import { getConfig } from "./config.js";
import { getDb } from "./db.js";

const DEFAULT_DAILY_COLLECTION_NAME = "daily_death_stats";
const SPECIES_KEYS = ["human", "orc", "skeleton", "slime", "wolf", "bear"];

let dailyIndexesReady;

export async function deathStatsRoutes(fastify) {
  fastify.get("/today", async () => {
    return getTodayDeathStats();
  });

  fastify.post("/today", async (request) => {
    const payload = parseJsonBody(request.body);
    const deathsBySpecies = normalizeDeathCounts(payload.deathsBySpecies);
    const totalDeaths = totalCount(deathsBySpecies);
    const now = new Date();
    const date = dayKey(now);
    const collection = await getDailyCollection();

    await ensureDailyDeathStatsIndex(collection);

    if (totalDeaths === 0) {
      const today = await collection.findOne({ _id: date });

      return {
        saved: false,
        today: formatDailyStats(today, date),
      };
    }

    await collection.updateOne(
      { _id: date },
      {
        $setOnInsert: {
          _id: date,
          date,
          createdAt: now,
        },
        $set: {
          updatedAt: now,
        },
        $inc: {
          battles: 1,
          totalDeaths,
          ...speciesIncrements(deathsBySpecies),
        },
      },
      { upsert: true },
    );

    const today = await collection.findOne({ _id: date });

    return {
      saved: true,
      today: formatDailyStats(today, date),
    };
  });
}

async function getTodayDeathStats() {
  const collection = await getDailyCollection();
  await ensureDailyDeathStatsIndex(collection);

  const date = dayKey(new Date());
  const today = await collection.findOne({ _id: date });

  return formatDailyStats(today, date);
}

async function getDailyCollection() {
  const db = await getDb();
  return db.collection(
    getConfig().MONGODB_DAILY_DEATH_COLLECTION || DEFAULT_DAILY_COLLECTION_NAME,
  );
}

async function ensureDailyDeathStatsIndex(collection) {
  if (!dailyIndexesReady) {
    dailyIndexesReady = collection.createIndex({ updatedAt: -1 });
  }

  return dailyIndexesReady;
}

function parseJsonBody(body) {
  if (!body) {
    return {};
  }

  if (typeof body === "object") {
    return body;
  }

  try {
    return JSON.parse(body);
  } catch {
    return {};
  }
}

function normalizeDeathCounts(value = {}) {
  return SPECIES_KEYS.reduce((counts, species) => {
    counts[species] = Math.max(0, Math.round(Number(value?.[species]) || 0));
    return counts;
  }, {});
}

function speciesIncrements(deathsBySpecies) {
  return SPECIES_KEYS.reduce((increments, species) => {
    increments[`deathsBySpecies.${species}`] = deathsBySpecies[species] ?? 0;
    return increments;
  }, {});
}

function formatDailyStats(document, date) {
  const deathsBySpecies = normalizeDeathCounts(document?.deathsBySpecies);

  return {
    date,
    battles: Math.max(0, Math.round(Number(document?.battles) || 0)),
    deathsBySpecies,
    totalDeaths: Math.max(
      totalCount(deathsBySpecies),
      Math.round(Number(document?.totalDeaths) || 0),
    ),
    updatedAt: document?.updatedAt?.toISOString?.() ?? null,
  };
}

function totalCount(deathsBySpecies) {
  return SPECIES_KEYS.reduce((sum, species) => sum + (deathsBySpecies[species] ?? 0), 0);
}

function dayKey(date) {
  const timeZone = getConfig().DEATH_STATS_TIME_ZONE || "Asia/Seoul";

  try {
    const parts = new Intl.DateTimeFormat("en-US", {
      day: "2-digit",
      month: "2-digit",
      timeZone,
      year: "numeric",
    })
      .formatToParts(date)
      .reduce((result, part) => {
        result[part.type] = part.value;
        return result;
      }, {});

    return `${parts.year}-${parts.month}-${parts.day}`;
  } catch {
    return date.toISOString().slice(0, 10);
  }
}