import { MongoClient } from 'mongodb'

// Available platforms for region-specific match data
const PLATFORMS = ['EUW1', 'EUN1', 'NA1', 'KR'] as const
type Platform = (typeof PLATFORMS)[number]

async function connectToDatabase() {
  // Create a MongoClient with a MongoClientOptions object to set the Stable API version
  let uri = `mongodb://${process.env.MONGO_USER}:${process.env.MONGO_PASS}@${process.env.MONGO_HOST}`
  if (
    process.env.MONGO_URI != undefined &&
    process.env.MONGO_URI != null &&
    process.env.MONGO_URI != ''
  ) {
    uri = process.env.MONGO_URI
  }
  const client = new MongoClient(uri)
  await client.connect()
  return client
}

async function fetchLatestPatch(client: MongoClient) {
  const database = client.db('patches')
  const patches = database.collection('patches')
  const latestPatch = await patches.find().limit(1).sort({ date: -1 }).next()
  return latestPatch!.patch as string
}

/**
 * Get available platforms for a given patch by checking which match collections exist
 * Note: Match collections are platform-specific (e.g., "15.1_EUW1")
 * Champion collections are aggregated across all platforms (e.g., "15.1")
 */
async function getAvailablePlatforms(client: MongoClient, patch: string): Promise<Platform[]> {
  const matchesDb = client.db('matches')
  const collections = await matchesDb.listCollections().toArray()
  const collectionNames = collections.map(c => c.name)

  const availablePlatforms: Platform[] = []
  for (const platform of PLATFORMS) {
    if (collectionNames.includes(`${patch}_${platform}`)) {
      availablePlatforms.push(platform)
    }
  }

  return availablePlatforms
}

export { connectToDatabase, fetchLatestPatch, getAvailablePlatforms, PLATFORMS }
export type { Platform }