package http

import (
	"net/http"

	roomv1 "hyapp/api/proto/room/v1"
	"hyapp/pkg/idgen"
	"hyapp/services/gateway-service/internal/auth"
	"hyapp/services/gateway-service/internal/client"
)

// Handler 是 gateway 的 HTTP transport adapter。
// 它只依赖跨服务 client，不持有房间状态，也不直接实现房间命令语义。
type Handler struct {
	roomClient         client.RoomClient
	userClient         client.UserAuthClient
	userIdentityClient client.UserIdentityClient
}

// NewHandler 装配 gateway HTTP handler 的内部依赖。
func NewHandler(roomClient client.RoomClient, userClient ...client.UserAuthClient) *Handler {
	handler := &Handler{roomClient: roomClient}
	if len(userClient) > 0 {
		handler.userClient = userClient[0]
	}

	return handler
}

// NewHandlerWithClients 装配完整 gateway HTTP handler。
// 保留 NewHandler 是为了不破坏只测 room/auth transport 的旧测试构造。
func NewHandlerWithClients(roomClient client.RoomClient, userClient client.UserAuthClient, userIdentityClient client.UserIdentityClient) *Handler {
	return &Handler{
		roomClient:         roomClient,
		userClient:         userClient,
		userIdentityClient: userIdentityClient,
	}
}

// meta 把外部 HTTP 请求上下文转换成 room-service 命令元信息。
// 当前 gateway 只生成命令入口所需的最小追踪字段，状态版本和幂等落点由 room-service 负责。
func meta(request *http.Request, roomID string) *roomv1.RequestMeta {
	return &roomv1.RequestMeta{
		RequestId:     requestIDFromContext(request.Context()),
		CommandId:     idgen.New("cmd"),
		ActorUserId:   auth.UserIDFromContext(request.Context()),
		RoomId:        roomID,
		GatewayNodeId: "gateway-local",
		SessionId:     idgen.New("sess"),
		SentAtMs:      0,
	}
}

// decode 统一处理 HTTP JSON 入参解析失败分支。
// gateway 在这里拒绝非法 JSON，不做房间业务校验，避免把 Room Cell 规则复制到入口层。
func decode(writer http.ResponseWriter, request *http.Request, out any) bool {
	if err := decodeJSON(request.Body, out); err != nil {
		writeError(writer, request, http.StatusBadRequest, codeInvalidJSON, "invalid request body")
		return false
	}

	return true
}

// write 统一把内部 gRPC 调用结果转换为 HTTP JSON 响应。
// 首版不在 gateway 细分 gRPC 错误码，避免入口层提前耦合 room-service 的业务错误模型。
func write(writer http.ResponseWriter, request *http.Request, body any, err error) {
	if err != nil {
		writeRPCError(writer, request, err)
		return
	}

	writeOK(writer, request, body)
}