package llm

import (
	"context"
	"encoding/json"
	"errors"
	"io"
	"net/http"
	"os"
	"path/filepath"
	"strings"
	"sync"
	"sync/atomic"
	"testing"
	"testing/fstest"
	"time"

	"gitea.maximumdirect.net/eric/notarius/internal/framework/contracts"
	"gitea.maximumdirect.net/eric/promptkit"
)

func TestPromptKitClientMapsPromptRequestAndUnmarshalsOutput(t *testing.T) {
	fake := &fakePromptKitLLM{content: `{"ok":true}`}
	client := newTestPromptKitClient(t, fake)

	var out struct {
		OK bool `json:"ok"`
	}
	resp, err := client.CompleteStructured(context.Background(), contracts.StructuredCompletionRequest{
		StageName:     "test-stage",
		PromptID:      "adapter.test",
		PromptVersion: "v1",
		ProfileID:     "explicit-profile",
		SessionID:     "session-123",
		Inputs: contracts.LLMInputSet{
			"transcript": contracts.NewLLMInputMaterial("transcript", "application/json", []byte(`{"source":true}`), "sha256:source", "file:///source.json"),
		},
		Vars: map[string]any{"custom": "value"},
	}, &out)
	if err != nil {
		t.Fatalf("CompleteStructured() error = %v, want nil", err)
	}
	if !out.OK {
		t.Fatalf("decoded output OK = false, want true")
	}
	if resp.Provider != "promptkit" || resp.Model != "explicit-model" || resp.ProfileID != "explicit-profile" {
		t.Fatalf("response metadata = %#v", resp)
	}
	if resp.PromptTokens != 11 || resp.CompletionTokens != 7 || resp.TotalTokens != 18 {
		t.Fatalf("usage = %#v, want mapped token counts", resp)
	}
	if resp.Debug == nil || resp.Debug.Prompt == nil {
		t.Fatalf("debug prompt = nil, want prepared prompt material")
	}
	if resp.Debug.Prompt.PromptID != "adapter.test" || resp.Debug.Prompt.SelectedProfileID != "explicit-profile" {
		t.Fatalf("debug prompt metadata = %#v, want prompt/profile", resp.Debug.Prompt)
	}
	if len(resp.Debug.Prompt.Messages) != 1 || !strings.Contains(resp.Debug.Prompt.Messages[0].Content, `{"source":true}`) {
		t.Fatalf("debug prompt messages = %#v, want rendered input content", resp.Debug.Prompt.Messages)
	}
	if resp.Debug.Response == nil || resp.Debug.Response.Content != `{"ok":true}` {
		t.Fatalf("debug response = %#v, want raw response content", resp.Debug.Response)
	}
	if resp.Debug.Response.Usage.CachedTokens != 5 || resp.Debug.Response.Usage.CacheWriteTokens != 3 {
		t.Fatalf("debug usage = %#v, want cached token counts", resp.Debug.Response.Usage)
	}
	debugJSON, err := json.Marshal(resp.Debug)
	if err != nil {
		t.Fatalf("marshal debug material: %v", err)
	}
	if strings.Contains(string(debugJSON), "secret-token") || strings.Contains(string(debugJSON), "sk-") {
		t.Fatalf("debug material contains secret material: %s", debugJSON)
	}
	gotReq := fake.lastRequest()
	if gotReq.Prompt.SessionID != "session-123" {
		t.Fatalf("session id = %q, want session-123", gotReq.Prompt.SessionID)
	}
	if gotReq.Target.Model != "explicit-model" {
		t.Fatalf("model = %q, want explicit-model", gotReq.Target.Model)
	}
	if len(gotReq.Prompt.Messages) != 1 ||
		!strings.Contains(gotReq.Prompt.Messages[0].Content, `{"source":true}`) ||
		!strings.Contains(gotReq.Prompt.Messages[0].Content, "value") {
		t.Fatalf("rendered messages = %#v, want transcript input and variable content", gotReq.Prompt.Messages)
	}
	if gotReq.StructuredOutput == nil {
		t.Fatalf("structured output = nil, want JSON schema")
	}
	manifests := client.LLMProfileManifests()
	if len(manifests) != 1 ||
		manifests[0].ID != "explicit-profile" ||
		manifests[0].Provider != "promptkit" ||
		manifests[0].Model != "explicit-model" {
		t.Fatalf("profile manifests = %#v", manifests)
	}
}

