.then(([winnerStats, loserStats]) => {
// If player isn't on the leaderboard yet, then ELO defaults to 1000.
winnerStats = winnerStats || { wins: 0, losses: 0, elo: 1000, streak: 0 }
loserStats = loserStats || { wins: 0, losses: 0, elo: 1000, streak: 0 }
winner.beforeStats = winnerStats
winner.other.beforeStats = loserStats
const winnerElo = elo.ifWins(winnerStats.elo, loserStats.elo)
const loserElo = elo.ifLoses(loserStats.elo, winnerStats.elo)
const winnerStreak = winnerStats.streak <= 0 ? 1 : winnerStats.streak + 1
const loserStreak = loserStats.streak >= 0 ? -1 : loserStats.streak - 1
return db.batch([
db.saveMatch(match.id, winner, winner.other),
db.updateLeaderboard(winner, winnerStats.wins + 1, winnerStats.losses, winnerElo, winnerStreak),
db.updateLeaderboard(winner.other, loserStats.wins, loserStats.losses + 1, loserElo, loserStreak)
])
})
history.forEach(match => {
const winnerId = match.winner_id
const loserId = match.loser_id
const winner = leaderboard[winnerId] = leaderboard[winnerId] || Object.assign({}, entry, { player_id: winnerId })
const loser = leaderboard[loserId] = leaderboard[loserId] || Object.assign({}, entry, { player_id: loserId })
const winnerElo = winner.elo
const loserElo = loser.elo
winner.elo = elo.ifWins(winnerElo, loserElo)
loser.elo = elo.ifLoses(loserElo, winnerElo)
winner.wins += 1
loser.losses += 1
winner.streak = winner.streak <= 0 ? 1 : winner.streak + 1
loser.streak = loser.streak >= 0 ? -1 : loser.streak - 1
})