// Maze generation based on http://rosettacode.org/wiki/Maze_generation#JavaScript

var Drone = require('drone');
// User-facing code starts here
// Example: Try /js maze(5,7)
Drone.extend( function maze( size_x, size_y ) {
  m = maze_make(size_x, size_y);
  if (m.x > 0 && m.y > 0) {
    maze_draw(maze_display(m), this);
  }
} );
// 
// Implementation 
//
function maze_make(x,y) {
  var n=x*y-1;
  if (n<0) {
    echo("illegal maze dimensions");
    return ({x: 0, y: 0});
  }
  var horiz=[]; for (var j= 0; j<x+1; j++) horiz[j]= [];
  var verti=[]; for (var j= 0; j<y+1; j++) verti[j]= [];
  var here= [Math.floor(Math.random()*x), Math.floor(Math.random()*y)];
  var path= [here];
  var unvisited= [];
  for (var j= 0; j<x+2; j++) {
    unvisited[j]= [];
    for (var k= 0; k<y+1; k++)
      unvisited[j].push(j>0 && j<x+1 && k>0 && (j != here[0]+1 || k != here[1]+1));
  }
  while (0<n) {
    var potential= [[here[0]+1, here[1]], [here[0],here[1]+1],
        [here[0]-1, here[1]], [here[0],here[1]-1]];
    var neighbors= [];
    for (var j= 0; j < 4; j++)
      if (unvisited[potential[j][0]+1][potential[j][1]+1])
        neighbors.push(potential[j]);
    if (neighbors.length) {
      n= n-1;
      next= neighbors[Math.floor(Math.random()*neighbors.length)];
      unvisited[next[0]+1][next[1]+1]= false;
      if (next[0] == here[0])
        horiz[next[0]][(next[1]+here[1]-1)/2]= true;
      else 
        verti[(next[0]+here[0]-1)/2][next[1]]= true;
      path.push(here= next);
    } else 
      here= path.pop();
  }
  return ({x: x, y: y, horiz: horiz, verti: verti});
}

function maze_display(m) {
  var text= [];
  for (var j= 0; j<m.x*2+1; j++) {
    var line= [];
    if (0 == j%2)
      for (var k=0; k<m.y*4+1; k++)
        if (0 == k%4) 
          line[k]= '+';
        else
          if (j>0 && m.verti[j/2-1][Math.floor(k/4)])
            line[k]= ' ';
          else
            line[k]= '-';
    else
      for (var k=0; k<m.y*4+1; k++)
        if (0 == k%4)
          if (k>0 && m.horiz[(j-1)/2][k/4-1])
            line[k]= ' ';
          else
            line[k]= '|';
        else
          line[k]= ' ';
    if (0 == j) line[1]= line[2]= line[3]= ' ';
    if (m.x*2-1 == j) line[4*m.y]= ' ';
    text.push(line.join('')+' \r\n'); // TWEAKED: space added to get an even number of columns
  }
  return text.join('');
}

// ScriptCraft stuff starts here
// Helper function to parse the ASCII art into Drone actions
// You might also consider creating a new maze_display but for now this will do the work
function maze_draw(maze_string, d) {
  // d is the Drone to use
  d.chkpt('maze-start');
  for (var j = 0; j < maze_string.length; j += 2) {
    switch(maze_string.substr(j, 2)) {
    case '  ':
      d.box(0).fwd(); // Make sure to empty this position
      break;
    case '\r\n':
      d.move('maze-start');
      d.right().chkpt('maze-start');
      break;
    default: // '+ ', '+-', '--', '| '
      if (j == 0) {
        d.box(blocks.glowstone,1,2,1); // highlight the maze entry and exit
      } else if (j == maze_string.length - 4) {
        d.box(blocks.glass,1,2,1);
      } else {
        d.box(blocks.oak,1,2,1);
      }
      d.fwd();
    }
  }
}