package com.chowbox.service;

import com.baomidou.mybatisplus.core.conditions.query.QueryWrapper;
import com.chowbox.mapper.RecipeIngredientMapper;
import com.chowbox.mapper.RecipeMapper;
import com.chowbox.mapper.RecipeStepMapper;
import com.chowbox.model.FridgeMatchResult;
import com.chowbox.model.Recipe;
import com.chowbox.model.RecipeIngredient;
import com.chowbox.model.RecipeStep;
import lombok.extern.slf4j.Slf4j;
import org.springframework.beans.factory.annotation.Autowired;
import org.springframework.stereotype.Service;

import java.time.LocalDate;
import java.time.LocalTime;
import java.util.*;
import java.util.stream.Collectors;

@Slf4j
@Service
public class FridgeService {

    @Autowired
    private RecipeMapper recipeMapper;

    @Autowired
    private RecipeIngredientMapper ingredientMapper;

    @Autowired
    private RecipeStepMapper stepMapper;

    private static final Set<String> DEFAULT_STAPLES = new HashSet<>(Arrays.asList(
            "油", "盐", "酱油", "生抽", "老抽", "醋", "料酒", "蚝油",
            "糖", "白糖", "淀粉", "香油", "姜", "蒜", "葱", "干辣椒", "花椒"
    ));

    private static final Random RANDOM = new Random();

    public List<FridgeMatchResult> matchRecipes(List<String> userIngredients, List<String> customStaples) {
        Set<String> userSet = new HashSet<>();
        for (String ing : userIngredients) {
            userSet.add(ing.trim());
        }

        // 合并系统默认 + 用户自定义常备调料
        Set<String> allStaples = new HashSet<>(DEFAULT_STAPLES);
        if (customStaples != null) {
            for (String s : customStaples) {
                allStaples.add(s.trim());
            }
        }
        userSet.addAll(allStaples);

        List<Recipe> allRecipes = recipeMapper.selectList(null);
        log.info("FridgeService: total recipes in DB = {}", allRecipes.size());
        List<FridgeMatchResult> results = new ArrayList<>();

        int currentHour = LocalTime.now().getHour();
        int currentMonth = LocalDate.now().getMonthValue();
        String mealTime = getMealTime(currentHour);
        String season = getSeason(currentMonth);
        log.info("FridgeService: current mealTime={}, season={}", mealTime, season);

        for (Recipe recipe : allRecipes) {
            List<RecipeIngredient> recipeIngredients = ingredientMapper.selectList(
                    new QueryWrapper<RecipeIngredient>().eq("recipe_id", recipe.getId())
            );

            List<String> recipeIngNames = recipeIngredients.stream()
                    .map(ri -> ri.getIngredientName().trim())
                    .collect(Collectors.toList());

            // 计算交集
            long matchCount = recipeIngNames.stream()
                    .filter(userSet::contains)
                    .count();

            double matchRate = recipeIngNames.isEmpty() ? 0 :
                    (double) matchCount / recipeIngNames.size() * 100;

            // 找出缺失的食材（非调料类）
            List<String> missing = recipeIngNames.stream()
                    .filter(name -> !userSet.contains(name) && !allStaples.contains(name))
                    .collect(Collectors.toList());

            // 时段/季节加权：匹配当前时段或季节 +8%
            double timeBoost = 0;
            if (mealTime.equals(recipe.getMealTime())) timeBoost += 8;
            if (season.equals(recipe.getSeason())) timeBoost += 8;

            FridgeMatchResult result = new FridgeMatchResult();
            result.setRecipe(recipe);
            result.setMatchRate(Math.round(matchRate + timeBoost));
            result.setMissingIngredients(missing);
            results.add(result);
        }

        // 按匹配度降序排列，取 Top10 候选池，加权随机选 3-5 个
        List<FridgeMatchResult> pool = results.stream()
                .sorted((a, b) -> Double.compare(b.getMatchRate(), a.getMatchRate()))
                .limit(10)
                .collect(Collectors.toList());

        return weightedRandomPick(pool);
    }

    /**
     * 从候选池加权随机选 3-5 个。
     * 权重 = matchRate²，保证高分菜更有机会但不乏惊喜。
     */
    private List<FridgeMatchResult> weightedRandomPick(List<FridgeMatchResult> pool) {
        if (pool.size() <= 3) return pool;

        int pickCount = 3 + RANDOM.nextInt(Math.min(3, pool.size() - 2)); // 3-5

        List<FridgeMatchResult> shuffled = new ArrayList<>(pool);
        Collections.shuffle(shuffled, RANDOM);

        // 加权随机
        List<FridgeMatchResult> picked = new ArrayList<>();
        List<FridgeMatchResult> remaining = new ArrayList<>(shuffled);

        for (int i = 0; i < pickCount && !remaining.isEmpty(); i++) {
            double totalWeight = remaining.stream()
                    .mapToDouble(r -> Math.pow(r.getMatchRate(), 2))
                    .sum();

            if (totalWeight <= 0) {
                int idx = RANDOM.nextInt(remaining.size());
                picked.add(remaining.remove(idx));
                continue;
            }

            double dart = RANDOM.nextDouble() * totalWeight;
            double cumulative = 0;
            int selectedIdx = 0;
            for (int j = 0; j < remaining.size(); j++) {
                cumulative += Math.pow(remaining.get(j).getMatchRate(), 2);
                if (dart <= cumulative) {
                    selectedIdx = j;
                    break;
                }
            }
            picked.add(remaining.remove(selectedIdx));
        }

        // 匹配度高的排前面
        picked.sort((a, b) -> Double.compare(b.getMatchRate(), a.getMatchRate()));
        return picked;
    }

    private String getMealTime(int hour) {
        if (hour >= 5 && hour < 10) return "早餐";
        if (hour >= 10 && hour < 14) return "午餐";
        if (hour >= 14 && hour < 17) return "下午茶";
        if (hour >= 17 && hour < 21) return "晚餐";
        return "夜宵";
    }

    private String getSeason(int month) {
        if (month >= 3 && month <= 5) return "春季";
        if (month >= 6 && month <= 8) return "夏季";
        if (month >= 9 && month <= 11) return "秋季";
        return "冬季";
    }

    public Recipe getRecipeDetail(Long recipeId) {
        Recipe recipe = recipeMapper.selectById(recipeId);
        if (recipe == null) return null;

        List<RecipeIngredient> ingredients = ingredientMapper.selectList(
                new QueryWrapper<RecipeIngredient>().eq("recipe_id", recipeId)
        );
        List<RecipeStep> steps = stepMapper.selectList(
                new QueryWrapper<RecipeStep>().eq("recipe_id", recipeId).orderByAsc("step_order")
        );

        recipe.setIngredients(ingredients);
        recipe.setSteps(steps);
        return recipe;
    }
}