package auth

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

	"github.com/iceBear67/simplepages/api"
	"github.com/iceBear67/simplepages/internal/httpx"
	"github.com/iceBear67/simplepages/internal/store"
)

// okHandler records that the request got past the middleware.
func okHandler(reached *bool) http.Handler {
	return http.HandlerFunc(func(w http.ResponseWriter, r *http.Request) {
		if reached != nil {
			*reached = true
		}
		w.WriteHeader(http.StatusNoContent)
	})
}

func errorCode(t *testing.T, body []byte) api.Code {
	t.Helper()
	var env api.ErrorEnvelope
	if err := json.Unmarshal(body, &env); err != nil {
		t.Fatalf("response is not an error envelope: %v (%s)", err, body)
	}
	if env.Error.Code == "" {
		t.Fatalf("envelope has no error code: %s", body)
	}
	return env.Error.Code
}

func newMiddleware(t *testing.T, db *store.DB, logTo *bytes.Buffer) *Middleware {
	t.Helper()
	var h slog.Handler = slog.NewTextHandler(logTo, &slog.HandlerOptions{Level: slog.LevelDebug})
	log := slog.New(h)
	return &Middleware{
		V:       NewVerifier(db, log, DefaultCacheTTL),
		Limiter: NewLimiter(5, time.Minute, 128),
		Trusted: []netip.Prefix{netip.MustParsePrefix("127.0.0.1/32")},
		Log:     log,
	}
}

func TestAuthenticateAcceptsValidToken(t *testing.T) {
	db := testStore(t)
	m := newMiddleware(t, db, &bytes.Buffer{})
	token, keyID := mintInto(t, db, store.ScopeAdmin, nil)

	var gotID *Identity
	h := m.Authenticate(http.HandlerFunc(func(w http.ResponseWriter, r *http.Request) {
		id, ok := IdentityFrom(r.Context())
		if !ok {
			t.Error("no identity in context behind Authenticate")
		}
		gotID = id
		w.WriteHeader(http.StatusNoContent)
	}))

	req := httptest.NewRequest(http.MethodGet, "/api/v1/whoami", nil)
	req.Header.Set("Authorization", "Bearer "+token)
	rec := httptest.NewRecorder()
	h.ServeHTTP(rec, req)

	if rec.Code != http.StatusNoContent {
		t.Fatalf("status = %d, want 204: %s", rec.Code, rec.Body)
	}
	if gotID == nil || gotID.KeyID != keyID {
		t.Errorf("identity = %+v, want key %s", gotID, keyID)
	}
}

func TestAuthenticateRejects(t *testing.T) {
	db := testStore(t)
	m := newMiddleware(t, db, &bytes.Buffer{})
	token, keyID := mintInto(t, db, store.ScopeAdmin, nil)
	_, secret, err := Parse(token)
	if err != nil {
		t.Fatal(err)
	}
	unknown, _, _, err := Mint()
	if err != nil {
		t.Fatal(err)
	}

	cases := []struct {
		name   string
		header string
	}{
		{"no header", ""},
		{"empty bearer", "Bearer "},
		{"wrong scheme", "Basic " + token},
		{"token without scheme", token},
		{"malformed token", "Bearer not-a-token"},
		{"unknown key", "Bearer " + unknown},
		{"truncated secret", "Bearer " + Prefix + "_" + keyID + "_" + secret[:42]},
	}
	for _, tc := range cases {
		t.Run(tc.name, func(t *testing.T) {
			reached := false
			h := m.Authenticate(okHandler(&reached))
			req := httptest.NewRequest(http.MethodGet, "/api/v1/whoami", nil)
			if tc.header != "" {
				req.Header.Set("Authorization", tc.header)
			}
			rec := httptest.NewRecorder()
			h.ServeHTTP(rec, req)

			if reached {
				t.Error("request reached the handler")
			}
			if rec.Code != http.StatusUnauthorized {
				t.Fatalf("status = %d, want 401: %s", rec.Code, rec.Body)
			}
			if got := errorCode(t, rec.Body.Bytes()); got != api.CodeUnauthorized {
				t.Errorf("code = %q, want %q", got, api.CodeUnauthorized)
			}
			if got := rec.Header().Get("WWW-Authenticate"); !strings.Contains(got, "Bearer") {
				t.Errorf("WWW-Authenticate = %q", got)
			}
			// The client must not learn which check failed.
			body := rec.Body.String()
			for _, leak := range []string{"revoked", "expired", "unknown key", "secret mismatch"} {
				if strings.Contains(strings.ToLower(body), leak) {
					t.Errorf("response distinguishes the failure reason (%q): %s", leak, body)
				}
			}
		})
	}
}

// The scheme is case-insensitive per RFC 7235, and some CI clients send "bearer".
func TestAuthenticateAcceptsAnyCaseScheme(t *testing.T) {
	db := testStore(t)
	m := newMiddleware(t, db, &bytes.Buffer{})
	token, _ := mintInto(t, db, store.ScopeAdmin, nil)

	for _, scheme := range []string{"Bearer", "bearer", "BEARER", "BeArEr"} {
		reached := false
		h := m.Authenticate(okHandler(&reached))
		req := httptest.NewRequest(http.MethodGet, "/x", nil)
		req.Header.Set("Authorization", scheme+" "+token)
		rec := httptest.NewRecorder()
		h.ServeHTTP(rec, req)
		if !reached {
			t.Errorf("scheme %q rejected: %d %s", scheme, rec.Code, rec.Body)
		}
	}
}

