'use strict';

exports = module.exports = {
    search: search,
    verifyPassword: verifyPassword,
    createAndVerifyUserIfNotExist: createAndVerifyUserIfNotExist,

    testConfig: testConfig,
    startSyncer: startSyncer,

    injectPrivateFields: injectPrivateFields,
    removePrivateFields: removePrivateFields,

    sync: sync
};

var assert = require('assert'),
    async = require('async'),
    auditSource = require('./auditsource.js'),
    BoxError = require('./boxerror.js'),
    constants = require('./constants.js'),
    debug = require('debug')('box:externalldap'),
    ldap = require('ldapjs'),
    settings = require('./settings.js'),
    tasks = require('./tasks.js'),
    users = require('./users.js');

function injectPrivateFields(newConfig, currentConfig) {
    if (newConfig.bindPassword === constants.SECRET_PLACEHOLDER) newConfig.bindPassword = currentConfig.bindPassword;
}

function removePrivateFields(ldapConfig) {
    assert.strictEqual(typeof ldapConfig, 'object');
    if (ldapConfig.bindPassword) ldapConfig.bindPassword = constants.SECRET_PLACEHOLDER;
    return ldapConfig;
}

function translateUser(ldapConfig, ldapUser) {
    assert.strictEqual(typeof ldapConfig, 'object');

    return {
        username: ldapUser[ldapConfig.usernameField],
        email: ldapUser.mail,
        displayName: ldapUser.cn // user.giveName + ' ' + user.sn
    };
}

function validUserRequirements(user) {
    if (!user.username || !user.email || !user.displayName) {
        debug(`[LDAP user empty username/email/displayName] username=${user.username} email=${user.email} displayName=${user.displayName}`);
        return false;
    } else {
        return true;
    }
}

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

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

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

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


// TODO support search by email
function ldapSearch(externalLdapConfig, options, callback) {
    assert.strictEqual(typeof externalLdapConfig, 'object');
    assert.strictEqual(typeof options, 'object');
    assert.strictEqual(typeof callback, 'function');

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

        let searchOptions = {
            paged: true,
            filter: ldap.parseFilter(externalLdapConfig.filter),
            scope: 'sub'    // We may have to make this configurable
        };

        if (options.filter) { // https://github.com/ldapjs/node-ldapjs/blob/master/docs/filters.md
            let extraFilter = ldap.parseFilter(options.filter);
            searchOptions.filter = new ldap.AndFilter({ filters: [ extraFilter, searchOptions.filter ] });
        }

        debug(`Listing users at ${externalLdapConfig.baseDn} with filter ${searchOptions.filter.toString()}`);

        client.search(externalLdapConfig.baseDn, searchOptions, function (error, result) {
            if (error instanceof ldap.NoSuchObjectError) return callback(new BoxError(BoxError.NOT_FOUND));
            if (error) return callback(new BoxError(BoxError.EXTERNAL_ERROR, error));

            let ldapUsers = [];

            result.on('searchEntry', entry => ldapUsers.push(entry.object));
            result.on('error', error => callback(new BoxError(BoxError.EXTERNAL_ERROR, error)));

            result.on('end', function (result) {
                client.unbind();

                if (result.status !== 0) return callback(new BoxError(BoxError.EXTERNAL_ERROR, 'Server returned status ' + result.status));

                callback(null, ldapUsers);
            });
        });
    });
}

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

    if (config.provider === 'noop') return callback();

    if (!config.url) return callback(new BoxError(BoxError.BAD_FIELD, 'url must not be empty'));
    if (!config.url.startsWith('ldap://') && !config.url.startsWith('ldaps://')) return callback(new BoxError(BoxError.BAD_FIELD, 'url is missing ldap:// or ldaps:// prefix'));
    if (!config.usernameField) config.usernameField = 'uid';

    // bindDn may not be a dn!
    if (!config.baseDn) return callback(new BoxError(BoxError.BAD_FIELD, 'basedn must not be empty'));
    try { ldap.parseDN(config.baseDn); } catch (e) { return callback(new BoxError(BoxError.BAD_FIELD, 'invalid baseDn')); }

    if (!config.filter) return callback(new BoxError(BoxError.BAD_FIELD, 'filter must not be empty'));
    try { ldap.parseFilter(config.filter); } catch (e) { return callback(new BoxError(BoxError.BAD_FIELD, 'invalid filter')); }

    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 BoxError(BoxError.EXTERNAL_ERROR, error));

            result.on('searchEntry', function (/* entry */) {});
            result.on('error', function (error) { client.unbind(); callback(new BoxError(BoxError.BAD_FIELD, `Unable to search directory: ${error.message}`)); });
            result.on('end', function (/* result */) { client.unbind(); callback(); });
        });
    });
}

function search(identifier, callback) {
    assert.strictEqual(typeof identifier, 'string');
    assert.strictEqual(typeof callback, 'function');

    settings.getExternalLdapConfig(function (error, externalLdapConfig) {
        if (error) return callback(error);
        if (externalLdapConfig.provider === 'noop') return callback(new BoxError(BoxError.BAD_STATE, 'not enabled'));

        ldapSearch(externalLdapConfig, { filter: `${externalLdapConfig.usernameField}=${identifier}` }, function (error, ldapUsers) {
            if (error) return callback(error);

