{-|
Module      : Werewolf.Command.Start
Description : Options and handler for the start subcommand.

Copyright   : (c) Henry J. Wylde, 2016
License     : BSD3
Maintainer  : public@hjwylde.com

Options and handler for the start subcommand.
-}

{-# LANGUAGE FlexibleContexts      #-}
{-# LANGUAGE MultiParamTypeClasses #-}

module Werewolf.Command.Start (
    -- * Options
    Options(..), ExtraRoles(..),

    -- * Handle
    handle,
) where

import Control.Lens.Extra
import Control.Monad.Except
import Control.Monad.Extra
import Control.Monad.Random
import Control.Monad.State
import Control.Monad.Writer

import Data.Text (Text)

import Game.Werewolf
import Game.Werewolf.Engine
import Game.Werewolf.Message.Error

import System.Random.Shuffle

import Werewolf.System

data Options = Options
    { optExtraRoles :: ExtraRoles
    , optVariant    :: Variant
    , argPlayers    :: [Text]
    } deriving (Eq, Show)

data ExtraRoles = None | Random | Use [Text]
    deriving (Eq, Show)

handle :: (MonadIO m, MonadRandom m) => Text -> Text -> Options -> m ()
handle callerName tag (Options extraRoles variant playerNames) = do
    whenM (doesGameExist tag &&^ (hasn't (stage . _GameOver) <$> readGame tag)) $ exitWith failure
        { messages = [gameAlreadyRunningMessage callerName]
        }

    result <- runExceptT $ do
        extraRoles' <- case extraRoles of
            None            -> return []
            Random          -> randomExtraRoles $ length playerNames
            Use roleNames   -> useExtraRoles callerName roleNames

        let roles = padRoles extraRoles' (length playerNames + 1)

        players <- createPlayers (callerName:playerNames) <$> shuffleM roles

        runWriterT $ startGame callerName variant players >>= execStateT checkStage

    case result of
        Left errorMessages      -> exitWith failure { messages = errorMessages }
        Right (game, messages)  -> writeOrDeleteGame tag game >> exitWith success { messages = messages }

randomExtraRoles :: MonadRandom m => Int -> m [Role]
randomExtraRoles n = do
    let minimum = n `div` 4 + 1
    let maximum = n `div` 3 + 1

    count <- getRandomR (minimum, maximum)

    take count <$> shuffleM restrictedRoles

useExtraRoles :: MonadError [Message] m => Text -> [Text] -> m [Role]
useExtraRoles callerName roleNames = forM roleNames $ \roleName -> case findByTag roleName of
    Just role   -> return role
    Nothing     -> throwError [roleDoesNotExistMessage callerName roleName]

findByTag :: Text -> Maybe Role
findByTag tag' = restrictedRoles ^? traverse . filteredBy tag tag'

padRoles :: [Role] -> Int -> [Role]
padRoles roles n = roles ++ simpleVillagerRoles ++ simpleWerewolfRoles
    where
        goal                    = 3
        m                       = max (n - length roles) 0
        startingBalance         = sumOf (traverse . balance) roles
        simpleWerewolfBalance   = simpleWerewolfRole ^. balance

        -- Little magic here to calculate how many Werewolves and Villagers we want.
        -- This tries to ensure that the balance of the game is between -3 and 2.
        simpleWerewolvesCount   = (goal - m - startingBalance) `div` (simpleWerewolfBalance - 1) + 1
        simpleVillagersCount    = m - simpleWerewolvesCount

        -- N.B., if roles is quite unbalanced then one list will be empty.
        simpleVillagerRoles = replicate simpleVillagersCount simpleVillagerRole
        simpleWerewolfRoles = replicate simpleWerewolvesCount simpleWerewolfRole

createPlayers :: [Text] -> [Role] -> [Player]
createPlayers = zipWith newPlayer