package app

import (
	"context"
	"errors"
	"os"
	"path/filepath"
	"strings"
	"testing"
	"time"

	"gitea.maximumdirect.net/eric/narratio/internal/artifacts"
	"gitea.maximumdirect.net/eric/narratio/internal/config"
	"gitea.maximumdirect.net/eric/narratio/internal/manifest"
	"gitea.maximumdirect.net/eric/narratio/internal/stage"
)

func TestValidateBoundedPrerequisitesRejectsFirstUnusablePrefixStatus(t *testing.T) {
	plan := mustBoundedPlan(t, "render", "extract")
	now := time.Date(2026, 5, 3, 10, 0, 0, 0, time.UTC)
	for _, test := range []struct {
		name   string
		status manifest.StageStatus
		want   string
	}{
		{name: "absent", want: "absent"},
		{name: "pending", status: manifest.StatusPending, want: "pending"},
		{name: "running", status: manifest.StatusRunning, want: "running"},
		{name: "failed", status: manifest.StatusFailed, want: "failed"},
		{name: "stale", status: manifest.StatusStale, want: "stale"},
		{name: "interrupted", status: manifest.StatusInterrupted, want: "interrupted"},
	} {
		t.Run(test.name, func(t *testing.T) {
			m := manifest.New("session", now)
			if test.status != "" {
				m.Stages["prepare"] = &manifest.StageRecord{Name: "prepare", Status: test.status}
			}
			// A later terminal prefix must not hide the first unusable one.
			m.MarkStageSucceeded("transcribe", now, nil)
			err := validateBoundedPrerequisites(plan, m)
			if err == nil {
				t.Fatal("validateBoundedPrerequisites() error = nil")
			}
			for _, detail := range []string{`stage "prepare"`, `status "` + test.want + `"`, `selected start "render"`, "--from prepare", "recover prepare"} {
				if !strings.Contains(err.Error(), detail) {
					t.Fatalf("error = %q, want detail %q", err, detail)
				}
			}
		})
	}
}

func TestValidateBoundedPrerequisitesAcceptsSucceededAndSkippedPrefix(t *testing.T) {
	plan := mustBoundedPlan(t, "render", "render")
	m := manifest.New("session", time.Now().UTC())
	for index, name := range plan.PrefixNames() {
		if index%2 == 0 {
			m.MarkStageSucceeded(name, time.Now().UTC(), nil)
		} else {
			m.MarkStageSkipped(name, time.Now().UTC(), "not applicable")
		}
	}
	if err := validateBoundedPrerequisites(plan, m); err != nil {
		t.Fatalf("validateBoundedPrerequisites() error = %v", err)
	}
}

func TestValidateBoundedPrerequisitesHasNoPrefixAtPrepareAndIgnoresSuffix(t *testing.T) {
	preparePlan := mustBoundedPlan(t, "prepare", "prepare")
	if err := validateBoundedPrerequisites(preparePlan, nil); err != nil {
		t.Fatalf("prepare prerequisite validation error = %v", err)
	}

	renderPlan := mustBoundedPlan(t, "render", "render")
	m := manifest.New("session", time.Now().UTC())
	markPrefixSucceeded(m, renderPlan)
	m.MarkStageFailed("analyze", time.Now().UTC(), "later failure")
	if err := validateBoundedPrerequisites(renderPlan, m); err != nil {
		t.Fatalf("suffix status affected prerequisite validation: %v", err)
	}
}

func TestExecuteStagesRejectsBoundedPrerequisitesBeforePersistentMutation(t *testing.T) {
	cfg := testConfig(t)
	plan := mustBoundedPlan(t, "render", "render")
	m := manifest.New(cfg.Session.SessionID, time.Now().UTC())
	m.Campaign = cfg.Session.Campaign
	m.MarkStageRunning("prepare", time.Now().UTC())
	manifestPath := saveBoundedManifest(t, cfg, m)
	before, err := os.ReadFile(manifestPath)
	if err != nil {
		t.Fatalf("read seeded manifest: %v", err)
	}

	store := &prerequisiteMutationSpy{local: &manifest.LocalStore{}}
	runs := 0
	_, err = executeStages(context.Background(), cfg, []stage.Stage{countingStage{name: "render", runs: &runs}}, RunOptions{
		Plan: plan,
		Env:  &Env{ManifestStore: store},
	})
	if err == nil || !strings.Contains(err.Error(), `stage "prepare" has unusable status "running"`) {
		t.Fatalf("executeStages() error = %v, want running prerequisite", err)
	}
	if runs != 0 || store.creates != 0 || store.saves != 0 {
		t.Fatalf("runs=%d manifest creates=%d saves=%d, want no mutation", runs, store.creates, store.saves)
	}
	after, err := os.ReadFile(manifestPath)
	if err != nil {
		t.Fatalf("read manifest after rejection: %v", err)
	}
	if string(after) != string(before) {
		t.Fatal("manifest changed after prerequisite rejection")
	}
	if _, err := os.Stat(artifacts.SessionRunsDirForCampaign(cfg.Pipeline.Workspace.Root, cfg.Session.Campaign, cfg.Session.SessionID)); !os.IsNotExist(err) {
		t.Fatalf("runs directory stat error = %v, want not exist", err)
	}
}

