import { NextRequest, NextResponse } from "next/server";
import { db, cookingHistory, recipes, userNutritionGoals, eq, and, gte, lt } from "@epicure/db";
import { requireSession } from "@/lib/api-auth";

function isValidDate(value: string): boolean {
  return /^\d{4}-\d{2}-\d{2}$/.test(value) && !isNaN(new Date(`${value}T00:00:00.000Z`).getTime());
}

const VALID_RANGES = [7, 30, 90];

export async function GET(req: NextRequest) {
  const { session, response } = await requireSession();
  if (response) return response;
  const userId = session!.user.id;

  const rangeParam = req.nextUrl.searchParams.get("range");
  const range = rangeParam ? parseInt(rangeParam, 10) : null;
  if (range && VALID_RANGES.includes(range)) {
    return getTrend(userId, range);
  }

  const dateParam = req.nextUrl.searchParams.get("date");
  const date = dateParam && isValidDate(dateParam) ? dateParam : new Date().toISOString().slice(0, 10);

  const dayStart = new Date(`${date}T00:00:00.000Z`);
  const dayEnd = new Date(dayStart.getTime() + 24 * 60 * 60 * 1000);

  const rows = await db
    .select({
      id: cookingHistory.id,
      recipeId: cookingHistory.recipeId,
      servings: cookingHistory.servings,
      cookedAt: cookingHistory.cookedAt,
      recipeTitle: recipes.title,
      baseServings: recipes.baseServings,
      nutritionData: recipes.nutritionData,
    })
    .from(cookingHistory)
    .leftJoin(recipes, eq(cookingHistory.recipeId, recipes.id))
    .where(
      and(
        eq(cookingHistory.userId, userId),
        gte(cookingHistory.cookedAt, dayStart),
        lt(cookingHistory.cookedAt, dayEnd)
      )
    )
    .orderBy(cookingHistory.cookedAt);

  const totals = { calories: 0, proteinG: 0, carbsG: 0, fatG: 0, fiberG: 0, sodiumMg: 0 };
  const entries: {
    id: string;
    recipeId: string;
    title: string;
    servings: number;
    cookedAt: string;
    nutritionKnown: boolean;
  }[] = [];
  let unknownCount = 0;

  for (const row of rows) {
    const servings = row.servings ?? row.baseServings ?? 1;
    const perServing = row.nutritionData?.perServing;
    const nutritionKnown = !!perServing;

    if (perServing) {
      totals.calories += perServing.calories * servings;
      totals.proteinG += perServing.proteinG * servings;
      totals.carbsG += perServing.carbsG * servings;
      totals.fatG += perServing.fatG * servings;
      totals.fiberG += perServing.fiberG * servings;
      totals.sodiumMg += perServing.sodiumMg * servings;
    } else {
      unknownCount += 1;
    }

    entries.push({
      id: row.id,
      recipeId: row.recipeId,
      title: row.recipeTitle ?? "Unknown recipe",
      servings,
      cookedAt: row.cookedAt.toISOString(),
      nutritionKnown,
    });
  }

  for (const key of Object.keys(totals) as (keyof typeof totals)[]) {
    totals[key] = Math.round(totals[key]);
  }

  const goalsRow = await db.query.userNutritionGoals.findFirst({
    where: eq(userNutritionGoals.userId, userId),
  });

  const goals = goalsRow
    ? {
        caloriesKcal: goalsRow.caloriesKcal,
        proteinG: goalsRow.proteinG,
        carbsG: goalsRow.carbsG,
        fatG: goalsRow.fatG,
      }
    : null;

  const coverage = {
    calories: goals?.caloriesKcal ? Math.round((totals.calories / goals.caloriesKcal) * 100) : 0,
    protein: goals?.proteinG ? Math.round((totals.proteinG / goals.proteinG) * 100) : 0,
    carbs: goals?.carbsG ? Math.round((totals.carbsG / goals.carbsG) * 100) : 0,
    fat: goals?.fatG ? Math.round((totals.fatG / goals.fatG) * 100) : 0,
  };

  return NextResponse.json({ date, totals, goals, coverage, entries, unknownCount });
}

/** Multi-day trend: daily calorie/macro totals over the last N days, one
 * bucket per calendar day (UTC, matching the single-day endpoint's own
 * dayStart/dayEnd math above) — days with nothing cooked still appear with
 * zero totals so the chart has a continuous x-axis. */
async function getTrend(userId: string, days: number): Promise<NextResponse> {
  const todayStr = new Date().toISOString().slice(0, 10);
  const since = new Date(`${todayStr}T00:00:00.000Z`);
  since.setUTCDate(since.getUTCDate() - (days - 1));

  const rows = await db
    .select({
      servings: cookingHistory.servings,
      cookedAt: cookingHistory.cookedAt,
      baseServings: recipes.baseServings,
      nutritionData: recipes.nutritionData,
    })
    .from(cookingHistory)
    .leftJoin(recipes, eq(cookingHistory.recipeId, recipes.id))
    .where(and(eq(cookingHistory.userId, userId), gte(cookingHistory.cookedAt, since)));

  const buckets = new Map<string, { calories: number; proteinG: number; carbsG: number; fatG: number }>();
  for (let i = 0; i < days; i++) {
    const d = new Date(since);
    d.setUTCDate(d.getUTCDate() + i);
    buckets.set(d.toISOString().slice(0, 10), { calories: 0, proteinG: 0, carbsG: 0, fatG: 0 });
  }

  for (const row of rows) {
    const perServing = row.nutritionData?.perServing;
    if (!perServing) continue;
    const servings = row.servings ?? row.baseServings ?? 1;
    const key = row.cookedAt.toISOString().slice(0, 10);
    const bucket = buckets.get(key);
    if (!bucket) continue;
    bucket.calories += perServing.calories * servings;
    bucket.proteinG += perServing.proteinG * servings;
    bucket.carbsG += perServing.carbsG * servings;
    bucket.fatG += perServing.fatG * servings;
  }

  const goalsRow = await db.query.userNutritionGoals.findFirst({ where: eq(userNutritionGoals.userId, userId) });

  const daysOut = [...buckets.entries()].map(([date, totals]) => ({
    date,
    calories: Math.round(totals.calories),
    proteinG: Math.round(totals.proteinG),
    carbsG: Math.round(totals.carbsG),
    fatG: Math.round(totals.fatG),
  }));

  return NextResponse.json({ range: days, days: daysOut, goalCalories: goalsRow?.caloriesKcal ?? null });
}