/*
 * js.js
 * Neighbourhood Fix-It JavaScript
 * 
 * TODO
 * Run all this onDocumentReady rather than onLoad
 * Investigate jQuery
 * Stop annoying flickers/map spasms when dragging
 * Tidy it all up
 * Selection of pin doesn't really need a server request, but I don't really care
 * 
 */


window.onload = onLoad;

// I love the global
var tile_x = 0;
var tile_y = 0;
var tilewidth = 254;
var tileheight = 254;

var in_drag;
function onLoad() {
    var compass = document.getElementById('compass');
    if (compass) {
        var points = compass.getElementsByTagName('a');
        points[1].onclick = function() { pan(0, tileheight); return false; };
        points[3].onclick = function() { pan(tilewidth, 0); return false; };
        points[4].onclick = function() { pan(-tilewidth, 0); return false; };
        points[6].onclick = function() { pan(0, -tileheight); return false; };
        points[0].onclick = function() { pan(tilewidth, tileheight); return false; };
        points[2].onclick = function() { pan(-tilewidth, tileheight); return false; };
        points[5].onclick = function() { pan(tilewidth, -tileheight); return false; };
        points[7].onclick = function() { pan(-tilewidth, -tileheight); return false; };
    }

    var drag = document.getElementById('drag');
    var form = document.getElementById('mapForm');
    if (form) form.onsubmit = form_submit;
    if (drag) {
        var inputs = drag.getElementsByTagName('input');
        update_tiles(0, 0, false, true);
        var map = document.getElementById('map');
        map.onmousedown = drag_start;
        document.onmouseout = drag_end_out;
    }
}

/*
    var targ = '';
    if (!e) e = window.event;
    if (e.target) targ = e.target;
    else if (e.srcElement) targ = e.srcElement;
    if (targ.nodeType == 3) // defeat Safari bug
        targ = targ.parentNode;
*/

function form_submit() {
    this.x.value = x + 2;
    this.y.value = y + 2;
    return true;
}

function image_rotate(i, j, x, y) {
    var id = 't' + i + '.' + j;
    var img = document.getElementById(id);
    // img.src = '/i/grey.gif';
    if (x)
        img.style.left = (img.offsetLeft + x*tilewidth) + 'px';
    if (y)
        img.style.top = (img.offsetTop + y*tileheight) + 'px';
}

var myAnim;
function pan(x, y) {
    if (!myAnim || !myAnim.isAnimated()) {
        update_tiles(x, y, true, false);
        myAnim = new YAHOO.util.Motion('drag', { points:{by:[x,y]} }, 1, YAHOO.util.Easing.easeBoth);
        myAnim.animate();
    }
}

function update_tiles(dx, dy, noMove, force) {
    if (!dx && !dy && !force) return;

    var old_drag_x = drag_x;
    var old_drag_y = drag_y;
    drag_x += dx;
    drag_y += dy;

    if (!noMove) {
        var drag = document.getElementById('drag');
        drag.style.left = drag_x + 'px';
        drag.style.top = drag_y + 'px';
    }

    var horizontal = Math.floor(old_drag_x/tilewidth) - Math.floor(drag_x/tilewidth);
    var vertical = Math.floor(old_drag_y/tileheight) - Math.floor(drag_y/tileheight);
    if (!horizontal && !vertical && !force) return;

    for (var j=0; j<horizontal; j++) {
        for (var i=0; i<6; i++) { image_rotate(i, mod(j + tile_x, 6),  6, 0); }
    }
    for (var j=horizontal; j<0; j++) {
        for (var i=0; i<6; i++) { image_rotate(i, mod(j + tile_x, 6), -6, 0); }
    }
    for (var i=0; i<vertical; i++) {
        for (var j=0; j<6; j++) { image_rotate(mod(i + tile_y, 6), j, 0,  6); }
    }
    for (var i=vertical; i<0; i++) {
        for (var j=0; j<6; j++) { image_rotate(mod(i + tile_y, 6), j, 0, -6); }
    }

    x += horizontal;
    tile_x = mod((tile_x + horizontal), 6);
    y -= vertical;
    tile_y = mod((tile_y + vertical), 6);

    var url = '/tilma/tileserver/10k-full-london/' + x + '-' + (x+5) + ',' + y + '-' + (y+5) + '/JSON';
    var req = YAHOO.util.Connect.asyncRequest('GET', url, async_response);
}

