get-access-token.ts

// https://www.rfc-editor.org/rfc/rfc6749#section-5

/**
 * OAuth credentials from
 * https://github.com/organizations/<org>/settings/apps/<app>
 */
export interface ClientCredentials {
	id: string;
	secret: string;
}

export interface AccessTokenRequest {
	client: ClientCredentials;
	code: string;
	userAgent?: string;
}

export function accessTokenRequest(x: AccessTokenRequest): Request {
	const headers = new Headers();
	headers.set("Accept", "application/json");
	headers.set("Content-Type", "application/json");
	if (x.userAgent !== undefined) headers.set("User-Agent", x.userAgent);
	return new Request("https://github.com/login/oauth/access_token", {
		method: "POST",
		body: JSON.stringify({
			client_id: x.client.id,
			client_secret: x.client.secret,
			code: x.code,
		}),
		headers,
	});
}

export type AccessTokenResponse =
	| ({ success: true } & AccessTokenSuccess)
	| ({ success: false } & AccessTokenFailure);

export interface AccessTokenSuccess {
	accessToken: string;
	object: object;
	status: number;
}

export interface AccessTokenFailure {
	fetchError?: unknown;
	jsonError?: unknown;
	status?: number;
	object?: object;
}

export async function getAccessToken(
	x: AccessTokenRequest,
): Promise<AccessTokenResponse> {
	const request = accessTokenRequest(x);

	let response: Response | undefined;
	let fetchError: unknown;
	try {
		response = await fetch(request);
	} catch (e) {
		fetchError = e;
	}

	let object: object | undefined;
	let jsonError: unknown;
	try {
		const value = await response?.json();
		if (typeof value === 'object' && value !== null) {
			object = value
		} else {
			jsonError = 'JSON response body is not an object'
		}
	} catch (e) {
		jsonError = e;
	}

	if (
		response?.ok &&
		object !== undefined &&
		"access_token" in object &&
		typeof object.access_token === "string"
	)
		return {
			success: true,
			accessToken: object.access_token,
			status: response.status,
			object,
		};
	else
		return {
			success: false,
			status: response?.status,
			object,
			fetchError,
			jsonError,
		};
}