package auth_test

import (
	"context"
	"crypto/rand"
	"crypto/rsa"
	"encoding/json"
	"net/http"
	"net/http/httptest"
	"testing"
	"time"

	"github.com/lestrrat-go/jwx/v2/jwa"
	"github.com/lestrrat-go/jwx/v2/jwk"
	"github.com/lestrrat-go/jwx/v2/jwt"
	"github.com/mathiasbq/supervisor/internal/auth"
	"github.com/stretchr/testify/assert"
	"github.com/stretchr/testify/require"
)

type testKeys struct {
	priv jwk.Key
	pub  jwk.Key
}

func generateRSAKeys(t *testing.T) testKeys {
	t.Helper()
	raw, err := rsa.GenerateKey(rand.Reader, 2048)
	require.NoError(t, err)

	priv, err := jwk.FromRaw(raw)
	require.NoError(t, err)
	require.NoError(t, priv.Set(jwk.KeyIDKey, "test-kid"))
	require.NoError(t, priv.Set(jwk.AlgorithmKey, jwa.RS256))

	pub, err := jwk.PublicKeyOf(priv)
	require.NoError(t, err)

	return testKeys{priv: priv, pub: pub}
}

func mockOIDCServer(t *testing.T, keys testKeys) *httptest.Server {
	t.Helper()
	set := jwk.NewSet()
	require.NoError(t, set.AddKey(keys.pub))
	jwksBytes, err := json.Marshal(set)
	require.NoError(t, err)

	mux := http.NewServeMux()
	var srv *httptest.Server
	mux.HandleFunc("/.well-known/openid-configuration", func(w http.ResponseWriter, _ *http.Request) {
		w.Header().Set("Content-Type", "application/json")
		_ = json.NewEncoder(w).Encode(map[string]string{
			"issuer":   srv.URL,
			"jwks_uri": srv.URL + "/jwks",
		})
	})
	mux.HandleFunc("/jwks", func(w http.ResponseWriter, _ *http.Request) {
		w.Header().Set("Content-Type", "application/json")
		_, _ = w.Write(jwksBytes)
	})
	srv = httptest.NewServer(mux)
	t.Cleanup(srv.Close)
	return srv
}

func signToken(t *testing.T, keys testKeys, issuer, audience, subject string, exp time.Time) string {
	t.Helper()
	b := jwt.NewBuilder().
		Issuer(issuer).
		Subject(subject).
		Expiration(exp)
	if audience != "" {
		b = b.Audience([]string{audience})
	}
	tok, err := b.Build()
	require.NoError(t, err)
	signed, err := jwt.Sign(tok, jwt.WithKey(jwa.RS256, keys.priv))
	require.NoError(t, err)
	return string(signed)
}

func TestValidator(t *testing.T) {
	keys := generateRSAKeys(t)
	srv := mockOIDCServer(t, keys)
	ctx := context.Background()

	v, err := auth.NewValidator(srv.URL, "brain")
	require.NoError(t, err)

	tests := []struct {
		name      string
		token     string
		wantSub   string
		wantErr   bool
	}{
		{
			name:    "valid jwt",
			token:   signToken(t, keys, srv.URL, "brain", "test-user", time.Now().Add(time.Hour)),
			wantSub: "test-user",
		},
		{
			name:    "expired jwt",
			token:   signToken(t, keys, srv.URL, "brain", "test-user", time.Now().Add(-time.Hour)),
			wantErr: true,
		},
		{
			name:    "wrong issuer",
			token:   signToken(t, keys, "https://evil.example.com", "brain", "test-user", time.Now().Add(time.Hour)),
			wantErr: true,
		},
		{
			name:    "wrong audience",
			token:   signToken(t, keys, srv.URL, "other-service", "test-user", time.Now().Add(time.Hour)),
			wantErr: true,
		},
		{
			name:    "tampered token",
			token:   signToken(t, keys, srv.URL, "brain", "test-user", time.Now().Add(time.Hour)) + "tampered",
			wantErr: true,
		},
		{
			name:    "not a jwt",
			token:   "not-a-jwt",
			wantErr: true,
		},
	}

	for _, tc := range tests {
		t.Run(tc.name, func(t *testing.T) {
			sub, err := v.Validate(ctx, tc.token)
			if tc.wantErr {
				assert.Error(t, err)
				assert.Empty(t, sub)
			} else {
				require.NoError(t, err)
				assert.Equal(t, tc.wantSub, sub)
			}
		})
	}
}

func TestNewValidator_NoAudience(t *testing.T) {
	keys := generateRSAKeys(t)
	srv := mockOIDCServer(t, keys)
	ctx := context.Background()

	v, err := auth.NewValidator(srv.URL, "")
	require.NoError(t, err)

	// Token without audience passes when audience validation is disabled.
	tok, err := jwt.NewBuilder().
		Issuer(srv.URL).
		Subject("sub").
		Expiration(time.Now().Add(time.Hour)).
		Build()
	require.NoError(t, err)
	signed, err := jwt.Sign(tok, jwt.WithKey(jwa.RS256, keys.priv))
	require.NoError(t, err)

	sub, err := v.Validate(ctx, string(signed))
	require.NoError(t, err)
	assert.Equal(t, "sub", sub)
}

func TestNewValidator_BadDiscoveryURL(t *testing.T) {
	_, err := auth.NewValidator("http://127.0.0.1:1", "brain")
	assert.Error(t, err)
}