package middleware_test

import (
	"encoding/base64"
	"io"
	"log/slog"
	"net/http"
	"net/http/httptest"
	"strings"
	"testing"

	"github.com/travelswitch/travelhub/backend/internal/auth"
	"github.com/travelswitch/travelhub/backend/internal/middleware"
	"github.com/travelswitch/travelhub/backend/internal/testsupport"
)

func quietLogger() *slog.Logger {
	return slog.New(slog.NewTextHandler(io.Discard, nil))
}

func basic(email, password string) string {
	return "Basic " + base64.StdEncoding.EncodeToString([]byte(email+":"+password))
}

// guarded wraps a handler that records the identity the middleware resolved.
func guarded(f *testsupport.Fixture, seen *auth.Identity) http.Handler {
	inner := http.HandlerFunc(func(w http.ResponseWriter, r *http.Request) {
		if id, err := auth.FromContext(r.Context()); err == nil && seen != nil {
			*seen = id
		}
		w.WriteHeader(http.StatusOK)
	})
	return middleware.BasicAuth(f.Repo, quietLogger())(inner)
}

func TestBasicAuthAcceptsValidCredentials(t *testing.T) {
	f := testsupport.Setup(t)

	var got auth.Identity
	req := httptest.NewRequest(http.MethodGet, "/api/session", nil)
	req.Header.Set("Authorization", basic(f.Agent.Email, testsupport.Password))
	req.Header.Set(middleware.TenantHeader, f.Tenant.Slug)

	rec := httptest.NewRecorder()
	guarded(f, &got).ServeHTTP(rec, req)

	if rec.Code != http.StatusOK {
		t.Fatalf("status = %d, want 200 (body: %s)", rec.Code, rec.Body)
	}
	if got.User.ID != f.Agent.ID {
		t.Errorf("resolved user %s, want %s", got.User.ID, f.Agent.ID)
	}
	if got.Tenant.ID != f.Tenant.ID {
		t.Errorf("resolved tenant %s, want %s", got.Tenant.ID, f.Tenant.ID)
	}
}

func TestBasicAuthIsCaseInsensitiveOnEmail(t *testing.T) {
	f := testsupport.Setup(t)

	req := httptest.NewRequest(http.MethodGet, "/api/session", nil)
	req.Header.Set("Authorization", basic(strings.ToUpper(f.Agent.Email), testsupport.Password))
	req.Header.Set(middleware.TenantHeader, f.Tenant.Slug)

	rec := httptest.NewRecorder()
	guarded(f, nil).ServeHTTP(rec, req)

	if rec.Code != http.StatusOK {
		t.Errorf("status = %d, want 200", rec.Code)
	}
}

func TestBasicAuthRejections(t *testing.T) {
	f := testsupport.Setup(t)
	other := testsupport.Setup(t)

	cases := []struct {
		name       string
		authHeader string
		tenant     string
		wantStatus int
	}{
		{
			name:       "no credentials at all",
			tenant:     f.Tenant.Slug,
			wantStatus: http.StatusUnauthorized,
		},
		{
			name:       "wrong password",
			authHeader: basic(f.Agent.Email, "not-the-password"),
			tenant:     f.Tenant.Slug,
			wantStatus: http.StatusUnauthorized,
		},
		{
			name:       "unknown user",
			authHeader: basic("nobody@nowhere.test", testsupport.Password),
			tenant:     f.Tenant.Slug,
			wantStatus: http.StatusUnauthorized,
		},
		{
			name:       "unknown tenant",
			authHeader: basic(f.Agent.Email, testsupport.Password),
			tenant:     "no-such-agency",
			wantStatus: http.StatusUnauthorized,
		},
		{
			// The central rule: right password, wrong agency.
			name:       "valid credentials against another tenant",
			authHeader: basic(f.Agent.Email, testsupport.Password),
			tenant:     other.Tenant.Slug,
			wantStatus: http.StatusUnauthorized,
		},
		{
			name:       "missing tenant header",
			authHeader: basic(f.Agent.Email, testsupport.Password),
			tenant:     "",
			wantStatus: http.StatusBadRequest,
		},
		{
			name:       "malformed authorization header",
			authHeader: "Bearer some.jwt.token",
			tenant:     f.Tenant.Slug,
			wantStatus: http.StatusUnauthorized,
		},
	}

