'use strict';

exports = module.exports = {
    ExternalLdapError: ExternalLdapError,

    verifyPassword: verifyPassword,

    testConfig: testConfig,
    startSyncer: startSyncer,

    sync: sync
};

var assert = require('assert'),
    async = require('async'),
    auditsource = require('./auditsource.js'),
    debug = require('debug')('box:ldapclient'),
    ldap = require('ldapjs'),
    settings = require('./settings.js'),
    tasks = require('./tasks.js'),
    users = require('./users.js'),
    UserError = users.UsersError,
    util = require('util');

function ExternalLdapError(reason, errorOrMessage) {
    assert.strictEqual(typeof reason, 'string');
    assert(errorOrMessage instanceof Error || typeof errorOrMessage === 'string' || typeof errorOrMessage === 'undefined');

    Error.call(this);
    Error.captureStackTrace(this, this.constructor);

    this.name = this.constructor.name;
    this.reason = reason;
    if (typeof errorOrMessage === 'undefined') {
        this.message = reason;
    } else if (typeof errorOrMessage === 'string') {
        this.message = errorOrMessage;
    } else {
        this.message = 'Internal error';
        this.nestedError = errorOrMessage;
    }
}
util.inherits(ExternalLdapError, Error);
ExternalLdapError.EXTERNAL_ERROR = 'external error';
ExternalLdapError.INTERNAL_ERROR = 'internal error';
ExternalLdapError.INVALID_CREDENTIALS = 'invalid credentials';
ExternalLdapError.BAD_STATE = 'bad state';
ExternalLdapError.BAD_FIELD = 'bad field';
ExternalLdapError.NOT_FOUND = 'not found';

// performs service bind if required
function getClient(externalLdapConfig, callback) {
    assert.strictEqual(typeof callback, 'function');

    // basic validation to not crash
    try { ldap.parseDN(externalLdapConfig.baseDn); } catch (e) { return callback(new ExternalLdapError(ExternalLdapError.BAD_FIELD, 'invalid baseDn')); }
    try { ldap.parseFilter(externalLdapConfig.filter); } catch (e) { return callback(new ExternalLdapError(ExternalLdapError.BAD_FIELD, 'invalid filter')); }
    if (externalLdapConfig.bindDn) try { ldap.parseFilter(externalLdapConfig.bindDn); } catch (e) { return callback(new ExternalLdapError(ExternalLdapError.INVALID_CREDENTIALS)); }

    var client;
    try {
        client = ldap.createClient({ url: externalLdapConfig.url });
    } catch (e) {
        if (e instanceof ldap.ProtocolError) return callback(new ExternalLdapError(ExternalLdapError.BAD_FIELD, 'url protocol is invalid'));
        return callback(new ExternalLdapError(ExternalLdapError.INTERNAL_ERROR, e));
    }

    if (!externalLdapConfig.bindDn) return callback(null, client);

    client.bind(externalLdapConfig.bindDn, externalLdapConfig.bindPassword, function (error) {
        if (error instanceof ldap.InvalidCredentialsError) return callback(new ExternalLdapError(ExternalLdapError.INVALID_CREDENTIALS));
        if (error) return callback(new ExternalLdapError(ExternalLdapError.EXTERNAL_ERROR, error));

        callback(null, client, externalLdapConfig);
    });
}

function testConfig(config, callback) {
    assert.strictEqual(typeof config, 'object');
    assert.strictEqual(typeof callback, 'function');

    if (!config.enabled) return callback();

    if (!config.url) return callback(new ExternalLdapError(ExternalLdapError.BAD_FIELD, 'url must not be empty'));
    if (!config.baseDn) return callback(new ExternalLdapError(ExternalLdapError.BAD_FIELD, 'basedn must not be empty'));
    if (!config.filter) return callback(new ExternalLdapError(ExternalLdapError.BAD_FIELD, 'filter must not be empty'));

    getClient(config, function (error, client) {
        if (error) return callback(error);

        var opts = {
            filter: config.filter,
            scope: 'sub'
        };

        client.search(config.baseDn, opts, function (error, result) {
            if (error) return callback(new ExternalLdapError(ExternalLdapError.EXTERNAL_ERROR, error));

