//go:build integration

package integration_test

import (
	"bytes"
	"context"
	"encoding/json"
	"fmt"
	"io"
	"log/slog"
	"net"
	"net/http"
	"net/http/httptest"
	"strings"
	"testing"
	"time"

	"github.com/alicebob/miniredis/v2"
	"github.com/google/uuid"
	"github.com/redis/go-redis/v9"
	"google.golang.org/grpc"

	"github.com/alchemistkay/guestguard/internal/api"
	"github.com/alchemistkay/guestguard/internal/auth"
	"github.com/alchemistkay/guestguard/internal/fraud"
	pb "github.com/alchemistkay/guestguard/internal/fraudpb"
	"github.com/alchemistkay/guestguard/internal/storage"
)

// recordingRSVPSender captures the most recent RSVP edit-link send so the
// test can pull the magic URL out of "the email" without standing up an
// SMTP server.
type recordingRSVPSender struct {
	lastEditLink string
}

func (s *recordingRSVPSender) SendVerification(context.Context, string, string, string) error { return nil }
func (s *recordingRSVPSender) SendPasswordReset(context.Context, string, string, string) error { return nil }
func (s *recordingRSVPSender) SendCollaboratorInvite(context.Context, string, string, string, string, string) error { return nil }
func (s *recordingRSVPSender) SendRSVPEditLink(_ context.Context, _, _, _, link string) error {
	s.lastEditLink = link
	return nil
}

// TestForwardedInvitationLinkDefence covers the Block G follow-up:
//   - A guest submits their RSVP from device A.
//   - A different device opens the same invitation link.
//   - The /access response no longer surfaces the RSVP details.
//   - A PATCH from the foreign device is refused with 403.
//   - The original guest can request an edit link to their email, follow
//     the magic URL, and successfully edit from the new device.
func TestForwardedInvitationLinkDefence(t *testing.T) {
	if testing.Short() {
		t.Skip("skipping integration test in -short mode")
	}
	ctx, cancel := context.WithTimeout(context.Background(), 3*time.Minute)
	t.Cleanup(cancel)

	logger := slog.New(slog.NewTextHandler(io.Discard, nil))
	dsn := startPostgres(t, ctx)
	db, err := storage.NewDB(ctx, dsn)
	must(t, err, "connect db")
	t.Cleanup(db.Close)
	must(t, db.Migrate(ctx), "migrate")

	// Redis: miniredis is enough — the edit-nonce store only does
	// SET / GET with a TTL. No need for a real Redis container here.
	mr, err := miniredis.Run()
	must(t, err, "miniredis")
	t.Cleanup(mr.Close)
	rdb := redis.NewClient(&redis.Options{Addr: mr.Addr()})

	// In-process stub fraud scorer so PATCH/POST score paths don't reach
	// for the Python service. We make it return LOW for every call.
	stub := startStubFraudGRPCLocal(t)
	fraudClient, err := fraud.Dial(ctx, stub.Addr, 2*time.Second, logger)
	must(t, err, "dial fraud")
	t.Cleanup(func() { _ = fraudClient.Close() })

	// Capture-the-link email sender so the test can pull the magic
	// edit URL out of "the inbox" without standing up SMTP.
	emails := &recordingRSVPSender{}

	apiSrv, err := api.NewServer(api.ServerDeps{
		Logger:               logger,
		DB:                   db,
		FraudScorer:          fraudClient,
		TokenTTL:             24 * time.Hour,
		JWTSecret:            testJWTSecret,
		JWTIssuer:            testJWTIssuer,
		AccessTokenTTL:       5 * time.Minute,
		RefreshTokenTTL:      24 * time.Hour,
		EmailVerificationTTL: 1 * time.Hour,
		PasswordResetTTL:     1 * time.Hour,
		PublicBaseURL:        "http://localhost",
		Redis:                rdb,
		EmailSender:          emails,
	})
	must(t, err, "build api server")
	srv := httptest.NewServer(apiSrv.Handler())
	t.Cleanup(srv.Close)

	// Set up host, event, guest with email on file.
	host := insertHost(t, ctx, db.Pool)
	hostToken := issueHostToken(t, host)
	eventID := createEvent(t, srv.URL, hostToken, "Forwarded Link", "forwarded-link")
	guestEmail := fmt.Sprintf("guest+%d@guestguard.test", time.Now().UnixNano())
	guestID := createGuestWithFields(t, srv.URL, hostToken, eventID, "Sam", guestEmail)
	token := issueToken(t, srv.URL, hostToken, eventID, guestID)

	const uaA = "Mozilla/5.0 (Macintosh) AppleWebKit/605 Browser-A"
	const uaB = "Mozilla/5.0 (X11; Linux) Firefox/120 Browser-B"

