permissions.js

const createResolver = (resolver) => {
  const baseResolver = resolver
  baseResolver.createResolver = (childResolver) => {
    const newResolver = async (parent, args, context, info) => {
      await resolver(parent, args, context, info)
      return childResolver(parent, args, context, info)
    }
    return createResolver(newResolver)
  }
  return baseResolver
}

// requiresAuth
export default createResolver((parent, args, { user }) => {
  if (!user || !user.id) {
    throw new Error('Not authenticated')
  }
})

export const requiresTeamAccess = createResolver(
  async (parent, { channelId }, { user, models }) => {
    if (!user || !user.id) {
      throw new Error('Not authenticated')
    }
    // check if part of the team
    const channel = await models.Channel.findOne({ where: { id: channelId } })
    const member = await models.Member.findOne({
      where: { teamId: channel.teamId, userId: user.id },
    })
    if (!member) {
      throw new Error('You have to be a member of the team to subcribe to it\'s messages')
    }
  }
)

export const directMessageSubscription = createResolver(
  async (parent, { teamId, userId }, { user, models }) => {
    if (!user || !user.id) {
      throw new Error('Not authenticated')
    }

    const members = await models.Member.findAll({
      where: { teamId, [models.sequelize.Op.or]: [{ userId }, { userId: user.id }] },
    })

    if (members.length !== 2) {
      throw new Error('You have to be a member of the team to subscribe to its message')
    }
  }
)