/* Information used to draw the ships
    */
    var ship =  [[[1,5], [1,2,5], [1,2,3,5], [1,2,3,4,5]], [[6,10], [6,7,10], [6,7,8,10], [6,7,8,9,10]]];
    
    /* Information used to draw sunk ships
    */
    var dead = [[[201,203], [201,202,203], [201,202,202,203], [201,202,202,202,203]], [[204,206], [204,205,206], [204,205,205,206], [204,205,205,205,206]]];
    
    /* Information used to describe ships
     * name, length, number
    */
    var shiptypes = [["Destroyer",2,4],["Frigate",3,3],[ "Cruiser",4,2],[ "Battleship",5,1]];
    
    var gridx = 16, gridy = 16;
    var player = [], computer = [], playersships = [], computersships = [];
    var playerlives = 0, computerlives = 0, playflag=true, statusmsg="";
    
    var commentary;
    
    /* Function to preload all the images, to prevent delays during play
    */
    var preloaded = [];
    function imagePreload() {
        var i,ids = [1,2,3,4,5,6,7,8,9,10,100,101,102,103,201,202,203,204,205,206];
        window.status = "Preloading images...please wait";
        var water = new Image();
        water.src="http://battleships.ws/img/Water-4.jpg";
	var img;
        for (i=0;i<ids.length;++i) {
            img = new Image();
	    img.src = "http://battleships.ws/img/batt"+ids[i]+".gif";
            preloaded[i] = img;
        }
        window.status = "";
    }
    
    /* Function to place the ships in the grid
    */
    function setupPlayer(ispc) {
        var y,x;
        grid = [];
        for (y=0;y<gridx;++y) {
            grid[y] = [];
            for (x=0;x<gridx;++x) {
                grid[y][x] = [100,-1,0];
            }
        }
        
        var shipno = 0;
        var s;
        for (s=shiptypes.length-1;s>=0;--s) {
            var i;
            for (i=0;i<shiptypes[s][2];++i) {
                var d = Math.floor(Math.random()*2);
                var len = shiptypes[s][1], lx=gridx, ly=gridy, dx=0, dy=0;
                if ( d===0) {
                    lx = gridx-len;
                    dx=1;
                }
                else {
                    ly = gridy-len;
                    dy=1;
                }
                var ok;
                do {
                    y = Math.floor(Math.random()*ly);
                    x = Math.floor(Math.random()*lx);
                    var j,cx=x,cy=y;
                    ok = true;
                    for (j=0;j<len;++j) {
                        if (grid[cy][cx][0] < 100) {
                            ok=false;
                            break;
                        }
                        cx+=dx;
                        cy+=dy;
                   }
                } while(!ok);
                cx=x,cy=y;
                for (j=0;j<len;++j) {
                    grid[cy][cx][0] = ship[d][s][j];
                    grid[cy][cx][1] = shipno;
                    grid[cy][cx][2] = dead[d][s][j];
                    cx+=dx;
                    cy+=dy;
                }
                if (ispc) {
                    computersships[shipno] = [s,shiptypes[s][1]];
                    computerlives++;
                }
                else {
                    playersships[shipno] = [s,shiptypes[s][1]];
                    playerlives++;
                }
                shipno++;
           }
        }
        return grid;
    }
    
    /* Function to change an image shown on a grid
    */
    function setImage(y,x,id,ispc) {
        if ( ispc ) {
            computer[y][x][0] = id;
            document.images["pc"+y+"_"+x].src = "img/batt"+id+".gif";
        }
        else {
            player[y][x][0] = id;
            document.images["ply"+y+"_"+x].src = "img/batt"+id+".gif";
       }
    }
    
    /* Function to insert HTML source for a grid
    */
    function showGrid(ispc) {
	var outy = [];
        var out="";
        var y,x;
        for (y=0;y<gridy;++y) {
            out="";
            for (x=0;x<gridx;++x) {
                if ( ispc ) {
                    out = out +'<a href="#" onclick="gridClick('+y+','+x+'); return false;"><img name="pc'+y+'_'+x+'" src="img/Water-4.jpg" width="16" height="16"/></a>';
		} else {
                    if(player[y][x][0] == '100') {
			out = out +'<a href="javascript:void(0);"><img name="ply'+y+'_'+x+'" src="http://battleships.ws/img/Water-4.jpg" width="16" height="16"/></a>';
		    } else {
                        out = out +'<a href="javascript:void(0);"><img name="ply'+y+'_'+x+'" src="http://battleships.ws/img/batt'+player[y][x][0]+'.gif" width="16" height="16"/></a>';
		    }
		}
            }
            outy[y]=out+'<br>';
        }
        out="";
        for (y=0;y<gridy;++y) {
	    out = out + outy[y];
        }
	//alert(out);
        return out;
    }
    
    /* Handler for clicking on the grid
    */
    function gridClick(y,x) {
	    //alert("clicked: "+x+", "+y );
        if ( playflag ) {
            if (computer[y][x][0] < 100) {
	        //explode();
                setImage(y,x,103,true);
                var shipno = computer[y][x][1];
                if ( --computersships[shipno][1] == 0 ) {
                    sinkShip(computer,shipno,true);
                    commentary.innerHTML="You sank my "+shiptypes[computersships[shipno][0]][0]+"!";
                    updateStatus();
                    if ( --computerlives == 0 ) {
                        commentary.innerHTML="You win! Press the Refresh button on\n"+"your browser to play another game.";
                        playflag = false;
                    }
               }
                if ( playflag ) computerMove();
            }
            else if (computer[y][x][0] == 100) {
		//splash();
                setImage(y,x,102,true);
                computerMove();
            }
        }
    }
    
