package controllers

import akka.stream.scaladsl._
import play.api.libs.json._
import play.api.mvc._
import scala.concurrent.duration._
import scala.util.chaining._

import lila.api.{ Context, GameApiV2 }
import lila.app._
import lila.common.config.{ MaxPerPage, MaxPerSecond }
import lila.common.{ HTTPRequest, IpAddress }

final class Api(
    env: Env,
    gameC: => Game
) extends LilaController(env) {

  import Api._

  private val userApi = env.api.userApi
  private val gameApi = env.api.gameApi

  private lazy val apiStatusJson = {
    val api = lila.api.Mobile.Api
    Json.obj(
      "api" -> Json.obj(
        "current" -> api.currentVersion.value,
        "olds"    -> Json.arr()
      )
    )
  }

  val status = Action { req =>
    val appVersion  = get("v", req)
    val mustUpgrade = appVersion exists lila.api.Mobile.AppVersion.mustUpgrade
    JsonOk(apiStatusJson.add("mustUpgrade", mustUpgrade))
  }

  def index =
    Action {
      Ok(views.html.site.bits.api)
    }

  def user(name: String) =
    CookieBasedApiRequest { ctx =>
      userApi.extended(name, ctx.me, userWithFollows(ctx.req)) map toApiResult
    }

  private[controllers] def userWithFollows(req: RequestHeader) =
    HTTPRequest.apiVersion(req).exists(_ < 6) && !getBool("noFollows", req)

  private[controllers] val UsersRateLimitPerIP = lila.memo.RateLimit.composite[IpAddress](
    key = "users.api.ip",
    enforce = env.net.rateLimit.value
  )(
    ("fast", 2000, 10.minutes),
    ("slow", 40000, 1.day)
  )

  def usersByIds =
    Action.async(parse.tolerantText) { req =>
      val usernames = req.body.replace("\n", "").split(',').take(300).map(_.trim).toList
      val ip        = HTTPRequest ipAddress req
      val cost      = usernames.size / 4
      UsersRateLimitPerIP(ip, cost = cost) {
        lila.mon.api.users.increment(cost.toLong)
        env.user.repo named usernames map {
          _.map { env.user.jsonView.full(_, none, withOnline = false) }
        } map toApiResult map toHttp
      }(rateLimitedFu)
    }

  def usersStatus =
    ApiRequest { req =>
      val ids = get("ids", req).??(_.split(',').take(100).toList map lila.user.User.normalize)
      env.user.lightUserApi asyncMany ids dmap (_.flatten) map { users =>
        val streamingIds = env.streamer.liveStreamApi.userIds
        toApiResult {
          users.map { u =>
            lila.common.LightUser.lightUserWrites
              .writes(u)
              .add("online" -> env.socket.isOnline(u.id))
              .add("playing" -> env.round.playing(u.id))
              .add("streaming" -> streamingIds(u.id))
          }
        }
      }
    }

  private val UserGamesRateLimitPerIP = new lila.memo.RateLimit[IpAddress](
    credits = 10 * 1000,
    duration = 10.minutes,
    key = "user_games.api.ip"
  )

  private val UserGamesRateLimitPerUA = new lila.memo.RateLimit[String](
    credits = 10 * 1000,
    duration = 5.minutes,
    key = "user_games.api.ua"
  )

  private val UserGamesRateLimitGlobal = new lila.memo.RateLimit[String](
    credits = 20 * 1000,
    duration = 2.minute,
    key = "user_games.api.global"
  )

  private def UserGamesRateLimit(cost: Int, req: RequestHeader)(run: => Fu[ApiResult]) = {
    val ip = HTTPRequest ipAddress req
    UserGamesRateLimitPerIP(ip, cost = cost) {
      UserGamesRateLimitPerUA(~HTTPRequest.userAgent(req), cost = cost, msg = ip.value) {
        UserGamesRateLimitGlobal("-", cost = cost, msg = ip.value) {
          run
        }(fuccess(Limited))
      }(fuccess(Limited))
    }(fuccess(Limited))
  }

  private def gameFlagsFromRequest(req: RequestHeader) =
    lila.api.GameApi.WithFlags(
      analysis = getBool("with_analysis", req),
      moves = getBool("with_moves", req),
      fens = getBool("with_fens", req),
      opening = getBool("with_opening", req),
      moveTimes = getBool("with_movetimes", req),
      token = get("token", req)
    )

