package web_test

import (
	"context"
	"crypto"
	"crypto/ecdsa"
	"crypto/elliptic"
	"crypto/rand"
	"crypto/x509"
	"crypto/x509/pkix"
	"encoding/asn1"
	"fmt"
	"math/big"
	"net/http"
	"net/http/httptest"
	"net/url"
	"os"
	"strings"
	"sync"
	"testing"
	"time"

	"github.com/digitorus/timestamp"

	"github.com/netcell-it/deklarix/internal/extract"
	"github.com/netcell-it/deklarix/internal/rules"
	"github.com/netcell-it/deklarix/internal/store"
	"github.com/netcell-it/deklarix/internal/web"
)

// ─── Fakes ────────────────────────────────────────────────────────────

type fakeExtractor struct {
	facts rules.Facts
	raw   []byte
	err   error
}

func (f fakeExtractor) Extract(ctx context.Context, in extract.Input) (extract.Result, error) {
	if f.err != nil {
		return extract.Result{}, f.err
	}
	raw := f.raw
	if raw == nil {
		raw = []byte(`{}`)
	}
	return extract.Result{Facts: f.facts, RawJSON: raw}, nil
}

func (f fakeExtractor) ModelVersion() string { return "fake-model-v0" }

// fakeStore ist eine In-Memory-Implementierung von web.Store, damit die
// Handler-Tests keine echte Postgres-Instanz brauchen.
type fakeStore struct {
	mu           sync.Mutex
	nextID       int
	submissions  map[string]store.Submission
	extractions  map[string]store.Extraction
	findings     map[string][]store.Finding
	evidencePkgs map[string]store.EvidencePackage
}

func newFakeStore() *fakeStore {
	return &fakeStore{
		submissions:  map[string]store.Submission{},
		extractions:  map[string]store.Extraction{},
		findings:     map[string][]store.Finding{},
		evidencePkgs: map[string]store.EvidencePackage{},
	}
}

func (f *fakeStore) newID() string {
	f.nextID++
	return fmt.Sprintf("id-%d", f.nextID)
}

func (f *fakeStore) CreateSubmission(ctx context.Context, platform, postType, caption string) (store.Submission, error) {
	f.mu.Lock()
	defer f.mu.Unlock()
	sub := store.Submission{
		ID: f.newID(), Platform: platform, PostType: postType, Caption: caption,
		Status: "draft", CreatedAt: time.Now(), UpdatedAt: time.Now(),
	}
	f.submissions[sub.ID] = sub
	return sub, nil
}

func (f *fakeStore) GetSubmission(ctx context.Context, id string) (store.Submission, error) {
	f.mu.Lock()
	defer f.mu.Unlock()
	sub, ok := f.submissions[id]
	if !ok {
		return store.Submission{}, fmt.Errorf("fakeStore: submission %s nicht gefunden", id)
	}
	return sub, nil
}

func (f *fakeStore) SetSubmissionStatus(ctx context.Context, id, status string) error {
	f.mu.Lock()
	defer f.mu.Unlock()
	sub, ok := f.submissions[id]
	if !ok {
		return fmt.Errorf("fakeStore: submission %s nicht gefunden", id)
	}
	sub.Status = status
	f.submissions[id] = sub
	return nil
}

func (f *fakeStore) CreateExtraction(ctx context.Context, submissionID string, payload []byte, modelVersion, promptVersion string) (store.Extraction, error) {
	f.mu.Lock()
	defer f.mu.Unlock()
	ext := store.Extraction{
		ID: f.newID(), SubmissionID: submissionID, Payload: payload,
		ModelVersion: modelVersion, PromptVersion: promptVersion, CreatedAt: time.Now(),
	}
	f.extractions[submissionID] = ext
	return ext, nil
}

func (f *fakeStore) GetLatestExtraction(ctx context.Context, submissionID string) (store.Extraction, error) {
	f.mu.Lock()
	defer f.mu.Unlock()
	ext, ok := f.extractions[submissionID]
	if !ok {
		return store.Extraction{}, fmt.Errorf("fakeStore: keine Extraktion fuer %s", submissionID)
	}
	return ext, nil
}

func (f *fakeStore) CreateFinding(ctx context.Context, submissionID string, extractionID *string, ruleID string, ruleVersion int, severity, title, fix string, sources []string) (store.Finding, error) {
	f.mu.Lock()
	defer f.mu.Unlock()
	finding := store.Finding{
		ID: f.newID(), SubmissionID: submissionID, ExtractionID: extractionID,
		RuleID: ruleID, RuleVersion: ruleVersion, Severity: severity,
		Title: title, Fix: fix, Sources: sources, CreatedAt: time.Now(),
	}
	f.findings[submissionID] = append(f.findings[submissionID], finding)
	return finding, nil
}

