package proposal_generation

import (
	"context"
	"encoding/json"
	"errors"
	"os"
	"path/filepath"
	"reflect"
	"strings"
	"testing"

	ck "gitea.maximumdirect.net/eric/ConfigKit"
	"gitea.maximumdirect.net/eric/audita/v3/internal/core/config"
	"gitea.maximumdirect.net/eric/audita/v3/internal/core/schema"
	"gitea.maximumdirect.net/eric/audita/v3/internal/framework/contracts"
	"gitea.maximumdirect.net/eric/audita/v3/internal/framework/outcomes"
	"gitea.maximumdirect.net/eric/audita/v3/internal/framework/proposals"
	"gitea.maximumdirect.net/eric/audita/v3/internal/framework/responseschema"
	"gitea.maximumdirect.net/eric/audita/v3/internal/framework/structuredoutput"
)

type fakeStructuredClient struct {
	responses  []StructuredCorrectionSet
	err        error
	completion contracts.StructuredCompletionResponse
	calls      []contracts.StructuredCompletionRequest
}

func (f *fakeStructuredClient) CompleteStructured(ctx context.Context, req contracts.StructuredCompletionRequest, out any) (contracts.StructuredCompletionResponse, error) {
	_ = ctx
	f.calls = append(f.calls, req)
	if f.err != nil {
		return f.completion, f.err
	}
	target, ok := out.(*StructuredCorrectionSet)
	if !ok {
		return contracts.StructuredCompletionResponse{}, errors.New("unexpected output type")
	}
	if len(f.responses) == 0 {
		return contracts.StructuredCompletionResponse{}, errors.New("unexpected call")
	}
	*target = f.responses[0]
	f.responses = f.responses[1:]
	var content strings.Builder
	for _, value := range req.Variables {
		content.WriteString(value)
	}
	response := f.completion
	response.Prepared = &structuredoutput.PreparedSnapshot{Messages: []structuredoutput.Message{{Role: "user", Content: content.String()}}}
	return response, nil
}

type captureDiagnosticsWriter struct {
	err                 error
	lastStage           string
	lastRequestMetadata any
	lastRequestPayload  any
}

func (w *captureDiagnosticsWriter) WriteInteraction(stage string, requestMetadata any, requestPayload any, responsePayload any, errorPayload any) (InteractionArtifacts, error) {
	w.lastStage = stage
	w.lastRequestMetadata = requestMetadata
	w.lastRequestPayload = requestPayload
	_ = responsePayload
	_ = errorPayload
	return InteractionArtifacts{}, w.err
}

func defaultRequest(t *testing.T) Request {
	t.Helper()
	cfg := config.Config{}
	return Request{
		ModuleKey:         "test_module",
		ModuleInstance:    "test_module",
		ReplacementPolicy: proposals.ReplacementPolicyRequireUnique,
		Config:            &cfg,
		PromptID:          "modules.grammar.proposal",
		PromptVersion:     "v1",
		Variables:         map[string]string{"SectionJSON": "[]"},
		WorkingTranscript: &schema.Transcript{Segments: []schema.Segment{{ID: 7, Text: "teh"}, {ID: 25, Text: "other"}}},
		StartIndex:        0,
	}
}

func TestGenerateCandidatesSuccess(t *testing.T) {
	client := &fakeStructuredClient{
		responses: []StructuredCorrectionSet{
			{
				Corrections: []StructuredCorrectionProposal{
					{SegmentReference: 1, OriginalText: "teh", CorrectedText: "the", Confidence: 0.9},
				},
			},
		},
	}
	section := contracts.SectionMetadata{Index: 2}
	req := defaultRequest(t)
	req.LLMClient = client
	req.StartIndex = 10
	req.Section = &section

