package stage

import (
	"context"
	"fmt"
	"os"
	"path/filepath"
	"strings"

	"gitea.maximumdirect.net/eric/narratio/internal/adapters/storage"
	"gitea.maximumdirect.net/eric/narratio/internal/artifacts"
	"gitea.maximumdirect.net/eric/narratio/internal/manifest"
)

type publishStage struct{}

var publishPrerequisiteStages = []string{
	"prepare",
	"transcribe",
	"merge",
	"polish",
	"normalize",
	"trim",
	"render",
	"analyze",
}

func (publishStage) Name() string { return "publish" }

func (publishStage) Run(ctx context.Context, env *Env, m *manifest.Manifest) (*StageResult, error) {
	if env == nil || env.Config == nil || env.Config.Pipeline == nil || env.Config.Session == nil {
		return nil, fmt.Errorf("publish: resolved config must include pipeline and session")
	}

	if publishDisabled(env) {
		return &StageResult{
			Metadata: map[string]any{
				"stage":                "publish",
				"skipped":              true,
				"publish_enabled":      false,
				"audio_upload_skipped": true,
			},
		}, nil
	}
	if publishRunUploadDisabled(env) {
		return &StageResult{
			Metadata: map[string]any{
				"stage":                "publish",
				"skipped":              true,
				"upload_run_enabled":   false,
				"audio_upload_skipped": true,
			},
		}, nil
	}

	if err := validatePublishPrerequisites(m); err != nil {
		return nil, fmt.Errorf("publish: %w", err)
	}
	if env.ObjectStore == nil {
		return nil, fmt.Errorf("publish: remote object store backend is required when publish run upload is enabled")
	}

	runRoot, err := resolvePublishRunRoot(env, m)
	if err != nil {
		return nil, fmt.Errorf("publish: resolve run root: %w", err)
	}

	runPrefix, err := artifacts.ResolvePublishRunPrefix(env.Config, m)
	if err != nil {
		return nil, fmt.Errorf("publish: resolve s3 run prefix: %w", err)
	}
	sessionPrefix, err := artifacts.ResolvePublishSessionPrefix(env.Config, m)
	if err != nil {
		return nil, fmt.Errorf("publish: resolve s3 session prefix: %w", err)
	}
	bucket := artifacts.ResolvePublishBucket(env.Config, m)
	if bucket == "" {
		return nil, fmt.Errorf("publish: resolve s3 bucket: bucket is required")
	}
	runID := strings.TrimSpace(m.RunID)
	if runID == "" {
		return nil, fmt.Errorf("publish: run id is required")
	}

	runFiles, err := collectPublishRunFiles(runRoot, m)
	if err != nil {
		return nil, fmt.Errorf("publish: collect run files: %w", err)
	}
	runSources, err := openPublishRunFiles(runRoot, runFiles)
	if err != nil {
		return nil, fmt.Errorf("publish: verify run files: %w", err)
	}
	defer closePublishSources(runSources)
	uploader, ok := env.ObjectStore.(storage.ReaderUploader)
	if !ok {
		return nil, fmt.Errorf("publish: object store does not support verified source uploads")
	}
	sessionPaths := publishSessionPaths(env, m)
	previousFiles, err := collectPublishPreviousFiles(ctx, sessionPaths.PreviousDir)
	if err != nil {
		return nil, fmt.Errorf("publish: collect previous files: %w", err)
	}
	previousSources, err := openPublishRunFiles(sessionPaths.PreviousDir, previousFiles)
	if err != nil {
		return nil, fmt.Errorf("publish: verify previous files: %w", err)
	}
	defer closePublishSources(previousSources)
	runtimeCatalog, err := buildPublishRuntimeArtifactCatalog(
		sessionPaths,
		m,
		env.Config.Pipeline.Scriptorium,
		env.Config.Pipeline.Notarius,
	)
	if err != nil {
		return nil, fmt.Errorf("publish: build runtime artifact catalog: %w", err)
	}
	publishOutputs, skippedOptionalOutputs, skippedUnselectedOutputs, lockedOutputs, err := resolvePublishOutputs(
		sessionPaths,
		m,
		runtimeCatalog,
		env.Config.Pipeline.Publish.Outputs,
		env.Config.Pipeline.Publish.Locks,
		env.SelectedArtifactKeys,
		runPrefix,
	)
	if err != nil {
		return nil, fmt.Errorf("publish: resolve publish output rules: %w", err)
	}

