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
}

/**
 * Get the latest patch from existing match collections in the database.
 * Collections are named like "15.1_EUW1", "15.2_NA1", etc.
 */
async function fetchLatestPatch(client: MongoClient): Promise<string> {
  const matchesDb = client.db('matches')
  const collections = await matchesDb.listCollections().toArray()
  const collectionNames = collections.map(c => c.name)

  // Extract unique patch versions from collection names
  const patches = new Set<string>()
  for (const name of collectionNames) {
    // Collection names are either "patch_platform" or just "patch"
    const patch = name.split('_')[0]
    if (patch && /^\d+\.\d+$/.test(patch)) {
      patches.add(patch)
    }
  }

  if (patches.size === 0) {
    throw new Error('No patch collections found in database')
  }

  // Sort patches and return the latest (highest version number)
  const sortedPatches = Array.from(patches).sort((a, b) => {
    const [aMajor, aMinor] = a.split('.').map(Number)
    const [bMajor, bMinor] = b.split('.').map(Number)
    if (aMajor !== bMajor) return bMajor - aMajor
    return bMinor - aMinor
  })

  return sortedPatches[0]
}

/**
 * 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 }