// A token in the query string ends up in proxy logs and browser history, so it
// must never be accepted as a credential.
func TestTokenInQueryStringIsNotAccepted(t *testing.T) {
	db := testStore(t)
	m := newMiddleware(t, db, &bytes.Buffer{})
	token, _ := mintInto(t, db, store.ScopeAdmin, nil)

	reached := false
	h := m.Authenticate(okHandler(&reached))
	req := httptest.NewRequest(http.MethodGet, "/api/v1/whoami?token="+token+"&access_token="+token, nil)
	rec := httptest.NewRecorder()
	h.ServeHTTP(rec, req)

	if reached {
		t.Fatal("a query-string token authenticated the request")
	}
	if rec.Code != http.StatusUnauthorized {
		t.Errorf("status = %d, want 401", rec.Code)
	}
}

// The load-bearing one: nothing this middleware logs may contain the secret.
func TestAuthLogsNeverContainCredentials(t *testing.T) {
	db := testStore(t)
	var logBuf bytes.Buffer
	m := newMiddleware(t, db, &logBuf)
	token, keyID := mintInto(t, db, store.ScopeAdmin, nil)
	_, secret, err := Parse(token)
	if err != nil {
		t.Fatal(err)
	}

	handler := httpx.Chain(
		m.Authenticate(okHandler(nil)),
		httpx.WithRequestID(m.Trusted),
		httpx.AccessLog(m.Log, m.Trusted),
		httpx.Recover(m.Log),
	)

	// A successful request, a wrong-secret request, and a garbage request: the
	// three paths that each touch the token.
	for _, hdr := range []string{
		"Bearer " + token,
		"Bearer " + Prefix + "_" + keyID + "_" + strings.Repeat("z", 43),
		"Bearer " + token + "trailing",
	} {
		req := httptest.NewRequest(http.MethodGet, "/api/v1/whoami", nil)
		req.Header.Set("Authorization", hdr)
		req.RemoteAddr = "10.1.2.3:5555"
		handler.ServeHTTP(httptest.NewRecorder(), req)
	}

	out := logBuf.String()
	if out == "" {
		t.Fatal("nothing was logged; the test would pass vacuously")
	}
	for _, forbidden := range []string{secret, token, "Bearer", "Authorization"} {
		if strings.Contains(out, forbidden) {
			t.Errorf("log contains %q:\n%s", forbidden, out)
		}
	}
	// The public half is supposed to be there — otherwise an operator cannot
	// tell which key made a request.
	if !strings.Contains(out, keyID) {
		t.Errorf("log does not record the key id:\n%s", out)
	}
}

func TestAuthenticateRateLimitsFailures(t *testing.T) {
	db := testStore(t)
	m := newMiddleware(t, db, &bytes.Buffer{})
	m.Limiter = NewLimiter(3, time.Minute, 32)
	bad, _, _, err := Mint()
	if err != nil {
		t.Fatal(err)
	}
	good, _ := mintInto(t, db, store.ScopeAdmin, nil)

	send := func(token, remote string) *httptest.ResponseRecorder {
		h := m.Authenticate(okHandler(nil))
		req := httptest.NewRequest(http.MethodGet, "/api/v1/whoami", nil)
		req.Header.Set("Authorization", "Bearer "+token)
		req.RemoteAddr = remote
		rec := httptest.NewRecorder()
		h.ServeHTTP(rec, req)
		return rec
	}

	for i := 0; i < 3; i++ {
		if got := send(bad, "10.1.2.3:5555").Code; got != http.StatusUnauthorized {
			t.Fatalf("attempt %d: status = %d, want 401", i, got)
		}
	}
	rec := send(bad, "10.1.2.3:5555")
	if rec.Code != http.StatusTooManyRequests {
		t.Fatalf("status = %d, want 429: %s", rec.Code, rec.Body)
	}
	if got := errorCode(t, rec.Body.Bytes()); got != api.CodeRateLimited {
		t.Errorf("code = %q, want %q", got, api.CodeRateLimited)
	}
	if rec.Header().Get("Retry-After") == "" {
		t.Error("429 without a Retry-After header")
	}

