type Convertkit = {

	apiSecret: string

}

export async function main(

	resource: Convertkit,

	subscriberId: string,

	payload: {

		firstName?: string

		email?: string

		fields?: { [key: string]: string }

	}

) {

	if (!Object.keys(payload).length) {

		throw new Error(`Provide at least one key-value pair in the payload!`)

	}

	const endpoint = `https://api.convertkit.com/v3/subscribers/${subscriberId}`

	const body = {

		api_secret: resource.apiSecret,

		...(payload.firstName && { first_name: payload.firstName }),

		...(payload.email && { email_address: payload.email }),

		...(payload.fields && { fields: payload.fields })

	}

	const response = await fetch(endpoint, {

		method: 'PUT',

		headers: {

			'Content-Type': 'application/json; charset=utf-8'

		},

		body: JSON.stringify(body)

	})

	if (!response.ok) {

		throw new Error(`HTTP error! status: ${response.status}`)

	}

	const data = await response.json()

	return data.subscriber

}