/**
 * @fileoverview Util class to find config files.
 * @author Aliaksei Shytkin
 * @copyright 2014 Michael McLaughlin. All rights reserved.
 * @copyright 2014 Aliaksei Shytkin. All rights reserved.
 * See LICENSE in root directory for full license.
 */
"use strict";

//------------------------------------------------------------------------------
// Requirements
//------------------------------------------------------------------------------

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

//------------------------------------------------------------------------------
// Helpers
//------------------------------------------------------------------------------

/**
 * Get the entries for a directory. Including a try-catch may be detrimental to
 * function performance, so move it out here a separate function.
 * @param {string} directory The directory to search in.
 * @returns {string[]} The entries in the directory or an empty array on error.
 * @private
 */
function getDirectoryEntries(directory) {
    try {
        return fs.readdirSync(directory);
    } catch (ex) {
        return [];
    }
}

//------------------------------------------------------------------------------
// API
//------------------------------------------------------------------------------

/**
 * FileFinder
 * @constructor
 * @param {...string} arguments The basename(s) of the file(s) to find.
 */
function FileFinder() {
    this.fileNames = Array.prototype.slice.call(arguments);
    this.cache = {};
}

/**
 * Find one instance of a specified file name in directory or in a parent directory.
 * Cache the results.
 * Does not check if a matching directory entry is a file, and intentionally
 * only searches for the first file name in this.fileNames.
 * Is currently used by lib/ignored_paths.js to find an .eslintignore file.
 * @param  {string} directory The directory to start the search from.
 * @returns {string} Path of the file found, or an empty string if not found.
 */
FileFinder.prototype.findInDirectoryOrParents = function(directory) {
    var cache = this.cache,
        child,
        dirs,
        filePath,
        i,
        name,
        names,
        searched;

    if (!directory) {
        directory = process.cwd();
    }

    if (cache.hasOwnProperty(directory)) {
        return cache[directory];
    }

    dirs = [];
    searched = 0;
    name = this.fileNames[0];
    names = Array.isArray(name) ? name : [name];

    (function() {
        while (directory !== child) {
            dirs[searched++] = directory;

            for (var k = 0, found = false; k < names.length && !found; k++) {

                if (getDirectoryEntries(directory).indexOf(names[k]) !== -1 && fs.statSync(path.resolve(directory, names[k])).isFile()) {
                    filePath = path.resolve(directory, names[k]);
                    return;
                }
            }

            child = directory;

            // Assign parent directory to directory.
            directory = path.dirname(directory);
        }
    }());

    for (i = 0; i < searched; i++) {
        cache[dirs[i]] = filePath;
    }

    return filePath || String();
};

/**
 * Find all instances of files with the specified file names, in directory and
 * parent directories. Cache the results.
 * Does not check if a matching directory entry is a file.
 * Searches for all the file names in this.fileNames.
 * Is currently used by lib/config.js to find .eslintrc and package.json files.
 * @param  {string} directory The directory to start the search from.
 * @returns {string[]} The file paths found.
 */
FileFinder.prototype.findAllInDirectoryAndParents = function(directory) {
    var cache = this.cache,
        child,
        dirs,
        name,
        fileNames,
        fileNamesCount,
        filePath,
        i,
        j,
        searched;

    if (!directory) {
        directory = process.cwd();
    }

    if (cache.hasOwnProperty(directory)) {
        return cache[directory];
    }

    dirs = [];
    searched = 0;
    fileNames = this.fileNames;
    fileNamesCount = fileNames.length;

    do {
        dirs[searched++] = directory;
        cache[directory] = [];

        for (i = 0; i < fileNamesCount; i++) {
            name = fileNames[i];

            // convert to an array for easier handling
            if (!Array.isArray(name)) {
                name = [name];
            }

            for (var k = 0, found = false; k < name.length && !found; k++) {

                if (getDirectoryEntries(directory).indexOf(name[k]) !== -1 && fs.statSync(path.resolve(directory, name[k])).isFile()) {
                    filePath = path.resolve(directory, name[k]);
                    found = true;

                    // Add the file path to the cache of each directory searched.
                    for (j = 0; j < searched; j++) {
                        cache[dirs[j]].push(filePath);
                    }
                }
            }

        }
        child = directory;

        // Assign parent directory to directory.
        directory = path.dirname(directory);

        if (directory === child) {
            return cache[dirs[0]];
        }
    } while (!cache.hasOwnProperty(directory));

    // Add what has been cached previously to the cache of each directory searched.
    for (i = 0; i < searched; i++) {
        dirs.push.apply(cache[dirs[i]], cache[directory]);
    }

    return cache[dirs[0]];
};

module.exports = FileFinder;