	// A different address is unaffected...
	if got := send(bad, "10.9.9.9:5555").Code; got != http.StatusUnauthorized {
		t.Errorf("unrelated client got %d, want 401", got)
	}
	// ...and a client that had never failed can still authenticate.
	if got := send(good, "10.8.8.8:5555").Code; got != http.StatusNoContent {
		t.Errorf("valid token from a clean client got %d, want 204", got)
	}
}

func TestRequireAdmin(t *testing.T) {
	db := testStore(t)
	log := slog.New(slog.NewTextHandler(&bytes.Buffer{}, nil))
	p := store.DefaultProject("demo")
	if err := db.CreateProject(context.Background(), p); err != nil {
		t.Fatal(err)
	}

	cases := []struct {
		name       string
		identity   *Identity
		wantStatus int
	}{
		{"admin", &Identity{KeyID: "a", Scope: store.ScopeAdmin}, http.StatusNoContent},
		{"project", &Identity{KeyID: "b", Scope: store.ScopeProject, ProjectID: &p.ID}, http.StatusForbidden},
		{"none", nil, http.StatusUnauthorized},
	}
	for _, tc := range cases {
		t.Run(tc.name, func(t *testing.T) {
			reached := false
			h := RequireAdmin(log)(okHandler(&reached))
			req := httptest.NewRequest(http.MethodGet, "/api/v1/projects", nil)
			if tc.identity != nil {
				req = req.WithContext(ContextWithIdentity(req.Context(), tc.identity))
			}
			rec := httptest.NewRecorder()
			h.ServeHTTP(rec, req)
			if rec.Code != tc.wantStatus {
				t.Errorf("status = %d, want %d: %s", rec.Code, tc.wantStatus, rec.Body)
			}
			if reached != (tc.wantStatus == http.StatusNoContent) {
				t.Errorf("handler reached = %v", reached)
			}
		})
	}
}

func TestRequireProject(t *testing.T) {
	db := testStore(t)
	ctx := context.Background()
	log := slog.New(slog.NewTextHandler(&bytes.Buffer{}, nil))

	mine := store.DefaultProject("mine")
	theirs := store.DefaultProject("theirs")
	if err := db.CreateProject(ctx, mine); err != nil {
		t.Fatal(err)
	}
	if err := db.CreateProject(ctx, theirs); err != nil {
		t.Fatal(err)
	}

	resolver := ResolverFunc(func(ctx context.Context, name string) (int64, error) {
		p, err := db.ProjectByName(ctx, name)
		if err != nil {
			return 0, err
		}
		return p.ID, nil
	})

	admin := &Identity{KeyID: "admin00000000000", Scope: store.ScopeAdmin}
	owner := &Identity{KeyID: "owner00000000000", Scope: store.ScopeProject, ProjectID: &mine.ID}

	cases := []struct {
		name       string
		identity   *Identity
		project    string
		wantStatus int
	}{
		{"owner on own project", owner, "mine", http.StatusNoContent},
		{"owner on another project", owner, "theirs", http.StatusForbidden},
		{"admin on any project", admin, "theirs", http.StatusNoContent},
		{"admin on unknown project", admin, "ghost", http.StatusNotFound},
		// An unknown name must look exactly like someone else's project to a
		// project-scoped key, or the API becomes a project-name oracle.
		{"owner on unknown project", owner, "ghost", http.StatusForbidden},
		{"no identity", nil, "mine", http.StatusUnauthorized},
		{"missing name", owner, "", http.StatusBadRequest},
	}
	for _, tc := range cases {
		t.Run(tc.name, func(t *testing.T) {
			reached := false
			mux := http.NewServeMux()
			mux.Handle("GET /api/v1/projects/{name}", RequireProject("name", resolver, log)(okHandler(&reached)))
			// The "missing name" case cannot be produced through the mux, so it
			// exercises the handler directly.
			var h http.Handler = mux
			target := "/api/v1/projects/" + tc.project
			if tc.project == "" {
				h = RequireProject("name", resolver, log)(okHandler(&reached))
				target = "/api/v1/projects/"
			}

			req := httptest.NewRequest(http.MethodGet, target, nil)
			if tc.identity != nil {
				req = req.WithContext(ContextWithIdentity(req.Context(), tc.identity))
			}
			rec := httptest.NewRecorder()
			h.ServeHTTP(rec, req)

			if rec.Code != tc.wantStatus {
				t.Errorf("status = %d, want %d: %s", rec.Code, tc.wantStatus, rec.Body)
			}
			if reached != (tc.wantStatus == http.StatusNoContent) {
				t.Errorf("handler reached = %v", reached)
			}
		})
	}
}

// Ownership is decided on row ids. A project key must not gain access to a
// project just because a name resolves to it.
func TestOwnsComparesIDsNotNames(t *testing.T) {
	one := int64(1)
	two := int64(2)
	cases := []struct {
		name string
		id   *Identity
		ask  int64
		want bool
	}{
		{"admin owns anything", &Identity{Scope: store.ScopeAdmin}, 42, true},
		{"project owns itself", &Identity{Scope: store.ScopeProject, ProjectID: &one}, 1, true},
		{"project does not own another", &Identity{Scope: store.ScopeProject, ProjectID: &two}, 1, false},
		{"project key without a project owns nothing", &Identity{Scope: store.ScopeProject}, 1, false},
		{"nil identity owns nothing", nil, 1, false},
	}
	for _, tc := range cases {
		t.Run(tc.name, func(t *testing.T) {
			if got := tc.id.Owns(tc.ask); got != tc.want {
				t.Errorf("Owns(%d) = %v, want %v", tc.ask, got, tc.want)
			}
		})
	}
}