package taskloop

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

	"iop/packages/go/agentconfig"
	"iop/packages/go/agentguard"
	"iop/packages/go/agenttask"
	"iop/packages/go/agentworkspace"
)

// ReviewExecutor invokes the official review provider boundary. Tests inject a
// deterministic fake; production uses the common catalog provider.
type ReviewExecutor interface {
	ExecuteReview(context.Context, agenttask.ReviewRequest, string, string, string) error
}

// ArtifactRootResolver resolves only the retained task view associated with an
// exact work attempt. Evidence and recovery never fall back to the canonical
// registered workspace because provider output exists only in the task view.
type ArtifactRootResolver interface {
	ArtifactRoot(agenttask.WorkRecord) (string, error)
}

type retainedArtifactResolver struct {
	backend *agentworkspace.Backend
}

type retainedIsolationBackend interface {
	agenttask.IsolationBackend
	LoadRecord(agentguard.IsolationDescriptor) (agentworkspace.OverlayRecord, error)
}

func (resolver retainedArtifactResolver) ArtifactRoot(
	work agenttask.WorkRecord,
) (string, error) {
	descriptor, err := loadOverlayDescriptor(resolver.backend, work)
	if err != nil {
		return "", err
	}
	return descriptor.WorkingDir, nil
}

type Reviewer struct {
	snapshot agentconfig.RuntimeSnapshot
	backend  *agentworkspace.Backend
	executor ReviewExecutor
}

var _ agenttask.Reviewer = (*Reviewer)(nil)

func NewReviewer(
	snapshot agentconfig.RuntimeSnapshot,
	backend *agentworkspace.Backend,
	executor ReviewExecutor,
) (*Reviewer, error) {
	if backend == nil {
		return nil, errors.New("taskloop: review requires the retained workspace backend")
	}
	return &Reviewer{snapshot: snapshot, backend: backend, executor: executor}, nil
}

func (reviewer *Reviewer) Review(
	ctx context.Context,
	request agenttask.ReviewRequest,
) (agenttask.ReviewResult, error) {
	if err := ctx.Err(); err != nil {
		return agenttask.ReviewResult{}, err
	}
	if request.Work.Submission == nil ||
		request.Work.Submission.ArtifactID != request.Submission.ArtifactID ||
		request.Work.AttemptID != request.Submission.AttemptID {
		return agenttask.ReviewResult{}, errors.New("taskloop: review submission identity mismatch")
	}
	_, ok := reviewer.snapshot.Project(string(request.Project.ProjectID))
	if !ok {
		return agenttask.ReviewResult{}, errors.New("taskloop: review project is not registered")
	}
	planRelative := request.Work.Unit.Metadata["plan_path"]
	reviewRelative := request.Work.Unit.Metadata["review_path"]
	if planRelative == "" || reviewRelative == "" {
		return agenttask.ReviewResult{}, errors.New("taskloop: review artifact locators are incomplete")
	}
	root, err := reviewer.taskView(request.Work)
	if err != nil {
		return agenttask.ReviewResult{}, err
	}
	reviewPath := filepath.Join(root, filepath.FromSlash(reviewRelative))
	verdict, message, verdictErr := readReviewVerdict(reviewPath)
	if errors.Is(verdictErr, errVerdictMissing) && reviewer.executor != nil {
		if err := reviewer.executor.ExecuteReview(
			ctx,
			request,
			root,
			planRelative,
			reviewRelative,
		); err != nil {
			return agenttask.ReviewResult{}, fmt.Errorf("taskloop: official review invocation: %w", err)
		}
		verdict, message, verdictErr = readReviewVerdict(reviewPath)
	}
	if verdictErr != nil {
		return agenttask.ReviewResult{}, verdictErr
	}
	result := agenttask.ReviewResult{
		ProjectID:  request.Project.ProjectID,
		WorkUnitID: request.Work.Unit.ID,
		AttemptID:  request.Work.AttemptID,
		ArtifactID: request.Submission.ArtifactID,
		Verdict:    verdict,
		Message:    message,
		Rework:     verdict == agenttask.ReviewVerdictWarn || verdict == agenttask.ReviewVerdictFail,
	}
	if verdict != agenttask.ReviewVerdictPass {
		return result, nil
	}
	descriptor, err := reviewer.overlayDescriptor(request.Work)
	if err != nil {
		return agenttask.ReviewResult{}, err
	}
	content, err := os.ReadFile(reviewPath)
	if err != nil {
		return agenttask.ReviewResult{}, err
	}
	changeSet, err := reviewer.backend.Freeze(ctx, agentworkspace.FreezeRequest{
		Descriptor: descriptor,
		ArtifactID: request.Submission.ArtifactID,
		ValidationEvidence: []agentworkspace.ValidationEvidence{{
			Name:   "official-review",
			Result: "pass",
			Digest: digestBytes(reviewRelative, content),
		}},
	})
	if err != nil {
		return agenttask.ReviewResult{}, fmt.Errorf("taskloop: freeze reviewed change set: %w", err)
	}
	identity := changeSet.Identity()
	result.ChangeSet = &identity
	return result, nil
}