  // for mobile app
  def userGames(name: String) =
    MobileApiRequest { req =>
      val page = (getInt("page", req) | 1) atLeast 1 atMost 200
      val nb   = MaxPerPage((getInt("nb", req) | 10) atLeast 1 atMost 100)
      val cost = page * nb.value + 10
      UserGamesRateLimit(cost, req) {
        lila.mon.api.userGames.increment(cost.toLong)
        env.user.repo named name flatMap {
          _ ?? { user =>
            gameApi.byUser(
              user = user,
              rated = getBoolOpt("rated", req),
              playing = getBoolOpt("playing", req),
              analysed = getBoolOpt("analysed", req),
              withFlags = gameFlagsFromRequest(req),
              nb = nb,
              page = page
            ) map some
          }
        } map toApiResult
      }
    }

  private val GameRateLimitPerIP = new lila.memo.RateLimit[IpAddress](
    credits = 100,
    duration = 1.minute,
    key = "game.api.one.ip"
  )

  def game(id: String) =
    ApiRequest { req =>
      GameRateLimitPerIP(HTTPRequest ipAddress req, cost = 1) {
        lila.mon.api.game.increment(1)
        gameApi.one(id take lila.game.Game.gameIdSize, gameFlagsFromRequest(req)) map toApiResult
      }(fuccess(Limited))
    }

  private val CrosstableRateLimitPerIP = new lila.memo.RateLimit[IpAddress](
    credits = 30,
    duration = 10.minutes,
    key = "crosstable.api.ip"
  )

  def crosstable(name1: String, name2: String) =
    ApiRequest { req =>
      CrosstableRateLimitPerIP(HTTPRequest ipAddress req, cost = 1) {
        import lila.user.User.normalize
        val (u1, u2) = (normalize(name1), normalize(name2))
        env.game.crosstableApi(u1, u2) flatMap { ct =>
          (ct.results.nonEmpty && getBool("matchup", req)).?? {
            env.game.crosstableApi.getMatchup(u1, u2)
          } map { matchup =>
            toApiResult {
              lila.game.JsonView.crosstable(ct, matchup).some
            }
          }
        }
      }(fuccess(Limited))
    }

  def currentTournaments =
    ApiRequest { implicit req =>
      implicit val lang = reqLang
      env.tournament.api.fetchVisibleTournaments flatMap
        env.tournament.apiJsonView.apply map Data.apply
    }

  def tournament(id: String) =
    ApiRequest { implicit req =>
      env.tournament.tournamentRepo byId id flatMap {
        _ ?? { tour =>
          val page = (getInt("page", req) | 1) atLeast 1 atMost 200
          env.tournament.jsonView(
            tour = tour,
            page = page.some,
            me = none,
            getUserTeamIds = _ => fuccess(Nil),
            getTeamName = env.team.getTeamName.apply,
            playerInfoExt = none,
            socketVersion = none,
            partial = false
          )(reqLang) map some
        }
      } map toApiResult
    }

  def tournamentGames(id: String) =
    Action.async { req =>
      env.tournament.tournamentRepo byId id flatMap {
        _ ?? { tour =>
          val onlyUserId = get("player", req) map lila.user.User.normalize
          val config = GameApiV2.ByTournamentConfig(
            tournamentId = tour.id,
            format = GameApiV2.Format byRequest req,
            flags = gameC.requestPgnFlags(req, extended = false),
            perSecond = MaxPerSecond(20)
          )
          GlobalConcurrencyLimitPerIP(HTTPRequest ipAddress req)(
            env.api.gameApiV2.exportByTournament(config, onlyUserId)
          ) { source =>
            val filename = env.api.gameApiV2.filename(tour, config.format)
            Ok.chunked(source)
              .pipe(asAttachmentStream(env.api.gameApiV2.filename(tour, config.format)))
              .as(gameC gameContentType config)
          }.fuccess
        }
      }
    }

  def tournamentResults(id: String) =
    Action.async { implicit req =>
      val csv = HTTPRequest.acceptsCsv(req) || get("as", req).has("csv")
      env.tournament.tournamentRepo byId id map {
        _ ?? { tour =>
          import lila.tournament.JsonView.playerResultWrites
          val source =
            env.tournament.api
              .resultStream(tour, MaxPerSecond(40), getInt("nb", req) | Int.MaxValue)
          val result =
            if (csv) csvStream(lila.tournament.TournamentCsv(source))
            else jsonStream(source.map(lila.tournament.JsonView.playerResultWrites.writes))
          result.pipe(asAttachment(env.api.gameApiV2.filename(tour, if (csv) "csv" else "ndjson")))
        }
      }
    }

  def tournamentTeams(id: String) =
    Action.async {
      env.tournament.tournamentRepo byId id flatMap {
        _ ?? { tour =>
          env.tournament.jsonView.apiTeamStanding(tour) map { arr =>
            JsonOk(
              Json.obj(
                "id"    -> tour.id,
                "teams" -> arr
              )
            )
          }
        }
      }
    }

