// Issues:
//  no comment handling within strings
//  no string concatenation
//  no variable values yet

// Grammar implemented here:
//  bibtex -> (string | preamble | comment | entry)*;
//  string -> '@STRING' '{' key_equals_value '}';
//  preamble -> '@PREAMBLE' '{' value '}';
//  comment -> '@COMMENT' '{' value '}';
//  entry -> '@' key '{' key ',' key_value_list '}';
//  key_value_list -> key_equals_value (',' key_equals_value)*;
//  key_equals_value -> key '=' value;
//  value -> value_quotes | value_braces | key;
//  value_quotes -> '"' .*? '"'; // not quite
//  value_braces -> '{' .*? '"'; // not quite
function BibtexParser() {
    this.pos = 0;
    this.input = "";
    this.entries = {};
    this.strings = {
        JAN: "January",
        FEB: "February",
        MAR: "March",
        APR: "April",
        MAY: "May",
        JUN: "June",
        JUL: "July",
        AUG: "August",
        SEP: "September",
        OCT: "October",
        NOV: "November",
        DEC: "December"
    };
    this.currentKey = "";
    this.currentEntry = "";


    this.setInput = function (t) {
        this.input = t;
    }

    this.getEntries = function () {
        return this.entries;
    }

    this.isWhitespace = function (s) {
        return (s == ' ' || s == '\r' || s == '\t' || s == '\n');
    }

    this.match = function (s) {
        this.skipWhitespace();
        if (this.input.substring(this.pos, this.pos + s.length) == s) {
            this.pos += s.length;
        } else {
            throw "Token mismatch, expected " + s + ", found " + this.input.substring(this.pos);
        }
        this.skipWhitespace();
    }

    this.tryMatch = function (s) {
        this.skipWhitespace();
        if (this.input.substring(this.pos, this.pos + s.length) == s) {
            return true;
        } else {
            return false;
        }
        this.skipWhitespace();
    }

    this.skipWhitespace = function () {
        while (this.isWhitespace(this.input[this.pos])) {
            this.pos++;
        }
        if (this.input[this.pos] == "%") {
            while (this.input[this.pos] != "\n") {
                this.pos++;
            }
            this.skipWhitespace();
        }
    }

    this.value_braces = function () {
        var bracecount = 0;
        this.match("{");
        var start = this.pos;
        while (true) {
            if (this.input[this.pos] == '}' && this.input[this.pos - 1] != '\\') {
                if (bracecount > 0) {
                    bracecount--;
                } else {
                    var end = this.pos;
                    this.match("}");
                    return this.input.substring(start, end);
                }
            } else if (this.input[this.pos] == '{') {
                bracecount++;
            } else if (this.pos == this.input.length - 1) {
                throw "Unterminated value";
            }
            this.pos++;
        }
    }

    this.value_quotes = function () {
        this.match('"');
        var start = this.pos;
        while (true) {
            if (this.input[this.pos] == '"' && this.input[this.pos - 1] != '\\') {
                var end = this.pos;
                this.match('"');
                return this.input.substring(start, end);
            } else if (this.pos == this.input.length - 1) {
                throw "Unterminated value:" + this.input.substring(start);
            }
            this.pos++;
        }
    }

    this.single_value = function () {
        var start = this.pos;
        if (this.tryMatch("{")) {
            return this.value_braces();
        } else if (this.tryMatch('"')) {
            return this.value_quotes();
        } else {
            var k = this.key();
            //if (this.strings[k.toUpperCase()]) {
            if (this.strings[k]) {
                return this.strings[k];
            } else if (k.match("^[0-9]+$")) {
                return k;
            } else {
                throw "Value expected:" + this.input.substring(start);
            }
        }
    }

    this.value = function () {
        var values = [];
        values.push(this.single_value());
        while (this.tryMatch("#")) {
            this.match("#");
            values.push(this.single_value());
        }
        return values.join("");
    }

    this.key = function () {
        var start = this.pos;
        while (true) {
            if (this.pos == this.input.length) {
                throw "Runaway key";
            }

            if (this.input[this.pos].match("[a-zA-Z0-9_:\\./-]")) {
                this.pos++
            } else {
                //return this.input.substring(start, this.pos).toUpperCase();
                return this.input.substring(start, this.pos);
            }
        }
    }

    this.key_equals_value = function () {
        var key = this.key();
        if (this.tryMatch("=")) {
            this.match("=");
            var val = this.value();
            return [key, val];
        } else {
            throw "... = value expected, equals sign missing:" + this.input.substring(this.pos);
        }
    }

    this.key_value_list = function () {
        var kv = this.key_equals_value();
        this.entries[this.currentEntry][kv[0]] = kv[1];
        while (this.tryMatch(",")) {
            this.match(",");
            // fixes problems with commas at the end of a list
            if (this.tryMatch("}")) {
                break;
            }
            kv = this.key_equals_value();
            this.entries[this.currentEntry][kv[0]] = kv[1];
        }
    }

    this.entry_body = function (d) {
        this.currentEntry = this.key();
        this.entries[this.currentEntry] = new Object();
        this.entries[this.currentEntry]["type"] = d;
        this.match(",");
        this.key_value_list();
    }

    this.directive = function () {
        this.match("@");
        return "@" + this.key();
    }

    this.string = function () {
        var kv = this.key_equals_value();
        //this.strings[kv[0].toUpperCase()] = kv[1];
        this.strings[kv[0]] = kv[1];
    }

