import {
  existsSync,
  mkdirSync,
  readFileSync,
  unlinkSync,
  writeFileSync
} from 'node:fs'
import { join } from 'node:path'
import { randomBytes, timingSafeEqual } from 'node:crypto'
import { app } from 'electron'
import type { GameProvider, ProviderEventHandler } from './provider'
import { findGameInstall } from './steam'
import { registerGsiRoute, getGsiBaseUrl, getGsiPort } from './gsi-server'
import {
  ensureLaunchOption,
  ensureLaunchOptionRemoved,
  isLaunchOptionPresent,
  isSteamRunning
} from './steam-launch-options'
import type { GameId, GameStatus, LaunchOptionStatus } from '@shared/types'
import { log } from '../logger'

const APP_ID = '570'
const INSTALL_DIR = 'dota 2 beta'
const CFG_NAME = 'gamestate_integration_exercise_reminder.cfg'
const ROUTE = '/dota2'
const LAUNCH_OPTION = '-gamestateintegration'

type DotaGsi = {
  provider?: { name?: string }
  auth?: { token?: string }
  map?: {
    game_state?: string
    win_team?: 'radiant' | 'dire' | 'none'
    game_time?: number
    clock_time?: number
  }
  player?: {
    kills?: number
    deaths?: number
    assists?: number
    last_hits?: number
    denies?: number
    team_name?: 'radiant' | 'dire'
    steamid?: string
  }
}

/**
 * Constant-time string equality. Avoids early-exit timing oracles that could
 * leak the token byte-by-byte to a local attacker who can measure response
 * latency on the loopback HTTP server. (Practical risk is tiny; correctness
 * matters anyway.)
 */
function safeEqualStrings(a: string, b: string): boolean {
  const A = Buffer.from(a, 'utf-8')
  const B = Buffer.from(b, 'utf-8')
  if (A.length !== B.length) return false
  return timingSafeEqual(A, B)
}

function tokenStorePath(): string {
  return join(app.getPath('userData'), 'dota2-gsi-token.txt')
}

function getOrCreateToken(): string {
  const p = tokenStorePath()
  if (existsSync(p)) {
    const v = readFileSync(p, 'utf-8').trim()
    if (v) return v
  }
  const token = randomBytes(16).toString('hex')
  writeFileSync(p, token, 'utf-8')
  return token
}

function cfgDir(installPath: string): string {
  return join(installPath, 'game', 'dota', 'cfg', 'gamestate_integration')
}

function cfgPath(installPath: string): string {
  return join(cfgDir(installPath), CFG_NAME)
}

function buildCfg(token: string): string {
  const uri = `${getGsiBaseUrl()}${ROUTE}`
  return `"Exercise Reminder Integration"
{
    "uri"           "${uri}"
    "timeout"       "5.0"
    "buffer"        "0.1"
    "throttle"      "0.5"
    "heartbeat"     "10.0"
    "auth"
    {
        "token"     "${token}"
    }
    "data"
    {
        "provider"          "1"
        "map"               "1"
        "player"            "1"
        "hero"              "1"
        "abilities"         "0"
        "items"             "0"
        "events"            "0"
        "buildings"         "0"
        "league"            "0"
        "draft"             "0"
        "wearables"         "0"
    }
}
`
}

export class Dota2Provider implements GameProvider {
  readonly id: GameId = 'dota2'
  readonly displayName = 'Dota 2'

  private installPath: string | undefined
  private unregister: (() => void) | undefined
  private emit: ProviderEventHandler | undefined
  private prevState: string | undefined
  private latest: DotaGsi | undefined
  private lastMatchEndAt = 0
  private token: string = getOrCreateToken()

  async detect(): Promise<GameStatus> {
    const path = await findGameInstall(APP_ID, INSTALL_DIR)
    this.installPath = path
    const integrationActive = !!path && existsSync(cfgPath(path))
    let launchOptionStatus: LaunchOptionStatus = 'not_needed'
    let steamRunning: boolean | undefined
    if (integrationActive) {
      const present = await isLaunchOptionPresent(APP_ID, LAUNCH_OPTION)
      if (present) launchOptionStatus = 'applied'
      else {
        steamRunning = await isSteamRunning()
        // Either Steam is open (we can't write while it runs -> 'queued') or
        // closed (apply on next ensureLaunchOption call -> still queued until
        // the watcher tick actually writes). 'queued' is correct for both.
        launchOptionStatus = 'queued'
      }
    }
    return {
      id: this.id,
      name: this.displayName,
      installed: !!path,
      installPath: path,
      integrationActive,
      launchOption: LAUNCH_OPTION,
      launchOptionStatus,
      steamRunning,
      enabled: false
    }
  }

