$.autocomplete = function(input, options) {
    // Create a link to self
    var me = this;

    // Create jQuery object for input element
    var $input = $(input).attr("autocomplete", "off");;

    // Apply inputClass if necessary
    if (options.inputClass) $input.addClass(options.inputClass);

    // Create results
    var results = document.createElement("div");
    // Create jQuery object for results
    var $results = $(results);
    // Set default values for results
    var pos = findPos(input);
    $results.hide().addClass(options.resultsClass).css({
        position: "absolute",
        top: (pos.y + input.offsetHeight) + "px",
        left: pos.x + "px"
    });
    // Add to body element
    $("body").append(results);

    input.autocompleter = me;
    input.lastSelected = $input.val();

    var timeout = null;
    var prev = "";
    var active = -1;
    var cache = {};
    var keyb = false;

    $input
    .keydown(function(e) {
        switch(e.keyCode) {
            case 38: // up
                e.preventDefault();
                moveSelect(-1);
                break;
            case 40: // down
                e.preventDefault();
                moveSelect(1);
                break;
            case 9:  // tab
            case 13: // return
                if (selectCurrent()) {
                    e.preventDefault();
                }
                break;
            default:
                active = -1;
                if (timeout) clearTimeout(timeout);
                timeout = setTimeout(onChange, options.delay);
                break;
        }
    })
    .blur(function() {
        hideResults();
    });

    hideResultsNow();

    function onChange() {
        var v = $input.val();
        if (v == prev) return;
        prev = v;
        if (v.length >= options.minChars) {
            $input.addClass(options.loadingClass);
            requestData(v);
        } else {
            $input.removeClass(options.loadingClass);
            $results.hide();
        }
    };

    function moveSelect(step) {

        var lis = $("li", results);
        if (!lis) return;

        active += step;

        if (active < 0) {
            active = 0;
        } else if (active >= lis.size()) {
            active = lis.size() - 1;
        }

        lis.removeClass("over");

        $(lis[active]).addClass("over");

        // Weird behaviour in IE
        // if (lis[active] && lis[active].scrollIntoView) {
        //      lis[active].scrollIntoView(false);
        // }

    };

    function selectCurrent() {
        var li = $("li.over", results)[0];
        if (!li) {
            var $li = $("li", results);
            if (options.selectOnly) {
                if ($li.length == 1) li = $li[0];
            } else if (options.selectFirst) {
                li = $li[0];
            }
        }
        if (li) {
            selectItem(li);
            return true;
        } else {
            return false;
        }
    };

    function selectItem(li) {
        if (!li) {
            li = document.createElement("li");
            li.extra = [];
            li.selectValue = "";
        }
        var v = $.trim(li.selectValue ? li.selectValue : li.innerHTML);
        input.lastSelected = v;
        prev = v;
        $results.html("");
        $input.val(v);
        hideResultsNow();
        if (options.onItemSelect) setTimeout(function() { options.onItemSelect(li) }, 1);
    };

    function hideResults() {
        if (timeout) clearTimeout(timeout);
        timeout = setTimeout(hideResultsNow, 200);
    };

    function hideResultsNow() {
        if (timeout) clearTimeout(timeout);
        $input.removeClass(options.loadingClass);
        if ($results.is(":visible")) {
            $results.hide();
        }
        if (options.mustMatch) {
            var v = $input.val();
            if (v != input.lastSelected) {
                selectItem(null);
            }
        }
    };

    function receiveData(q, data) {
        if (data) {
            $input.removeClass(options.loadingClass);
            results.innerHTML = "";
            if ($.browser.msie) {
                // we put a styled iframe behind the calendar so HTML SELECT elements don't show through
                $results.append(document.createElement('iframe'));
            }
            results.appendChild(dataToDom(data));
            $results.show();
        } else {
            hideResultsNow();
        }
    };

    function parseData(data) {
        if (!data) return null;
        var parsed = [];
        var rows = data.split(options.lineSeparator);
        for (var i=0; i < rows.length; i++) {
            var row = $.trim(rows[i]);
            if (row) {
                parsed[parsed.length] = row.split(options.cellSeparator);
            }
        }
        return parsed;
    };