    this.preamble = function () {
        this.value();
    }

    this.comment = function () {
        this.value(); // this is wrong
    }

    this.entry = function (d) {
        this.entry_body(d);
    }

    this.bibtex = function () {
        while (this.tryMatch("@")) {
            //var d = this.directive().toUpperCase();
            var d = this.directive();
            this.match("{");
            if (d == "@STRING") {
                this.string();
            } else if (d == "@PREAMBLE") {
                this.preamble();
            } else if (d == "@COMMENT") {
                this.comment();
            } else {
                this.entry(d.substr(1).toLowerCase());
            }
            this.match("}");
        }
    }
}

function BibtexDisplay() {
    this.fixValue = function (value) {
        value = value.replace(/\\glqq\s?/g, "„");
        value = value.replace(/\\grqq\s?/g, '”');
        value = value.replace(/\\ /g, ' ');
        value = value.replace(/\\url/g, '');
        value = value.replace(/---/g, '—');
        value = value.replace(/{\\"a}/g, 'ä');
        value = value.replace(/\{\\"o\}/g, 'ö');
        value = value.replace(/{\\"u}/g, 'ü');
        value = value.replace(/{\\"A}/g, 'Ä');
        value = value.replace(/{\\"O}/g, 'Ö');
        value = value.replace(/{\\"U}/g, 'Ü');
        value = value.replace(/\\ss/g, 'ß');
        value = value.replace(/\{(.*?)\}/g, '$1');
        return value;
    }

    this.displayBibtex2 = function (i, o) {
        var b = new BibtexParser();
        b.setInput(i);
        b.bibtex();

        var e = b.getEntries();
        var old = o.find("*");

        for (var item in e) {
            var tpl = $(".bibtex_template").clone().removeClass('bibtex_template');
            tpl.addClass("unused");

            for (var key in e[item]) {

                var fields = tpl.find("." + key.toLowerCase());
                for (var i = 0; i < fields.size(); i++) {
                    var f = $(fields[i]);
                    f.removeClass("unused");
                    var value = this.fixValue(e[item][key]);
                    if (f.is("a")) {
                        f.attr("href", value);
                    } else {
                        var currentHTML = f.html() || "";
                        if (currentHTML.match("%")) {
                            // "complex" template field
                            f.html(currentHTML.replace("%", value));
                        } else {
                            // simple field
                            f.html(value);
                        }
                    }
                }
            }

            var emptyFields = tpl.find("span .unused");
            emptyFields.each(function (key, f) {
                if (f.innerHTML.match("%")) {
                    f.innerHTML = "";
                }
            });

            o.append(tpl);
            tpl.show();
        }

        old.remove();
    }


    this.displayBibtex = function (input, output) {
        // parse bibtex input
        var b = new BibtexParser();
        b.setInput(input);
        b.bibtex();

        // save old entries to remove them later
        var old = output.find("*");

        // iterate over bibTeX entries
        var entries = b.getEntries();
        for (var entryKey in entries) {
            var entry = entries[entryKey];

            // find template
            var tpl = $(".bibtex_template").clone().removeClass('bibtex_template');

            // find all keys in the entry
            var keys = [];
            for (var key in entry) {
                //keys.push(key.toUpperCase());
                keys.push(key);
            }

            // find all ifs and check them
            var removed = false;
            do {
                // find next if
                var conds = tpl.find(".if");
                if (conds.size() == 0) {
                    break;
                }

                // check if
                var cond = conds.first();
                cond.removeClass("if");
                var ifTrue = true;
                var classList = cond.attr('class').split(' ');
                $.each(classList, function (index, cls) {
                    //if (keys.indexOf(cls.toUpperCase()) < 0) {
                    if (keys.indexOf(cls) < 0) {
                        ifTrue = false;
                    }
                    cond.removeClass(cls);
                });

                // remove false ifs
                if (!ifTrue) {
                    cond.remove();
                }
            } while (true);

            // fill in remaining fields
            for (var index in keys) {
                var key = keys[index];
                var value = entry[key] || "";
                tpl.find("span:not(a)." + key.toLowerCase()).html(this.fixValue(value));
                tpl.find("a." + key.toLowerCase()).attr('href', this.fixValue(value));
            }

            output.append(tpl);
            tpl.show();
        }

        // remove old entries
        old.remove();
    }

}

function bibtex_js_draw() {
    $(".bibtex_template").hide();
//  (new BibtexDisplay()).displayBibtex($("#bibtex_input").val(), $("#bibtex_display"));
}

// check whether or not jquery is present
//if (typeof jQuery == 'undefined') {
//    // an interesting idea is loading jquery here. this might be added
//    // in the future.
//    console.error("Please include jquery in all pages using bibtex_js!");
//} else {
//    // draw bibtex when loaded
//    $(document).ready(function () {
//        // check for template, add default
//        if ($(".bibtex_template").size() == 0) {
//            $("body").append("<div class=\"bibtex_template\"><div class=\"if author\" style=\"font-weight: bold;\">\n  <span class=\"if year\">\n    <span class=\"year\"></span>, \n  </span>\n  <span class=\"author\"></span>\n  <span class=\"if url\" style=\"margin-left: 20px\">\n    <a class=\"url\" style=\"color:black; font-size:10px\">(view online)</a>\n  </span>\n</div>\n<div style=\"margin-left: 10px; margin-bottom:5px;\">\n  <span class=\"title\"></span>\n</div></div>");
//        }
//
//        bibtex_js_draw();
//    });
//}