order.js

/*
 * Return a promise object
 * On success, it passes (response, true/false) to the resolve
 *  passes true if the user exists
 *  false if the user does not exist
 * On error passes the error object, the structure should
 * be similar as defined in the JSON AP specification
 *
*/
const userExists = (email) => {
     let config = {
         method: 'GET',
         headers: { 'Content-Type': 'application/json' }
     }
     fetch(`${server}/users/${email}`, config)
     .then(response => {
         if (response.status === 200) {
             return Promise.resolve(response, true)
         } else if (response.status === 404) {
             return Promise.resolve(response, false)
         } else {
            return Promise.reject(new Error('Error'))
         }
     })
}

export const submitShippingAddress = (values, dispatch) => {
    const email = values.email

    return new Promise((resolve, reject) => {
        userExists(email)
        .then((response, isthere) => {
            if (isthere) { # HTTP GET with 200
                # PATCH it up
                # run another separate method that returns promise
                # it will look like this
                patchDataStr = # write some code
                updateUser(patchDataStr)
                .then(patchResponse => {
                    dispatch("... to payee screen") # update reducer with state
                    resolve()
                })
                .catch(error => {
                    dispatch("... show error")
                    reject({})
                })
            } else {
                # HTTP GET with 404, no user
                # POST the user
                # run the create user method which returns promise
                postDataStr = # write some code
                createUser(postDataStr)
                .then(response => {
                    dispatch("... to payee screen") # update reducer with state
                    resolve()
                })
                .catch(error => {
                    dispatch("show error")
                    reject({})
                })
            }
        })
        .catch(error => {
            dispatch("...show error")
            reject({})
        })
    })
}