func TestExecuteStagesRechecksBoundedPrerequisitesUnderSessionLock(t *testing.T) {
	cfg := testConfig(t)
	plan := mustBoundedPlan(t, "render", "render")
	m := manifest.New(cfg.Session.SessionID, time.Now().UTC())
	m.Campaign = cfg.Session.Campaign
	markPrefixSucceeded(m, plan)
	saveBoundedManifest(t, cfg, m)

	store := &prerequisiteChangingStore{local: &manifest.LocalStore{}}
	runs := 0
	_, err := executeStages(context.Background(), cfg, []stage.Stage{countingStage{name: "render", runs: &runs}}, RunOptions{
		Plan: plan,
		Env:  &Env{ManifestStore: store},
	})
	if err == nil || !strings.Contains(err.Error(), `stage "prepare" has unusable status "running"`) {
		t.Fatalf("executeStages() error = %v, want changed prerequisite rejection", err)
	}
	if store.loads != 2 {
		t.Fatalf("manifest loads = %d, want preflight and locked reload", store.loads)
	}
	if runs != 0 || store.creates != 0 || store.saves != 0 {
		t.Fatalf("runs=%d manifest creates=%d saves=%d, want no run or manifest mutation", runs, store.creates, store.saves)
	}
}

func TestExecuteStagesBoundedCompositionUsesOnlySelectedCollaborators(t *testing.T) {
	for _, test := range []struct {
		name        string
		stageName   string
		configure   func(*config.Config)
		assertProbe func(*testing.T, *stage.Env)
	}{
		{
			name:      "render",
			stageName: "render",
			assertProbe: func(t *testing.T, env *stage.Env) {
				if env.Seriatim == nil || env.Notarius != nil || env.Scriptorium != nil {
					t.Fatalf("render collaborators: seriatim=%v notarius=%v scriptorium=%v", env.Seriatim, env.Notarius, env.Scriptorium)
				}
			},
		},
		{
			name:      "extract",
			stageName: "extract",
			configure: func(cfg *config.Config) {
				cfg.Pipeline.Notarius = &config.NotariusConfig{Enabled: true}
			},
			assertProbe: func(t *testing.T, env *stage.Env) {
				if env.Notarius == nil || env.Scriptorium != nil || env.Seriatim != nil {
					t.Fatalf("extract collaborators: notarius=%v scriptorium=%v seriatim=%v", env.Notarius, env.Scriptorium, env.Seriatim)
				}
			},
		},
		{
			name:      "analyze",
			stageName: "analyze",
			assertProbe: func(t *testing.T, env *stage.Env) {
				if env.Scriptorium == nil || env.Notarius != nil || env.Seriatim != nil || env.WhisperX != nil || env.Audita != nil {
					t.Fatalf("analyze collaborators: scriptorium=%v notarius=%v seriatim=%v whisperx=%v audita=%v", env.Scriptorium, env.Notarius, env.Seriatim, env.WhisperX, env.Audita)
				}
			},
		},
	} {
		t.Run(test.name, func(t *testing.T) {
			cfg := testConfig(t)
			if test.configure != nil {
				test.configure(cfg)
			}
			plan := mustBoundedPlan(t, test.stageName, test.stageName)
			m := manifest.New(cfg.Session.SessionID, time.Now().UTC())
			m.Campaign = cfg.Session.Campaign
			markPrefixSucceeded(m, plan)
			saveBoundedManifest(t, cfg, m)

			var captured *stage.Env
			_, err := executeStages(context.Background(), cfg, []stage.Stage{collaboratorProbeStage{name: test.stageName, captured: &captured}}, RunOptions{Plan: plan})
			if err != nil {
				t.Fatalf("executeStages() error = %v", err)
			}
			if captured == nil {
				t.Fatal("selected stage did not run")
			}
			test.assertProbe(t, captured)
		})
	}
}