  async install(): Promise<void> {
    if (!this.installPath) {
      const status = await this.detect()
      if (!status.installPath)
        throw new Error('Dota 2 не найдена в Steam-библиотеках')
    }
    const dir = cfgDir(this.installPath!)
    if (!existsSync(dir)) mkdirSync(dir, { recursive: true })
    writeFileSync(cfgPath(this.installPath!), buildCfg(this.token), 'utf-8')
    await ensureLaunchOption(APP_ID, LAUNCH_OPTION)
  }

  async uninstall(): Promise<void> {
    await ensureLaunchOptionRemoved(APP_ID, LAUNCH_OPTION)
    if (!this.installPath) return
    const p = cfgPath(this.installPath)
    if (existsSync(p)) unlinkSync(p)
  }

  async reconcile(): Promise<void> {
    if (!this.installPath) await this.detect()
    if (!this.installPath || !existsSync(cfgPath(this.installPath))) return
    await ensureLaunchOption(APP_ID, LAUNCH_OPTION)
  }

  async start(emit: ProviderEventHandler): Promise<void> {
    this.emit = emit
    // Defensive double-register guard: free any previous registration first.
    this.unregister?.()
    this.unregister = registerGsiRoute(ROUTE, (payload) => {
      // Runtime shape check — payload comes from a network socket.
      if (typeof payload !== 'object' || payload === null) return
      this.handle(payload as DotaGsi)
    })
  }

  async stop(): Promise<void> {
    this.unregister?.()
    this.unregister = undefined
    this.emit = undefined
    this.prevState = undefined
    this.latest = undefined
  }

  private rejectedTokenLogged = false

  private handle(g: DotaGsi): void {
    // Verify the per-install token. Dota always sends auth.token; anything
    // without it (or with the wrong one) is some other process on localhost
    // trying to fake a match-end event.
    const incoming = g.auth?.token
    if (
      typeof incoming !== 'string' ||
      !safeEqualStrings(incoming, this.token)
    ) {
      // Логируем только ОДИН раз за процесс — Dota шлёт payload каждые
      // ~100ms во время матча, иначе zass'мём latest.log.
      if (!this.rejectedTokenLogged) {
        this.rejectedTokenLogged = true
        log.warn(
          '[dota2] GSI payload with invalid/missing token rejected. ' +
            'Если приложение переустанавливалось — заново подключи Dota 2 в Games.'
        )
      }
      return
    }

    // Narrow the shape before spread-merging. A payload like `{player:"x"}`
    // would otherwise let `{...this.latest?.player, ...g.player}` throw.
    const playerObj =
      typeof g.player === 'object' && g.player !== null ? g.player : undefined
    const mapObj =
      typeof g.map === 'object' && g.map !== null ? g.map : undefined

    if (playerObj || mapObj) {
      this.latest = {
        ...this.latest,
        ...g,
        player: { ...this.latest?.player, ...playerObj },
        map: { ...this.latest?.map, ...mapObj }
      }
    }

    const state = mapObj?.game_state ?? this.latest?.map?.game_state
    if (!state) return

    const prev = this.prevState
    this.prevState = state

    if (prev && prev !== state && state === 'DOTA_GAMERULES_STATE_POST_GAME') {
      // De-dupe: Dota can fire POST_GAME repeatedly while the scoreboard is open.
      const now = Date.now()
      if (now - this.lastMatchEndAt < 30_000) {
        log.debug('[dota2] suppressed duplicate POST_GAME within 30s window')
        return
      }
      this.lastMatchEndAt = now
      log.info('[dota2] POST_GAME detected, emitting match_end event')

      const p = this.latest?.player ?? {}
      const m = this.latest?.map ?? {}
      const playerTeam = p.team_name
      const winner = m.win_team
      const won =
        winner === 'radiant' || winner === 'dire'
          ? playerTeam === winner
          : undefined
      const durationMs = (m.game_time ?? m.clock_time ?? 0) * 1000

      this.emit?.({
        type: 'match_end',
        payload: {
          durationMs,
          won,
          stats: {
            deaths: p.deaths ?? 0,
            kills: p.kills ?? 0,
            assists: p.assists ?? 0,
            last_hits: p.last_hits ?? 0,
            denies: p.denies ?? 0,
            duration_min: Math.floor(durationMs / 60_000)
          }
        }
      })

      // Reset stale state so the NEXT match starts from a clean slate even if
      // the user re-enters the same lobby or Dota's GSI restarts mid-session.
      this.latest = undefined
      this.prevState = undefined
    }
  }
}

export function dota2DebugInfo(): { port: number; route: string } {
  return { port: getGsiPort(), route: ROUTE }
}