{
 "cells": [
  {
   "cell_type": "code",
   "execution_count": 1,
   "metadata": {},
   "outputs": [],
   "source": [
    "{-# LANGUAGE NegativeLiterals #-}\n",
    "{-# LANGUAGE FlexibleContexts #-}\n",
    "{-# LANGUAGE OverloadedStrings #-}\n",
    "{-# LANGUAGE TypeFamilies #-}"
   ]
  },
  {
   "cell_type": "code",
   "execution_count": 2,
   "metadata": {},
   "outputs": [],
   "source": [
    "import Data.List\n",
    "import Data.Char"
   ]
  },
  {
   "cell_type": "code",
   "execution_count": 3,
   "metadata": {},
   "outputs": [
    {
     "data": {
      "text/plain": [
       "[\"     |          \",\"     |  +--+    \",\"     A  |  C    \",\" F---|----E|--+ \",\"     |  |  |  D \",\"     +B-+  +--+ \",\"                \"]"
      ]
     },
     "metadata": {},
     "output_type": "display_data"
    }
   ],
   "source": [
    "sampleText <- readFile \"sample-maze.txt\"\n",
    "sample = lines sampleText\n",
    "print sample"
   ]
  },
  {
   "cell_type": "code",
   "execution_count": 4,
   "metadata": {},
   "outputs": [],
   "source": [
    "type Maze = [String]"
   ]
  },
  {
   "cell_type": "code",
   "execution_count": 5,
   "metadata": {},
   "outputs": [],
   "source": [
    "data Direction = Up | Down | Left | Right deriving (Show, Eq)"
   ]
  },
  {
   "cell_type": "code",
   "execution_count": 6,
   "metadata": {},
   "outputs": [],
   "source": [
    "data Progress = Progress { row :: Int\n",
    "                         , column :: Int\n",
    "                         , direction :: Direction\n",
    "                         , letters :: String\n",
    "                         , stepCount :: Int\n",
    "                         } deriving (Show, Eq)"
   ]
  },
  {
   "cell_type": "code",
   "execution_count": 7,
   "metadata": {},
   "outputs": [],
   "source": [
    "startProgress :: Maze -> Progress\n",
    "startProgress maze = Progress {row = 0, column = startCol, direction = Down, letters = \"\", stepCount = 0}\n",
    "    where topRow = maze!!0\n",
    "          startCol = head $ elemIndices '|' topRow"
   ]
  },
  {
   "cell_type": "code",
   "execution_count": 8,
   "metadata": {},
   "outputs": [],
   "source": [
    "delta :: Direction -> (Int, Int)\n",
    "delta Up    = (-1,  0)\n",
    "delta Down  = ( 1,  0)\n",
    "delta Left  = ( 0, -1)\n",
    "delta Right = ( 0,  1)"
   ]
  },
  {
   "cell_type": "code",
   "execution_count": 9,
   "metadata": {},
   "outputs": [],
   "source": [
    "isContinuation '|' = True\n",
    "isContinuation '-' = True\n",
    "isContinuation  _  = False\n",
    "\n",
    "isJunction '+' = True\n",
    "isJunction  _  = False "
   ]
  },
  {
   "cell_type": "code",
   "execution_count": 10,
   "metadata": {},
   "outputs": [],
   "source": [
    "location :: Maze -> Int -> Int -> Char\n",
    "location maze r c = (maze!!r)!!c"
   ]
  },
  {
   "cell_type": "code",
   "execution_count": 11,
   "metadata": {},
   "outputs": [],
   "source": [
    "newDirection :: Maze -> Progress -> Direction\n",
    "newDirection maze progress = \n",
    "    if d == Up || d == Down \n",
    "    then if isSpace leftChar then Right else Left\n",
    "    else if isSpace upChar then Down else Up\n",
    "    where d = direction progress\n",
    "          r = row progress\n",
    "          c = column progress\n",
    "          upChar = location maze (r - 1) c\n",
    "--           downChar = location maze (r + 1) c\n",
    "          leftChar = location maze r (c - 1)\n",
    "--           rightChar = location maze r (c + 1)\n",
    "          "
   ]
  },
  {
   "cell_type": "code",
   "execution_count": 12,
   "metadata": {},
   "outputs": [],
   "source": [
    "step :: Maze -> Progress -> Progress\n",
    "step maze progress = progress {row = r', column = c', direction = d', letters = l', stepCount = sc'}\n",
    "    where r = row progress\n",
    "          c = column progress\n",
    "          thisChar = location maze r c\n",
    "          l' = if isAlpha thisChar then (letters progress) ++ [thisChar] else letters progress\n",
    "          d' = if isJunction thisChar then newDirection maze progress else direction progress \n",
    "          (dr, dc) = delta d'\n",
    "          r' = r + dr\n",
