// CodeMirror, copyright (c) by Marijn Haverbeke and others
// Distributed under an MIT license: https://codemirror.net/5/LICENSE

(function (mod) {
    if (typeof exports == "object" && typeof module == "object") // CommonJS
        mod(require("../../lib/codemirror"));
    else if (typeof define == "function" && define.amd) // AMD
        define(["../../lib/codemirror"], mod);
    else // Plain browser env
        mod(CodeMirror);
})(function (CodeMirror) {
    "use strict";

    CodeMirror.registerHelper("fold", "markdown", function (cm, start) {
        var maxDepth = 100;

        function isHeader(lineNo) {
            var tokentype = cm.getTokenTypeAt(CodeMirror.Pos(lineNo, 0));
            return tokentype && /\bheader\b/.test(tokentype);
        }

        function headerLevel(lineNo, line, nextLine) {
            var match = line && line.match(/^#+/);
            if (match && isHeader(lineNo)) return match[0].length;
            match = nextLine && nextLine.match(/^[=\-]+\s*$/);
            if (match && isHeader(lineNo + 1)) return nextLine[0] == "=" ? 1 : 2;
            return maxDepth;
        }

        var firstLine = cm.getLine(start.line), nextLine = cm.getLine(start.line + 1);
        var level = headerLevel(start.line, firstLine, nextLine);
        if (level === maxDepth) return undefined;

        var lastLineNo = cm.lastLine();
        var end = start.line, nextNextLine = cm.getLine(end + 2);
        while (end < lastLineNo) {
            if (headerLevel(end + 1, nextLine, nextNextLine) <= level) break;
            ++end;
            nextLine = nextNextLine;
            nextNextLine = cm.getLine(end + 2);
        }

        return {
            from: CodeMirror.Pos(start.line, firstLine.length),
            to: CodeMirror.Pos(end, cm.getLine(end).length)
        };
    });

});
