package auth

import (
	"context"
	"net/http"
	"net/http/httptest"
	"testing"
	"time"
)

type fakeStore struct {
	session  Session
	err      error
	lookups  int
	digest   []byte
	touched  int
	touchTTL time.Duration
}

func (f *fakeStore) Lookup(_ context.Context, digest []byte, _ time.Time) (Session, error) {
	f.lookups++
	f.digest = digest
	return f.session, f.err
}

func (f *fakeStore) Touch(_ context.Context, _ []byte, _ time.Time, ttl time.Duration) error {
	f.touched++
	f.touchTTL = ttl
	return nil
}

func newAuth(store SessionStore, now time.Time) (*Authenticator, *int) {
	denied := 0
	return &Authenticator{
		Sessions: store,
		IdleTTL:  time.Hour,
		Now:      func() time.Time { return now },
		Deny: http.HandlerFunc(func(w http.ResponseWriter, _ *http.Request) {
			denied++
			w.WriteHeader(http.StatusUnauthorized)
		}),
	}, &denied
}

func TestBothPresentationsYieldAPrincipal(t *testing.T) {
	now := time.Now()
	token := NewToken()
	for name, arm := range map[string]struct {
		set func(*http.Request)
		via Presentation
	}{
		"cookie": {func(r *http.Request) { r.AddCookie(&http.Cookie{Name: CookieName, Value: token}) }, ViaCookie},
		"bearer": {func(r *http.Request) { r.Header.Set("Authorization", "Bearer "+token) }, ViaBearer},
	} {
		t.Run(name, func(t *testing.T) {
			store := &fakeStore{session: Session{
				UserID:            "u1",
				IdleExpiresAt:     now.Add(time.Hour),
				AbsoluteExpiresAt: now.Add(24 * time.Hour),
			}}
			a, denied := newAuth(store, now)
			var seen Principal
			h := a.Require(http.HandlerFunc(func(_ http.ResponseWriter, r *http.Request) {
				seen, _ = FromContext(r.Context())
			}))
			r := httptest.NewRequest(http.MethodGet, "/v0/books", nil)
			arm.set(r)
			h.ServeHTTP(httptest.NewRecorder(), r)

			if *denied != 0 {
				t.Fatalf("denied a live session")
			}
			if seen.UserID != "u1" || seen.Via != arm.via {
				t.Fatalf("principal = %+v", seen)
			}
			// What reaches the store is the digest, never the token itself.
			if string(store.digest) == token {
				t.Fatal("plaintext token reached the store")
			}
		})
	}
}

func TestNoOrBrokenCredentialIsDenied(t *testing.T) {
	now := time.Now()
	for name, set := range map[string]func(*http.Request){
		"nothing":       func(*http.Request) {},
		"empty cookie":  func(r *http.Request) { r.AddCookie(&http.Cookie{Name: CookieName, Value: ""}) },
		"wrong scheme":  func(r *http.Request) { r.Header.Set("Authorization", "Basic abc") },
		"bearer empty":  func(r *http.Request) { r.Header.Set("Authorization", "Bearer ") },
		"other cookie":  func(r *http.Request) { r.AddCookie(&http.Cookie{Name: "tm_session", Value: "x"}) },
		"store failure": func(r *http.Request) { r.Header.Set("Authorization", "Bearer t") },
	} {
		t.Run(name, func(t *testing.T) {
			store := &fakeStore{err: ErrNoSession}
			a, denied := newAuth(store, now)
			reached := false
			h := a.Require(http.HandlerFunc(func(http.ResponseWriter, *http.Request) { reached = true }))
			r := httptest.NewRequest(http.MethodGet, "/v0/books", nil)
			set(r)
			h.ServeHTTP(httptest.NewRecorder(), r)
			if reached {
				t.Fatal("handler ran without a live session")
			}
			if *denied != 1 {
				t.Fatalf("deny count = %d", *denied)
			}
		})
	}
}

// Found by running the binary without a database: a presented token used to reach a nil store and
// panic into a 500. Nothing can be proven without a store, so it must deny like any other miss.
func TestNoStoreDeniesInsteadOfPanicking(t *testing.T) {
	a, denied := newAuth(nil, time.Now())
	h := a.Require(http.HandlerFunc(func(http.ResponseWriter, *http.Request) {
		t.Fatal("handler ran with no session store")
	}))
	r := httptest.NewRequest(http.MethodGet, "/v0/books", nil)
	r.Header.Set("Authorization", "Bearer t")
	h.ServeHTTP(httptest.NewRecorder(), r)
	if *denied != 1 {
		t.Fatalf("deny count = %d", *denied)
	}
}

func TestBearerWinsOverCookie(t *testing.T) {
	r := httptest.NewRequest(http.MethodGet, "/v0/books", nil)
	r.AddCookie(&http.Cookie{Name: CookieName, Value: "cookie-token"})
	r.Header.Set("Authorization", "Bearer bearer-token")
	token, via, ok := present(r)
	if !ok || token != "bearer-token" || via != ViaBearer {
		t.Fatalf("present() = %q %q %v", token, via, ok)
	}
}

func TestIdleWindowSlidesOnlyInItsSecondHalf(t *testing.T) {
	now := time.Now()
	for name, tc := range map[string]struct {
		remaining time.Duration
		want      int
	}{
		"fresh": {50 * time.Minute, 0},
		"stale": {10 * time.Minute, 1},
	} {
		t.Run(name, func(t *testing.T) {
			store := &fakeStore{session: Session{
				UserID:            "u1",
				IdleExpiresAt:     now.Add(tc.remaining),
				AbsoluteExpiresAt: now.Add(24 * time.Hour),
			}}
			a, _ := newAuth(store, now)
			h := a.Require(http.HandlerFunc(func(http.ResponseWriter, *http.Request) {}))
			r := httptest.NewRequest(http.MethodGet, "/v0/books", nil)
			r.Header.Set("Authorization", "Bearer t")
			h.ServeHTTP(httptest.NewRecorder(), r)
			if store.touched != tc.want {
				t.Fatalf("touches = %d, want %d", store.touched, tc.want)
			}
		})
	}
}

func TestTokensAreUniqueAndDigestIsStable(t *testing.T) {
	seen := make(map[string]bool, 64)
	for range 64 {
		tok := NewToken()
		if len(tok) < 40 { // 32 bytes base64url ≈ 43 chars
			t.Fatalf("token too short: %q", tok)
		}
		if seen[tok] {
			t.Fatal("token repeated")
		}
		seen[tok] = true
		d := Digest(tok)
		if len(d) != 32 {
			t.Fatalf("digest is %d bytes", len(d))
		}
		if string(d) == tok {
			t.Fatal("the stored form is the token itself")
		}
	}
}