const http = require("http");
const fs = require("fs");
const path = require("path");

const PORT = process.env.PORT || 3000;
const DATA = path.join(__dirname, "data.json");

function readData() {
  try { return JSON.parse(fs.readFileSync(DATA, "utf8")); } catch (_) { return { meals: [], products: [], weekly_plan: [], shopping_list: [], timeline: [] }; }
}
function writeData(data) {
  fs.writeFileSync(DATA, JSON.stringify(data, null, 2));
}
function body(req) {
  return new Promise((resolve) => {
    let s = "";
    req.on("data", (c) => (s += c));
    req.on("end", () => { try { resolve(JSON.parse(s || "{}")); } catch (_) { resolve({}); } });
  });
}

function generateWeeklyPlan() {
  const data = readData();
  const days = ["Понедельник", "Вторник", "Среда", "Четверг", "Пятница", "Суббота", "Воскресенье"];
  const breakfasts = data.meals.filter(m => m.type === "завтрак");
  const lunches = data.meals.filter(m => m.type === "обед");
  const dinners = data.meals.filter(m => m.type === "ужин");
  
  const plan = [];
  let totalCalories = 0, totalProtein = 0, totalFat = 0, totalCarbs = 0, totalCost = 0;
  
  days.forEach((day, i) => {
    const b = breakfasts[i % breakfasts.length];
    const l = lunches[i % lunches.length];
    const d = dinners[i % dinners.length];
    const dayCalories = b.calories + l.calories + d.calories;
    const dayProtein = b.protein + l.protein + d.protein;
    const dayFat = b.fat + l.fat + d.fat;
    const dayCarbs = b.carbs + l.carbs + d.carbs;
    
    const dayCost = calculateDayCost([b, l, d], data.products);
    
    plan.push({
      day,
      date: new Date(Date.now() + i * 86400000).toISOString().slice(0, 10),
      breakfast: { id: b.id, name: b.name, calories: b.calories, protein: b.protein, fat: b.fat, carbs: b.carbs, time_min: b.time_min },
      lunch: { id: l.id, name: l.name, calories: l.calories, protein: l.protein, fat: l.fat, carbs: l.carbs, time_min: l.time_min },
      dinner: { id: d.id, name: d.name, calories: d.calories, protein: d.protein, fat: d.fat, carbs: d.carbs, time_min: d.time_min },
      daily_total: { calories: dayCalories, protein: dayProtein, fat: dayFat, carbs: dayCarbs, cost: dayCost }
    });
    
    totalCalories += dayCalories;
    totalProtein += dayProtein;
    totalFat += dayFat;
    totalCarbs += dayCarbs;
    totalCost += dayCost;
  });
  
  const weekly_totals = {
    calories: Math.round(totalCalories),
    protein: Math.round(totalProtein),
    fat: Math.round(totalFat),
    carbs: Math.round(totalCarbs),
    cost: Math.round(totalCost),
    avg_daily_calories: Math.round(totalCalories / 7)
  };
  
  return { plan, weekly_totals };
}

function calculateDayCost(meals, products) {
  const productMap = {};
  products.forEach(p => { productMap[p.id] = { ...p }; });
  
  meals.forEach(m => {
    m.ingredients.forEach(ing => {
      if (!productMap[ing.product_id]) return;
      const existing = productMap[ing.product_id];
      const amountKg = ing.amount / 1000;
      if (!existing.total_amount) existing.total_amount = 0;
      existing.total_amount += amountKg;
    });
  });
  
  let total = 0;
  Object.values(productMap).forEach(p => {
    if (p.total_amount) {
      total += p.total_amount * p.price_per_kg;
    }
  });
  return total;
}

function generateShoppingList(weeklyPlan) {
  const data = readData();
  const productMap = {};
  data.products.forEach(p => { productMap[p.id] = { ...p, total_amount: 0, total_cost: 0 }; });
  
  weeklyPlan.forEach(day => {
    [day.breakfast, day.lunch, day.dinner].forEach(meal => {
      const mealData = data.meals.find(m => m.id === meal.id);
      if (!mealData) return;
      mealData.ingredients.forEach(ing => {
        if (productMap[ing.product_id]) {
          productMap[ing.product_id].total_amount += ing.amount;
        }
      });
    });
  });
  
  const shoppingList = [];
  let totalCost = 0;
  
