#include <stdio.h>
#include <stdbool.h>
// Including a header file lets your file refer to the functions *declared* in
// that header file.  The functions are usually *defined* elsewhere though, in
// this case, mazelib.c
#include "mazelib.h"

#define NORTH 0
#define EAST 1
#define SOUTH 2
#define WEST 3

// function prototypes
void breadcrumb(int row, int column);
bool checkForwardBlocked(int row, int column, int heading);
bool checkLeftBlocked(int row, int column, int heading);
bool checkRightBlocked(int row, int column, int heading);
int turnLeft(int heading);
int turnRight(int heading);

void runner_solve(void) {
  // set the runner in the maze
  int row = 1;
  int column = 2;
  int heading = EAST;

  // "indefinately move through the maze"
  for (int i = 0; i < 100; i++)
  {
    // check to see if the end of the maze is here
    if (maze_get_char(row, column) == 'E')
    {
      return;
    }
    // set a breadcrumb through the maze
    breadcrumb(row, column);
    // check to see if the forward position is blocked
    if (checkForwardBlocked(row, column, heading))
    {
      // check to see if the left position is blocked
      if (checkLeftBlocked(row, column, heading))
      {
        // check to see if the right position is blocked
        if (checkRightBlocked(row, column, heading))
        {
          // if it is, then turn left instead.
          heading = turnLeft(heading);
        }
        else
        {
          // otherwise, turn right instead.
          heading = turnRight(heading);
        }
      }
    }
    // keep track of the heading through the maze, "moving" the 'S'
    if (heading == NORTH)
    {
      row = row + 1;
    }
    if (heading == EAST)
    {
      column = column + 1;
    }
    if (heading == SOUTH)
    {
      row = row - 1;
    }
    if (heading == WEST)
    {
      column = column - 1;
    }
  }
}

// function definitions, given logical breakdown of the problem.
int turnLeft(int heading)
{
  // turns left given the current direction.
  if (heading == NORTH)
  {
    heading = WEST;
  }
  if (heading == EAST)
  {
    heading = NORTH;
  }
  if (heading == SOUTH)
  {
    heading = EAST;
  }
  if (heading == WEST)
  {
    heading = SOUTH;
  }
  // returns the new heading.
  return heading;
}

int turnRight(int heading)
{
  // turns right given current direction
  if (heading == NORTH)
  {
    heading = EAST;
  }
  if (heading == EAST)
  {
    heading = SOUTH;
  }
  if (heading == SOUTH)
  {
    heading = WEST;
  }
  if (heading == WEST)
  {
    heading = NORTH;
  }
  // returns the new direction
  return heading;
}

void breadcrumb(int row, int column)
{
  // leaves a "breadcrumb" as given by the spec
  if(maze_get_char(row, column) == '.')
  {
    // set a 'o'
    maze_set_char(row, column, 'o');
  }
  else if (maze_get_char(row, column) == 'o')
  {
    // set a 'O'
    maze_set_char(row, column, 'O');
  }
  else if (maze_get_char(row, column) == 'O')
  {
    // set a '@'
    maze_set_char(row, column, '@');
  }
  else
  {
    // set a '.'
    maze_set_char(row, column, '.');
  }
}

bool checkForwardBlocked(int row, int column, int heading)
{
  // checks to see if the path is blocked from where the runner is in each
  // direction.
  if (heading == NORTH)
  {
    if (maze_get_char(row - 1, column) == '#')
    {
      return true;
    }
  }
  if (heading == EAST)
  {
    if (maze_get_char(row, column + 1) == '#')
    {
      return true;
    }
  }
  if (heading == SOUTH)
  {
    if (maze_get_char(row + 1, column) == '#')
    {
      return true;
    }
  }
  if (heading == WEST)
  {
    if (maze_get_char(row, column - 1) == '#')
    {
      return true;
    }
  }
  // return false if there is no # within the given area.
  return false;
}

bool checkLeftBlocked(int row, int column, int heading)
{
  // checks to see if the path is blocked from where the runner is in each
  // direction.
  if (heading == NORTH)
  {
    if (maze_get_char(row, column - 1) == '#')
    {
      return true;
    }
  }
  if (heading == EAST)
  {
    if (maze_get_char(row - 1, column) == '#')
    {
      return true;
    }
  }
  if (heading == SOUTH)
  {
    if (maze_get_char(row, column + 1) == '#')
    {
      return true;
    }
  }
  if (heading == WEST)
  {
    if (maze_get_char(row + 1, column) == '#')
    {
      return true;
    }
  }
  // return false if there is no # within the given area.
  return false;
}

bool checkRightBlocked(int row, int column, int heading)
{
  // checks to see if the path is blocked from where the runner is in each
  // direction.
  if (heading == NORTH)
  {
    if (maze_get_char(row, column + 1) == '#')
    {
      return true;
    }
  }
  if (heading == EAST)
  {
    if (maze_get_char(row + 1, column + 1) == '#')
    {
      return true;
    }
  }
  if (heading == SOUTH)
  {
    if (maze_get_char(row, column - 1) == '#')
    {
      return true;
    }
  }
  if (heading == WEST)
  {
    if (maze_get_char(row - 1, column) == '#')
    {
      return true;
    }
  }
  // return false if there is no # within the given area.
  return false;
}