	// 1. Submit from device A.
	stub.SetNext(5, "low", nil)
	submitFromUA(t, srv.URL, token, uaA, "attending", 0, http.StatusCreated)

	// 2. Open the same invitation from device B — RSVP is hidden,
	//    rsvp_submitted_elsewhere=true, can_request_edit_link=true.
	access := accessFromUA(t, srv.URL, token, uaB)
	if access.RSVP != nil {
		t.Fatalf("expected hidden rsvp on different device; got %+v", access.RSVP)
	}
	if !access.RSVPSubmittedElsewhere {
		t.Fatalf("expected rsvp_submitted_elsewhere=true; got false")
	}
	if !access.CanRequestEditLink {
		t.Fatalf("expected can_request_edit_link=true (email on file)")
	}

	// 3. Device A still sees its own RSVP (sanity).
	accessA := accessFromUA(t, srv.URL, token, uaA)
	if accessA.RSVP == nil {
		t.Fatalf("device A should still see its own RSVP")
	}

	// 4. PATCH from device B without a nonce — refused.
	patchFromUA(t, srv.URL, token, uaB, map[string]any{
		"response":  "declined",
		"plus_ones": 0,
	}, http.StatusForbidden)

	// 5. Request an edit link from device B.
	resp := postRequestEditLink(t, srv.URL, token, http.StatusAccepted)
	if resp.Channel != "email" {
		t.Errorf("expected channel=email, got %q", resp.Channel)
	}
	if emails.lastEditLink == "" {
		t.Fatal("expected email sender to have captured a link")
	}

	// Extract nonce from the magic URL the email contained.
	nonce := extractEditNonce(emails.lastEditLink)
	if nonce == "" {
		t.Fatalf("could not parse nonce from %q", emails.lastEditLink)
	}

	// 6. GET /access?edit=<nonce> from device B unhides the RSVP.
	accessWithNonce := accessFromUAWithNonce(t, srv.URL, token, uaB, nonce)
	if accessWithNonce.RSVP == nil {
		t.Fatalf("nonce should have unhidden the RSVP")
	}

	// 7. PATCH from device B carrying the nonce — accepted.
	stub.SetNext(5, "low", nil)
	patchFromUAWithNonce(t, srv.URL, token, uaB, nonce, map[string]any{
		"response":  "declined",
		"plus_ones": 0,
	}, http.StatusOK)

	// 8. A third device (UA-C) with a made-up nonce stays refused.
	// At this point the stored fingerprint is UA-B (step 7 legitimately
	// updated it), so UA-C is again a stranger and the gate fires.
	const uaC = "Mozilla/5.0 (iPhone) Safari/17 Browser-C"
	patchFromUAWithNonce(t, srv.URL, token, uaC, "deadbeefdeadbeef", map[string]any{
		"response":  "attending",
		"plus_ones": 0,
	}, http.StatusForbidden)
}

// --- helpers (kept local to this file so we don't bloat the shared scaffold) ---

func submitFromUA(t *testing.T, base, token, ua, response string, plusOnes int, want int) {
	t.Helper()
	body, _ := json.Marshal(map[string]any{
		"response":  response,
		"plus_ones": plusOnes,
	})
	req, _ := http.NewRequest(http.MethodPost, base+"/rsvp/"+token, bytes.NewReader(body))
	req.Header.Set("Content-Type", "application/json")
	req.Header.Set("User-Agent", ua)
	resp, err := http.DefaultClient.Do(req)
	must(t, err, "submit")
	defer resp.Body.Close()
	if resp.StatusCode != want {
		b, _ := io.ReadAll(resp.Body)
		t.Fatalf("submit status=%d want=%d body=%s", resp.StatusCode, want, b)
	}
}