func (reviewer *Reviewer) taskView(work agenttask.WorkRecord) (string, error) {
	return retainedArtifactResolver{backend: reviewer.backend}.ArtifactRoot(work)
}

func (reviewer *Reviewer) overlayDescriptor(
	work agenttask.WorkRecord,
) (agentguard.IsolationDescriptor, error) {
	return loadOverlayDescriptor(reviewer.backend, work)
}

func loadOverlayDescriptor(
	backend retainedIsolationBackend,
	work agenttask.WorkRecord,
) (agentguard.IsolationDescriptor, error) {
	descriptor, _, err := loadOverlayState(backend, work)
	return descriptor, err
}

func loadOverlayState(
	backend retainedIsolationBackend,
	work agenttask.WorkRecord,
) (agentguard.IsolationDescriptor, agentworkspace.OverlayRecord, error) {
	if backend == nil {
		return agentguard.IsolationDescriptor{}, agentworkspace.OverlayRecord{},
			errors.New("taskloop: retained workspace backend is unavailable")
	}
	if work.Isolation == nil || work.Isolation.ID == "" || work.Isolation.TaskRoot == "" {
		return agentguard.IsolationDescriptor{}, agentworkspace.OverlayRecord{},
			errors.New("taskloop: reviewed work has no retained isolation")
	}
	recordPath := filepath.Join(work.Isolation.TaskRoot, "overlay.json")
	content, err := os.ReadFile(recordPath)
	if err != nil {
		return agentguard.IsolationDescriptor{}, agentworkspace.OverlayRecord{},
			fmt.Errorf("taskloop: read retained overlay: %w", err)
	}
	var record agentworkspace.OverlayRecord
	if err := decodeStrictJSON(content, &record); err != nil {
		return agentguard.IsolationDescriptor{}, agentworkspace.OverlayRecord{},
			fmt.Errorf("taskloop: decode retained overlay: %w", err)
	}
	descriptor := agentguard.IsolationDescriptor{
		ID:                  record.IsolationID,
		Revision:            record.Revision,
		Mode:                record.Mode,
		BaseRoot:            record.CanonicalRoot,
		TaskRoot:            filepath.Dir(record.Locator.OverlayRecord),
		WorkingDir:          record.Locator.ViewRoot,
		WritableRoots:       []string{record.Locator.ViewRoot, record.Locator.TempRoot, record.Locator.CacheRoot},
		PinnedBaseRevision:  record.SnapshotRevision,
		ConfinementRevision: record.ConfinementRevision,
	}
	if record.ProjectID == "" ||
		record.WorkUnitID != string(work.Unit.ID) ||
		record.AttemptID != string(work.AttemptID) ||
		record.IsolationID != work.Isolation.ID ||
		record.Revision != work.Isolation.Revision {
		return agentguard.IsolationDescriptor{}, agentworkspace.OverlayRecord{},
			errors.New("taskloop: retained overlay identity mismatch")
	}
	loaded, err := backend.LoadRecord(descriptor)
	if err != nil {
		return agentguard.IsolationDescriptor{}, agentworkspace.OverlayRecord{}, err
	}
	if !reflect.DeepEqual(loaded, record) {
		return agentguard.IsolationDescriptor{}, agentworkspace.OverlayRecord{},
			errors.New("taskloop: retained overlay record identity mismatch")
	}
	return descriptor, record, nil
}