  Object.values(productMap).forEach(p => {
    if (p.total_amount > 0) {
      const cost = (p.total_amount / 1000) * p.price_per_kg;
      shoppingList.push({
        id: p.id,
        name: p.name,
        category: p.category,
        amount: Math.round(p.total_amount),
        unit: p.total_amount >= 1000 ? "кг" : "г",
        price_per_kg: p.price_per_kg,
        cost: Math.round(cost)
      });
      totalCost += cost;
    }
  });
  
  shoppingList.sort((a, b) => a.category.localeCompare(b.category) || a.name.localeCompare(b.name));
  
  return { items: shoppingList, total_cost: Math.round(totalCost), budget: 100000, remaining: 100000 - Math.round(totalCost) };
}

function generateTimeline(weeklyPlan) {
  const data = readData();
  const timeline = [];
  
  weeklyPlan.forEach((day, dayIndex) => {
    const prepTime = [];
    [day.breakfast, day.lunch, day.dinner].forEach((meal, mealIdx) => {
      const mealData = data.meals.find(m => m.id === meal.id);
      if (!mealData) return;
      
      const mealTypes = ["завтрак", "обед", "ужин"];
      prepTime.push({
        day: day.day,
        date: day.date,
        meal_type: mealTypes[mealIdx],
        dish: mealData.name,
        prep_time_min: mealData.time_min,
        ingredients: mealData.ingredients.map(i => i.name)
      });
    });
    
    if (dayIndex === 0) {
      timeline.push({
        day: "Воскресенье (перед неделей)",
        date: new Date(Date.now() - 86400000).toISOString().slice(0, 10),
        action: "Закупка продуктов",
        details: "Купить все продукты по списку на неделю",
        time_min: 90
      });
    }
    
    prepTime.forEach(p => timeline.push({
      day: p.day,
      date: p.date,
      action: `Приготовление: ${p.meal_type}`,
      details: p.dish,
      time_min: p.prep_time_min,
      ingredients: p.ingredients
    }));
  });
  
  return timeline;
}

http.createServer(async (req, res) => {
  res.setHeader("Access-Control-Allow-Origin", "*");
  res.setHeader("Access-Control-Allow-Methods", "GET, POST, OPTIONS");
  res.setHeader("Access-Control-Allow-Headers", "Content-Type");
  
  if (req.method === "OPTIONS") {
    res.writeHead(200);
    return res.end();
  }
  
  if (req.method === "GET" && req.url === "/api/meals") {
    const data = readData();
    res.writeHead(200, { "Content-Type": "application/json" });
    return res.end(JSON.stringify(data.meals));
  }
  
  if (req.method === "GET" && req.url === "/api/products") {
    const data = readData();
    res.writeHead(200, { "Content-Type": "application/json" });
    return res.end(JSON.stringify(data.products));
  }
  
  if (req.method === "GET" && req.url.startsWith("/api/meal/")) {
    const id = req.url.split("/")[3];
    const data = readData();
    const meal = data.meals.find(m => m.id === id);
    res.writeHead(200, { "Content-Type": "application/json" });
    return res.end(JSON.stringify(meal || {}));
  }
  
  if (req.method === "POST" && req.url === "/api/generate-plan") {
    const result = generateWeeklyPlan();
    const data = readData();
    data.weekly_plan = result.plan;
    writeData(data);
    res.writeHead(200, { "Content-Type": "application/json" });
    return res.end(JSON.stringify(result));
  }
  
  if (req.method === "GET" && req.url === "/api/plan") {
    const data = readData();
    res.writeHead(200, { "Content-Type": "application/json" });
    return res.end(JSON.stringify(data.weekly_plan || []));
  }
  
  if (req.method === "POST" && req.url === "/api/shopping-list") {
    const bodyData = await body(req);
    const shoppingList = generateShoppingList(bodyData.plan || []);
    const data = readData();
    data.shopping_list = shoppingList;
    writeData(data);
    res.writeHead(200, { "Content-Type": "application/json" });
    return res.end(JSON.stringify(shoppingList));
  }
  
  if (req.method === "GET" && req.url === "/api/shopping-list") {
    const data = readData();
    res.writeHead(200, { "Content-Type": "application/json" });
    return res.end(JSON.stringify(data.shopping_list || { items: [], total_cost: 0 }));
  }
  
  if (req.method === "POST" && req.url === "/api/timeline") {
    const bodyData = await body(req);
    const timeline = generateTimeline(bodyData.plan || []);
    const data = readData();
    data.timeline = timeline;
    writeData(data);
    res.writeHead(200, { "Content-Type": "application/json" });
    return res.end(JSON.stringify(timeline));
  }
  
  if (req.method === "GET" && req.url === "/api/timeline") {
    const data = readData();
    res.writeHead(200, { "Content-Type": "application/json" });
    return res.end(JSON.stringify(data.timeline || []));
  }
  
  let file = req.url === "/" ? "/index.html" : req.url.split("?")[0];
  const full = path.join(__dirname, file);
  if (full.startsWith(__dirname) && fs.existsSync(full) && fs.statSync(full).isFile()) {
    const ext = path.extname(full);
    const type = ext === ".css" ? "text/css" : ext === ".js" ? "application/javascript" : "text/html";
    res.writeHead(200, { "Content-Type": type + "; charset=utf-8" });
    return res.end(fs.readFileSync(full));
  }
  
  res.writeHead(404);
  res.end("Not found");
}).listen(PORT, () => console.log("Сервер запущен на порту " + PORT));