func TestNewPromptKitClientReportsAssetAndEngineConstructionFailures(t *testing.T) {
	t.Run("assets", func(t *testing.T) {
		registry := NewAssetRegistry()
		for _, root := range []string{"one", "two"} {
			if err := registry.RegisterPromptFS(fstest.MapFS{
				root + "/prompt.yaml": {Data: []byte("id: duplicate")},
			}, root); err != nil {
				t.Fatalf("RegisterPromptFS() error = %v", err)
			}
		}
		if _, err := NewPromptKitClient(PromptKitClientConfig{Assets: registry}); err == nil ||
			!strings.Contains(err.Error(), "duplicate asset path") {
			t.Fatalf("NewPromptKitClient() error = %v, want asset construction failure", err)
		}
	})

	t.Run("engine", func(t *testing.T) {
		if _, err := NewPromptKitClient(PromptKitClientConfig{
			Assets:        newTestPromptKitAssets(t),
			EngineOptions: []promptkit.Option{promptkit.WithProfileFile("")},
		}); err == nil || !strings.Contains(err.Error(), "create PromptKit engine") {
			t.Fatalf("NewPromptKitClient() error = %v, want engine construction failure", err)
		}
	})
}

func TestPromptKitClientCheckpointFingerprintTracksProfileSource(t *testing.T) {
	profilePath := filepath.Join(t.TempDir(), "profiles.yml")
	writeProfile := func(model string) {
		t.Helper()
		content := "id: checkpoint-profile\nendpoint: http://promptkit.test/v1\nmodel: " + model + "\n"
		if err := os.WriteFile(profilePath, []byte(content), 0o600); err != nil {
			t.Fatal(err)
		}
	}
	fingerprintFor := func() CheckpointFingerprint {
		t.Helper()
		client, err := NewPromptKitClient(PromptKitClientConfig{
			Assets:      newTestPromptKitAssets(t),
			ProfileFile: profilePath,
		})
		if err != nil {
			t.Fatal(err)
		}
		values, err := client.LLMCheckpointFingerprints()
		if err != nil {
			t.Fatal(err)
		}
		if len(values) != 1 || values[0].Name != promptKitProfileFingerprintName {
			t.Fatalf("checkpoint fingerprints = %#v, want one profile-source identity", values)
		}
		return values[0]
	}

	writeProfile("model-one")
	first := fingerprintFor()
	writeProfile("model-two")
	second := fingerprintFor()
	if first == second {
		t.Fatalf("profile-source fingerprint = %#v for both profile models", first)
	}
	if strings.Contains(first.Value, profilePath) || strings.Contains(first.Value, "model-one") {
		t.Fatalf("profile-source fingerprint exposes source details: %#v", first)
	}

	client, err := NewPromptKitClient(PromptKitClientConfig{Assets: newTestPromptKitAssets(t)})
	if err != nil {
		t.Fatal(err)
	}
	copy, err := client.LLMCheckpointFingerprints()
	if err != nil {
		t.Fatal(err)
	}
	copy[0].Value = "mutated"
	fresh, err := client.LLMCheckpointFingerprints()
	if err != nil {
		t.Fatal(err)
	}
	if fresh[0].Value == "mutated" {
		t.Fatal("LLMCheckpointFingerprints exposed mutable backing storage")
	}
	const wantBuiltinFingerprint = "sha256:4b48cd1ef010b587cd8d56bc13b73a0cdd84da1414a8de9f9a2adc695dfcf0a7"
	if fresh[0].Value != wantBuiltinFingerprint {
		t.Fatalf("built-in profile fingerprint = %q, want %q", fresh[0].Value, wantBuiltinFingerprint)
	}
}

func TestPromptKitClientUsesPromptDefaultProfileWhenRequestProfileEmpty(t *testing.T) {
	fake := &fakePromptKitLLM{content: `{"ok":true}`}
	client := newTestPromptKitClient(t, fake)

	var out map[string]any
	if _, err := client.CompleteStructured(context.Background(), contracts.StructuredCompletionRequest{
		PromptID:  "adapter.test",
		SessionID: "session-123",
		Inputs: contracts.LLMInputSet{
			"transcript": contracts.NewLLMInputMaterial("transcript", "application/json", []byte(`{"source":true}`), "", ""),
		},
	}, &out); err != nil {
		t.Fatalf("CompleteStructured() error = %v, want nil", err)
	}
	if got := fake.lastRequest().Target.Model; got != "default-model" {
		t.Fatalf("model = %q, want prompt default profile model", got)
	}
}

func TestPromptKitClientValidationFailureReturnsError(t *testing.T) {
	client := newTestPromptKitClient(t, &fakePromptKitLLM{content: `{"bad":true}`})