	runUploaded := publishUploadPaths(runFiles)
	publishedUploaded := publishOutputPaths(publishOutputs)
	previousUploaded := publishUploadPaths(previousFiles)
	commitKey := artifacts.S3RunCommitKey(sessionPrefix, runID)
	pointerKey := artifacts.S3CurrentCommitPointerKey(sessionPrefix)

	transfers, err := buildPublishTransferPlan(runPrefix, runFiles, runSources, previousFiles, previousSources, publishOutputs)
	if err != nil {
		return nil, fmt.Errorf("publish: build immutable upload mapping: %w", err)
	}
	defer func() { closePublishTransfers(transfers) }()

	manifestTempPath, err := writeCommittedSessionManifest(m, publishMetadata(
		bucket,
		runPrefix,
		runID,
		runUploaded,
		publishedUploaded,
		previousUploaded,
		skippedOptionalOutputs,
		skippedUnselectedOutputs,
		lockedOutputs,
		commitKey,
		pointerKey,
	))
	if err != nil {
		return nil, fmt.Errorf("publish: build committed session manifest: %w", err)
	}
	if err := appendCommittedSessionManifest(&transfers, manifestTempPath, artifacts.S3RunSessionManifestKey(sessionPrefix, runID)); err != nil {
		return nil, fmt.Errorf("publish: add committed session manifest: %w", err)
	}
	if err := validatePublishTransferPlan(transfers, commitKey); err != nil {
		return nil, fmt.Errorf("publish: validate immutable upload mapping: %w", err)
	}

	// Durability boundary: transfer every declared immutable object, write the
	// immutable commit, perform pre-pointer checks, then write the sole mutable
	// current pointer exactly once.
	declarations, err := uploadPublishTransfers(ctx, env.ObjectStore, uploader, transfers)
	if err != nil {
		return nil, fmt.Errorf("publish: %w", err)
	}
	committed, err := writeImmutablePublishCommit(
		ctx,
		env.ObjectStore,
		uploader,
		sessionPrefix,
		m.Campaign,
		m.SessionID,
		runID,
		declarations,
	)
	if err != nil {
		return nil, fmt.Errorf("publish: %w", err)
	}
	if err := revalidatePublishCommitLocks(ctx, env, publishOutputs); err != nil {
		return nil, fmt.Errorf("publish: revalidate locks before current commit selection: %w", err)
	}
	if err := writePublishCurrentPointer(ctx, uploader, committed); err != nil {
		return nil, fmt.Errorf("publish: %w", err)
	}

	return &StageResult{
		Metadata: map[string]any{
			"stage":                      "publish",
			"uploaded":                   true,
			"s3_bucket":                  bucket,
			"s3_run_prefix":              runPrefix,
			"run_files_uploaded":         len(runUploaded),
			"run_uploaded_paths":         runUploaded,
			"published_files_uploaded":   len(publishedUploaded),
			"published_paths":            publishedUploaded,
			"previous_files_uploaded":    len(previousUploaded),
			"previous_uploaded_paths":    previousUploaded,
			"skipped_optional_outputs":   skippedOptionalOutputs,
			"skipped_unselected_outputs": skippedUnselectedOutputMetadata(skippedUnselectedOutputs),
			"locked_output_count":        len(lockedOutputs),
			"locked_outputs":             lockedOutputMetadata(lockedOutputs),
			"remote_commit_key":          commitKey,
			"current_commit_pointer_key": pointerKey,
			"audio_upload_skipped":       true,
		},
	}, nil
}

func revalidatePublishCommitLocks(ctx context.Context, env *Env, outputs []publishOutput) error {
	if env == nil || env.RevalidatePublishLocks == nil || len(outputs) == 0 {
		return nil
	}
	locks, err := env.RevalidatePublishLocks(ctx)
	if err != nil {
		return err
	}
	lockSet := publishLockSet(locks)
	for _, output := range outputs {
		if lock, locked := lockSet[output.Source]; locked {
			return fmt.Errorf("source %q is locked: %s", output.Source, strings.TrimSpace(lock.Reason))
		}
	}
	return nil
}

func publishDisabled(env *Env) bool {
	cfg := env.Config.Pipeline.Publish
	if cfg == nil {
		return true
	}
	return cfg.Enabled != nil && !*cfg.Enabled
}

func publishRunUploadDisabled(env *Env) bool {
	cfg := env.Config.Pipeline.Publish
	if cfg == nil {
		return true
	}
	return cfg.UploadRun != nil && !*cfg.UploadRun
}