func patchFromUA(t *testing.T, base, token, ua string, body map[string]any, want int) {
	t.Helper()
	b, _ := json.Marshal(body)
	req, _ := http.NewRequest(http.MethodPatch, base+"/rsvp/"+token, bytes.NewReader(b))
	req.Header.Set("Content-Type", "application/json")
	req.Header.Set("User-Agent", ua)
	resp, err := http.DefaultClient.Do(req)
	must(t, err, "patch")
	defer resp.Body.Close()
	if resp.StatusCode != want {
		body, _ := io.ReadAll(resp.Body)
		t.Fatalf("patch status=%d want=%d body=%s", resp.StatusCode, want, body)
	}
}

func patchFromUAWithNonce(t *testing.T, base, token, ua, nonce string, body map[string]any, want int) {
	t.Helper()
	body["edit_nonce"] = nonce
	patchFromUA(t, base, token, ua, body, want)
}

type accessLite struct {
	RSVP                   *struct{ Response string `json:"response"` } `json:"rsvp"`
	RSVPSubmittedElsewhere bool                                          `json:"rsvp_submitted_elsewhere"`
	CanRequestEditLink     bool                                          `json:"can_request_edit_link"`
}

func accessFromUA(t *testing.T, base, token, ua string) accessLite {
	t.Helper()
	return accessFromUAWithNonce(t, base, token, ua, "")
}

func accessFromUAWithNonce(t *testing.T, base, token, ua, nonce string) accessLite {
	t.Helper()
	url := base + "/access/" + token
	if nonce != "" {
		url += "?edit=" + nonce
	}
	req, _ := http.NewRequest(http.MethodGet, url, nil)
	req.Header.Set("User-Agent", ua)
	resp, err := http.DefaultClient.Do(req)
	must(t, err, "access")
	defer resp.Body.Close()
	if resp.StatusCode != http.StatusOK {
		b, _ := io.ReadAll(resp.Body)
		t.Fatalf("access status=%d body=%s", resp.StatusCode, b)
	}
	var out accessLite
	must(t, json.NewDecoder(resp.Body).Decode(&out), "decode access")
	return out
}

type editLinkResp struct {
	Channel string `json:"channel"`
}

func postRequestEditLink(t *testing.T, base, token string, want int) editLinkResp {
	t.Helper()
	req, _ := http.NewRequest(http.MethodPost, base+"/access/"+token+"/request-edit-link", nil)
	resp, err := http.DefaultClient.Do(req)
	must(t, err, "request edit link")
	defer resp.Body.Close()
	if resp.StatusCode != want {
		b, _ := io.ReadAll(resp.Body)
		t.Fatalf("request-edit-link status=%d want=%d body=%s", resp.StatusCode, want, b)
	}
	var out editLinkResp
	if resp.ContentLength != 0 {
		_ = json.NewDecoder(resp.Body).Decode(&out)
	}
	return out
}

func extractEditNonce(link string) string {
	i := strings.Index(link, "edit=")
	if i < 0 {
		return ""
	}
	rest := link[i+len("edit="):]
	// Strip any trailing fragment / extra query separators.
	if j := strings.IndexAny(rest, "&#"); j > 0 {
		return rest[:j]
	}
	return rest
}

// createGuestWithFields lets us pass an email so the request-edit-link
// path has somewhere to deliver to. The shared createGuest helper doesn't
// accept extras.
func createGuestWithFields(t *testing.T, base, hostToken string, eventID uuid.UUID, name, email string) uuid.UUID {
	t.Helper()
	var out struct{ ID uuid.UUID `json:"id"` }
	postJSONAuthed(t,
		fmt.Sprintf("%s/events/%s/guests", base, eventID),
		hostToken,
		map[string]any{"name": name, "email": email},
		http.StatusCreated, &out)
	return out.ID
}

// startStubFraudGRPCLocal is a copy of the e2e_test scaffold's stub
// scorer. Replicated here so this file is self-contained when run on
// its own (go test -run TestForwarded...).
func startStubFraudGRPCLocal(t *testing.T) *stubFraud {
	t.Helper()
	lis, err := net.Listen("tcp", "127.0.0.1:0")
	must(t, err, "listen for stub fraud")

	s := &stubFraud{Addr: lis.Addr().String()}
	s.risk.Store("low")
	s.reasons.Store([]string(nil))

	s.server = grpc.NewServer()
	pb.RegisterFraudServiceServer(s.server, s)

	go func() { _ = s.server.Serve(lis) }()
	t.Cleanup(s.server.Stop)
	return s
}

// satisfy the EmailSender interface check at compile time.
var _ auth.EmailSender = (*recordingRSVPSender)(nil)