--
-- Copyright (c) 2014 Justus Winter <4winter@informatik.uni-hamburg.de>
--
-- Permission to use, copy, modify, and distribute this software for any
-- purpose with or without fee is hereby granted, provided that the above
-- copyright notice and this permission notice appear in all copies.
--
-- THE SOFTWARE IS PROVIDED "AS IS" AND THE AUTHOR DISCLAIMS ALL WARRANTIES
-- WITH REGARD TO THIS SOFTWARE INCLUDING ALL IMPLIED WARRANTIES OF
-- MERCHANTABILITY AND FITNESS. IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR
-- ANY SPECIAL, DIRECT, INDIRECT, OR CONSEQUENTIAL DAMAGES OR ANY DAMAGES
-- WHATSOEVER RESULTING FROM LOSS OF USE, DATA OR PROFITS, WHETHER IN AN
-- ACTION OF CONTRACT, NEGLIGENCE OR OTHER TORTIOUS ACTION, ARISING OUT OF
-- OR IN CONNECTION WITH THE USE OR PERFORMANCE OF THIS SOFTWARE.
--

{-# LANGUAGE DeriveDataTypeable #-}

module Main where

import Control.Monad (when)
import Data.Array (Array, array, bounds, (!), (//))
import Data.Functor ((<$>))
import Data.Maybe
import Data.List (sort, intersperse)
import Data.Ord (compare)
import Data.Char (toUpper)
import Debug.Trace (traceShow)
import System.Console.CmdArgs (Data, Typeable, cmdArgs)
import System.IO (hPutStrLn, stderr)
import System.Random (RandomGen, getStdGen, split, randomR, randomRs)
import System.Random.Shuffle

traceShow' x = traceShow x x

-- Vectors to represent position and orientation.
data Vec = Vec { x::Int, y::Int } deriving (Show, Eq)

origin = Vec 0 0
left = Vec (-1) 0
right = Vec 1 0
up = Vec 0 (-1)
down = Vec 0 1

add :: Vec -> Vec -> Vec
add a b = Vec (x a + x b) (y a + y b)

index :: Vec -> (Int, Int)
index p = (x p, y p)

-- Pose is a tuple of position and orientation.
data Pose = Pose { position::Vec, orientation::Vec } deriving (Show, Eq)

advance :: Pose -> Pose
advance p = p {position = add (position p) (orientation p)}

-- Move is a pose combined with a cost.
data Move = Move { pose::Pose, cost::Int } deriving (Show, Eq)

instance Ord Move where
    (Move _ a) `compare` (Move _ b) = a `compare` b

-- We just use Char for each field.
empty = '.'

-- Board is an immutable array.
type Board = Array (Int, Int) Char

showBoard :: Board -> String
showBoard arr =
  unlines $ map (map (arr !)) indices
  where indices = [[(x, y) | x <- [sX..eX]] | y <- [sY..eY]]
        ((sX, sY), (eX, eY)) = bounds arr

mkBoard :: (Int, Int) -> Array (Int, Int) Char
mkBoard (d, e) = array ((0, 0), (m, n)) [((x, y), empty) | x<-[0..m], y<-[0..n]]
  where m = d-1
        n = e-1

charAt :: Board -> Vec -> Maybe Char
charAt b p =
    if x p >= 0 && y p >= 0 && x p <= eX && y p <= eY then
        Just (b ! index p)
    else
        Nothing
  where ((sX, sY), (eX, eY)) = bounds b

allPoses :: Board -> [Pose]
allPoses b =
    [Pose (Vec x y) o | x <- [sX..eX], y <- [sY..eY], o <- [right, down]]
  where
    ((sX, sY), (eX, eY)) = bounds b

-- Test whether it's possible to insert a string at the given pose.
-- Return the associated cost or Nothing, if the string didn't fit.
computeCost :: String -> Pose -> Board -> Maybe Int
computeCost [] _ _ = Just 0
computeCost (w:ws) p b =
  case charAt b (position p) of
    Nothing -> Nothing
    Just c ->
        if c /= empty && c /= w then
            Nothing
        else do
          t <- computeCost ws (advance p) b
          return ((if c == w then 0 else 1) + t)

tryInsert :: String -> Pose -> Board -> Maybe Move
tryInsert w p b = do
  cost <- computeCost w p b
  return $ Move p cost

