/**
 * File system based on storage provider
 */

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

module.exports = FileSystemProvider;

function FileSystemProvider(options) {
    options = options || {};
    this.root = options.root;
    var stat = fs.statSync(this.root);
    if (!stat.isDirectory()) {
        throw new Error('Invalid directory: ' + this.root);
    }
}

var namePattern = new RegExp('[^' + path.sep + '/]+');

function validateName(name, cb) {
    if (!name) {
        cb && process.nextTick(cb.bind(null, new Error('Invalid name: ' + name)));
        return false;
    }
    var match = namePattern.exec(name);
    if (match && match.index === 0 && match[0].length === name.length) {
        return true;
    } else {
        cb && process.nextTick(cb.bind(null, new Error('Invalid name: ' + name)));
        return false;
    }
}

// Container related functions
FileSystemProvider.prototype.getContainers = function (cb) {
    var self = this;
    fs.readdir(self.root, function (err, files) {
        var dirs = [];
        var tasks = [];
        files.forEach(function (f) {
            tasks.push(fs.stat.bind(null, path.join(self.root, f)));
        });
        async.parallel(tasks, function (err, stats) {
            if (err) {
                cb && cb(err);
            } else {
                stats.forEach(function (stat, index) {
                    if (stat.isDirectory()) {
                        dirs.push(files[index]);
                    }
                });
                cb && cb(err, dirs);
            }
        });
    });
}

FileSystemProvider.prototype.createContainer = function (options, cb) {
    var name = options.name;
    var mode = options.mode || 0777;
    validateName(name, cb) && fs.mkdir(path.join(this.root, name), options, cb);
}

FileSystemProvider.prototype.destroyContainer = function (containerName, cb) {
    if(!validateName(containerName, cb)) return;

    var dir = path.join(this.root, containerName);
    fs.readdir(dir, function (err, files) {
        var tasks = [];
        files.forEach(function (f) {
            tasks.push(fs.unlink.bind(null, path.join(dir, f)));
        });
        async.parallel(tasks, function (err) {
            if (err) {
                cb && cb(err);
            } else {
                fs.rmdir(dir, cb);
            }
        });
    });
}

FileSystemProvider.prototype.getContainer = function (containerName, cb) {
    if(!validateName(containerName, cb)) return;
    var dir = path.join(this.root, containerName);
    fs.stat(dir, cb);
}


// File related functions
FileSystemProvider.prototype.upload = function (options, cb) {
    var container = options.container;
    if(!validateName(container, cb)) return;
    var file = options.remote;
    if(!validateName(file, cb)) return;
    var filePath = path.join(this.root, container, file);

    var fileOpts = {flags: 'w+',
        encoding: null,
        mode: 0666 };

    return fs.createWriteStream(filePath, fileOpts);
}

FileSystemProvider.prototype.download = function (options, cb) {
    var container = options.container;
    if(!validateName(container, cb)) return;
    var file = options.remote;
    if(!validateName(file, cb)) return;

    var filePath = path.join(this.root, container, file);

    var fileOpts = {flags: 'r',
        autoClose: true };

    return fs.createReadStream(filePath, fileOpts);

}

FileSystemProvider.prototype.getFiles = function (container, cb) {
    if(!validateName(container, cb)) return;
    var dir = path.join(this.root, container);
    fs.readdir(dir, function (err, files) {
        var dirs = [];
        var tasks = [];
        files.forEach(function (f) {
            tasks.push(fs.stat.bind(null, path.join(dir, f)));
        });
        async.parallel(tasks, function (err, stats) {
            if (err) {
                cb && cb(err);
            } else {
                stats.forEach(function (stat, index) {
                    if (stat.isFile()) {
                        dirs.push(files[index]);
                    }
                });
                cb && cb(err, dirs);
            }
        });
    });

}

FileSystemProvider.prototype.getFile = function (container, file, cb) {
    if(!validateName(container, cb)) return;
    if(!validateName(file, cb)) return;
    var filePath = path.join(this.root, container, file);
    fs.stat(filePath, cb);
}

FileSystemProvider.prototype.removeFile = function (container, file, cb) {
    if(!validateName(container, cb)) return;
    if(!validateName(file, cb)) return;

    var filePath = path.join(this.root, container, file);
    fs.unlink(filePath, cb);
}