var fs = require('fs'),
    path = require('path');

/**
 * find all files or subdirs (recursive) and pass to callback fn
 *
 * @param {string} dir directory in which to recurse files or subdirs
 * @param {string} type type of dir entry to recurse ('file', 'dir', or 'all', defaults to 'file')
 * @param {function(error, <Array.<string>)} callback fn to call when done
 * @example
 * dir.files(__dirname, function(err, files) {
 *      if (err) throw err;
 *      console.log('files:', files);
 *  });
 */
exports.files = function files(dir, type, callback, /* used internally */ ignoreType) {

    var pending,
        results = {
            files: [],
            dirs: []
        };
    var done = function() {
        if (ignoreType || type === 'all') {
            callback(null, results);
        } else {
            callback(null, results[type + 's']);
        }
    };

    var getStatHandler = function(statPath) {
        return function(err, stat) {
            if (err) return callback(err);
            if (stat && stat.isDirectory() && stat.mode !== 17115) {
                if (type !== 'file') {
                    results.dirs.push(statPath);
                }
                files(statPath, type, function(err, res) {
                    if (err) return callback(err);
                    if (type === 'all') {
                        results.files = results.files.concat(res.files);
                        results.dirs = results.dirs.concat(res.dirs);
                    } else if (type === 'file') {
                        results.files = results.files.concat(res.files);
                    } else {
                        results.dirs = results.dirs.concat(res.dirs);
                    }
                    if (!--pending) done();
                }, true);
            } else {
                if (type !== 'dir') {
                    results.files.push(statPath);
                }
                // should be the last statement in statHandler
                if (!--pending) done();
            }
        };
    };

    if (typeof type !== 'string') {
        ignoreType = callback;
        callback = type;
        type = 'file';
    }

    if (fs.statSync(dir).mode !== 17115) {
        fs.readdir(dir, function(err, list) {
            if (err) return callback(err);
            pending = list.length;
            if (!pending) return done();
            for (var file, i = 0, l = list.length; i < l; i++) {
                file = path.join(dir, list[i]);
                fs.stat(file, getStatHandler(file));
            }
        });
    } else {
        return done();
    }
};


/**
 * find all files and subdirs in  a directory (recursive) and pass them to callback fn
 *
 * @param {string} dir directory in which to recurse files or subdirs
 * @param {boolean} combine whether to combine both subdirs and filepaths into one array (default false)
 * @param {function(error, Object.<<Array.<string>, Array.<string>>)} callback fn to call when done
 * @example
 * dir.paths(__dirname, function (err, paths) {
 *     if (err) throw err;
 *     console.log('files:', paths.files);
 *     console.log('subdirs:', paths.dirs);
 * });
 * dir.paths(__dirname, true, function (err, paths) {
 *      if (err) throw err;
 *      console.log('paths:', paths);
 * });
 */
exports.paths = function paths(dir, combine, callback) {

    var type;

    if (typeof combine === 'function') {
        callback = combine;
        combine = false;
    }

    exports.files(dir, 'all', function(err, results) {
        if (err) return callback(err);
        if (combine) {

            callback(null, results.files.concat(results.dirs));
        } else {
            callback(null, results);
        }
    });
};


/**
 * find all subdirs (recursive) of a directory and pass them to callback fn
 *
 * @param {string} dir directory in which to find subdirs
 * @param {string} type type of dir entry to recurse ('file' or 'dir', defaults to 'file')
 * @param {function(error, <Array.<string>)} callback fn to call when done
 * @example
 * dir.subdirs(__dirname, function (err, paths) {
 *      if (err) throw err;
 *      console.log('files:', paths.files);
 *      console.log('subdirs:', paths.dirs);
 * });
 */
exports.subdirs = function subdirs(dir, callback) {
    exports.files(dir, 'dir', function(err, subdirs) {
        if (err) return callback(err);
        callback(null, subdirs);
    });
};