	}
	if cfg.DatasetCacheTTL == 0 {
		cfg.DatasetCacheTTL = datasetCacheDefaultTTL
	}
	return &Worker{
		id:              cfg.WorkerID,
		config:          cfg,
		logger:          logger,
		queue:           tq,
		metrics:         &metrics.Metrics{},
		ctx:             ctx,
		cancel:          cancel,
		running:         make(map[string]context.CancelFunc),
		datasetCache:    make(map[string]time.Time),
		datasetCacheTTL: cfg.DatasetCacheTTL,
	}
}

func NewTestWorkerWithJupyter(cfg *Config, tq queue.Backend, jm JupyterManager) *Worker {
	w := NewTestWorkerWithQueue(cfg, tq)
	w.jupyter = jm
	return w
}