//This is the image directory
dir = "";

var mines = [];
var shown = [];
var gridx = 16, gridy = 16, maxmines = 40;
var squaresleft, flagsleft;
var elapsedtime;
var playing;
var placeflag;

function keyDown(e) {
if(document.layers)
placeflag = (e.modifiers & Event.CONTROL_MASK) > 0;
else
placeflag = window.event.ctrlKey;
setStatus();
}
function keyUp(e) {
placeflag = false;
setStatus();
}

function newgame() {
// reset state arrays. mines holds the position of each mine. shown keeps
// track of the image shown at each grid location
var y;
for(y = 0; y < gridy; ++y)
{
mines[y] = [false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false];
shown[y] = [0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0];
}

// Place the mines, making sure positions are unique
var m;
for(m = 0; m < maxmines; ++m) {
var x,y;
do {
x = Math.floor(Math.random() * gridx);
y = Math.floor(Math.random() * gridy);
} while(mines[y][x]);
mines[y][x] = true;
}

// initialise game variables
squaresleft = gridy * gridx;
flagsleft = maxmines;
elapsedtime = 0;
playing = true;
placeflag = false;

// insert the grid into the document
buildgrid();

// Set up keypress handlers
if (document.layers)
window.captureEvents(Event.KEYDOWN | Event.KEYUP);
window.onKeyDown = keyDown;
window.onKeyUp = keyUp;

// start the clock
setInterval("ticker()", 1000);
}

// clock tick handler
function ticker() {
if (playing) {
elapsedtime++;
setStatus();
   }
}

// status bar refresh
function setStatus() {
var s = flagsleft + " mines remaining, " + elapsedtime + " seconds. " 
if(placeflag) s = s + " [Ctrl] pressed to place a flag!";
set_status(s);
}

// function to insert all the IMG tags into the document
function buildgrid() {
var s = "";
var x, y;
for(y = 0; y < gridy; ++y) {
for(x = 0; x < gridx; ++x) {
s = s + '<a href="javascript:gridclick(' + y + ',' + x +');">' +
'<img src="' + dir + 'tile0.gif" name="grd'+y+'_'+x+'"></a>'
}
s = s + "<br>";
}
document.write(s);
}

// Function to calculate the number of mines adjacent to a grid location
function surrounding(y,x) {
var count = 0;
if (y > 0 && x > 0 && mines[y-1][x-1]) count++;
if (y > 0 && mines[y-1][x]) count++;
if (y > 0 && x < gridx-1 && mines[y-1][x+1]) count++;
if (x > 0 && mines[y][x-1]) count++;
if (x < gridx-1 && mines[y][x+1]) count++;
if (y < gridy-1 && x > 0 && mines[y+1][x-1]) count++;
if (y < gridy-1 && mines[y+1][x]) count++;
if (y < gridy-1 && x < gridx-1 && mines[y+1][x+1]) count++;
return count;
}

// Recursive function to 'roll back' the grid when user clicks on a tile
// with no surrounding mines
function rollback(y,x) {
if (y >= 0 && y < gridy && x >=0 && x < gridx) {
if (shown[y][x] != 3) {
var c = surrounding(y,x);
shown[y][x] = 3;
squaresleft--;
document.images["grd"+y+"_"+x].src = dir + "blank"+c+".gif";
if (c == 0) {
rollback(y-1,x-1);
rollback(y-1,x);
rollback(y-1,x+1);
rollback(y,x-1);
rollback(y,x+1);
rollback(y+1,x-1);
rollback(y+1,x);
rollback(y+1,x+1);
         }
      }
   }
}

// Function called when player steps on a mine. All mine locations are uncovered
function dead() {
var y, x;
for(y = 0; y < gridy; ++y) {
for(x = 0; x < gridx; ++x) {
if (mines[y][x]) {
if (shown[y][x] != 1) {
document.images["grd"+y+"_"+x].src = dir + "bomb.gif";
   }
}
else if (shown[y][x] == 1) {
document.images["grd"+y+"_"+x].src = dir + "nobomb.gif";
      }
   }
}
alert("Oops! you set off a mine.  Game Over!\n" + 
"Press your browser's 'Refresh' button to play again.");
playing = false;
}

// handler called whenever the grid is clicked
function gridclick(y, x) {
if (playing) {
if (placeflag) {
if (shown[y][x] < 3) {
var s = shown[y][x];
var change = true;
if (s == 1) {
flagsleft++;
squaresleft++;
}
if (flagsleft == 0 && s == 0) {
change = false;
}
else {
if (s == 2) s = 0;
else s++;
if (s == 1) {
flagsleft--;
squaresleft--;
   }
}
if (change) {
shown[y][x] = s;
document.images["grd"+y+"_"+x].src = dir + "tile"+s+".gif";
setStatus();
}
if (squaresleft == 0) {
alert("Well done! you found all the mines in "+elapsedtime+" seconds.\n"+
"Press your browser's 'Refresh' button to play again.");
playing = false;
      }
   }
}

// check not flagged as a mine
else if (shown[y][x] != 1) {
if (mines[y][x]) {
document.images["grd"+y+"_"+x].src = dir + "bomb.gif";
dead();
}
else  {
rollback(y,x);
         }
      }
   }
}

// Start the game
newgame();



//Added by Steve (03/03/04):

function set_status(statustxt){
window.status = statustxt;
show_text(statustxt,'stats')
}

var ns6=document.getElementById&&!document.all
var ie=document.all

function show_text(thetext, whichdiv){
if (ie) eval("document.all."+whichdiv).innerHTML=thetext
else if (ns6) document.getElementById(whichdiv).innerHTML=thetext
}