package httpapi

import (
	"context"
	"encoding/json"
	"errors"
	"net/http"
	"net/http/httptest"
	"regexp"
	"strings"
	"testing"
	"time"

	"cmroubao/backend-api/internal/domain"

	"github.com/gin-gonic/gin"
)

type fakePinger struct {
	err error
}

func (p fakePinger) PingContext(context.Context) error {
	return p.err
}

func TestHealthzReturnsStableHealthyResponse(t *testing.T) {
	router, err := newTestRouter(fakePinger{}, discardEvent)
	if err != nil {
		t.Fatalf("NewRouter() error = %v", err)
	}

	response := performRequest(t, router, http.MethodGet, "/healthz")

	if response.Code != http.StatusOK {
		t.Fatalf("status = %d", response.Code)
	}
	assertJSON(t, response, map[string]any{"status": "ok"})
	if response.Header().Get("Cache-Control") != "no-store" {
		t.Fatalf("Cache-Control = %q", response.Header().Get("Cache-Control"))
	}
	if response.Header().Get("Access-Control-Allow-Origin") != "" {
		t.Fatal("default CORS must remain disabled")
	}
}

func TestHealthzReturns503WithoutLeakingDatabaseError(t *testing.T) {
	router, err := newTestRouter(fakePinger{
		err: errors.New("private database path and driver details"),
	}, discardEvent)
	if err != nil {
		t.Fatalf("NewRouter() error = %v", err)
	}

	response := performRequest(t, router, http.MethodGet, "/healthz")

	if response.Code != http.StatusServiceUnavailable {
		t.Fatalf("status = %d", response.Code)
	}
	if strings.Contains(response.Body.String(), "private database") {
		t.Fatal("health response leaked the database error")
	}
	assertJSON(t, response, map[string]any{"status": "unavailable"})
}

func TestUnknownRouteAndMethodUseStableErrors(t *testing.T) {
	router, err := newTestRouter(fakePinger{}, discardEvent)
	if err != nil {
		t.Fatalf("NewRouter() error = %v", err)
	}

	notFound := performRequest(t, router, http.MethodGet, "/missing")
	if notFound.Code != http.StatusNotFound {
		t.Fatalf("not found status = %d", notFound.Code)
	}
	assertErrorCode(t, notFound, "NOT_FOUND")

	notAllowed := performRequest(t, router, http.MethodPost, "/healthz")
	if notAllowed.Code != http.StatusMethodNotAllowed {
		t.Fatalf("not allowed status = %d", notAllowed.Code)
	}
	assertErrorCode(t, notAllowed, "METHOD_NOT_ALLOWED")
}

func TestSafeRecoveryReturnsStableErrorWithoutLoggingRequestHeaders(t *testing.T) {
	var events []string
	router, err := newTestRouter(
		panicPinger{},
		func(event string) {
			events = append(events, event)
		},
	)
	if err != nil {
		t.Fatalf("NewRouter() error = %v", err)
	}
	request := httptest.NewRequest(http.MethodGet, "/healthz", nil)
	request.Header.Set("Authorization", "Bearer private-token")
	request.Header.Set("Cookie", "session=private-cookie")
	response := httptest.NewRecorder()

	router.ServeHTTP(response, request)

	if response.Code != http.StatusInternalServerError {
		t.Fatalf("status = %d", response.Code)
	}
	assertErrorCode(t, response, "INTERNAL_ERROR")
	if len(events) != 1 || events[0] != "HTTP handler panic recovered" {
		t.Fatalf("events = %#v", events)
	}
	eventText := strings.Join(events, " ")
	if strings.Contains(eventText, "private") ||
		strings.Contains(eventText, "Bearer") ||
		strings.Contains(eventText, "session") {
		t.Fatalf("event log leaked request or panic content")
	}
}