    function dataToDom(data) {
        var ul = document.createElement("ul");
        var num = data.length;
        for (var i=0; i < num; i++) {
            var row = data[i];
            if (!row) continue;
            var li = document.createElement("li");
            if (options.formatItem) {
                li.innerHTML = options.formatItem(row, i, num);
                li.selectValue = row[0];
            } else {
                li.innerHTML = row[0];
            }
            var extra = null;
            if (row.length > 1) {
                extra = [];
                for (var j=1; j < row.length; j++) {
                    extra[extra.length] = row[j];
                }
            }
            li.extra = extra;
            ul.appendChild(li);
            $(li).hover(
                function() { $("li", ul).removeClass("over"); $(this).addClass("over"); },
                function() { $(this).removeClass("over"); }
            ).click(function(e) { e.preventDefault(); e.stopPropagation(); selectItem(this) });
        }
        return ul;
    };

    function requestData(q) {
        if (!options.matchCase) q = q.toLowerCase();
        var data = options.cacheLength ? loadFromCache(q) : null;
        if (data) {
            receiveData(q, data);
        } else {
            $.get(makeUrl(q), function(data) {
                data = parseData(data)
                addToCache(q, data);
                receiveData(q, data);
            });
        }
    };

    function makeUrl(q) {
        var url = options.url + "?q=" + q;
        for (var i in options.extraParams) {
            url += "&" + i + "=" + options.extraParams[i];
        }
        return url;
    };

    function loadFromCache(q) {
        if (!q) return null;
        if (cache[q]) return cache[q];
        if (options.matchSubset) {
            for (var i = q.length - 1; i >= options.minChars; i--) {
                var qs = q.substr(0, i);
                var c = cache[qs];
                if (c) {
                    var csub = [];
                    for (var j = 0; j < c.length; j++) {
                        var x = c[j];
                        var x0 = x[0];
                        if (matchSubset(x0, q)) {
                            csub[csub.length] = x;
                        }
                    }
                    return csub;
                }
            }
        }
        return null;
    };

    function matchSubset(s, sub) {
        if (!options.matchCase) s = s.toLowerCase();
        var i = s.indexOf(sub);
        if (i == -1) return false;
        return i == 0 || options.matchContains;
    };

    this.flushCache = function() {
        cache = {};
    };

    this.setExtraParams = function(p) {
        options.extraParams = p;
    };

    function addToCache(q, data) {
        if (!data || !q || !options.cacheLength) return;
        if (!cache.length || cache.length > options.cacheLength) {
            cache = {};
            cache.length = 1; // we know we're adding something
        } else if (!cache[q]) {
            cache.length++;
        }
        cache[q] = data;
    };

    function findPos(obj) {
        var curleft = obj.offsetLeft || 0;
        var curtop = obj.offsetTop || 0;
        while (obj = obj.offsetParent) {
            curleft += obj.offsetLeft
            curtop += obj.offsetTop
        }
        return {x:curleft,y:curtop};
    }
}

$.fn.autocomplete = function(url, options) {
    // Make sure options exists
    options = options || {};
    // Set url as option
    options.url = url;
    // Set default values for required options
    options.inputClass = options.inputClass || "ac_input";
    options.resultsClass = options.resultsClass || "ac_results";
    options.lineSeparator = options.lineSeparator || "\n";
    options.cellSeparator = options.cellSeparator || "|";
    options.minChars = options.minChars || 1;
    options.delay = options.delay || 400;
    options.matchCase = options.matchCase || 0;
    options.matchSubset = options.matchSubset || 1;
    options.matchContains = options.matchContains || 0;
    options.cacheLength = options.cacheLength || 1;
    options.mustMatch = options.mustMatch || 0;
    options.extraParams = options.extraParams || {};
    options.loadingClass = options.loadingClass || "ac_loading";
    options.selectFirst = options.selectFirst || false;
    options.selectOnly = options.selectOnly || false;

    this.each(function() {
        var input = this;
        new $.autocomplete(input, options);
    });

    // Don't break the chain
    return this;
}