func validatePublishPrerequisites(m *manifest.Manifest) error {
	if m == nil {
		return fmt.Errorf("manifest is required")
	}
	for _, stageName := range publishPrerequisiteStages {
		sr := m.Stages[stageName]
		if sr == nil {
			return fmt.Errorf("prerequisite stage %q has not succeeded", stageName)
		}
		if sr.Status != manifest.StatusSucceeded {
			return fmt.Errorf("prerequisite stage %q status is %q (want %q)", stageName, sr.Status, manifest.StatusSucceeded)
		}
	}
	return nil
}

func resolvePublishRunRoot(env *Env, m *manifest.Manifest) (string, error) {
	sessionID := strings.TrimSpace(env.Config.Session.SessionID)
	if sessionID == "" && m != nil {
		sessionID = strings.TrimSpace(m.SessionID)
	}
	campaign := strings.TrimSpace(env.Config.Session.Campaign)
	if campaign == "" && m != nil {
		campaign = strings.TrimSpace(m.Campaign)
	}
	runID := ""
	if m != nil {
		runID = strings.TrimSpace(m.RunID)
	}
	if sessionID == "" || campaign == "" {
		return "", fmt.Errorf("campaign and session id are required")
	}
	if runID == "" {
		return "", fmt.Errorf("run id is required")
	}

	canonical := filepath.Clean(artifacts.SessionRunRootForCampaign(env.Config.Pipeline.Workspace.Root, campaign, sessionID, runID))
	info, err := os.Lstat(canonical)
	if err != nil {
		return "", fmt.Errorf("inspect canonical run root %q: %w", canonical, err)
	}
	if info.Mode()&os.ModeSymlink != 0 || !info.IsDir() {
		return "", fmt.Errorf("canonical run root %q is not a directory", canonical)
	}
	return canonical, nil
}

func publishSessionPaths(env *Env, m *manifest.Manifest) artifacts.SessionPaths {
	sessionID := strings.TrimSpace(env.Config.Session.SessionID)
	if sessionID == "" && m != nil {
		sessionID = strings.TrimSpace(m.SessionID)
	}
	campaign := strings.TrimSpace(env.Config.Session.Campaign)
	if campaign == "" && m != nil {
		campaign = strings.TrimSpace(m.Campaign)
	}
	store := artifacts.NewLocalStore(env.Config.Pipeline.Workspace.Root)
	return store.SessionPathsFor(campaign, sessionID)
}

func publishMetadata(
	bucket, runPrefix, runID string,
	runUploaded []string,
	publishedUploaded []string,
	previousUploaded []string,
	skippedOptionalOutputs []string,
	skippedUnselectedOutputs []publishSkippedUnselectedOutput,
	lockedOutputs []publishLockedOutput,
	commitKey string,
	pointerKey string,
) map[string]any {
	return map[string]any{
		"stage":                      "publish",
		"uploaded":                   true,
		"s3_bucket":                  bucket,
		"s3_run_prefix":              runPrefix,
		"published_run_id":           runID,
		"run_files_uploaded":         len(runUploaded),
		"run_uploaded_paths":         append([]string(nil), runUploaded...),
		"published_files_uploaded":   len(publishedUploaded),
		"published_paths":            append([]string(nil), publishedUploaded...),
		"previous_files_uploaded":    len(previousUploaded),
		"previous_uploaded_paths":    append([]string(nil), previousUploaded...),
		"skipped_optional_outputs":   append([]string(nil), skippedOptionalOutputs...),
		"skipped_unselected_outputs": skippedUnselectedOutputMetadata(skippedUnselectedOutputs),
		"locked_output_count":        len(lockedOutputs),
		"locked_outputs":             lockedOutputMetadata(lockedOutputs),
		"remote_commit_key":          commitKey,
		"current_commit_pointer_key": pointerKey,
		"audio_upload_skipped":       true,
	}
}

func skippedUnselectedOutputMetadata(skipped []publishSkippedUnselectedOutput) []map[string]any {
	out := make([]map[string]any, 0, len(skipped))
	for _, item := range skipped {
		out = append(out, map[string]any{
			"source":   item.Source,
			"dest":     item.Dest,
			"required": item.Required,
		})
	}
	return out
}

func lockedOutputMetadata(locked []publishLockedOutput) []map[string]any {
	out := make([]map[string]any, 0, len(locked))
	for _, item := range locked {
		out = append(out, map[string]any{
			"source":     item.Source,
			"dest":       item.Dest,
			"remote_key": item.RemoteKey,
			"reason":     item.Reason,
			"required":   item.Required,
			"local_path": item.LocalPath,
			"provenance": item.Provenance,
		})
	}
	return out
}