func TestRouterRequiresDependencies(t *testing.T) {
	valid := RouterDependencies{
		Database:             fakePinger{},
		RegisterPublicRoutes: discardRoutes,
		RegisterAdminRoutes:  discardRoutes,
		AdminSessions:        allowAdminAuthenticator{},
		LogEvent:             discardEvent,
	}
	missingDatabase := valid
	missingDatabase.Database = nil
	if _, err := NewRouter(missingDatabase); err == nil {
		t.Fatal("NewRouter(nil database) error = nil")
	}
	missingRoutes := valid
	missingRoutes.RegisterAdminRoutes = nil
	if _, err := NewRouter(missingRoutes); err == nil {
		t.Fatal("NewRouter(nil routes) error = nil")
	}
	missingPublicRoutes := valid
	missingPublicRoutes.RegisterPublicRoutes = nil
	if _, err := NewRouter(missingPublicRoutes); err == nil {
		t.Fatal("NewRouter(nil public routes) error = nil")
	}
	missingAuth := valid
	missingAuth.AdminSessions = nil
	if _, err := NewRouter(missingAuth); err == nil {
		t.Fatal("NewRouter(nil admin auth) error = nil")
	}
	missingLogger := valid
	missingLogger.LogEvent = nil
	if _, err := NewRouter(missingLogger); err == nil {
		t.Fatal("NewRouter(nil logger) error = nil")
	}
}

func newTestRouter(
	database DatabasePinger,
	logEvent EventLogger,
) (http.Handler, error) {
	return NewRouter(RouterDependencies{
		Database:             database,
		RegisterPublicRoutes: discardRoutes,
		RegisterAdminRoutes:  discardRoutes,
		AdminSessions:        allowAdminAuthenticator{},
		LogEvent:             logEvent,
	})
}

func performRequest(
	t *testing.T,
	handler http.Handler,
	method string,
	path string,
) *httptest.ResponseRecorder {
	t.Helper()
	request := httptest.NewRequest(method, path, nil)
	response := httptest.NewRecorder()
	handler.ServeHTTP(response, request)
	return response
}

func assertJSON(
	t *testing.T,
	response *httptest.ResponseRecorder,
	want map[string]any,
) {
	t.Helper()
	var got map[string]any
	if err := json.Unmarshal(response.Body.Bytes(), &got); err != nil {
		t.Fatalf("decode JSON: %v", err)
	}
	if len(got) != len(want) {
		t.Fatalf("JSON = %#v, want %#v", got, want)
	}
	for key, wantValue := range want {
		if got[key] != wantValue {
			t.Fatalf("JSON[%q] = %#v, want %#v", key, got[key], wantValue)
		}
	}
}

func assertErrorCode(
	t *testing.T,
	response *httptest.ResponseRecorder,
	want string,
) {
	t.Helper()
	var body struct {
		Error struct {
			Code      string         `json:"code"`
			Retryable bool           `json:"retryable"`
			Details   map[string]any `json:"details"`
		} `json:"error"`
		RequestID string `json:"request_id"`
	}
	if err := json.Unmarshal(response.Body.Bytes(), &body); err != nil {
		t.Fatalf("decode error JSON: %v", err)
	}
	if body.Error.Code != want {
		t.Fatalf("error code = %q, want %q", body.Error.Code, want)
	}
	if body.Error.Retryable {
		t.Fatal("retryable = true")
	}
	if body.Error.Details == nil || len(body.Error.Details) != 0 {
		t.Fatalf("details = %#v", body.Error.Details)
	}
	if !requestIDPattern.MatchString(body.RequestID) {
		t.Fatalf("request_id = %q", body.RequestID)
	}
	if response.Header().Get(requestIDHeader) != body.RequestID {
		t.Fatalf("request ID header does not match body")
	}
}

type panicPinger struct{}

func (panicPinger) PingContext(context.Context) error {
	panic("private failure detail")
}

func discardEvent(string) {}

func discardRoutes(gin.IRoutes) error { return nil }

type allowAdminAuthenticator struct{}

func (allowAdminAuthenticator) AuthenticateAdmin(
	context.Context,
	string,
) (domain.AuthPrincipal, error) {
	return domain.AuthPrincipal{
		UserID:    "00000000-0000-4000-8000-000000000099",
		Username:  "admin",
		Role:      domain.UserRoleAdmin,
		SessionID: "admin-session",
		ExpiresAt: time.Now().Add(time.Hour),
	}, nil
}

var requestIDPattern = regexp.MustCompile(
	`^[0-9a-f]{8}-[0-9a-f]{4}-4[0-9a-f]{3}-[89ab][0-9a-f]{3}-[0-9a-f]{12}$`,
)