var async_response = {
    success: urls_loaded,
    failure: urls_not_loaded
};

function urls_not_loaded(o) {
}

// Load 6x6 grid of tiles around current 2x2
function urls_loaded(o) {
    var tiles = eval(o.responseText);
    var drag = document.getElementById('drag');
    for (var i=0; i<6; i++) {
        var ii = (i + tile_y) % 6;
        for (var j=0; j<6; j++) {
            var jj = (j + tile_x) % 6;
            var id = 't'+ii+'.'+jj;
            var xx = x+j;
            var yy = y+5-i;
            var img = document.getElementById(id);
            if (img) {
                if (!img.galleryimg) { img.galleryimg = false; }
                img.onclick = drag_check;
                var new_src = 'http://tilma.mysociety.org/tileserver/10k-full-london/' + tiles[i][j];
                if (img.src != new_src) img.src = new_src;
                img.name = 'tile_' + xx + '.' + yy;
                continue;
            }
            img = document.createElement('input');
            img.type = 'image';
            img.src = 'http://tilma.mysociety.org/tileserver/10k-full-london/' + tiles[i][j];
            img.name = 'tile_' + xx + '.' + yy;
            img.id = id;
            img.onclick = drag_check;
            img.style.position = 'absolute';
            img.style.width = tilewidth + 'px';
            img.style.height = tileheight + 'px';
            img.style.top = ((ii-2)*tileheight) + 'px';
            img.style.left = ((jj-2)*tilewidth) + 'px';
            img.galleryimg = false;
            img.alt = 'Loading...';
            drag.appendChild(img);
        }
    }
}

// Floor always closer to 0
function floor(n) {
    if (n>=0) return Math.floor(n);
    return Math.ceil(n);
}

// Mod always to positive result
function mod(m, n) {
    if (m>=0) return m % n;
    return (m % n) + n;
}

/* Dragging */

var last_mouse_pos = {};
var mouse_pos = {};

function drag_move(e) {
    if (!e) var e = window.event;
    var point = get_posn(e);
    if (point == mouse_pos) return false;
    in_drag = true;
    last_mouse_pos = mouse_pos;
    mouse_pos = point;
    var dx = mouse_pos.x-last_mouse_pos.x;
    var dy = mouse_pos.y-last_mouse_pos.y;
    update_tiles(dx, dy, false, false);
    return false;
}

function drag_check() {
    if (in_drag) {
        in_drag=false;
        return false;
    }
    return true;
}

function drag_start(e) {
    if (!e) var e = window.event;
    mouse_pos = get_posn(e);
    setCursor('move');
    document.onmousemove = drag_move;
    document.onmouseup = drag_end;
    return false;
}

function drag_end(e) {
    if (!e) var e = window.event;
    if (e.stopPropagation) e.stopPropagation();
    document.onmousemove = null;
    document.onmouseup = null;
    setCursor('crosshair');
    //if (in_drag) return false; // XXX I don't understand!
}

function drag_end_out(e) {
    if (!e) var e = window.event;
    var relTarg;
    if (e.relatedTarget) { relTarg = e.relatedTarget; }
    else if (e.toElement) { relTarg = e.toElement; }
    if (!relTarg) {
        // mouse out to unknown = left the window?
        document.onmousemove = null;
        document.onmouseup = null;
        setCursor('crosshair');
    }
    return false;
}

/* Called every mousemove, so on first call, overwrite itself with quicker version */
function get_posn(ev) {
    var posx, posy;
    if (ev.pageX || ev.pageY) {
        get_posn = function(e) {
            return { x: e.pageX, y: e.pageY };
        };
    } else if (ev.clientX || ev.clientY) {
        get_posn = function(e) {
            return {
                x: e.clientX + document.body.scrollLeft + document.documentElement.scrollLeft,
                y: e.clientY + document.body.scrollTop + document.documentElement.scrollTop
            };
        };
    } else {
        get_posn = function(e) {
            return { x: undef, y: undef };
        };
    }
    return get_posn(ev);
}

function setCursor(s) {
    var drag = document.getElementById('drag');
    var inputs = drag.getElementsByTagName('input');
    for (var i=0; i<inputs.length; i++) {
        inputs[i].style.cursor = s;
    }
}