	var out map[string]any
	resp, err := client.CompleteStructured(context.Background(), contracts.StructuredCompletionRequest{
		PromptID:  "adapter.test",
		SessionID: "session-123",
		Inputs: contracts.LLMInputSet{
			"transcript": contracts.NewLLMInputMaterial("transcript", "application/json", []byte(`{"source":true}`), "", ""),
		},
	}, &out)
	if err == nil || !errors.Is(err, contracts.ErrInvalidStructuredOutput) || !strings.Contains(err.Error(), "validation failed") {
		t.Fatalf("CompleteStructured() error = %v, want validation failure", err)
	}
	if got := string(resp.Content); got != `{"bad":true}` {
		t.Fatalf("response content = %q, want raw failed output", got)
	}
	if resp.Debug == nil || resp.Debug.Response == nil || resp.Debug.Response.Content != `{"bad":true}` {
		t.Fatalf("debug response = %#v, want raw failed output", resp.Debug)
	}
	if resp.Debug.Prompt == nil || len(resp.Debug.Prompt.Messages) == 0 {
		t.Fatalf("debug prompt = %#v, want prepared prompt material", resp.Debug.Prompt)
	}
}

func TestPromptKitClientDecodeFailureReturnsRawResponse(t *testing.T) {
	client := newTestPromptKitClient(t, &fakePromptKitLLM{content: `{"ok":true}`})

	var out []any
	resp, err := client.CompleteStructured(context.Background(), contracts.StructuredCompletionRequest{
		PromptID:  "adapter.test",
		SessionID: "session-123",
		Inputs: contracts.LLMInputSet{
			"transcript": contracts.NewLLMInputMaterial("transcript", "application/json", []byte(`{"source":true}`), "", ""),
		},
	}, &out)
	if err == nil || !errors.Is(err, contracts.ErrInvalidStructuredOutput) || !strings.Contains(err.Error(), "decode PromptKit structured output") {
		t.Fatalf("CompleteStructured() error = %v, want decode failure", err)
	}
	if got := string(resp.Content); got != `{"ok":true}` {
		t.Fatalf("response content = %q, want raw decode-failed output", got)
	}
	if resp.Debug == nil || resp.Debug.Response == nil || resp.Debug.Response.Content != `{"ok":true}` {
		t.Fatalf("debug response = %#v, want raw decode-failed output", resp.Debug)
	}
}

func TestPromptKitClientProviderFailureIncludesContextAndRedactsBearerToken(t *testing.T) {
	client := newTestPromptKitClient(t, &fakePromptKitLLM{err: errors.New("provider failed with Bearer secret-token")})

	var out map[string]any
	resp, err := client.CompleteStructured(context.Background(), contracts.StructuredCompletionRequest{
		PromptID:  "adapter.test",
		SessionID: "session-123",
		Inputs: contracts.LLMInputSet{
			"transcript": contracts.NewLLMInputMaterial("transcript", "application/json", []byte(`{"source":true}`), "", ""),
		},
	}, &out)
	if err == nil {
		t.Fatalf("CompleteStructured() error = nil, want provider error")
	}
	if errors.Is(err, contracts.ErrInvalidStructuredOutput) {
		t.Fatalf("provider error = %v, must not be classified as invalid structured output", err)
	}
	if !strings.Contains(err.Error(), `run PromptKit prompt "adapter.test"`) {
		t.Fatalf("error = %q, want operation context", err.Error())
	}
	if strings.Contains(err.Error(), "secret-token") || !strings.Contains(err.Error(), "Bearer [REDACTED]") {
		t.Fatalf("error = %q, want redacted bearer token", err.Error())
	}
	if resp.Debug != nil {
		t.Fatalf("debug material = %#v, want none for provider failure without result", resp.Debug)
	}
}

func TestPromptKitClientContextCancellationIsRespected(t *testing.T) {
	ctx, cancel := context.WithCancel(context.Background())
	cancel()
	client := newTestPromptKitClient(t, &fakePromptKitLLM{content: `{"ok":true}`})

	var out map[string]any
	_, err := client.CompleteStructured(ctx, contracts.StructuredCompletionRequest{
		PromptID: "adapter.test",
		Inputs: contracts.LLMInputSet{
			"transcript": contracts.NewLLMInputMaterial("transcript", "application/json", []byte(`{"source":true}`), "", ""),
		},
	}, &out)
	if !errors.Is(err, context.Canceled) || errors.Is(err, contracts.ErrInvalidStructuredOutput) {
		t.Fatalf("CompleteStructured() error = %v, want context canceled", err)
	}
}