	for _, tc := range cases {
		t.Run(tc.name, func(t *testing.T) {
			req := httptest.NewRequest(http.MethodGet, "/api/session", nil)
			if tc.authHeader != "" {
				req.Header.Set("Authorization", tc.authHeader)
			}
			if tc.tenant != "" {
				req.Header.Set(middleware.TenantHeader, tc.tenant)
			}

			rec := httptest.NewRecorder()
			guarded(f, nil).ServeHTTP(rec, req)

			if rec.Code != tc.wantStatus {
				t.Errorf("status = %d, want %d (body: %s)", rec.Code, tc.wantStatus, rec.Body)
			}
		})
	}
}

func TestBasicAuthRefusesSuspendedTenant(t *testing.T) {
	f := testsupport.Setup(t)
	f.Suspend(t)

	req := httptest.NewRequest(http.MethodGet, "/api/session", nil)
	req.Header.Set("Authorization", basic(f.Agent.Email, testsupport.Password))
	req.Header.Set(middleware.TenantHeader, f.Tenant.Slug)

	rec := httptest.NewRecorder()
	guarded(f, nil).ServeHTTP(rec, req)

	if rec.Code != http.StatusUnauthorized {
		t.Errorf("status = %d, want 401 for a suspended tenant", rec.Code)
	}
}

// Sending WWW-Authenticate would make the browser pop its own login dialog over
// the Angular sign-in screen, so its absence is a deliberate contract.
func TestUnauthorizedDoesNotTriggerTheBrowserDialog(t *testing.T) {
	f := testsupport.Setup(t)

	req := httptest.NewRequest(http.MethodGet, "/api/session", nil)
	req.Header.Set("Authorization", basic(f.Agent.Email, "wrong"))
	req.Header.Set(middleware.TenantHeader, f.Tenant.Slug)

	rec := httptest.NewRecorder()
	guarded(f, nil).ServeHTTP(rec, req)

	if got := rec.Header().Get("WWW-Authenticate"); got != "" {
		t.Errorf("WWW-Authenticate = %q, want it absent", got)
	}
	if ct := rec.Header().Get("Content-Type"); ct != "application/json" {
		t.Errorf("Content-Type = %q, want application/json", ct)
	}
}

// Deployments that give each agency a subdomain need no client changes.
func TestTenantFallsBackToSubdomain(t *testing.T) {
	f := testsupport.Setup(t)

	req := httptest.NewRequest(http.MethodGet, "/api/session", nil)
	req.Header.Set("Authorization", basic(f.Agent.Email, testsupport.Password))
	req.Host = f.Tenant.Slug + ".travelhub.example.com:8080"

	rec := httptest.NewRecorder()
	guarded(f, nil).ServeHTTP(rec, req)

	if rec.Code != http.StatusOK {
		t.Errorf("status = %d, want 200 resolving the tenant from the subdomain", rec.Code)
	}
}

func TestTenantHeaderBeatsSubdomain(t *testing.T) {
	f := testsupport.Setup(t)
	other := testsupport.Setup(t)

	var got auth.Identity
	req := httptest.NewRequest(http.MethodGet, "/api/session", nil)
	req.Header.Set("Authorization", basic(f.Agent.Email, testsupport.Password))
	req.Header.Set(middleware.TenantHeader, f.Tenant.Slug)
	req.Host = other.Tenant.Slug + ".travelhub.example.com"

	rec := httptest.NewRecorder()
	guarded(f, &got).ServeHTTP(rec, req)

	if rec.Code != http.StatusOK {
		t.Fatalf("status = %d, want 200", rec.Code)
	}
	if got.Tenant.ID != f.Tenant.ID {
		t.Error("the subdomain overrode the explicit tenant header")
	}
}

func TestRequireAdmin(t *testing.T) {
	f := testsupport.Setup(t)

	adminOnly := middleware.BasicAuth(f.Repo, quietLogger())(
		middleware.RequireAdmin(http.HandlerFunc(func(w http.ResponseWriter, _ *http.Request) {
			w.WriteHeader(http.StatusOK)
		})),
	)