  def tournamentsByOwner(name: String, status: List[Int]) =
    Action.async { implicit req =>
      implicit val lang = reqLang
      (name != lila.user.User.lichessId) ?? env.user.repo.named(name) flatMap {
        _ ?? { user =>
          val nb = getInt("nb", req) | Int.MaxValue
          jsonStream {
            env.tournament.api
              .byOwnerStream(user, status flatMap lila.tournament.Status.apply, MaxPerSecond(20), nb)
              .mapAsync(1)(env.tournament.apiJsonView.fullJson)
          }.fuccess
        }
      }
    }

  def swissGames(id: String) =
    Action.async { req =>
      env.swiss.api byId lila.swiss.Swiss.Id(id) flatMap {
        _ ?? { swiss =>
          val config = GameApiV2.BySwissConfig(
            swissId = swiss.id,
            format = GameApiV2.Format byRequest req,
            flags = gameC.requestPgnFlags(req, extended = false),
            perSecond = MaxPerSecond(20)
          )
          GlobalConcurrencyLimitPerIP(HTTPRequest ipAddress req)(
            env.api.gameApiV2.exportBySwiss(config)
          ) { source =>
            val filename = env.api.gameApiV2.filename(swiss, config.format)
            Ok.chunked(source)
              .pipe(asAttachmentStream(filename))
              .as(gameC gameContentType config)
          }.fuccess
        }
      }
    }

  def swissResults(id: String) = Action.async { implicit req =>
    val csv = HTTPRequest.acceptsCsv(req) || get("as", req).has("csv")
    env.swiss.api byId lila.swiss.Swiss.Id(id) map {
      _ ?? { swiss =>
        val source = env.swiss.api
          .resultStream(swiss, MaxPerSecond(50), getInt("nb", req) | Int.MaxValue)
          .mapAsync(8) { p =>
            env.user.lightUserApi.asyncFallback(p.player.userId) map p.withUser
          }
        val result =
          if (csv) csvStream(lila.swiss.SwissCsv(source))
          else jsonStream(source.map(env.swiss.json.playerResult))
        result.pipe(asAttachment(env.api.gameApiV2.filename(swiss, if (csv) "csv" else "ndjson")))
      }
    }
  }

  def gamesByUsersStream =
    AnonOrScopedBody(parse.tolerantText)() { req => me =>
      val max = me.fold(300) { u => if (u.id == "lichess4545") 900 else 500 }
      GlobalConcurrencyLimitPerIP(HTTPRequest ipAddress req)(
        addKeepAlive(
          env.game.gamesByUsersStream(
            userIds = req.body.split(',').view.take(max).map(lila.user.User.normalize).toSet,
            withCurrentGames = getBool("withCurrentGames", req)
          )
        )
      )(sourceToNdJsonOption).fuccess
    }

  def cloudEval =
    Action.async { req =>
      get("fen", req).fold(notFoundJson("Missing FEN")) { fen =>
        JsonOptionOk(
          env.evalCache.api.getEvalJson(
            chess.variant.Variant orDefault ~get("variant", req),
            chess.format.FEN(fen),
            getInt("multiPv", req) | 1
          )
        )
      }
    }

  def eventStream =
    Scoped(_.Bot.Play, _.Board.Play, _.Challenge.Read) { _ => me =>
      env.round.proxyRepo.urgentGames(me) flatMap { povs =>
        env.challenge.api.createdByDestId(me.id) map { challenges =>
          sourceToNdJsonOption(env.api.eventStream(me, povs.map(_.game), challenges))
        }
      }
    }

  private val UserActivityRateLimitPerIP = new lila.memo.RateLimit[IpAddress](
    credits = 15,
    duration = 2.minutes,
    key = "user_activity.api.ip"
  )

  def activity(name: String) =
    ApiRequest { implicit req =>
      implicit val lang = reqLang
      UserActivityRateLimitPerIP(HTTPRequest ipAddress req, cost = 1) {
        lila.mon.api.activity.increment(1)
        env.user.repo named name flatMap {
          _ ?? { user =>
            env.activity.read.recent(user) flatMap {
              _.map { env.activity.jsonView(_, user) }.sequenceFu
            }
          }
        } map toApiResult
      }(fuccess(Limited))
    }

  private val ApiMoveStreamGlobalConcurrencyLimitPerIP =
    new lila.memo.ConcurrencyLimit[IpAddress](
      name = "API concurrency per IP",
      key = "round.apiMoveStream.ip",
      ttl = 20.minutes,
      maxConcurrency = 8
    )

  def moveStream(gameId: String) =
    Action.async { req =>
      env.round.proxyRepo.gameIfPresent(gameId) map {
        case None => NotFound
        case Some(game) =>
          ApiMoveStreamGlobalConcurrencyLimitPerIP(HTTPRequest ipAddress req)(
            addKeepAlive(env.round.apiMoveStream(game, gameC.delayMovesFromReq(req)))
          )(sourceToNdJsonOption)
      }
    }