func TestPromptKitClientForwardsConfiguredTransportTimeout(t *testing.T) {
	var remaining time.Duration
	transport := roundTripFunc(func(req *http.Request) (*http.Response, error) {
		deadline, ok := req.Context().Deadline()
		if !ok {
			t.Fatal("outbound request context has no deadline")
		}
		remaining = time.Until(deadline)
		return &http.Response{
			StatusCode: http.StatusOK,
			Status:     "200 OK",
			Header:     make(http.Header),
			Body: io.NopCloser(strings.NewReader(
				`{"choices":[{"message":{"content":"{\"ok\":true}"}}]}`,
			)),
			Request: req,
		}, nil
	})
	const configuredTimeout = 2 * time.Second
	client, err := NewPromptKitClient(PromptKitClientConfig{
		Assets:     newTestPromptKitAssets(t),
		Timeout:    configuredTimeout,
		HTTPClient: &http.Client{Transport: transport},
		EngineOptions: []promptkit.Option{
			promptkit.WithProfiles(promptkit.OpenAICompatibleProfile(promptkit.OpenAICompatibleProfileConfig{
				ID:       "default-profile",
				Endpoint: "http://promptkit.test/v1",
				Model:    "default-model",
			})),
		},
	})
	if err != nil {
		t.Fatalf("NewPromptKitClient() error = %v", err)
	}
	var out map[string]any
	if _, err := client.CompleteStructured(context.Background(), contracts.StructuredCompletionRequest{
		PromptID:  "adapter.test",
		SessionID: "session-123",
		Inputs: contracts.LLMInputSet{
			"transcript": contracts.NewLLMInputMaterial("transcript", "application/json", []byte(`{"source":true}`), "", ""),
		},
	}, &out); err != nil {
		t.Fatalf("CompleteStructured() error = %v", err)
	}
	if remaining < configuredTimeout-time.Second || remaining > configuredTimeout {
		t.Fatalf("transport deadline remaining = %v, want near %v", remaining, configuredTimeout)
	}
}

func TestPromptKitClientClassifiesEmptyStructuredCompletion(t *testing.T) {
	client := newTestPromptKitClient(t, &fakePromptKitLLM{allowEmpty: true})

	var out map[string]any
	_, err := client.CompleteStructured(context.Background(), contracts.StructuredCompletionRequest{
		PromptID:  "adapter.test",
		SessionID: "session-123",
		Inputs: contracts.LLMInputSet{
			"transcript": contracts.NewLLMInputMaterial("transcript", "application/json", []byte(`{"source":true}`), "", ""),
		},
	}, &out)
	if !errors.Is(err, contracts.ErrInvalidStructuredOutput) {
		t.Fatalf("CompleteStructured() error = %v, want invalid structured output", err)
	}
}

func TestScheduledPromptKitClientBoundsConcurrentCalls(t *testing.T) {
	fake := &fakePromptKitLLM{
		content: `{"ok":true}`,
		block:   make(chan struct{}),
	}
	client := newTestPromptKitClient(t, fake)
	scheduler, err := NewScheduler(1)
	if err != nil {
		t.Fatalf("NewScheduler() error = %v, want nil", err)
	}
	scheduled := NewScheduledClient(client, scheduler)

	var wg sync.WaitGroup
	for i := 0; i < 3; i++ {
		wg.Add(1)
		go func() {
			defer wg.Done()
			var out map[string]any
			_, callErr := scheduled.CompleteStructured(context.Background(), contracts.StructuredCompletionRequest{
				PromptID:  "adapter.test",
				SessionID: "session-123",
				Inputs: contracts.LLMInputSet{
					"transcript": contracts.NewLLMInputMaterial("transcript", "application/json", []byte(`{"source":true}`), "", ""),
				},
			}, &out)
			if callErr != nil {
				t.Errorf("CompleteStructured() error = %v, want nil", callErr)
			}
		}()
	}
	waitForAtomicAtLeast(t, &fake.calls, 1)
	time.Sleep(20 * time.Millisecond)
	if got := atomic.LoadInt32(&fake.maxInFlight); got > 1 {
		t.Fatalf("max in-flight calls = %d, want <= 1", got)
	}
	close(fake.block)
	wg.Wait()
}

