package auth

import (
	"context"
	"encoding/json"
	"errors"
	"log/slog"
	"net/http"
	"net/http/httptest"
	"testing"
	"time"
)

// mockMCIAS returns a test HTTP server that simulates MCIAS endpoints.
func mockMCIAS(t *testing.T) *httptest.Server {
	t.Helper()
	mux := http.NewServeMux()

	mux.HandleFunc("POST /v1/auth/login", func(w http.ResponseWriter, r *http.Request) {
		var req struct {
			Username    string `json:"username"`
			Password    string `json:"password"`
			ServiceName string `json:"service_name"`
		}
		if err := json.NewDecoder(r.Body).Decode(&req); err != nil {
			http.Error(w, `{"error":"bad request"}`, http.StatusBadRequest)
			return
		}
		if req.Username == "admin" && req.Password == "secret" {
			w.Header().Set("Content-Type", "application/json")
			exp := time.Now().Add(1 * time.Hour).Format(time.RFC3339)
			_ = json.NewEncoder(w).Encode(map[string]string{
				"token":      "tok-admin-123",
				"expires_at": exp,
			})
			return
		}
		if req.Username == "denied" && req.Password == "secret" {
			http.Error(w, `{"error":"forbidden by policy"}`, http.StatusForbidden)
			return
		}
		http.Error(w, `{"error":"invalid credentials"}`, http.StatusUnauthorized)
	})

	mux.HandleFunc("POST /v1/token/validate", func(w http.ResponseWriter, r *http.Request) {
		var req struct {
			Token string `json:"token"`
		}
		if err := json.NewDecoder(r.Body).Decode(&req); err != nil {
			http.Error(w, `{"error":"bad request"}`, http.StatusBadRequest)
			return
		}
		switch req.Token {
		case "tok-admin-123":
			w.Header().Set("Content-Type", "application/json")
			_ = json.NewEncoder(w).Encode(map[string]interface{}{
				"valid":        true,
				"sub":          "uuid-admin",
				"username":     "admin",
				"account_type": "human",
				"roles":        []string{"admin", "user"},
			})
		case "tok-user-456":
			w.Header().Set("Content-Type", "application/json")
			_ = json.NewEncoder(w).Encode(map[string]interface{}{
				"valid":        true,
				"sub":          "uuid-user",
				"username":     "alice",
				"account_type": "human",
				"roles":        []string{"user"},
			})
		case "tok-expired":
			w.Header().Set("Content-Type", "application/json")
			_ = json.NewEncoder(w).Encode(map[string]interface{}{
				"valid": false,
			})
		default:
			http.Error(w, `{"error":"unauthorized"}`, http.StatusUnauthorized)
		}
	})

	mux.HandleFunc("POST /v1/auth/logout", func(w http.ResponseWriter, _ *http.Request) {
		w.WriteHeader(http.StatusNoContent)
	})

	return httptest.NewServer(mux)
}

func newTestAuth(t *testing.T, serverURL string) *Authenticator {
	t.Helper()
	a, err := New(Config{
		ServerURL:   serverURL,
		ServiceName: "test-service",
		Tags:        []string{"env:test"},
	}, slog.Default())
	if err != nil {
		t.Fatalf("New: %v", err)
	}
	return a
}

func TestLogin(t *testing.T) {
	srv := mockMCIAS(t)
	defer srv.Close()
	a := newTestAuth(t, srv.URL)

	token, exp, err := a.Login("admin", "secret", "")
	if err != nil {
		t.Fatalf("Login: %v", err)
	}
	if token != "tok-admin-123" {
		t.Fatalf("token = %q, want %q", token, "tok-admin-123")
	}
	if exp.IsZero() {
		t.Fatal("expiresAt is zero")
	}
}

func TestLoginInvalidCredentials(t *testing.T) {
	srv := mockMCIAS(t)
	defer srv.Close()
	a := newTestAuth(t, srv.URL)

	_, _, err := a.Login("admin", "wrong", "")
	if err == nil {
		t.Fatal("expected error for invalid credentials")
	}
	if !errors.Is(err, ErrInvalidCredentials) {
		t.Fatalf("err = %v, want ErrInvalidCredentials", err)
	}
}

func TestLoginForbidden(t *testing.T) {
	srv := mockMCIAS(t)
	defer srv.Close()
	a := newTestAuth(t, srv.URL)

	_, _, err := a.Login("denied", "secret", "")
	if err == nil {
		t.Fatal("expected error for forbidden login")
	}
	if !errors.Is(err, ErrForbidden) {
		t.Fatalf("err = %v, want ErrForbidden", err)
	}
}

func TestValidateToken(t *testing.T) {
	srv := mockMCIAS(t)
	defer srv.Close()
	a := newTestAuth(t, srv.URL)

	info, err := a.ValidateToken("tok-admin-123")
	if err != nil {
		t.Fatalf("ValidateToken: %v", err)
	}
	if info.Username != "admin" {
		t.Fatalf("Username = %q, want %q", info.Username, "admin")
	}
	if info.AccountType != "human" {
		t.Fatalf("AccountType = %q, want %q", info.AccountType, "human")
	}
	if !info.IsAdmin {
		t.Fatal("IsAdmin = false, want true")
	}
	if len(info.Roles) != 2 {
		t.Fatalf("Roles = %v, want 2 roles", info.Roles)
	}
}

func TestValidateTokenNonAdmin(t *testing.T) {
	srv := mockMCIAS(t)
	defer srv.Close()
	a := newTestAuth(t, srv.URL)

	info, err := a.ValidateToken("tok-user-456")
	if err != nil {
		t.Fatalf("ValidateToken: %v", err)
	}
	if info.Username != "alice" {
		t.Fatalf("Username = %q, want %q", info.Username, "alice")
	}
	if info.IsAdmin {
		t.Fatal("IsAdmin = true, want false")
	}
}

func TestValidateTokenExpired(t *testing.T) {
	srv := mockMCIAS(t)
	defer srv.Close()
	a := newTestAuth(t, srv.URL)