	got, err := GenerateCandidates(context.Background(), req)
	if err != nil {
		t.Fatalf("GenerateCandidates error: %v", err)
	}
	if len(got.Corrections) != 1 || len(got.Enriched) != 1 {
		t.Fatalf("unexpected proposal lengths: %+v", got)
	}
	if got.Corrections[0].TargetSegmentID != 7 {
		t.Fatalf("local reference not resolved: %+v", got.Corrections)
	}
	if got.Enriched[0].ProposalIndex != 10 {
		t.Fatalf("expected proposal index 10, got %d", got.Enriched[0].ProposalIndex)
	}
	if got.Enriched[0].SectionIndex == nil || *got.Enriched[0].SectionIndex != 2 {
		t.Fatalf("expected section index 2, got %v", got.Enriched[0].SectionIndex)
	}
	if len(got.Operations) != 1 || !got.Operations[0].Succeeded || got.Operations[0].Reference.SectionIndex != 2 || got.Operations[0].Reference.Kind != outcomes.OperationProposal {
		t.Fatalf("proposal operation identity: %+v", got.Operations)
	}
}

func TestGenerateCandidatesUsesCorrectionSetSchema(t *testing.T) {
	client := &fakeStructuredClient{
		responses: []StructuredCorrectionSet{
			{Corrections: []StructuredCorrectionProposal{{SegmentReference: 1, OriginalText: "teh", CorrectedText: "the", Confidence: 0.9}}},
		},
	}
	req := defaultRequest(t)
	req.LLMClient = client

	_, err := GenerateCandidates(context.Background(), req)
	if err != nil {
		t.Fatalf("GenerateCandidates error: %v", err)
	}
	if len(client.calls) != 1 {
		t.Fatalf("expected 1 LLM call, got %d", len(client.calls))
	}
	call := client.calls[0]
	if call.Schema != responseschema.CorrectionSetKey || call.PromptID != req.PromptID || call.Context.Role != "proposal" {
		t.Fatalf("unexpected call contract: %+v", call)
	}
}

func TestGenerateCandidatesDiagnosticsIncludeSchemaMetadata(t *testing.T) {
	client := &fakeStructuredClient{
		responses: []StructuredCorrectionSet{
			{Corrections: []StructuredCorrectionProposal{{SegmentReference: 1, OriginalText: "teh", CorrectedText: "the", Confidence: 0.9}}},
		},
	}
	diag := &captureDiagnosticsWriter{}
	req := defaultRequest(t)
	req.LLMClient = client
	req.DiagnosticsWriter = diag

	_, err := GenerateCandidates(context.Background(), req)
	if err != nil {
		t.Fatalf("GenerateCandidates error: %v", err)
	}
	metadata, ok := diag.lastRequestMetadata.(map[string]any)
	if !ok {
		t.Fatalf("expected request metadata map, got %T", diag.lastRequestMetadata)
	}
	schemaMap, ok := metadata["response_schema"].(map[string]any)
	if !ok {
		t.Fatalf("expected response_schema metadata map, got %T", metadata["response_schema"])
	}
	want := responseschema.MustLookup(responseschema.CorrectionSetKey)
	if schemaMap["id"] != want.ID || schemaMap["version"] != want.Version || schemaMap["name"] != want.Name || schemaMap["sha256"] != want.SHA256 {
		t.Fatalf("unexpected diagnostics schema metadata: got=%v want=%+v", schemaMap, want)
	}

}

func TestGenerateCandidatesInvalidCorrectionIsPreservedForLaterValidation(t *testing.T) {
	client := &fakeStructuredClient{
		responses: []StructuredCorrectionSet{
			{
				Corrections: []StructuredCorrectionProposal{
					{SegmentReference: 0, OriginalText: "x", CorrectedText: "", Confidence: 1.2},
				},
			},
		},
	}
	req := defaultRequest(t)
	req.LLMClient = client