    "          c' = c + dc\n",
    "          sc' = stepCount progress + 1"
   ]
  },
  {
   "cell_type": "code",
   "execution_count": 13,
   "metadata": {},
   "outputs": [],
   "source": [
    "\n",
    "isFinished :: Maze -> Progress -> Bool\n",
    "isFinished maze progress = isSpace $ location maze (row progress) (column progress)"
   ]
  },
  {
   "cell_type": "code",
   "execution_count": 14,
   "metadata": {},
   "outputs": [],
   "source": [
    "navigate' maze progress = \n",
    "    if isFinished maze progress \n",
    "        then progress\n",
    "        else navigate' maze (step maze progress)"
   ]
  },
  {
   "cell_type": "code",
   "execution_count": 15,
   "metadata": {},
   "outputs": [],
   "source": [
    "navigate :: Maze -> Progress\n",
    "navigate maze = navigate' maze progress\n",
    "    where progress = startProgress maze"
   ]
  },
  {
   "cell_type": "code",
   "execution_count": 16,
   "metadata": {},
   "outputs": [
    {
     "data": {
      "text/plain": [
       "Progress {row = 3, column = 0, direction = Left, letters = \"ABCDEF\", stepCount = 38}"
      ]
     },
     "metadata": {},
     "output_type": "display_data"
    }
   ],
   "source": [
    "navigate sample"
   ]
  },
  {
   "cell_type": "code",
   "execution_count": 17,
   "metadata": {},
   "outputs": [
    {
     "data": {
      "text/plain": [
       "'+'"
      ]
     },
     "metadata": {},
     "output_type": "display_data"
    }
   ],
   "source": [
    "sample!!5!!8"
   ]
  },
  {
   "cell_type": "code",
   "execution_count": 18,
   "metadata": {},
   "outputs": [
    {
     "data": {
      "text/plain": [
       "False"
      ]
     },
     "metadata": {},
     "output_type": "display_data"
    }
   ],
   "source": [
    "isJunction '|'"
   ]
  },
  {
   "cell_type": "code",
   "execution_count": 19,
   "metadata": {},
   "outputs": [
    {
     "data": {
      "text/plain": [
       "Progress {row = 5, column = 8, direction = Right, letters = \"\", stepCount = 0}"
      ]
     },
     "metadata": {},
     "output_type": "display_data"
    }
   ],
   "source": [
    "pt = (startProgress sample) {row = 5, column = 8, direction = Right}\n",
    "pt"
   ]
  },
  {
   "cell_type": "code",
   "execution_count": 20,
   "metadata": {},
   "outputs": [
    {
     "data": {
      "text/plain": [
       "Up"
      ]
     },
     "metadata": {},
     "output_type": "display_data"
    }
   ],
   "source": [
    "newDirection sample pt"
   ]
  },
  {
   "cell_type": "code",
   "execution_count": 21,
   "metadata": {},
   "outputs": [
    {
     "data": {
      "text/plain": [
       "Progress {row = 4, column = 8, direction = Up, letters = \"\", stepCount = 1}"
      ]
     },
     "metadata": {},
     "output_type": "display_data"
    }
   ],
   "source": [
    "step sample pt"
   ]
  },
  {
   "cell_type": "code",
   "execution_count": 25,
   "metadata": {},
   "outputs": [],
   "source": [
    "part1 = letters "
   ]
  },
  {
   "cell_type": "code",
   "execution_count": 26,
   "metadata": {},
   "outputs": [],
   "source": [
    "part2 = stepCount"
   ]
  },
  {
   "cell_type": "code",
   "execution_count": 27,
   "metadata": {},
   "outputs": [],
   "source": [
    "main :: IO ()\n",
    "main = do \n",
    "        text <- readFile \"../../data/advent19.txt\"\n",
    "        let maze = lines text\n",
    "        let progress = navigate maze\n",
    "        print $ part1 progress\n",
    "        print $ part2 progress"
   ]
  },
  {
   "cell_type": "code",
   "execution_count": 28,
   "metadata": {},
   "outputs": [
    {
     "data": {
      "text/plain": [
       "\"XYFDJNRCQA\"\n",
       "17450"
      ]
     },
     "metadata": {},
     "output_type": "display_data"
    }
   ],
   "source": [
    "main"
   ]
  },
  {
   "cell_type": "code",
   "execution_count": null,
   "metadata": {},
   "outputs": [],
   "source": [
    "navigate "
   ]
  }
 ],
 "metadata": {
  "kernelspec": {
   "display_name": "Haskell",
   "language": "haskell",
   "name": "haskell"
  },
  "language_info": {
   "codemirror_mode": "ihaskell",
   "file_extension": ".hs",
   "name": "haskell",
   "version": "8.0.2"
  }
 },
 "nbformat": 4,
 "nbformat_minor": 2
}