package com.recipeapp.pantry;

import com.recipeapp.common.ResourceNotFoundException;
import com.recipeapp.common.ValidationException;
import com.recipeapp.household.HouseholdRepository;
import com.recipeapp.household.entity.Household;
import com.recipeapp.pantry.dto.*;
import com.recipeapp.pantry.entity.PantryItem;
import com.recipeapp.recipe.IngredientRepository;
import com.recipeapp.recipe.dto.RecipeDetailResponse.CategoryRef;
import com.recipeapp.recipe.entity.Ingredient;
import org.springframework.stereotype.Service;
import org.springframework.transaction.annotation.Transactional;

import java.util.List;
import java.util.UUID;

@Service
@Transactional
public class PantryServiceImpl implements PantryService {

    private final PantryItemRepository pantryItemRepository;
    private final HouseholdRepository householdRepository;
    private final IngredientRepository ingredientRepository;

    public PantryServiceImpl(PantryItemRepository pantryItemRepository,
                             HouseholdRepository householdRepository,
                             IngredientRepository ingredientRepository) {
        this.pantryItemRepository = pantryItemRepository;
        this.householdRepository = householdRepository;
        this.ingredientRepository = ingredientRepository;
    }

    @Override
    @Transactional(readOnly = true)
    public List<PantryItemResponse> listItems(UUID householdId) {
        return pantryItemRepository.findByHouseholdIdOrderByBestBeforeAscNullsLast(householdId)
                .stream()
                .map(this::toResponse)
                .toList();
    }

    @Override
    public PantryItemResponse createItem(UUID householdId, CreatePantryItemRequest request) {
        Household household = householdRepository.findById(householdId)
                .orElseThrow(() -> new ResourceNotFoundException("Household not found"));

        Ingredient ingredient = null;
        if (request.ingredientId() != null) {
            ingredient = ingredientRepository.findById(request.ingredientId())
                    .orElseThrow(() -> new ResourceNotFoundException("Ingredient not found"));
        }

        if (request.ingredientId() == null && (request.customName() == null || request.customName().isBlank())) {
            throw new ValidationException("Either ingredientId or customName must be provided");
        }

        PantryItem item = new PantryItem(household, ingredient, request.customName(),
                request.quantity(), request.unit(), request.bestBefore(), request.openedOn());
        item = pantryItemRepository.save(item);
        return toResponse(item);
    }

    @Override
    public PantryItemResponse updateItem(UUID householdId, UUID itemId, UpdatePantryItemRequest request) {
        PantryItem item = pantryItemRepository.findByIdAndHouseholdId(itemId, householdId)
                .orElseThrow(() -> new ResourceNotFoundException("Pantry item not found"));

        if (request.quantity() != null) item.setQuantity(request.quantity());
        if (request.unit() != null) item.setUnit(request.unit());
        if (request.bestBefore() != null) item.setBestBefore(request.bestBefore());
        if (request.openedOn() != null) item.setOpenedOn(request.openedOn());

        item = pantryItemRepository.save(item);
        return toResponse(item);
    }

    @Override
    public void deleteItem(UUID householdId, UUID itemId) {
        PantryItem item = pantryItemRepository.findByIdAndHouseholdId(itemId, householdId)
                .orElseThrow(() -> new ResourceNotFoundException("Pantry item not found"));
        pantryItemRepository.delete(item);
    }

    private PantryItemResponse toResponse(PantryItem item) {
        UUID ingredientId = item.getIngredient() != null ? item.getIngredient().getId() : null;
        String name = item.getIngredient() != null ? item.getIngredient().getName() : item.getCustomName();
        CategoryRef category = null;
        if (item.getIngredient() != null && item.getIngredient().getCategory() != null) {
            category = new CategoryRef(
                    item.getIngredient().getCategory().getId(),
                    item.getIngredient().getCategory().getName());
        }
        return new PantryItemResponse(
                item.getId(), ingredientId, name, category,
                item.getQuantity(), item.getUnit(), item.getBestBefore(), item.getOpenedOn());
    }
}