WP Plugin + GitHub OAuth app

github-oauth.php

<?php
/**
 * GitHub OAuth code.
 *
 * @package CreateBlockTheme
 */
add_action( 'init', 'github_oauth_init' );
function github_oauth_init() {
	if ( isset( $_GET['github_oauth'] ) && $_GET['github_oauth'] == 'authorize' ) {
		$client_id    = 'GITHUB_CLIENT_ID'; // Replace with your GitHub Client ID
		$redirect_uri = urlencode( admin_url( 'admin-ajax.php?action=github_oauth_callback' ) );
		$url          = "https://github.com/login/oauth/authorize?client_id={$client_id}&redirect_uri={$redirect_uri}&scope=user";
		wp_redirect( $url );
		exit;
	}
}

add_action( 'wp_ajax_github_oauth_callback', 'github_oauth_callback' );
add_action( 'wp_ajax_nopriv_github_oauth_callback', 'github_oauth_callback' );
function github_oauth_callback() {
	if ( isset( $_GET['code'] ) ) {
		$code          = $_GET['code'];
		$client_id     = 'GITHUB_CLIENT_ID'; // Replace with your GitHub Client ID
		$client_secret = 'GITHUB_CLIENT_SECRET'; // Replace with your GitHub Client Secret
		$url           = 'https://github.com/login/oauth/access_token';
		$body          = array(
			'client_id'     => $client_id,
			'client_secret' => $client_secret,
			'code'          => $code,
		);
		$options       = array(
			'body'    => $body,
			'headers' => array(
				'Accept' => 'application/json',
			),
		);
		$response      = wp_remote_post( $url, $options );
		if ( ! is_wp_error( $response ) ) {
			$data = json_decode( wp_remote_retrieve_body( $response ), true );
			if ( isset( $data['access_token'] ) ) {
				update_option( 'cbt_theme_manager_github_oauth_access_token', $data['access_token'] );
			}
		}
		wp_redirect( admin_url( 'site-editor.php?canvas=edit' ) );
	}
	exit;
}