// pichat.js

var Nick = null;

function handleMsgError(resp) {
    var respText = resp.responseText ? resp.responseText.trim() : false;
    if (respText  == 'UNKNOWN_USER') {
        alert("Can't send message! Please login.");
    } else if (respText) {
        alert("Cannot send message! (" + respText + ")");
    } else {
        alert("Cannot send message!");
    }
}

function escapeHtml(txt) {
    if (!txt) {
        return ""
    } else {
        return $("<span>").text(txt).html();
    }
}

function buildUserDiv(user) {
    return '<div>' + escapeHtml(user) + '</div>';
}

// http://stackoverflow.com/questions/37684/replace-url-with-html-links-javascript
function linkify(text) {
    var exp = /(\b(https?|ftp|file):\/\/[-A-Z0-9+&@#\/%?=~_|!:,.;]*[-A-Z0-9+&@#\/%=~_|])/gi;
    return text.replace(exp,"<a href='$1'>$1</a>"); 
}

// http://snippets.dzone.com/posts/show/6995
var URLRegex = /((http\:\/\/|https\:\/\/|ftp\:\/\/)|(www\.))+(\w+:{0,1}\w*@)?(\S+)(:[0-9]+)?(\/|\/([\w#!:.?+=&%@!\-\/]))?/i;
var PicRegex = /\.(jpg|jpeg|png|gif|bmp)$/i;

function buildMessageDiv(msg) {
    function buildContent(content) {
        var match = URLRegex.exec(content)
        if (match && PicRegex.test(match[0])) {
            return '<a href="' + match[0] + '" target="_blank">'
                + '<img src="'+ match[0] + '" /></a>';
        } else {
            return linkify(escapeHtml(msg.content));
        }
    }    
    return '<div class="msgDiv"><b>' + escapeHtml(msg.nick) + ': </b>'
        + buildContent(msg.content) + '</div>';
}

function submitMessage() {
    var content = $('#msgInput').val();
    var msg = { 'nick': Nick, 'content': content,  'timestamp': new Date() };
    if (content ==  '') { return; }

    var shouldScroll = isScrolledToBottom($('#messageList')[0]);

    $('#messageList').append($(buildMessageDiv(msg)));
    $('#msgInput').val('');

    if (shouldScroll) {
        scrollToBottom($('#messageList')[0]);
    }

    var onSuccess = function() {};
    var onError = function(resp, textStatus, errorThrown) {
        
        handleMsgError(resp);
    };

   $.ajax({
       type: 'GET',
       timeout: 5000,
       url: 'msg',
       data: {'content': content },
       cache: false,
       dataType: 'json',
       success: onSuccess,
       error: onError       
   });
}

function ifEnter(fn) {
    return function(e) {
        if (e.keyCode == 13) { fn(); }
    };
}

function isScrolledToBottom(div) {
    return Math.abs(div.scrollTop - (div.scrollHeight - div.offsetHeight)) <= 3;
}

function scrollToBottom(div) {
    div.scrollTop = div.scrollHeight;
}

function refresh() {
    var onSuccess = function(json) {        
        if (json.messages.length > 0) {
            var shouldScroll = isScrolledToBottom($('#messageList')[0]);

            // Ignore our own messages
            var filterFunc = function(m) { return m.nick != Nick };
            var msgStr = $.map($.grep(json.messages, filterFunc),
                               buildMessageDiv).join('');
            $('#messageList').append(msgStr);

            if (shouldScroll) {
                scrollToBottom($('#messageList')[0]);
            }
        }
        $("#userList").html($.map(json.users, buildUserDiv).join(''));
    };

    var onError = function(resp, textStatus, errorThrown) {};

    $.ajax({
        type: 'GET',
        timeout: 5000,
        url: 'refresh',
        cache: false,
        dataType: 'json',
        success: onSuccess,
        error: onError       
    });
}



function init() {
    var onSuccess = function(json) {
        $('#loadingbox').hide();
        Nick = json.nick;

        $('#nickspan').text(Nick);
        $('#welcomebar').show();
        
        var msgStr = $.map(json.messages, buildMessageDiv).join('');
        $('#messageList').append(msgStr);        
        $("#userList").html($.map(json.users, buildUserDiv).join(''));
        $('#nickInput, #nickSubmit, #msgInput, #msgSubmit').removeAttr('disabled');
        
        // Delay scrolling by .5 seconds so images can start loading.
        setTimeout(scrollToBottom, 500, $('#messageList')[0]);
        setInterval(refresh, 1000);
    };

    var onError = function(resp, textStatus, errorThrown) {
        alert("Error connecting to chat server!");
    };
    
    $.ajax({
        type: 'GET',
        timeout: 5000,
        url: 'init',
        cache: false,
        dataType: 'json',
        success: onSuccess,
        error: onError
    });

    $('#msgInput').keyup(ifEnter(submitMessage));
    $('#msgSubmit').click(submitMessage);
}