            // translate ldap properties to ours
            let users = ldapUsers.map(function (u) { return translateUser(externalLdapConfig, u); });

            callback(null, users);
        });
    });
}

function createAndVerifyUserIfNotExist(identifier, password, callback) {
    assert.strictEqual(typeof identifier, 'string');
    assert.strictEqual(typeof password, 'string');
    assert.strictEqual(typeof callback, 'function');

    settings.getExternalLdapConfig(function (error, externalLdapConfig) {
        if (error) return callback(error);
        if (externalLdapConfig.provider === 'noop') return callback(new BoxError(BoxError.BAD_STATE, 'not enabled'));
        if (!externalLdapConfig.autoCreate) return callback(new BoxError(BoxError.BAD_STATE, 'auto create not enabled'));

        ldapSearch(externalLdapConfig, { filter: `${externalLdapConfig.usernameField}=${identifier}` }, function (error, ldapUsers) {
            if (error) return callback(error);
            if (ldapUsers.length === 0) return callback(new BoxError(BoxError.NOT_FOUND));
            if (ldapUsers.length > 1) return callback(new BoxError(BoxError.CONFLICT));

            let user = translateUser(externalLdapConfig, ldapUsers[0]);
            if (!validUserRequirements(user)) return callback(new BoxError(BoxError.BAD_FIELD));

            users.create(user.username, null /* password */, user.email, user.displayName, { source: 'ldap' }, auditSource.EXTERNAL_LDAP_AUTO_CREATE, function (error, user) {
                if (error) {
                    console.error('Failed to auto create user', user.username, error);
                    return callback(new BoxError(BoxError.INTERNAL_ERROR));
                }

                verifyPassword(user, password, function (error) {
                    if (error) return callback(error);
                    callback(null, user);
                });
            });
        });
    });
}

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(error);
        if (externalLdapConfig.provider === 'noop') return callback(new BoxError(BoxError.BAD_STATE, 'not enabled'));

        ldapSearch(externalLdapConfig, { filter: `${externalLdapConfig.usernameField}=${user.username}` }, function (error, ldapUsers) {
            if (error) return callback(error);
            if (ldapUsers.length === 0) return callback(new BoxError(BoxError.NOT_FOUND));
            if (ldapUsers.length > 1) return callback(new BoxError(BoxError.CONFLICT));

            let client = ldap.createClient({ url: externalLdapConfig.url });
            client.bind(ldapUsers[0].dn, password, function (error) {
                if (error instanceof ldap.InvalidCredentialsError) return callback(new BoxError(BoxError.INVALID_CREDENTIALS));
                if (error) return callback(new BoxError(BoxError.EXTERNAL_ERROR, error));

                callback(null, translateUser(externalLdapConfig, ldapUsers[0]));
            });
        });
    });
}

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

    settings.getExternalLdapConfig(function (error, externalLdapConfig) {
        if (error) return callback(error);
        if (externalLdapConfig.provider === 'noop') return callback(new BoxError(BoxError.BAD_STATE, 'not enabled'));

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

    progressCallback({ percent: 10, message: 'Starting ldap user sync' });

    settings.getExternalLdapConfig(function (error, externalLdapConfig) {
        if (error) return callback(error);
        if (externalLdapConfig.provider === 'noop') return callback(new BoxError(BoxError.BAD_STATE, 'not enabled'));

        ldapSearch(externalLdapConfig, {}, function (error, ldapUsers) {
            if (error) return callback(error);

            debug(`Found ${ldapUsers.length} users`);
            let percent = 10;
            let step = 90/(ldapUsers.length+1); // ensure no divide by 0

            // we ignore all errors here and just log them for now
            async.eachSeries(ldapUsers, function (user, iteratorCallback) {
                user = translateUser(externalLdapConfig, user);

                if (!validUserRequirements(user)) return iteratorCallback();

                percent += step;
                progressCallback({ percent, message: `Syncing... ${user.username}` });

                users.getByUsername(user.username, function (error, result) {
                    if (error && error.reason !== BoxError.NOT_FOUND) {
                        debug(`Could not find user with username ${user.username}: ${error.message}`);
                        return iteratorCallback();
                    }

                    if (error) {
                        debug(`[adding user] username=${user.username} email=${user.email} displayName=${user.displayName}`);

                        users.create(user.username, null /* password */, user.email, user.displayName, { source: 'ldap' }, auditSource.EXTERNAL_LDAP_TASK, function (error) {
                            if (error) console.error('Failed to create user', user, error);
                            iteratorCallback();
                        });
                    } else if (result.source !== 'ldap') {
                        debug(`[conflicting user] username=${user.username} email=${user.email} displayName=${user.displayName}`);

                        iteratorCallback();
                    } else if (result.email !== user.email || result.displayName !== user.displayName) {
                        debug(`[updating user] username=${user.username} email=${user.email} displayName=${user.displayName}`);

                        users.update(result, { email: user.email, fallbackEmail: user.email, displayName: user.displayName }, auditSource.EXTERNAL_LDAP_TASK, function (error) {
                            if (error) debug('Failed to update user', user, error);

                            iteratorCallback();
                        });
                    } else {
                        // user known and up-to-date
                        debug(`[up-to-date user] username=${user.username} email=${user.email} displayName=${user.displayName}`);

                        iteratorCallback();
                    }
                });
            }, function (error) {
                debug('sync: ldap sync is done', error);
                callback(error);
            });
        });
    });
}