func (f *fakeStore) ListCurrentFindings(ctx context.Context, submissionID string) ([]store.Finding, error) {
	f.mu.Lock()
	defer f.mu.Unlock()
	return f.findings[submissionID], nil
}

func (f *fakeStore) CreateEvidencePackage(ctx context.Context, submissionID, dossierPath, sha256Hex string, timestampToken []byte) (store.EvidencePackage, error) {
	f.mu.Lock()
	defer f.mu.Unlock()
	pkg := store.EvidencePackage{
		ID: f.newID(), SubmissionID: submissionID, DossierPath: dossierPath,
		SHA256: sha256Hex, TimestampToken: timestampToken, CreatedAt: time.Now(),
	}
	f.evidencePkgs[submissionID] = pkg
	return pkg, nil
}

func (f *fakeStore) GetLatestEvidencePackage(ctx context.Context, submissionID string) (store.EvidencePackage, error) {
	f.mu.Lock()
	defer f.mu.Unlock()
	pkg, ok := f.evidencePkgs[submissionID]
	if !ok {
		return store.EvidencePackage{}, fmt.Errorf("fakeStore: kein evidence package fuer %s", submissionID)
	}
	return pkg, nil
}

// fakeTimestamper liefert einen offline erzeugten, strukturell gültigen
// (selbstsignierten) RFC-3161-Token — genug, damit evidence.TimestampTime
// ihn parsen kann, ohne eine echte TSA zu brauchen.
type fakeTimestamper struct{}

func (fakeTimestamper) Timestamp(ctx context.Context, hash []byte) ([]byte, error) {
	key, err := ecdsa.GenerateKey(elliptic.P256(), rand.Reader)
	if err != nil {
		return nil, err
	}
	now := time.Now()
	certTemplate := &x509.Certificate{
		SerialNumber: big.NewInt(1),
		Subject:      pkix.Name{CommonName: "deklarix-test-tsa"},
		NotBefore:    now.Add(-time.Hour),
		NotAfter:     now.Add(time.Hour),
		KeyUsage:     x509.KeyUsageDigitalSignature,
		ExtKeyUsage:  []x509.ExtKeyUsage{x509.ExtKeyUsageTimeStamping},
	}
	certDER, err := x509.CreateCertificate(rand.Reader, certTemplate, certTemplate, &key.PublicKey, key)
	if err != nil {
		return nil, err
	}
	cert, err := x509.ParseCertificate(certDER)
	if err != nil {
		return nil, err
	}
	ts := timestamp.Timestamp{
		HashAlgorithm: crypto.SHA256,
		HashedMessage: hash,
		Time:          now,
		SerialNumber:  big.NewInt(1),
		Policy:        asn1.ObjectIdentifier{1, 2, 3},
	}
	respDER, err := ts.CreateResponse(cert, key)
	if err != nil {
		return nil, err
	}
	parsed, err := timestamp.ParseResponse(respDER)
	if err != nil {
		return nil, err
	}
	return parsed.RawToken, nil
}

// ─── Test-Setup ───────────────────────────────────────────────────────

func loadRealRules(t *testing.T) []rules.Rule {
	t.Helper()
	rs, err := rules.Load(os.DirFS("../../rules"))
	if err != nil {
		t.Fatalf("rules.Load: %v", err)
	}
	return rs
}

func newTestServer(t *testing.T, ex web.Extractor) *web.Server {
	t.Helper()
	s, err := web.NewServer(ex, loadRealRules(t), newFakeStore(), fakeTimestamper{}, t.TempDir())
	if err != nil {
		t.Fatalf("NewServer: %v", err)
	}
	return s
}

// ─── Tests ────────────────────────────────────────────────────────────

func TestHandleHealth(t *testing.T) {
	s := newTestServer(t, fakeExtractor{})

	req := httptest.NewRequest(http.MethodGet, "/health", nil)
	w := httptest.NewRecorder()
	s.ServeHTTP(w, req)

	if w.Code != http.StatusOK {
		t.Fatalf("status = %d, want 200", w.Code)
	}
	if w.Body.String() != `{"ok":true}` {
		t.Fatalf("body = %q, want {\"ok\":true}", w.Body.String())
	}
}

func TestHandleIndexRendersForm(t *testing.T) {
	s := newTestServer(t, fakeExtractor{})

	req := httptest.NewRequest(http.MethodGet, "/", nil)
	w := httptest.NewRecorder()
	s.ServeHTTP(w, req)

