var SshClient = require('ssh2').Client;

/**
 * @example
 *
 * var sshExpect = require('./sshExpect');
 * sshExpect({
 *    host: '10.79.53.164',
 *    port: 22,
 *    username: 'admin',
 *    password: 'default',
 *    timeout: 6000,
 *    debug: false
 * }, function(stream) {
 *   stream.expect(/[$#]/, function(data, next) {
 *     stream.write('passwd root\n');
 *     next();
 *   });
 *   stream.expect('New password:', function(data, next) {
 *     stream.write('default\n');
 *     next();
 *   });
 *   stream.expect('Retype new password:', function(data, next) {
 *     stream.write('default\n');
 *     next();
 *   });
 *   stream.expect(/[$#]/, function(data, next) {
 *     stream.close();
 *   });
 * }, function(err) {
 *    if (err) throw err;
 * });
 */

module.exports = function sshExpect(config, expectFunc, callback) {

    var tty = config.tty || {};

    var sshc = new SshClient();

    sshc.on('ready', function() {
        sshc.shell({
            rows: tty.rows || 50,
            cols: tty.cols || 200
        }, function(err, stream) {
            if (err) callback(err);

            stream.on('close', function() {
                sshc.end();
            });

            var _data;
            var _expects = [];

            stream.ondata = function(data) {
                if (config.debug) {
                    process.stdout.write(data);
                }

                _data = (_data || '') + data;
                if (_expects.length > 0) {
                    var matched = (typeof _expects[0].pattern === 'string') ? (_data.indexOf(_expects[0].pattern) !== -1) : _data.match(_expects[0].pattern);
                    if (matched) {
                        var expect = _expects.shift();
                        clearTimeout(expect.timeoutId);
                        expect.fn(_data, function() {
                            stream.waitExpect();
                        });
                    }
                }
            };

            stream.on('data', stream.ondata);
            stream.stderr.on('data', stream.ondata);

            stream.waitExpect = function() {
                _data = '';
                if (_expects.length > 0) {
                    _expects[0].timeoutId = setTimeout(function() {
                        var err = new Error('timeout.\n  expect: ' + _expects[0].pattern + '\n  actual: ' + _data);
                        err.expect = _expects[0];
                        sshc.emit('expect.error', err);
                    }, config.timeout || 60000);
                }
            };

            stream.expect = function(pattern, fn) {
                _expects.push({
                    pattern: pattern,
                    fn: fn
                });
                if (_expects.length === 1) {
                    stream.waitExpect();
                }
            };

            sshc.emit('expect.ready', stream);
        });
    });

    sshc.on('expect.ready', function(stream) {
        expectFunc(stream);
    });

    sshc.on('expect.error', function(err) {
        callback(err);
    });
    sshc.on('close', function(code) {
        callback(null);
    });

    if (config.debug) {
        console.log('connecting %s@%s', config.username, config.host);
    }
    sshc.connect({
        host: config.host,
        port: config.port || 22,
        username: config.username || 'root',
        password: config.password || 'default'
    });
};