module HighScores where

import System.Directory
import Control.Monad
import Text.Printf
import System.Time

import Data.Binary
import qualified Data.List as L

import Utils.File
import qualified Config
import WorldLoc
import Geometry

-- | A single score.
-- TODO: add heroes' names, exp and level, cause of death, user number/name.
-- Note: I tried using Date.Time, but got all kinds of problems,
-- including build problems and opaque types that make serialization difficult,
-- and I couldn't use Datetime because it needs old base (and is under GPL).
-- TODO: When we finally move to Date.Time, let's take timezone into account.
data ScoreRecord = ScoreRecord
  { points  :: !Int
  , negTurn :: !Int
  , date    :: !ClockTime
  , status  :: !Status
  }
  deriving (Eq, Ord)

data Status = Killed !LevelId | Camping !LevelId | Victor
  deriving (Eq, Ord)

instance Binary Status where
  put (Killed ln)  = putWord8 0 >> put ln
  put (Camping ln) = putWord8 1 >> put ln
  put Victor       = putWord8 2
  get = do
          tag <- getWord8
          case tag of
            0 -> liftM Killed  get
            1 -> liftM Camping get
            2 -> return Victor
            _ -> fail "no parse (Status)"

instance Binary ScoreRecord where
  put (ScoreRecord p n (TOD cs cp) s) =
    do
      put p
      put n
      put cs
      put cp
      put s
  get =
    do
      p <- get
      n <- get
      cs <- get
      cp <- get
      s <- get
      return (ScoreRecord p n (TOD cs cp) s)

-- | Show a single high score.
showScore :: (Int, ScoreRecord) -> String
showScore (pos, score) =
  let died  =
        case status score of
          Killed (LambdaCave n)  -> "perished on level " ++ show n ++ ","
          Camping (LambdaCave n) -> "is camping on level " ++ show n ++ ","
          Victor     -> "emerged victorious"
      time  = calendarTimeToString . toUTCTime . date $ score
      big   = "                                                 "
      lil   = "              "
      steps = negTurn score `div` (-10)
  in
   printf
     "%s\n%4d. %6d  This adventuring party %s after %d steps  \n%son %s.  \n"
     big pos (points score) died steps lil time

-- | The list of scores, in decreasing order.
type ScoreTable = [ScoreRecord]

-- | Empty score table
empty :: ScoreTable
empty = []

-- | Name of the high scores file.
file :: Config.CP -> IO String
file config = Config.getFile config "files" "highScores"

-- | We save a simple serialized version of the high scores table.
-- The 'False' is used only as an EOF marker.
save :: Config.CP -> ScoreTable -> IO ()
save config scores = do
  f <- file config
  encodeEOF f scores

-- | Read the high scores table. Return the empty table if no file.
restore :: Config.CP -> IO ScoreTable
restore config = do
  f <- file config
  b <- doesFileExist f
  if not b
    then return []
    else do
      scores <- strictDecodeEOF f
      return scores

-- | Insert a new score into the table, Return new table and the position.
insertPos :: ScoreRecord -> ScoreTable -> (ScoreTable, Int)
insertPos s h =
  let (prefix, suffix) = L.span (> s) h in
  (prefix ++ [s] ++ suffix, L.length prefix + 1)

-- | Show a screenful of the high scores table.
-- Parameter height is the number of (3-line) scores to be shown.
showTable :: ScoreTable -> Int -> Int -> String
showTable h start height =
  let zipped    = zip [1..] h
      screenful = take height . drop (start - 1) $ zipped
  in
   L.concatMap showScore screenful

-- | Produces a couple of renderings of the high scores table.
slideshow :: Int -> ScoreTable -> Int -> [String]
slideshow pos h height =
  if pos <= height
  then [showTable h 1 height]
  else [showTable h 1 height,
        showTable h (max (height + 1) (pos - height `div` 2)) height]

-- | Take care of a new score, return a list of messages to display.
register :: Config.CP -> Bool -> ScoreRecord -> IO (String, [String])
register config write s =
  do
    h <- restore config
    let (h', pos) = insertPos s h
        (_, nlines) = normalLevelBound  -- TODO: query terminal size instead
        height = nlines `div` 3
        (msgCurrent, msgUnless) =
          case status s of
            Killed _  -> (" short-lived", " (score halved)")
            Camping _ -> (" current", " (unless you are slain)")
            Victor    -> (" glorious",
                          if pos <= height
                          then " among the greatest heroes"
                          else "")
        msg = printf "Your%s exploits award you place >> %d <<%s."
                msgCurrent pos msgUnless
    when write $ save config h'
    return (msg, slideshow pos h' height)