	if w.Code != http.StatusOK {
		t.Fatalf("status = %d, want 200", w.Code)
	}
	body := w.Body.String()
	for _, want := range []string{`name="platform"`, `name="post_type"`, `name="caption"`, `hx-post="/pruefen"`} {
		if !strings.Contains(body, want) {
			t.Errorf("index body missing %q\nbody: %s", want, body)
		}
	}
}

func TestHandleStaticServesHTMX(t *testing.T) {
	s := newTestServer(t, fakeExtractor{})

	req := httptest.NewRequest(http.MethodGet, "/static/htmx.min.js", nil)
	w := httptest.NewRecorder()
	s.ServeHTTP(w, req)

	if w.Code != http.StatusOK {
		t.Fatalf("status = %d, want 200", w.Code)
	}
	if w.Body.Len() < 1000 {
		t.Fatalf("htmx.min.js suspiciously small: %d bytes", w.Body.Len())
	}
}

func postForm(t *testing.T, s *web.Server, path string, form url.Values) *httptest.ResponseRecorder {
	t.Helper()
	req := httptest.NewRequest(http.MethodPost, path, strings.NewReader(form.Encode()))
	req.Header.Set("Content-Type", "application/x-www-form-urlencoded")
	w := httptest.NewRecorder()
	s.ServeHTTP(w, req)
	return w
}

func checkForm(extra ...string) url.Values {
	v := url.Values{"platform": {"instagram"}, "post_type": {"reel"}, "caption": {"..."}}
	for i := 0; i+1 < len(extra); i += 2 {
		v.Set(extra[i], extra[i+1])
	}
	return v
}

func TestHandleCheckRejectsMissingFields(t *testing.T) {
	s := newTestServer(t, fakeExtractor{})

	w := postForm(t, s, "/pruefen", url.Values{"platform": {"instagram"}})
	if w.Code != http.StatusBadRequest {
		t.Fatalf("status = %d, want 400 for missing fields", w.Code)
	}
}

func TestHandleCheckPropagatesExtractionError(t *testing.T) {
	s := newTestServer(t, fakeExtractor{err: fmt.Errorf("simulierter Extraktionsfehler")})

	w := postForm(t, s, "/pruefen", checkForm())
	if w.Code != http.StatusBadGateway {
		t.Fatalf("status = %d, want 502 when extraction fails", w.Code)
	}
}

func TestHandleCheckPersistsSubmissionExtractionAndFindings(t *testing.T) {
	fs := newFakeStore()
	s, err := web.NewServer(fakeExtractor{facts: rules.Facts{
		Platform: "instagram", Jurisdiction: "DE", Consideration: rules.ConsiderationPaid,
		DisclosurePresent: true, DisclosureWording: "Werbung", DisclosureBeforeCut: false,
	}, raw: []byte(`{"gegenleistung":"bezahlt"}`)}, loadRealRules(t), fs, fakeTimestamper{}, t.TempDir())
	if err != nil {
		t.Fatalf("NewServer: %v", err)
	}

	w := postForm(t, s, "/pruefen", checkForm())
	if w.Code != http.StatusOK {
		t.Fatalf("status = %d, want 200, body: %s", w.Code, w.Body.String())
	}
	if !strings.Contains(w.Body.String(), "WK-004") {
		t.Fatalf("expected WK-004 in result, got: %s", w.Body.String())
	}

	if len(fs.submissions) != 1 {
		t.Fatalf("expected 1 persisted submission, got %d", len(fs.submissions))
	}
	var subID string
	for id, sub := range fs.submissions {
		subID = id
		if sub.Status != "checked" {
			t.Errorf("submission status = %q, want checked", sub.Status)
		}
	}
	if _, ok := fs.extractions[subID]; !ok {
		t.Error("expected an extraction to be persisted")
	}
	if len(fs.findings[subID]) != 1 || fs.findings[subID][0].RuleID != "WK-004" {
		t.Errorf("expected exactly one persisted WK-004 finding, got %+v", fs.findings[subID])
	}
}

func TestHandleCheckRendersNeedsClarificationAndDoesNotOfferArchive(t *testing.T) {
	fs := newFakeStore()
	s, err := web.NewServer(fakeExtractor{facts: rules.Facts{
		Platform: "instagram", Jurisdiction: "DE", Consideration: rules.ConsiderationUnclear,
	}}, loadRealRules(t), fs, fakeTimestamper{}, t.TempDir())
	if err != nil {
		t.Fatalf("NewServer: %v", err)
	}