var errVerdictMissing = errors.New("taskloop: official review verdict is missing")

func readReviewVerdict(path string) (agenttask.ReviewVerdict, string, error) {
	content, err := os.ReadFile(path)
	if err != nil {
		return "", "", err
	}
	if len(content) == 0 || len(content) > maxWorkflowArtifactBytes {
		return "", "", errors.New("taskloop: official review artifact is not bounded")
	}
	lines := strings.Split(string(content), "\n")
	heading := -1
	for index, line := range lines {
		if strings.TrimSpace(line) == "## Code Review Result" {
			heading = index
		}
	}
	if heading < 0 {
		return "", "", errVerdictMissing
	}
	var values []string
	for _, line := range lines[heading+1:] {
		text := strings.TrimSpace(line)
		if strings.HasPrefix(text, "## ") {
			break
		}
		if strings.HasPrefix(text, "-") {
			text = strings.TrimSpace(strings.TrimPrefix(text, "-"))
		}
		field, value, ok := strings.Cut(text, ":")
		if ok && strings.TrimSpace(field) == "Overall Verdict" {
			values = append(values, strings.TrimSpace(value))
		}
	}
	if len(values) == 0 {
		return "", "", errVerdictMissing
	}
	if len(values) != 1 {
		return "", "", errors.New("taskloop: official review verdict is ambiguous")
	}
	switch values[0] {
	case "PASS":
		return agenttask.ReviewVerdictPass, "official review passed", nil
	case "WARN":
		return agenttask.ReviewVerdictWarn, "official review requested follow-up", nil
	case "FAIL":
		return agenttask.ReviewVerdictFail, "official review failed", nil
	case "USER_REVIEW":
		return agenttask.ReviewVerdictUserReview, "official review requires user review", nil
	default:
		return "", "", errors.New("taskloop: official review verdict is invalid")
	}
}

// CatalogReviewExecutor rehydrates the retained isolation and starts the
// official reviewer only through that exact executable confinement proof.
type CatalogReviewExecutor struct {
	catalog agentconfig.Catalog
	backend retainedIsolationBackend
}

func NewCatalogReviewExecutor(
	catalogConfig agentconfig.Catalog,
	backend retainedIsolationBackend,
) (*CatalogReviewExecutor, error) {
	if backend == nil {
		return nil, errors.New("taskloop: official review requires a retained isolation backend")
	}
	normalized, err := agentconfig.Normalize(catalogConfig)
	if err != nil {
		return nil, err
	}
	return &CatalogReviewExecutor{catalog: normalized, backend: backend}, nil
}

func (executor *CatalogReviewExecutor) ExecuteReview(
	ctx context.Context,
	request agenttask.ReviewRequest,
	workspace, planRelative, reviewRelative string,
) error {
	if request.Work.Target == nil {
		return errors.New("taskloop: official review has no selected provider target")
	}
	prepared, descriptor, err := rehydrateRetainedIsolation(
		ctx,
		executor.backend,
		executor.catalog,
		request.Project,
		request.Work,
	)
	if err != nil {
		return err
	}
	if workspace != descriptor.WorkingDir {
		return errors.New("taskloop: official review workspace is not the retained view")
	}
	resolved, ok := executor.catalog.ResolveProfile(request.Work.Target.ProfileID)
	if !ok {
		return errors.New("taskloop: official review profile is not declared")
	}
	prompt := officialReviewPrompt(planRelative, reviewRelative)
	command, _, err := prepareFreshCatalogCommand(
		resolved,
		*request.Work.Target,
		prepared.Confinement.Binding(),
		descriptor.WorkingDir,
		prompt,
		request.Project,
		request.Work,
		"official-review",
	)
	if err != nil {
		return err
	}
	return invokeConfined(ctx, prepared.Confinement, command)
}