	result, err := GenerateCandidates(context.Background(), req)
	if err != nil {
		t.Fatalf("expected invalid correction to survive generation, got %v", err)
	}
	if len(result.Corrections) != 1 {
		t.Fatalf("expected one correction, got %+v", result)
	}
	if result.Corrections[0].TargetSegmentID != 0 || result.Corrections[0].Confidence != 1.2 {
		t.Fatalf("unexpected preserved correction: %+v", result.Corrections[0])
	}
	if len(result.Operations) != 1 || !result.Operations[0].Succeeded {
		t.Fatalf("invalid individual correction should remain a usable response: %+v", result.Operations)
	}
}

func TestGenerateCandidatesMalformedStructuredOutputReturnsFailedOperation(t *testing.T) {
	client := &fakeStructuredClient{err: &structuredoutput.Failure{Class: structuredoutput.FailureRecoverable, Reason: outcomes.ReasonInvalidOutputExhausted, Message: "structured output remained invalid"}}
	req := defaultRequest(t)
	req.LLMClient = client

	result, err := GenerateCandidates(context.Background(), req)
	if err != nil {
		t.Fatalf("expected recoverable model operation, got %v", err)
	}
	if len(result.Corrections) != 0 || len(result.Enriched) != 0 {
		t.Fatalf("expected no proposals on malformed response, got %+v", result)
	}
	if len(result.Operations) != 1 || result.Operations[0].Succeeded || result.Operations[0].FailureReason != outcomes.ReasonInvalidOutputExhausted {
		t.Fatalf("expected one failed operation, got %+v", result.Operations)
	}
}

func TestGenerateCandidatesFatalSetupPreservesCallFacts(t *testing.T) {
	client := &fakeStructuredClient{err: &structuredoutput.Failure{Class: structuredoutput.FailureFatal, Reason: outcomes.ReasonSetupFailure, Message: "structured model setup failed", Cause: errors.New("broken prompt")}, completion: structuredoutput.Response{Execution: outcomes.ExecutionCounts{Available: true, ProviderAttempts: 0}}}
	req := defaultRequest(t)
	req.LLMClient = client
	result, err := GenerateCandidates(context.Background(), req)
	if err == nil || len(result.Operations) != 1 || result.Operations[0].FailureReason != outcomes.ReasonSetupFailure || !result.Operations[0].Counts.Available {
		t.Fatalf("fatal setup lost call facts: %+v, %v", result, err)
	}
}

func TestGenerateCandidatesValidEmptyResponseIsSuccessful(t *testing.T) {
	client := &fakeStructuredClient{responses: []StructuredCorrectionSet{{}}}
	req := defaultRequest(t)
	req.LLMClient = client
	result, err := GenerateCandidates(context.Background(), req)
	if err != nil || len(result.Corrections) != 0 || len(result.Operations) != 1 || !result.Operations[0].Succeeded {
		t.Fatalf("valid empty response: %+v, %v", result, err)
	}
}

func TestGenerateCandidatesDeterministicIndexAssignment(t *testing.T) {
	baseResponse := StructuredCorrectionSet{
		Corrections: []StructuredCorrectionProposal{
			{SegmentReference: 1, OriginalText: "a", CorrectedText: "A", Confidence: 0.9},
			{SegmentReference: 2, OriginalText: "b", CorrectedText: "B", Confidence: 0.9},
		},
	}
	clientA := &fakeStructuredClient{responses: []StructuredCorrectionSet{baseResponse}}
	clientB := &fakeStructuredClient{responses: []StructuredCorrectionSet{baseResponse}}

	reqA := defaultRequest(t)
	reqA.LLMClient = clientA
	reqA.StartIndex = 3
	first, err := GenerateCandidates(context.Background(), reqA)
	if err != nil {
		t.Fatalf("first generation failed: %v", err)
	}

	reqB := defaultRequest(t)
	reqB.LLMClient = clientB
	reqB.StartIndex = 3
	second, err := GenerateCandidates(context.Background(), reqB)
	if err != nil {
		t.Fatalf("second generation failed: %v", err)
	}