  def perfStat(username: String, perfKey: String) = ApiRequest { req =>
    implicit val lang = reqLang(req)
    env.perfStat.api.data(username, perfKey, none) map {
      _.fold[ApiResult](NoData) { data => Data(env.perfStat.jsonView(data)) }
    }
  }

  def CookieBasedApiRequest(js: Context => Fu[ApiResult]) =
    Open { ctx =>
      js(ctx) map toHttp
    }
  def ApiRequest(js: RequestHeader => Fu[ApiResult]) =
    Action.async { req =>
      js(req) map toHttp
    }
  def MobileApiRequest(js: RequestHeader => Fu[ApiResult]) =
    Action.async { req =>
      if (lila.api.Mobile.Api requested req) js(req) map toHttp
      else fuccess(NotFound)
    }

  def toApiResult(json: Option[JsValue]): ApiResult = json.fold[ApiResult](NoData)(Data.apply)
  def toApiResult(json: Seq[JsValue]): ApiResult    = Data(JsArray(json))

  def toHttp(result: ApiResult): Result =
    result match {
      case Limited          => rateLimitedJson
      case ClientError(msg) => BadRequest(jsonError(msg))
      case NoData           => NotFound
      case Custom(result)   => result
      case Done             => jsonOkResult
      case Data(json)       => JsonOk(json)
    }

  def jsonStream(makeSource: => Source[JsValue, _])(implicit req: RequestHeader): Result =
    GlobalConcurrencyLimitPerIP(HTTPRequest ipAddress req)(makeSource)(sourceToNdJson)

  def addKeepAlive(source: Source[JsValue, _]): Source[Option[JsValue], _] =
    source
      .map(some)
      .keepAlive(60.seconds, () => none) // play's idleTimeout = 75s

  def sourceToNdJson(source: Source[JsValue, _]): Result =
    sourceToNdJsonString {
      source.map { o =>
        Json.stringify(o) + "\n"
      }
    }

  def sourceToNdJsonOption(source: Source[Option[JsValue], _]): Result =
    sourceToNdJsonString {
      source.map { _ ?? Json.stringify + "\n" }
    }

  private def sourceToNdJsonString(source: Source[String, _]): Result =
    Ok.chunked(source).as(ndJsonContentType) pipe noProxyBuffer

  def csvStream(makeSource: => Source[String, _])(implicit req: RequestHeader): Result =
    GlobalConcurrencyLimitPerIP(HTTPRequest ipAddress req)(makeSource)(sourceToCsv)

  private def sourceToCsv(source: Source[String, _]): Result =
    Ok.chunked(source.map(_ + "\n")).as(csvContentType) pipe noProxyBuffer

  private[controllers] val GlobalConcurrencyLimitPerIP = new lila.memo.ConcurrencyLimit[IpAddress](
    name = "API concurrency per IP",
    key = "api.ip",
    ttl = 1.hour,
    maxConcurrency = 2
  )
  private[controllers] val GlobalConcurrencyLimitUser = new lila.memo.ConcurrencyLimit[lila.user.User.ID](
    name = "API concurrency per user",
    key = "api.user",
    ttl = 1.hour,
    maxConcurrency = 1
  )
  private[controllers] def GlobalConcurrencyLimitPerUserOption[T](
      user: Option[lila.user.User]
  ): Option[SourceIdentity[T]] =
    user.fold(some[SourceIdentity[T]](identity)) { u =>
      GlobalConcurrencyLimitUser.compose[T](u.id)
    }

  private[controllers] def GlobalConcurrencyLimitPerIpAndUserOption[T](
      req: RequestHeader,
      me: Option[lila.user.User]
  )(makeSource: => Source[T, _])(makeResult: Source[T, _] => Result): Result =
    GlobalConcurrencyLimitPerIP.compose[T](HTTPRequest ipAddress req) flatMap { limitIp =>
      GlobalConcurrencyLimitPerUserOption[T](me) map { limitUser =>
        makeResult(limitIp(limitUser(makeSource)))
      }
    } getOrElse lila.memo.ConcurrencyLimit.limitedDefault(1)

  private type SourceIdentity[T] = Source[T, _] => Source[T, _]
}

private[controllers] object Api {

  sealed trait ApiResult
  case class Data(json: JsValue)      extends ApiResult
  case class ClientError(msg: String) extends ApiResult
  case object NoData                  extends ApiResult
  case object Done                    extends ApiResult
  case object Limited                 extends ApiResult
  case class Custom(result: Result)   extends ApiResult
}