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 *
 * Copyright (c) 2012, Ajax.org B.V.
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 *       notice, this list of conditions and the following disclaimer.
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 *       notice, this list of conditions and the following disclaimer in the
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 *       names of its contributors may be used to endorse or promote products
 *       derived from this software without specific prior written permission.
 *
 * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS "AS IS" AND
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define(function (require, exports, module) {
    "use strict";

    var oop = require("../../lib/oop");
    var BaseFoldMode = require("./fold_mode").FoldMode;
    var Range = require("../../range").Range;
    var TokenIterator = require("../../token_iterator").TokenIterator;

    var FoldMode = exports.FoldMode = function () {
    };

    oop.inherits(FoldMode, BaseFoldMode);

    (function () {

        this.foldingStartMarker = /^\s*\\(begin)|(section|subsection|paragraph)\b|{\s*$/;
        this.foldingStopMarker = /^\s*\\(end)\b|^\s*}/;

        this.getFoldWidgetRange = function (session, foldStyle, row) {
            var line = session.doc.getLine(row);
            var match = this.foldingStartMarker.exec(line);
            if (match) {
                if (match[1])
                    return this.latexBlock(session, row, match[0].length - 1);
                if (match[2])
                    return this.latexSection(session, row, match[0].length - 1);

                return this.openingBracketBlock(session, "{", row, match.index);
            }

            var match = this.foldingStopMarker.exec(line);
            if (match) {
                if (match[1])
                    return this.latexBlock(session, row, match[0].length - 1);

                return this.closingBracketBlock(session, "}", row, match.index + match[0].length);
            }
        };

        this.latexBlock = function (session, row, column) {
            var keywords = {
                "\\begin": 1,
                "\\end": -1
            };

            var stream = new TokenIterator(session, row, column);
            var token = stream.getCurrentToken();
            if (!token || !(token.type == "storage.type" || token.type == "constant.character.escape"))
                return;

            var val = token.value;
            var dir = keywords[val];

            var getType = function () {
                var token = stream.stepForward();
                var type = token.type == "lparen" ? stream.stepForward().value : "";
                if (dir === -1) {
                    stream.stepBackward();
                    if (type)
                        stream.stepBackward();
                }
                return type;
            };
            var stack = [getType()];
            var startColumn = dir === -1 ? stream.getCurrentTokenColumn() : session.getLine(row).length;
            var startRow = row;

            stream.step = dir === -1 ? stream.stepBackward : stream.stepForward;
            while (token = stream.step()) {
                if (!token || !(token.type == "storage.type" || token.type == "constant.character.escape"))
                    continue;
                var level = keywords[token.value];
                if (!level)
                    continue;
                var type = getType();
                if (level === dir)
                    stack.unshift(type);
                else if (stack.shift() !== type || !stack.length)
                    break;
            }

            if (stack.length)
                return;

            var row = stream.getCurrentTokenRow();
            if (dir === -1)
                return new Range(row, session.getLine(row).length, startRow, startColumn);
            stream.stepBackward();
            return new Range(startRow, startColumn, row, stream.getCurrentTokenColumn());
        };

        this.latexSection = function (session, row, column) {
            var keywords = ["\\subsection", "\\section", "\\begin", "\\end", "\\paragraph"];

            var stream = new TokenIterator(session, row, column);
            var token = stream.getCurrentToken();
            if (!token || token.type != "storage.type")
                return;

            var startLevel = keywords.indexOf(token.value);
            var stackDepth = 0
            var endRow = row;

            while (token = stream.stepForward()) {
                if (token.type !== "storage.type")
                    continue;
                var level = keywords.indexOf(token.value);

                if (level >= 2) {
                    if (!stackDepth)
                        endRow = stream.getCurrentTokenRow() - 1;
                    stackDepth += level == 2 ? 1 : -1;
                    if (stackDepth < 0)
                        break
                } else if (level >= startLevel)
                    break;
            }

            if (!stackDepth)
                endRow = stream.getCurrentTokenRow() - 1;

            while (endRow > row && !/\S/.test(session.getLine(endRow)))
                endRow--;

            return new Range(
                row, session.getLine(row).length,
                endRow, session.getLine(endRow).length
            );
        };

    }).call(FoldMode.prototype);

});
