package user

import (
	"RenewCMS/api/pkg/apperr"
	"RenewCMS/api/pkg/response"
	domainUser "RenewCMS/internal/domain/user"
	"RenewCMS/internal/infrastructure/useCases"
	"errors"
	"net/http"
	"strconv"
	"strings"
)

type LookupHandler struct {
	LookupUseCase *useCases.LookupUserNamesUseCase
}

type userNameResponse struct {
	ID          uint32 `json:"id"`
	DisplayName string `json:"display_name"`
}

func NewLookupHandler(lookup *useCases.LookupUserNamesUseCase) *LookupHandler {
	return &LookupHandler{LookupUseCase: lookup}
}

func parseLookupIDs(raw string) ([]uint32, bool) {
	if raw == "" {
		return nil, false
	}
	if strings.Count(raw, ",")+1 > domainUser.MaxLookupIDs {
		return nil, false
	}
	parts := strings.Split(raw, ",")
	ids := make([]uint32, 0, len(parts))
	for _, part := range parts {
		id, err := strconv.ParseUint(part, 10, 32)
		if err != nil {
			return nil, false
		}
		ids = append(ids, uint32(id))
	}
	return ids, true
}

func (h *LookupHandler) Lookup(w http.ResponseWriter, r *http.Request) {
	ids, ok := parseLookupIDs(r.URL.Query().Get("ids"))
	if !ok {
		http.Error(w, apperr.BodyErrorMessage, http.StatusBadRequest)
		return
	}
	names, err := h.LookupUseCase.Lookup(ids)
	if errors.Is(err, domainUser.ErrInvalidLookup) {
		http.Error(w, apperr.BodyErrorMessage, http.StatusBadRequest)
		return
	}
	if err != nil {
		http.Error(w, "Internal server error", http.StatusInternalServerError)
		return
	}
	items := make([]userNameResponse, 0, len(names))
	for _, name := range names {
		items = append(items, userNameResponse{ID: name.ID, DisplayName: name.DisplayName})
	}
	response.WriteJSON(w, http.StatusOK, items)
}