	w := postForm(t, s, "/pruefen", checkForm())
	body := w.Body.String()
	if strings.Contains(body, "WK-") {
		t.Errorf("expected no rule findings for an unclear extraction, got: %s", body)
	}
	if !strings.Contains(body, "nicht sicher bestimmt") {
		t.Errorf("expected a clarification message, got: %s", body)
	}
	if strings.Contains(body, "veroeffentlichen") || strings.Contains(body, "/veroeffentlichen") {
		t.Errorf("expected no archive option when clarification is needed, got: %s", body)
	}
	for _, sub := range fs.submissions {
		if sub.Status == "checked" {
			t.Error("submission should not be marked checked when clarification is needed")
		}
	}
}

func TestFullCheckThenArchiveFlow(t *testing.T) {
	fs := newFakeStore()
	s, err := web.NewServer(fakeExtractor{facts: rules.Facts{
		Platform: "instagram", Jurisdiction: "DE", Consideration: rules.ConsiderationPaid,
		DisclosurePresent: true, DisclosureWording: "Werbung", DisclosureBeforeCut: false,
	}, raw: []byte(`{"gegenleistung":"bezahlt","kennzeichnung_vorhanden":true,"kennzeichnung_wortlaut":"Werbung","kennzeichnung_vor_kuerzung":false}`)},
		loadRealRules(t), fs, fakeTimestamper{}, t.TempDir())
	if err != nil {
		t.Fatalf("NewServer: %v", err)
	}

	checkResp := postForm(t, s, "/pruefen", checkForm())
	if checkResp.Code != http.StatusOK {
		t.Fatalf("check status = %d, body: %s", checkResp.Code, checkResp.Body.String())
	}
	if !strings.Contains(checkResp.Body.String(), `name="submission_id"`) {
		t.Fatalf("expected a hidden submission_id field in the result, got: %s", checkResp.Body.String())
	}

	var subID string
	for id := range fs.submissions {
		subID = id
	}

	archiveResp := postForm(t, s, "/veroeffentlichen", url.Values{"submission_id": {subID}})
	if archiveResp.Code != http.StatusOK {
		t.Fatalf("archive status = %d, body: %s", archiveResp.Code, archiveResp.Body.String())
	}
	if !strings.Contains(archiveResp.Body.String(), "/dossier/"+subID) {
		t.Fatalf("expected a dossier download link, got: %s", archiveResp.Body.String())
	}

	pkg, ok := fs.evidencePkgs[subID]
	if !ok {
		t.Fatal("expected an evidence package to be persisted")
	}
	if fs.submissions[subID].Status != "published" {
		t.Errorf("submission status = %q, want published", fs.submissions[subID].Status)
	}

	downloadReq := httptest.NewRequest(http.MethodGet, "/dossier/"+subID, nil)
	downloadReq.SetPathValue("id", subID)
	downloadW := httptest.NewRecorder()
	s.ServeHTTP(downloadW, downloadReq)
	if downloadW.Code != http.StatusOK {
		t.Fatalf("download status = %d", downloadW.Code)
	}
	if !strings.HasPrefix(downloadW.Body.String(), "%PDF-") {
		t.Fatal("downloaded dossier does not start with the PDF header")
	}

	if _, err := os.Stat(pkg.DossierPath); err != nil {
		t.Fatalf("dossier file does not exist on disk: %v", err)
	}
}

func TestHandleArchiveRejectsUnknownSubmission(t *testing.T) {
	s := newTestServer(t, fakeExtractor{})

	w := postForm(t, s, "/veroeffentlichen", url.Values{"submission_id": {"does-not-exist"}})
	if w.Code != http.StatusNotFound {
		t.Fatalf("status = %d, want 404 for an unknown submission", w.Code)
	}
}

func TestHandleCheckCleanCaseHasNoFindingsAndOffersArchive(t *testing.T) {
	s := newTestServer(t, fakeExtractor{facts: rules.Facts{
		Platform: "instagram", Jurisdiction: "DE", Consideration: rules.ConsiderationNone,
	}})

	w := postForm(t, s, "/pruefen", checkForm())
	if w.Code != http.StatusOK {
		t.Fatalf("status = %d, want 200", w.Code)
	}
	body := w.Body.String()
	if strings.Contains(body, "WK-") {
		t.Errorf("expected no findings for an organic post, got: %s", body)
	}
	if !strings.Contains(body, "Keine Kennzeichnungsrisiken") {
		t.Errorf("expected the no-findings message, got: %s", body)
	}
	if !strings.Contains(body, "/veroeffentlichen") {
		t.Errorf("expected an archive option even with no findings (still a real check), got: %s", body)
	}
}