	if !reflect.DeepEqual(first.Enriched, second.Enriched) {
		t.Fatalf("expected stable enriched proposals\nfirst=%+v\nsecond=%+v", first.Enriched, second.Enriched)
	}
}

func TestGenerateCandidatesMultipleSectionsStableMetadata(t *testing.T) {
	client := &fakeStructuredClient{
		responses: []StructuredCorrectionSet{
			{Corrections: []StructuredCorrectionProposal{{SegmentReference: 1, OriginalText: "alpha", CorrectedText: "ALPHA", Confidence: 0.9}}},
			{Corrections: []StructuredCorrectionProposal{{SegmentReference: 1, OriginalText: "charlie", CorrectedText: "CHARLIE", Confidence: 0.9}}},
		},
	}
	section0 := contracts.SectionMetadata{Index: 0}
	section1 := contracts.SectionMetadata{Index: 1}

	req0 := defaultRequest(t)
	req0.LLMClient = client
	req0.Section = &section0
	req0.WorkingTranscript = &schema.Transcript{Segments: []schema.Segment{{ID: 71, Text: "alpha"}}}
	req0.StartIndex = 0
	part0, err := GenerateCandidates(context.Background(), req0)
	if err != nil {
		t.Fatalf("section 0 generation failed: %v", err)
	}

	req1 := defaultRequest(t)
	req1.LLMClient = client
	req1.Section = &section1
	req1.WorkingTranscript = &schema.Transcript{Segments: []schema.Segment{{ID: 903, Text: "charlie"}}}
	req1.StartIndex = len(part0.Enriched)
	part1, err := GenerateCandidates(context.Background(), req1)
	if err != nil {
		t.Fatalf("section 1 generation failed: %v", err)
	}

	all := append(append([]proposals.EnrichedCorrectionProposal(nil), part0.Enriched...), part1.Enriched...)
	if len(all) != 2 {
		t.Fatalf("expected 2 proposals, got %d", len(all))
	}
	if all[0].TargetSegmentID != 71 || all[1].TargetSegmentID != 903 {
		t.Fatalf("section references did not reset: %+v", all)
	}
	if all[0].ProposalIndex != 0 || all[1].ProposalIndex != 1 {
		t.Fatalf("unexpected proposal indexes: %d, %d", all[0].ProposalIndex, all[1].ProposalIndex)
	}
	if all[0].SectionIndex == nil || *all[0].SectionIndex != 0 || all[1].SectionIndex == nil || *all[1].SectionIndex != 1 {
		t.Fatalf("unexpected section metadata: %+v", all)
	}
}

func TestGenerateCandidatesDiagnosticsWrittenAndRedacted(t *testing.T) {
	primarySecret := "proposal-primary-secret"
	validationSecret := "proposal-validation-secret"
	client := &fakeStructuredClient{
		responses: []StructuredCorrectionSet{
			{Corrections: []StructuredCorrectionProposal{{SegmentReference: 1, OriginalText: validationSecret, CorrectedText: "safe", Confidence: 0.9}}},
		},
	}
	t.Setenv("PRIMARY_SECRET", primarySecret)
	t.Setenv("VALIDATION_SECRET", validationSecret)
	loaded, loadErr := config.Load(ck.Bytes("config.yml", []byte("version: 2\nbackends:\n  primary:\n    endpoint: https://primary.invalid/v1\n    credential: PRIMARY_SECRET\n  validation:\n    endpoint: https://validation.invalid/v1\n    credential: VALIDATION_SECRET\nllm:\n  proposal_profile: base\n")), "")
	if loadErr != nil {
		t.Fatal(loadErr)
	}
	cfg := loaded.Config
	req := defaultRequest(t)
	req.Config = &cfg
	req.LLMClient = client
	req.DiagnosticsDir = t.TempDir()
	req.Variables = map[string]string{"SectionJSON": "include secret " + primarySecret}