func TestPromptKitClientValidatesRequest(t *testing.T) {
	client := newTestPromptKitClient(t, &fakePromptKitLLM{content: `{"ok":true}`})
	var out map[string]any
	if _, err := client.CompleteStructured(context.Background(), contracts.StructuredCompletionRequest{}, &out); err == nil || !strings.Contains(err.Error(), "prompt_id") {
		t.Fatalf("missing prompt id error = %v, want prompt_id validation", err)
	}
	if _, err := client.CompleteStructured(context.Background(), contracts.StructuredCompletionRequest{PromptID: "adapter.test"}, nil); err == nil || !strings.Contains(err.Error(), "non-nil pointer") {
		t.Fatalf("nil output error = %v, want output validation", err)
	}
}

func newTestPromptKitClient(t *testing.T, fake *fakePromptKitLLM) *PromptKitClient {
	t.Helper()
	registry := newTestPromptKitAssets(t)
	client, err := NewPromptKitClient(PromptKitClientConfig{
		Assets: registry,
		EngineOptions: []promptkit.Option{
			promptkit.WithProfiles(
				promptkit.OpenAICompatibleProfile(promptkit.OpenAICompatibleProfileConfig{
					ID:       "default-profile",
					Endpoint: "http://127.0.0.1:1/v1",
					Model:    "default-model",
				}),
				promptkit.OpenAICompatibleProfile(promptkit.OpenAICompatibleProfileConfig{
					ID:       "explicit-profile",
					Endpoint: "http://127.0.0.1:1/v1",
					Model:    "explicit-model",
				}),
			),
			promptkit.WithLLMClient(fake),
		},
	})
	if err != nil {
		t.Fatalf("NewPromptKitClient() error = %v, want nil", err)
	}
	return client
}

func newTestPromptKitAssets(t *testing.T) *AssetRegistry {
	t.Helper()
	registry := NewAssetRegistry()
	if err := registry.RegisterPromptFS(fstest.MapFS{
		"adapter.test.yaml": {Data: []byte(`id: adapter.test
version: "v1"
default_profile: default-profile
session_id: "{{ .session_id }}"
inputs:
  - name: transcript
    required: true
    content_type: application/json
messages:
  - role: user
    content: "Transcript: {{ input \"transcript\" }} Custom: {{ index . \"custom\" }}"
output:
  format: json
  validation_mode: json_schema
  schema_path: adapter.schema.json
  repair_attempts: 0
`)},
	}, "."); err != nil {
		t.Fatalf("RegisterPromptFS() error = %v", err)
	}
	if err := registry.RegisterSchemaFS(fstest.MapFS{
		"adapter.schema.json": {Data: []byte(`{"type":"object","required":["ok"],"properties":{"ok":{"type":"boolean"}}}`)},
	}, "."); err != nil {
		t.Fatalf("RegisterSchemaFS() error = %v", err)
	}
	return registry
}

type fakePromptKitLLM struct {
	content     string
	allowEmpty  bool
	err         error
	block       chan struct{}
	mu          sync.Mutex
	last        promptkit.GenerateRequest
	calls       int32
	inFlight    int32
	maxInFlight int32
}

func (f *fakePromptKitLLM) Generate(ctx context.Context, req promptkit.GenerateRequest) (*promptkit.GenerateResponse, error) {
	f.mu.Lock()
	f.last = req
	f.mu.Unlock()
	atomic.AddInt32(&f.calls, 1)
	current := atomic.AddInt32(&f.inFlight, 1)
	for {
		seen := atomic.LoadInt32(&f.maxInFlight)
		if current <= seen || atomic.CompareAndSwapInt32(&f.maxInFlight, seen, current) {
			break
		}
	}
	defer atomic.AddInt32(&f.inFlight, -1)
	if f.block != nil {
		select {
		case <-f.block:
		case <-ctx.Done():
			return nil, ctx.Err()
		}
	}
	if f.err != nil {
		return nil, f.err
	}
	content := f.content
	if content == "" && !f.allowEmpty {
		content = `{"ok":true}`
	}
	if !f.allowEmpty && !json.Valid([]byte(content)) {
		return nil, errors.New("test fake must return JSON content")
	}
	return &promptkit.GenerateResponse{
		Content: content,
		Usage: promptkit.TokenUsage{
			PromptTokens:     11,
			CompletionTokens: 7,
			TotalTokens:      18,
			CachedTokens:     5,
			CacheWriteTokens: 3,
		},
	}, nil
}

type roundTripFunc func(*http.Request) (*http.Response, error)

func (f roundTripFunc) RoundTrip(req *http.Request) (*http.Response, error) {
	return f(req)
}

func (f *fakePromptKitLLM) lastRequest() promptkit.GenerateRequest {
	f.mu.Lock()
	defer f.mu.Unlock()
	return f.last
}