	_, err := a.ValidateToken("tok-expired")
	if err == nil {
		t.Fatal("expected error for expired token")
	}
	if !errors.Is(err, ErrInvalidToken) {
		t.Fatalf("err = %v, want ErrInvalidToken", err)
	}
}

func TestValidateTokenUnknown(t *testing.T) {
	srv := mockMCIAS(t)
	defer srv.Close()
	a := newTestAuth(t, srv.URL)

	_, err := a.ValidateToken("tok-unknown")
	if err == nil {
		t.Fatal("expected error for unknown token")
	}
}

func TestValidateTokenCache(t *testing.T) {
	callCount := 0
	mux := http.NewServeMux()
	mux.HandleFunc("POST /v1/token/validate", func(w http.ResponseWriter, _ *http.Request) {
		callCount++
		w.Header().Set("Content-Type", "application/json")
		_ = json.NewEncoder(w).Encode(map[string]interface{}{
			"valid":    true,
			"username": "cached-user",
			"roles":    []string{"user"},
		})
	})
	srv := httptest.NewServer(mux)
	defer srv.Close()

	a := newTestAuth(t, srv.URL)

	// First call: cache miss, hits server.
	info1, err := a.ValidateToken("tok-cache-test")
	if err != nil {
		t.Fatalf("ValidateToken (1st): %v", err)
	}
	if callCount != 1 {
		t.Fatalf("server calls = %d, want 1", callCount)
	}

	// Second call: cache hit, no server call.
	info2, err := a.ValidateToken("tok-cache-test")
	if err != nil {
		t.Fatalf("ValidateToken (2nd): %v", err)
	}
	if callCount != 1 {
		t.Fatalf("server calls = %d, want 1 (cached)", callCount)
	}
	if info1.Username != info2.Username {
		t.Fatalf("cached username mismatch: %q vs %q", info1.Username, info2.Username)
	}
}

func TestValidateTokenCacheExpiry(t *testing.T) {
	callCount := 0
	mux := http.NewServeMux()
	mux.HandleFunc("POST /v1/token/validate", func(w http.ResponseWriter, _ *http.Request) {
		callCount++
		w.Header().Set("Content-Type", "application/json")
		_ = json.NewEncoder(w).Encode(map[string]interface{}{
			"valid":    true,
			"username": "user",
			"roles":    []string{"user"},
		})
	})
	srv := httptest.NewServer(mux)
	defer srv.Close()

	a := newTestAuth(t, srv.URL)

	// Override the cache clock to simulate time passing.
	now := time.Now()
	a.cache.now = func() time.Time { return now }

	_, err := a.ValidateToken("tok-expiry-test")
	if err != nil {
		t.Fatalf("ValidateToken (1st): %v", err)
	}
	if callCount != 1 {
		t.Fatalf("server calls = %d, want 1", callCount)
	}

	// Advance past cache TTL.
	now = now.Add(cacheTTL + 1*time.Second)

	_, err = a.ValidateToken("tok-expiry-test")
	if err != nil {
		t.Fatalf("ValidateToken (2nd): %v", err)
	}
	if callCount != 2 {
		t.Fatalf("server calls = %d, want 2 (cache expired)", callCount)
	}
}

func TestLogout(t *testing.T) {
	srv := mockMCIAS(t)
	defer srv.Close()
	a := newTestAuth(t, srv.URL)

	if err := a.Logout("tok-admin-123"); err != nil {
		t.Fatalf("Logout: %v", err)
	}
}

func TestNewRequiresServerURL(t *testing.T) {
	_, err := New(Config{}, slog.Default())
	if err == nil {
		t.Fatal("expected error for empty server_url")
	}
}

func TestContextRoundtrip(t *testing.T) {
	info := &TokenInfo{
		Username: "testuser",
		Roles:    []string{"user"},
		IsAdmin:  false,
	}

	ctx := ContextWithTokenInfo(context.Background(), info)
	got := TokenInfoFromContext(ctx)

	if got == nil {
		t.Fatal("TokenInfoFromContext returned nil")
	}
	if got.Username != "testuser" {
		t.Fatalf("Username = %q, want %q", got.Username, "testuser")
	}
}

func TestContextMissing(t *testing.T) {
	got := TokenInfoFromContext(context.Background())
	if got != nil {
		t.Fatalf("expected nil from empty context, got %v", got)
	}
}

func TestAdminDetection(t *testing.T) {
	tests := []struct {
		roles []string
		want  bool
	}{
		{[]string{"admin", "user"}, true},
		{[]string{"admin"}, true},
		{[]string{"user"}, false},
		{[]string{}, false},
		{nil, false},
	}
	for _, tt := range tests {
		got := hasRole(tt.roles, "admin")
		if got != tt.want {
			t.Errorf("hasRole(%v, admin) = %v, want %v", tt.roles, got, tt.want)
		}
	}
}