var oauth2orize      = require('oauth2orize'),
    models           = require('../models'),
    utils            = require('../utils'),
    errors           = require('../errors'),
    spamPrevention   = require('./spam-prevention'),
    i18n             = require('../i18n'),

    oauthServer,
    oauth;

function exchangeRefreshToken(client, refreshToken, scope, done) {
    models.Refreshtoken.findOne({token: refreshToken}).then(function then(model) {
        if (!model) {
            return done(new errors.NoPermissionError(i18n.t('errors.middleware.oauth.invalidRefreshToken')), false);
        } else {
            var token = model.toJSON(),
                accessToken = utils.uid(256),
                accessExpires = Date.now() + utils.ONE_HOUR_MS,
                refreshExpires = Date.now() + utils.ONE_WEEK_MS;

            if (token.expires > Date.now()) {
                models.Accesstoken.add({
                    token: accessToken,
                    user_id: token.user_id,
                    client_id: token.client_id,
                    expires: accessExpires
                }).then(function then() {
                    return models.Refreshtoken.edit({expires: refreshExpires}, {id: token.id});
                }).then(function then() {
                    return done(null, accessToken, {expires_in: utils.ONE_HOUR_S});
                }).catch(function handleError(error) {
                    return done(error, false);
                });
            } else {
                done(new errors.UnauthorizedError(i18n.t('errors.middleware.oauth.refreshTokenExpired')), false);
            }
        }
    });
}

function exchangePassword(client, username, password, scope, done) {
    // Validate the client
    models.Client.findOne({slug: client.slug}).then(function then(client) {
        if (!client) {
            return done(new errors.NoPermissionError(i18n.t('errors.middleware.oauth.invalidClient')), false);
        }
        // Validate the user
        return models.User.check({email: username, password: password}).then(function then(user) {
            // Everything validated, return the access- and refreshtoken
            var accessToken = utils.uid(256),
                refreshToken = utils.uid(256),
                accessExpires = Date.now() + utils.ONE_HOUR_MS,
                refreshExpires = Date.now() + utils.ONE_WEEK_MS;

            return models.Accesstoken.add(
                {token: accessToken, user_id: user.id, client_id: client.id, expires: accessExpires}
            ).then(function then() {
                return models.Refreshtoken.add(
                    {token: refreshToken, user_id: user.id, client_id: client.id, expires: refreshExpires}
                );
            }).then(function then() {
                spamPrevention.resetCounter(username);
                return done(null, accessToken, refreshToken, {expires_in: utils.ONE_HOUR_S});
            });
        }).catch(function handleError(error) {
            return done(error, false);
        });
    });
}

oauth = {

    init: function init() {
        oauthServer = oauth2orize.createServer();
        // remove all expired accesstokens on startup
        models.Accesstoken.destroyAllExpired();

        // remove all expired refreshtokens on startup
        models.Refreshtoken.destroyAllExpired();

        // Exchange user id and password for access tokens.  The callback accepts the
        // `client`, which is exchanging the user's name and password from the
        // authorization request for verification. If these values are validated, the
        // application issues an access token on behalf of the user who authorized the code.
        oauthServer.exchange(oauth2orize.exchange.password({userProperty: 'client'},
            exchangePassword));

        // Exchange the refresh token to obtain an access token.  The callback accepts the
        // `client`, which is exchanging a `refreshToken` previously issued by the server
        // for verification. If these values are validated, the application issues an
        // access token on behalf of the user who authorized the code.
        oauthServer.exchange(oauth2orize.exchange.refreshToken({userProperty: 'client'},
            exchangeRefreshToken));
    },

    // ### Generate access token Middleware
    // register the oauth2orize middleware for password and refresh token grants
    generateAccessToken: function generateAccessToken(req, res, next) {
        return oauthServer.token()(req, res, next);
    }
};

module.exports = oauth;