import { db, schema } from '../db/index.js'
import { eq, and, gte, lte, or, sql } from 'drizzle-orm'

// Season epoch: March 3, 2026 (a Monday)
const SEASON_EPOCH = new Date('2026-03-03T00:00:00Z').getTime()
const SEASON_DURATION_MS = 14 * 24 * 60 * 60 * 1000 // 2 weeks

const SEASON_NAMES = [
  'The Halvening',
  'Block 840000',
  'Segwit Wars',
  'Lightning Strike',
  'Satoshi Returns',
  'Genesis Block',
  'Pizza Day',
  'Difficulty Adjustment',
  'Mempool Madness',
  'Node Runners',
  'Proof of Work',
  'HODL Season',
  'Whitepaper Anniversary',
  'Timechain Tournament',
  'Cypherpunk Clash',
  'Hash Wars',
  'Block Size Battle',
  'Taproot Takeover',
  'Full Node Fury',
  'UTXO Showdown',
]

export interface Season {
  id: string
  number: number
  startDate: string
  endDate: string
  name: string
}

export function getCurrentSeason(): Season {
  const now = Date.now()
  const elapsed = now - SEASON_EPOCH
  const seasonNum = Math.floor(elapsed / SEASON_DURATION_MS) + 1
  const startMs = SEASON_EPOCH + (seasonNum - 1) * SEASON_DURATION_MS
  const endMs = startMs + SEASON_DURATION_MS

  return {
    id: `s${seasonNum}`,
    number: seasonNum,
    startDate: new Date(startMs).toISOString(),
    endDate: new Date(endMs).toISOString(),
    name: SEASON_NAMES[(seasonNum - 1) % SEASON_NAMES.length],
  }
}

export function getSeasonById(seasonId: string): Season | null {
  const match = seasonId.match(/^s(\d+)$/)
  if (!match) return null
  const seasonNum = parseInt(match[1])
  if (seasonNum < 1) return null

  const startMs = SEASON_EPOCH + (seasonNum - 1) * SEASON_DURATION_MS
  const endMs = startMs + SEASON_DURATION_MS

  return {
    id: `s${seasonNum}`,
    number: seasonNum,
    startDate: new Date(startMs).toISOString(),
    endDate: new Date(endMs).toISOString(),
    name: SEASON_NAMES[(seasonNum - 1) % SEASON_NAMES.length],
  }
}

interface SeasonLeaderboardEntry {
  botId: string
  botName: string
  archetype: string
  tier: number
  wins: number
  losses: number
  eloRating: number
}

export async function getSeasonLeaderboard(seasonId: string): Promise<SeasonLeaderboardEntry[]> {
  const season = getSeasonById(seasonId)
  if (!season) return []

  // Get all finished fights in this season
  const fights = await db.select({
    botAId: schema.fights.botAId,
    botBId: schema.fights.botBId,
    winnerId: schema.fights.winnerId,
  }).from(schema.fights)
    .where(and(
      eq(schema.fights.status, 'finished'),
      gte(schema.fights.createdAt, season.startDate),
      lte(schema.fights.createdAt, season.endDate),
    ))

  // Aggregate wins/losses per bot
  const stats = new Map<string, { wins: number; losses: number }>()
  for (const f of fights) {
    if (!stats.has(f.botAId)) stats.set(f.botAId, { wins: 0, losses: 0 })
    if (!stats.has(f.botBId)) stats.set(f.botBId, { wins: 0, losses: 0 })

    if (f.winnerId) {
      stats.get(f.winnerId)!.wins++
      const loserId = f.winnerId === f.botAId ? f.botBId : f.botAId
      stats.get(loserId)!.losses++
    }
  }

  if (stats.size === 0) return []

  // Fetch bot details
  const botIds = [...stats.keys()]
  const bots = await db.select({
    id: schema.bots.id,
    name: schema.bots.name,
    archetype: schema.bots.archetype,
    tier: schema.bots.tier,
    eloRating: schema.bots.eloRating,
    botType: schema.bots.botType,
  }).from(schema.bots)

  const botMap = new Map(bots.map(b => [b.id, b]))

  const entries: SeasonLeaderboardEntry[] = []
  for (const [botId, s] of stats) {
    const bot = botMap.get(botId)
    if (!bot || bot.botType === 'classic') continue
    entries.push({
      botId,
      botName: bot.name,
      archetype: bot.archetype,
      tier: bot.tier,
      wins: s.wins,
      losses: s.losses,
      eloRating: bot.eloRating,
    })
  }

  // Sort by wins desc, then win rate desc
  entries.sort((a, b) => {
    if (b.wins !== a.wins) return b.wins - a.wins
    const rateA = a.wins / (a.wins + a.losses || 1)
    const rateB = b.wins / (b.wins + b.losses || 1)
    return rateB - rateA
  })

  return entries
}

export async function resetSeasonElo(): Promise<void> {
  const allBots = await db.select({
    id: schema.bots.id,
    eloRating: schema.bots.eloRating,
  }).from(schema.bots)

  for (const bot of allBots) {
    const newElo = Math.round(bot.eloRating * 0.6 + 1200 * 0.4)
    await db.update(schema.bots).set({
      eloRating: newElo,
      winStreak: 0,
    }).where(eq(schema.bots.id, bot.id))
  }
}