import type { MongoClient } from 'mongodb'
import { connectToDatabase, fetchLatestPatch, getAvailablePlatforms } from '../utils/mongo'

interface StatsDocument {
  patch: string
  total: number
  platforms: Record<string, number>
  updatedAt: Date
}

async function fetchGameCount(client: MongoClient, patch: string) {
  const database = client.db('matches')
  const statsCollection = database.collection<StatsDocument>('stats')

  // Try to get stats from the pre-computed stats collection
  const stats = await statsCollection.findOne({ patch })

  if (stats) {
    return { total: stats.total, platforms: stats.platforms }
  }

  // Fallback: compute stats from collections if stats document doesn't exist
  // This handles the migration case where stats weren't pre-computed
  const platforms = await getAvailablePlatforms(client, patch)

  if (platforms.length > 0) {
    let totalCount = 0
    const platformCounts: Record<string, number> = {}

    for (const platform of platforms) {
      const collection = database.collection(`${patch}_${platform}`)
      const count = await collection.countDocuments()
      platformCounts[platform] = count
      totalCount += count
    }

    return { total: totalCount, platforms: platformCounts }
  }

  // Fall back to old format (single collection)
  const matches = database.collection(patch)
  const count = await matches.countDocuments()
  return { total: count, platforms: {} }
}

export default defineEventHandler(async _ => {
  const client = await connectToDatabase()
  const latestPatch = await fetchLatestPatch(client)
  const gameCountData = await fetchGameCount(client, latestPatch)

  await client.close()

  return {
    patch: latestPatch,
    count: gameCountData.total,
    platformCounts: gameCountData.platforms
  }
})