    /* Function to make the computers move. Note that the computer does not cheat, oh no!
    */
    function computerMove() {
        var x,y,pass;
        var sx,sy;
        var selected = false;
    
        /* Make two passes during 'shoot to kill' mode
        */
        for (pass=0;pass<2;++pass) {
            for (y=0;y<gridy && !selected;++y) {
                for (x=0;x<gridx && !selected;++x) {
                    /* Explosion shown at this position
                    */
                    if (player[y][x][0]==103) {
                        sx=x; sy=y;
                        var nup=(y>0 && player[y-1][x][0]<=100);
                        var ndn=(y<gridy-1 && player[y+1][x][0]<=100);
                        var nlt=(x>0 && player[y][x-1][0]<=100);
                        var nrt=(x<gridx-1 && player[y][x+1][0]<=100);
                        if ( pass == 0 ) {
                            /* On first pass look for two explosions
                               in a row - next shot will be inline
                            */
                            var yup=(y>0 && player[y-1][x][0]==103);
                            var ydn=(y<gridy-1 && player[y+1][x][0]==103);
                            var ylt=(x>0 && player[y][x-1][0]==103);
                            var yrt=(x<gridx-1 && player[y][x+1][0]==103);
                            if ( nlt && yrt) { sx = x-1; selected=true; }
                            else if ( nrt && ylt) { sx = x+1; selected=true; }
                            else if ( nup && ydn) { sy = y-1; selected=true; }
                            else if ( ndn && yup) { sy = y+1; selected=true; }
                        }
                        else {
                           /* Second pass look for single explosion -
                               fire shots all around it
                            */
                            if ( nlt ) { sx=x-1; selected=true; }
                            else if ( nrt ) { sx=x+1; selected=true; }
                            else if ( nup ) { sy=y-1; selected=true; }
                            else if ( ndn ) { sy=y+1; selected=true; }
                        }
                    }
                }
            }
        }
        if ( !selected ) {
            /* Nothing found in 'shoot to kill' mode, so we're just taking
               potshots. Random shots are in a chequerboard pattern for
               maximum efficiency, and never twice in the same place
            */
            do{
                sy = Math.floor(Math.random() * gridy);
                sx = Math.floor(Math.random() * gridx/2)*2+sy%2;
            } while( player[sy][sx][0]>100 );
    }
    if (player[sy][sx][0] < 100) {
    /* Hit something */
	//explode();
        setImage(sy,sx,103,false);
        var shipno = player[sy][sx][1];
        if ( --playersships[shipno][1] == 0 ) {
            sinkShip(player,shipno,false);
            commentary.innerHTML="I sank your "+shiptypes[playersships[shipno][0]][0]+"!";
            if ( --playerlives == 0 ) {
                knowYourEnemy();
                commentary.innerHTML="I win! Press the Refresh button on\n"+ "your browser to play another game.";
                playflag = false;
            }
        }
    } else {
        /* Missed */
	//splash();
        setImage(sy,sx,102,false);
        }
    }
    
    /* When whole ship is hit, show it using changed graphics */
    function sinkShip(grid,shipno,ispc) {
        var y,x;
        for (y=0;y<gridx;++y) {
            for (x=0;x<gridx;++x) {
                if ( grid[y][x][1] == shipno )
                    if (ispc) setImage(y,x,computer[y][x][2],true);
                    else setImage(y,x,player[y][x][2],false);
            }
        }
    }
    
    /* Show location of all the computers ships - when player has lost */
    function knowYourEnemy() {
        var y,x;
        for (y=0;y<gridx;++y) {
            for (x=0;x<gridx;++x) {
                if ( computer[y][x][0] == 103 )
                    setImage(y,x,computer[y][x][2],true);
                else if ( computer[y][x][0] < 100 )
                    setImage(y,x,computer[y][x][0],true);
            }
        }
    }
    
    /* Show how many ships computer has left */
    function updateStatus() {
        var f=false,i,s = "Computer has ";
        for (i=0;i<computersships.length;++i) {
            if (computersships[i][1] > 0) {
                if (f) s=s+", "; else f=true;
                s = s + shiptypes[computersships[i][0]][0];
            }
        }
        if (!f) s = s + "nothing left, thanks to you!";
        statusmsg = s;
        window.status = statusmsg;
    }

    function setStatus() {
        window.status = statusmsg;
    }

/*
    function DHTMLSound(surl) {
        document.getElementById("soundspan").innerHTML= '<embed src="'+surl+'" hidden="true" autostart="true" loop="false">';
    }

    function splash() {
        DHTMLSound("sounds/bigpoolsplash.wav");
    }

    function explode() {
        DHTMLSound("http://www.battleships.ws/sounds/implosion2.wav");
    }
    */


 


/* Start the game!
*/
init = function() {
    commentary=document.getElementById("commentary");
    var game=document.getElementById("game");
    imagePreload();
    player = setupPlayer(false);
    computer = setupPlayer(true);
    game.innerHTML="<center><table><tr><td align=center><p class='heading'>COMPUTER'S FLEET</p></td><td align=center><p class='heading'>PLAYER'S FLEET</p></td></tr><tr><td>"+ showGrid(true)+ "</td><td>" + showGrid(false) + "</td></tr></table></center>";
    updateStatus();
    setInterval(setStatus, 500);
};
    
playbattleship = function() {
   init();
};