-- Given a string and a pose, return a list of updates for a board to
-- insert the string.
mkPatch :: String -> Pose -> [((Int, Int), Char)]
mkPatch [] _ = []
mkPatch (w:ws) p = (index $ position p, w) : mkPatch ws (advance p)

-- Actually insert the string returning a new board.
insert :: String -> Pose -> Board -> Maybe Board
insert [] _ b = Just b
insert w p b =
  if isNothing (computeCost w p b) then
    Nothing
  else
    Just (b // mkPatch w p)

-- Insert all given words into the board.
insertAll :: RandomGen gen => gen -> [String] -> Board -> Maybe Board
insertAll _ [] b = Just b
insertAll rnd (w:ws) b = do
  when (null moves) Nothing
  b' <- insert w (pose $ sort moves !! nth) b
  insertAll rnd' ws b'
  where
    (nth, rnd') = randomR (0, min 10 (length moves - 1)) rnd
    moves = mapMaybe (\x -> tryInsert w x b) shuffled
    shuffled = shuffle' all (length all) rnd
    all = allPoses b

-- Fill all empty fields with a random character.
fill :: RandomGen gen => gen -> Board -> Board
fill rnd b = b // zip [(x, y) | x <- [sX..eX], y <- [sY..eY], (b ! (x, y)) == empty] (randomRs ('A', 'Z') rnd)
     where
       ((sX, sY), (eX, eY)) = bounds b

data Puzzle = Puzzle { blanks :: Bool
                     , latex :: Bool
                     , pages :: Int
                     , dimension :: (Int, Int)
                     } deriving (Data, Typeable, Show)

main :: IO ()
main = do
  args <- cmdArgs $ Puzzle False False 1 (30, 30)
  rnd <- getStdGen
  c <- getContents
  let guests = lines (map toUpper c)
  if latex args then
      generateLatex rnd (mkBoard (28, 39)) guests (pages args)
  else
    case (showBoard . (if blanks args then id else fill rnd)) <$> insertAll rnd guests (mkBoard $ dimension args) of
      Just s -> putStr s
      Nothing -> putStr "goesnt"

-- LaTeX generation ahead.
texBoard :: Board -> String
texBoard b =
  unlines $ map ((++ "\\\\") . intersperse '&') $ lines $ showBoard b

generateLatex :: (RandomGen gen) => gen -> Board -> [String] -> Int -> IO ()
generateLatex rnd b ws c = do
  putStr latexHeader
  generateLatexPage rnd b ws c
    where
      generateLatexPage _ _ _ 0 = putStr latexFooter
      generateLatexPage rnd b ws c = do
        hPutStrLn stderr $ show c ++ " more puzzles to go..."
        case (texBoard . fill rnd) <$> insertAll rnd ws b of
          Just s -> do
            putStr pageHeader
            putStr s
            putStr pageFooter
            when (c > 1) $ putStr "\\newpage\n"
            generateLatexPage rnd' b ws (c - 1)
          Nothing -> generateLatexPage rnd'' b ws c
          where
            (rnd', rnd'') = split rnd

latexHeader = unlines ["\\documentclass[11pt, a4paper]{article}"
                      ,"\\usepackage{libertine}"
                      ,"\\usepackage[cm]{fullpage}"
                      ,"\\usepackage{tikz}"
                      ,"\\usetikzlibrary{matrix,backgrounds}"
                      ,"\\begin{document}"
                      ]
latexFooter = "\\end{document}"

pageHeader = unlines ["\\thispagestyle{empty}"
                     ,"\\center"
                     ,"\\Huge"
                     ,"ABC-Konwaenschn-Puzzle"
                     ,"\\normalsize"
                     ,"\\\\"
                     ,"\\vspace{1cm}"
                     ,"\\begin{tikzpicture}"
                     ,"  \\matrix(m)["
                     ,"    matrix of nodes,"
                     ,"    every node/.append style={minimum size=2ex, inner sep=4pt},"
                     ,"  ]{"
                     ]
pageFooter = unlines ["  };"
                     ,"\\end{tikzpicture}"
                     ,"Waagerecht und senkrecht verstecken sich nette Menschen! Findest du sie?  Findest du sie auf der Convention?"
                     ]