	cases := []struct {
		name  string
		email string
		want  int
	}{
		{"admin passes", f.Admin.Email, http.StatusOK},
		{"agent is refused", f.Agent.Email, http.StatusForbidden},
	}

	for _, tc := range cases {
		t.Run(tc.name, func(t *testing.T) {
			req := httptest.NewRequest(http.MethodGet, "/api/admin", nil)
			req.Header.Set("Authorization", basic(tc.email, testsupport.Password))
			req.Header.Set(middleware.TenantHeader, f.Tenant.Slug)

			rec := httptest.NewRecorder()
			adminOnly.ServeHTTP(rec, req)

			if rec.Code != tc.want {
				t.Errorf("status = %d, want %d", rec.Code, tc.want)
			}
		})
	}
}

func TestCORS(t *testing.T) {
	allowed := []string{"http://localhost:4200", "https://app.example.com/"}
	ok := http.HandlerFunc(func(w http.ResponseWriter, _ *http.Request) {
		w.WriteHeader(http.StatusOK)
	})
	handler := middleware.CORS(allowed)(ok)

	t.Run("echoes an allowed origin", func(t *testing.T) {
		req := httptest.NewRequest(http.MethodGet, "/api/flights", nil)
		req.Header.Set("Origin", "http://localhost:4200")

		rec := httptest.NewRecorder()
		handler.ServeHTTP(rec, req)

		if got := rec.Header().Get("Access-Control-Allow-Origin"); got != "http://localhost:4200" {
			t.Errorf("Allow-Origin = %q", got)
		}
		if got := rec.Header().Get("Vary"); !strings.Contains(got, "Origin") {
			t.Errorf("Vary = %q, want it to include Origin", got)
		}
		if got := rec.Header().Get("Access-Control-Allow-Headers"); !strings.Contains(got, middleware.TenantHeader) {
			t.Errorf("Allow-Headers = %q, want it to include %s", got, middleware.TenantHeader)
		}
	})

	t.Run("tolerates a trailing slash in configuration", func(t *testing.T) {
		req := httptest.NewRequest(http.MethodGet, "/api/flights", nil)
		req.Header.Set("Origin", "https://app.example.com")

		rec := httptest.NewRecorder()
		handler.ServeHTTP(rec, req)

		if got := rec.Header().Get("Access-Control-Allow-Origin"); got != "https://app.example.com" {
			t.Errorf("Allow-Origin = %q, want the origin echoed", got)
		}
	})

	t.Run("ignores an origin that is not on the list", func(t *testing.T) {
		req := httptest.NewRequest(http.MethodGet, "/api/flights", nil)
		req.Header.Set("Origin", "https://evil.example.com")

		rec := httptest.NewRecorder()
		handler.ServeHTTP(rec, req)

		if got := rec.Header().Get("Access-Control-Allow-Origin"); got != "" {
			t.Errorf("Allow-Origin = %q, want it absent", got)
		}
	})

	t.Run("answers preflight without reaching the handler", func(t *testing.T) {
		reached := false
		h := middleware.CORS(allowed)(http.HandlerFunc(func(http.ResponseWriter, *http.Request) {
			reached = true
		}))

		req := httptest.NewRequest(http.MethodOptions, "/api/bookings", nil)
		req.Header.Set("Origin", "http://localhost:4200")

		rec := httptest.NewRecorder()
		h.ServeHTTP(rec, req)

		if rec.Code != http.StatusNoContent {
			t.Errorf("status = %d, want 204", rec.Code)
		}
		if reached {
			t.Error("preflight should short-circuit before the handler")
		}
	})
}

func TestRecovererTurnsPanicIntoFiveHundred(t *testing.T) {
	boom := http.HandlerFunc(func(http.ResponseWriter, *http.Request) {
		panic("something went very wrong")
	})
	handler := middleware.Recoverer(quietLogger())(boom)

	req := httptest.NewRequest(http.MethodGet, "/api/flights", nil)
	rec := httptest.NewRecorder()

	// The point is that this call returns rather than taking the process down.
	handler.ServeHTTP(rec, req)

	if rec.Code != http.StatusInternalServerError {
		t.Errorf("status = %d, want 500", rec.Code)
	}
	if !strings.Contains(rec.Body.String(), "internal server error") {
		t.Errorf("body = %s, want a JSON error", rec.Body)
	}
}