"use strict";

const Promise = require("bluebird");
const crypto = require("crypto");
const nanoid = require("nanoid");
const defaultValue = require("default-value");
const databaseError = require("database-error");

const errors = require("../errors");
const createDatabaseModule = require("../db-module");

function tokensMatch(a, b) {
	return crypto.timingSafeEqual(Buffer.from(a), Buffer.from(b));
}

module.exports = function ({ knex }) {
	return createDatabaseModule({
		create: function ({ name, deviceId, userId, token }, tx = knex) {
			return Promise.try(() => {
				let token_ = defaultValue(token, nanoid());
				let deviceId_ = defaultValue(deviceId, nanoid());

				return tx("devices").insert({
					device_id: deviceId_,
					user_id: userId,
					name: name,
					token: token_,
				}).returning("*");
			}).then((results) => {
				return results[0];
			});
		},
		byDeviceId: function ({ deviceId }, tx = knex) {
			return Promise.try(() => {
				return tx("devices").first().where({ device_id: deviceId });
			}).then((result) => {
				if (result != null) {
					return result;
				} else {
					throw new errors.NotFound("The specified device ID does not exist");
				}
			});
		},
		byDeviceIdAndToken: function ({ deviceId, token }, _tx = knex) {
			/* NOTE: This is intentionally a separate method as opposed to conditional logic in byDeviceId, to prevent cases where a bug results in a user-specified token not being passed in - which would fail unsafely by allowing any token, if conditional logic were used. */
			return Promise.try(() => {
				if (token != null) {
					return this.byDeviceId({ deviceId });
				} else {
					throw new errors.MissingAccessToken("No access token was specified");
				}
			}).then((device) => {
				if (tokensMatch(token, device.token)) {
					return device;
				} else {
					throw new errors.InvalidAccessToken("Specified token was invalid");
				}
			});
		},
		updateToken: function ({ userId, deviceId, token }, tx = knex) {
			return Promise.try(() => {
				return tx("devices")
					.update({ token: token })
					.where({
						device_id: deviceId,
						user_id: userId
					})
					.returning("*");
			}).then((results) => {
				if (results.length > 0) {
					return results[0];
				} else {
					throw new errors.NotFound("Specified Device ID does not exist");
				}
			});
		},
		createDeviceSession: function ({ name, deviceId, userId }, _tx = knex) {
			return Promise.try(() => {
				let token = nanoid();

				return Promise.try(() => {
					return this.create({ name, deviceId, userId, token });
				}).catch({ name: "UniqueConstraintViolationError", table: "devices", column: "device_id" }, (_error) => {
					return this.updateToken({ userId, deviceId, token });
				}).then((device) => {
					/* FIXME */
				});
			});
		}
	});
};