func TestExecuteStagesBoundedForceStalesButDoesNotRunDependentsOutsideRange(t *testing.T) {
	cfg := testConfig(t)
	plan := mustBoundedPlan(t, "render", "render")
	m := manifest.New(cfg.Session.SessionID, time.Now().UTC())
	m.Campaign = cfg.Session.Campaign
	for _, name := range []string{"prepare", "transcribe", "merge", "polish", "normalize", "trim", "render", "extract", "analyze", "publish", "notify"} {
		m.MarkStageSucceeded(name, time.Now().UTC(), nil)
	}
	saveBoundedManifest(t, cfg, m)
	runs := 0
	_, err := executeStages(context.Background(), cfg, []stage.Stage{countingStage{name: "render", runs: &runs}}, RunOptions{Plan: plan, Force: true})
	if err != nil {
		t.Fatalf("executeStages() error = %v", err)
	}
	if runs != 1 {
		t.Fatalf("selected render runs = %d, want 1", runs)
	}
	loaded, err := (&manifest.LocalStore{}).Load(context.Background(), manifestPathFor(cfg))
	if err != nil {
		t.Fatalf("load manifest: %v", err)
	}
	for _, name := range []string{"analyze", "publish", "notify"} {
		if loaded.Stages[name].Status != manifest.StatusStale {
			t.Fatalf("stage %q status = %q, want stale", name, loaded.Stages[name].Status)
		}
	}
	if loaded.Stages["extract"].Status != manifest.StatusSucceeded {
		t.Fatalf("extract status = %q, want succeeded", loaded.Stages["extract"].Status)
	}
}

func TestExecuteStagesBoundedFailureStopsWithinSelectedRange(t *testing.T) {
	cfg := testConfig(t)
	plan := mustBoundedPlan(t, "render", "extract")
	m := manifest.New(cfg.Session.SessionID, time.Now().UTC())
	m.Campaign = cfg.Session.Campaign
	markPrefixSucceeded(m, plan)
	saveBoundedManifest(t, cfg, m)
	extractRuns := 0
	_, err := executeStages(context.Background(), cfg, []stage.Stage{
		failingStage{name: "render", err: errors.New("render failed")},
		countingStage{name: "extract", runs: &extractRuns},
	}, RunOptions{Plan: plan})
	if err == nil || !strings.Contains(err.Error(), "render failed") {
		t.Fatalf("executeStages() error = %v", err)
	}
	if extractRuns != 0 {
		t.Fatalf("extract runs = %d, want 0", extractRuns)
	}
}

type collaboratorProbeStage struct {
	name     string
	captured **stage.Env
}

func (s collaboratorProbeStage) Name() string { return s.name }
func (s collaboratorProbeStage) Run(_ context.Context, env *stage.Env, _ *manifest.Manifest) (*stage.StageResult, error) {
	*s.captured = env
	return &stage.StageResult{}, nil
}

type prerequisiteMutationSpy struct {
	local   *manifest.LocalStore
	creates int
	saves   int
}

type prerequisiteChangingStore struct {
	local   *manifest.LocalStore
	loads   int
	creates int
	saves   int
}

func (s *prerequisiteChangingStore) Create(ctx context.Context, sessionID string) (*manifest.Manifest, error) {
	s.creates++
	return s.local.Create(ctx, sessionID)
}

func (s *prerequisiteChangingStore) Load(ctx context.Context, path string) (*manifest.Manifest, error) {
	s.loads++
	m, err := s.local.Load(ctx, path)
	if err != nil {
		return nil, err
	}
	if s.loads == 2 {
		m.MarkStageRunning("prepare", time.Now().UTC())
	}
	return m, nil
}

func (s *prerequisiteChangingStore) Save(ctx context.Context, path string, m *manifest.Manifest) error {
	s.saves++
	return s.local.Save(ctx, path, m)
}

func (s *prerequisiteMutationSpy) Create(ctx context.Context, sessionID string) (*manifest.Manifest, error) {
	s.creates++
	return s.local.Create(ctx, sessionID)
}

func (s *prerequisiteMutationSpy) Load(ctx context.Context, path string) (*manifest.Manifest, error) {
	return s.local.Load(ctx, path)
}

func (s *prerequisiteMutationSpy) Save(ctx context.Context, path string, m *manifest.Manifest) error {
	s.saves++
	return s.local.Save(ctx, path, m)
}

func mustBoundedPlan(t *testing.T, from, through string) BoundedPlan {
	t.Helper()
	plan, err := BuildBoundedPlan(from, through)
	if err != nil {
		t.Fatalf("BuildBoundedPlan(%q, %q) error = %v", from, through, err)
	}
	return plan
}

func markPrefixSucceeded(m *manifest.Manifest, plan BoundedPlan) {
	for _, name := range plan.PrefixNames() {
		m.MarkStageSucceeded(name, time.Now().UTC(), nil)
	}
}

func saveBoundedManifest(t *testing.T, cfg *config.Config, m *manifest.Manifest) string {
	t.Helper()
	path := manifestPathFor(cfg)
	if err := os.MkdirAll(filepath.Dir(path), 0o755); err != nil {
		t.Fatalf("create manifest directory: %v", err)
	}
	if err := (&manifest.LocalStore{}).Save(context.Background(), path, m); err != nil {
		t.Fatalf("save manifest: %v", err)
	}
	return path
}