func officialReviewPrompt(plan, review string) string {
	return fmt.Sprintf(
		"This is a bounded official-review step owned by the task loop, not task "+
			"finalization. Review %s against %s without implementing changes or "+
			"invoking a task-loop dispatcher. Do not modify review-only checklists, "+
			"write completion metadata, update a roadmap, or archive, move, rename, "+
			"or delete either active artifact. Append only one `## Code Review Result` "+
			"section to the existing review artifact, with exactly one "+
			"`Overall Verdict:` field whose value is PASS, WARN, FAIL, or USER_REVIEW.",
		plan,
		review,
	)
}

func rehydrateRetainedIsolation(
	ctx context.Context,
	backend retainedIsolationBackend,
	catalog agentconfig.Catalog,
	project agenttask.ProjectRecord,
	work agenttask.WorkRecord,
) (agenttask.PreparedIsolation, agentguard.IsolationDescriptor, error) {
	if work.Target == nil {
		return agenttask.PreparedIsolation{}, agentguard.IsolationDescriptor{},
			errors.New("taskloop: retained work has no selected target")
	}
	descriptor, record, err := loadOverlayState(backend, work)
	if err != nil {
		return agenttask.PreparedIsolation{}, agentguard.IsolationDescriptor{}, err
	}
	if record.ProjectID != string(project.ProjectID) ||
		record.WorkspaceID != string(project.WorkspaceID) ||
		record.ConfigRevision != string(work.Target.ConfigRevision) ||
		record.ProfileRevision != work.Target.ProfileRevision {
		return agenttask.PreparedIsolation{}, agentguard.IsolationDescriptor{},
			errors.New("taskloop: retained overlay policy identity mismatch")
	}
	resolved, ok := catalog.ResolveProfile(work.Target.ProfileID)
	if !ok || validateCatalogTarget(resolved, *work.Target) != nil {
		return agenttask.PreparedIsolation{}, agentguard.IsolationDescriptor{},
			errors.New("taskloop: retained target does not match the catalog")
	}
	prepared, err := backend.Prepare(ctx, agenttask.IsolationRequest{
		Project:        project,
		Work:           work,
		Target:         *work.Target,
		IdempotencyKey: record.IdempotencyKey,
	})
	if err != nil {
		return agenttask.PreparedIsolation{}, agentguard.IsolationDescriptor{}, err
	}
	if prepared.Descriptor == nil ||
		!reflect.DeepEqual(*prepared.Descriptor, descriptor) ||
		!reflect.DeepEqual(prepared.Profile, guardProfile(resolved)) ||
		prepared.Confinement == nil {
		return agenttask.PreparedIsolation{}, agentguard.IsolationDescriptor{},
			errors.New("taskloop: rehydrated isolation identity mismatch")
	}
	binding := prepared.Confinement.Binding()
	if prepared.Confinement.Revision() != record.ConfinementRevision ||
		binding.Revision != record.ConfinementRevision ||
		binding.IsolationID != record.IsolationID ||
		binding.IsolationRevision != record.Revision ||
		binding.PinnedBaseRevision != record.SnapshotRevision ||
		binding.ConfigRevision != record.ConfigRevision ||
		binding.GrantRevision != record.GrantRevision ||
		binding.ProfileRevision != record.ProfileRevision ||
		binding.BaseRoot != record.CanonicalRoot ||
		binding.SnapshotRoot != record.Locator.SnapshotRoot ||
		binding.TaskRoot != descriptor.TaskRoot ||
		binding.WorkingDir != descriptor.WorkingDir ||
		!reflect.DeepEqual(binding.WritableRoots, descriptor.WritableRoots) {
		return agenttask.PreparedIsolation{}, agentguard.IsolationDescriptor{},
			errors.New("taskloop: rehydrated confinement binding mismatch")
	}
	if err := prepared.Confinement.Validate(binding); err != nil {
		return agenttask.PreparedIsolation{}, agentguard.IsolationDescriptor{},
			fmt.Errorf("taskloop: validate retained confinement: %w", err)
	}
	return prepared, descriptor, nil
}