            result.on('searchEntry', function (entry) {});
            result.on('error', function (error) { callback(new ExternalLdapError(ExternalLdapError.BAD_FIELD, 'Unable to search directory')); });
            result.on('end', function (result) { callback(); });
        });
    });
}

function verifyPassword(user, password, callback) {
    assert.strictEqual(typeof user, 'object');
    assert.strictEqual(typeof password, 'string');
    assert.strictEqual(typeof callback, 'function');

    settings.getExternalLdapConfig(function (error, externalLdapConfig) {
        if (error) return callback(new ExternalLdapError(ExternalLdapError.INTERNAL_ERROR, error));
        if (!externalLdapConfig.enabled) return callback(new ExternalLdapError(ExternalLdapError.BAD_STATE, 'not enabled'));

        getClient(externalLdapConfig, function (error, client) {
            if (error) return callback(error);

            const dn = `uid=${user.username},${externalLdapConfig.baseDn}`;

            client.bind(dn, password, function (error) {
                if (error instanceof ldap.InvalidCredentialsError) return callback(new ExternalLdapError(ExternalLdapError.INVALID_CREDENTIALS));
                if (error) return callback(new ExternalLdapError(ExternalLdapError.EXTERNAL_ERROR, error));

                callback();
            });
        });
    });
}

function startSyncer(callback) {
    assert.strictEqual(typeof callback, 'function');

    settings.getExternalLdapConfig(function (error, externalLdapConfig) {
        if (error) return callback(new ExternalLdapError(ExternalLdapError.INTERNAL_ERROR, error));
        if (!externalLdapConfig.enabled) return callback(new ExternalLdapError(ExternalLdapError.BAD_STATE, 'not enabled'));

        tasks.add(tasks.TASK_SYNC_EXTERNAL_LDAP, [], function (error, taskId) {
            if (error) return callback(new ExternalLdapError(ExternalLdapError.INTERNAL_ERROR, error));

            tasks.startTask(taskId, {}, function (error, result) {
                debug('sync: done', error, result);
            });

            callback(null, taskId);
        });
    });
}

function sync(progressCallback, callback) {
    assert.strictEqual(typeof progressCallback, 'function');
    assert.strictEqual(typeof callback, 'function');

    settings.getExternalLdapConfig(function (error, externalLdapConfig) {
        if (error) return callback(new ExternalLdapError(ExternalLdapError.INTERNAL_ERROR, error));
        if (!externalLdapConfig.enabled) return callback(new ExternalLdapError(ExternalLdapError.BAD_STATE, 'not enabled'));

        getClient(externalLdapConfig, function (error, client) {
            if (error) return callback(error);

            var opts = {
                filter: externalLdapConfig.filter,
                scope: 'sub'    // We may have to make this configurable
            };

            // TODO this needs pagination!
            client.search(externalLdapConfig.baseDn, opts, function (error, result) {
                if (error) return callback(new ExternalLdapError(ExternalLdapError.EXTERNAL_ERROR, error));

                var ldapUsers = [];

                result.on('searchEntry', function (entry) {
                    ldapUsers.push(entry.object);
                });

                result.on('error', function (error) {
                    callback(new ExternalLdapError(ExternalLdapError.EXTERNAL_ERROR, error));
                });

                result.on('end', function (result) {
                    console.log('status: ' + result.status);

                    // we ignore all errors here and just log them for now
                    async.eachSeries(ldapUsers, function (user, callback) {

                        // ignore the bindDn user if any
                        if (user.dn === externalLdapConfig.bindDn) return callback();

                        users.getByUsername(user.uid, function (error, result) {
                            if (error && error.reason !== UserError.NOT_FOUND) {
                                console.error(error);
                                return callback();
                            }

                            if (error) {
                                users.create(user.uid, null, user.mail, user.cn, { source: 'ldap' }, auditsource.EXTERNAL_LDAP_TASK, function (error) {
                                    if (error) console.error('Failed to create user', user, error);
                                    callback();
                                });
                            } else if (result.email !== user.mail || result.displayName !== user.cn) {
                                users.update(result.id, { email: user.mail, displayName: user.cn }, auditsource.EXTERNAL_LDAP_TASK, function (error) {
                                    if (error) console.error('Failed to update user', user, error);
                                    callback();
                                });
                            } else {
                                // user known and up-to-date
                                callback();
                            }
                        });
                    }, callback);
                });
            });
        });
    });
}