	got, err := GenerateCandidates(context.Background(), req)
	if err != nil {
		t.Fatalf("GenerateCandidates error: %v", err)
	}
	if got.Artifacts.ResponsePayloadPath == "" || got.Artifacts.RequestPayloadPath == "" {
		t.Fatalf("expected diagnostics artifact paths, got %+v", got.Artifacts)
	}

	for _, path := range []string{got.Artifacts.RequestPayloadPath, got.Artifacts.ResponsePayloadPath} {
		raw, readErr := os.ReadFile(path)
		if readErr != nil {
			t.Fatalf("read artifact %q: %v", path, readErr)
		}
		if strings.Contains(string(raw), primarySecret) || strings.Contains(string(raw), validationSecret) {
			t.Fatalf("artifact leaked configured secret in %q: %s", path, string(raw))
		}
		if !strings.Contains(string(raw), "[REDACTED]") {
			t.Fatalf("expected redaction marker in artifact %q: %s", path, string(raw))
		}
	}

	raw, readErr := os.ReadFile(got.Artifacts.RequestMetadataPath)
	if readErr != nil {
		t.Fatalf("read metadata artifact %q: %v", got.Artifacts.RequestMetadataPath, readErr)
	}
	var metadata map[string]any
	if err := json.Unmarshal(raw, &metadata); err != nil {
		t.Fatalf("unmarshal metadata artifact: %v", err)
	}
	schemaMap, ok := metadata["response_schema"].(map[string]any)
	if !ok {
		t.Fatalf("expected response_schema metadata in diagnostics, got %T", metadata["response_schema"])
	}
	want := responseschema.MustLookup(responseschema.CorrectionSetKey)
	if schemaMap["id"] != want.ID || schemaMap["version"] != want.Version || schemaMap["name"] != want.Name || schemaMap["sha256"] != want.SHA256 {
		t.Fatalf("unexpected schema metadata in diagnostics: got=%v want=%+v", schemaMap, want)
	}
}

func TestGenerateCandidatesClientError(t *testing.T) {
	client := &fakeStructuredClient{err: errors.New("boom")}
	req := defaultRequest(t)
	req.LLMClient = client
	req.DiagnosticsDir = t.TempDir()

	got, err := GenerateCandidates(context.Background(), req)
	if err == nil || !strings.Contains(err.Error(), "completion failed") {
		t.Fatalf("expected completion failure, got %v", err)
	}
	if len(got.Operations) != 1 || got.Operations[0].FailureReason != outcomes.ReasonInternalFailure || len(got.Corrections) != 0 {
		t.Fatalf("expected fatal call facts without proposals, got %+v", got)
	}
	matches, globErr := filepath.Glob(filepath.Join(req.DiagnosticsDir, req.ModuleInstance, "*error-payload.json"))
	if globErr != nil {
		t.Fatalf("glob error: %v", globErr)
	}
	if len(matches) == 0 {
		t.Fatalf("expected error diagnostics artifact under %s", req.DiagnosticsDir)
	}
}

func TestProposalDiagnosticFailureDoesNotChangeOperation(t *testing.T) {
	cause := errors.New("diagnostic storage unavailable")
	req := defaultRequest(t)
	req.LLMClient = &fakeStructuredClient{responses: []StructuredCorrectionSet{{}}}
	req.DiagnosticsWriter = &captureDiagnosticsWriter{err: cause}
	var reported error
	req.ReportDiagnosticError = func(err error) { reported = err }
	result, err := GenerateCandidates(context.Background(), req)
	if err != nil || !errors.Is(reported, cause) || len(result.Operations) != 1 || !result.Operations[0].Succeeded || len(result.Operations[0].RecoveryReasons) != 0 || result.Artifacts.ResponsePayloadPath != "" {
		t.Fatalf("debug failure changed outcome: %+v %v reported=%v", result, err, reported)
	}
}