Retrieves an absence period by ID.

//native

type Personio = {

	clientId: string

	clientSecret: string

}

/**

 * Retrieves an absence period by ID.

 * Retrieves an absence period by ID.

 */

export async function main(auth: Personio, id: string, Beta: string) {

	const url = new URL(`https://api.personio.de/v2/absence-periods/${id}`)

	const response = await fetch(url, {

		method: 'GET',

		headers: {

			Beta: Beta,

			Authorization: 'Bearer ' + (await getOAuthToken(auth, 'https://api.personio.de/oauth2/token'))

		},

		body: undefined

	})

	if (!response.ok) {

		const text = await response.text()

		throw new Error(`${response.status} ${text}`)

	}

	return await response.json()

}

async function getOAuthToken(auth: Personio, tokenUrl: string): Promise<string> {

	const params = new URLSearchParams({

		grant_type: 'client_credentials',

		client_id: auth.clientId,

		client_secret: auth.clientSecret

	})

	const response = await fetch(tokenUrl, {

		method: 'POST',

		headers: {

			Authorization: 'Basic ' + btoa(`${auth.clientId}:${auth.clientSecret}`),

			'Content-Type': 'application/x-www-form-urlencoded'

		},

		body: params.toString()

	})

	if (!response.ok) {

		const text = await response.text()

		throw new Error(`OAuth token request failed: ${response.status} ${text}`)

	}

	const data = await response.json()

	return data.access_token

}