chenZhenTom

public string DecodeIdToken(string idToken, string claim)
{
    var handler = new JwtSecurityTokenHandler();
    var jwtSecurityToken = handler.ReadJwtToken(idToken);
    return jwtSecurityToken.Claims.First(c => c.Type == claim).Value;
}

chenZhenTom

namespace CloudBackup.Settings
{
    public class AppSettings
    {
        public GoogleDrive GoogleDrive { get; set; }
    }

    public class GoogleDrive
    {
        public string ClientId { get; set; }

chenZhenTom

using System.Text.Json;
using System.Web;
using CloudBackup.Dtos;
using CloudBackup.Settings;
using Google.Apis.Auth.OAuth2;
using Google.Apis.Auth.OAuth2.Flows;
using Google.Apis.Auth.OAuth2.Responses;
using Google.Apis.Drive.v3;
using Microsoft.Extensions.Options;

chenZhenTom

using CloudBackup.Dtos;
using CloudBackup.Services;
using Microsoft.AspNetCore.Mvc;

namespace CloudBackup.Controllers;

[ApiController]
[Route("api/[Controller]")]
public class GoogleController : ControllerBase
{

chenZhenTom

[HttpPut("Refresh/AccessToken")]
public async Task<IActionResult> RefreshAccessToken(RefreshAccessTokenRequest request)
{
    var token = await GoogleService.RefreshAccesstoken(request.AccessToken, request.RefreshToken);
    return Ok(token);
}

chenZhenTom

public async Task<UpdateCredentialResponse> RefreshAccesstoken(string accessToken, string refreshToken)
{
    var uri = "https://oauth2.googleapis.com/token";
    
    var postData = new Dictionary<string, string>
        {
            { "grant_type", "refresh_token" },
            { "client_id", AppSettings.Value.GoogleDrive.ClientId },
            { "client_secret", AppSettings.Value.GoogleDrive.ClientSecret },
            { "refresh_token", refreshToken }

chenZhenTom

[HttpGet("Auth")]
public async Task<IActionResult> Auth([FromQuery]string code, [FromQuery]string state)
{
    var token = await GoogleService.ExchangeCodeForToken(code);
    return Ok(token);
}

chenZhenTom

public async Task<string> GetOAuthUri(string state)
{
    // 此處的 GoogleDrive.ClientId & GoogleDrive.ClientSecret 就是上一篇申請的用戶端憑證。
    // 正常開發請勿將此資料放在 appsettings.json 中，以免洩漏。
    var flow = new GoogleAuthorizationCodeFlow(new GoogleAuthorizationCodeFlow.Initializer
    {
        ClientSecrets = new ClientSecrets
        {
            ClientId = AppSettings.Value.GoogleDrive.ClientId,
            ClientSecret = AppSettings.Value.GoogleDrive.ClientSecret

chenZhenTom

public async Task<TokenResponse> ExchangeCodeForToken(string code)
{
    // 下面的 ClientSecrets, Scopes, RedirectUri 都需要跟上面產生 OAuth URI 時使用的一模一樣才行。
    var flow = new GoogleAuthorizationCodeFlow(new GoogleAuthorizationCodeFlow.Initializer
    {
        ClientSecrets = new ClientSecrets
        {
            ClientId = AppSettings.Value.GoogleDrive.ClientId,
            ClientSecret = AppSettings.Value.GoogleDrive.ClientSecret
        },

chenZhenTom

await Task.Run(() =>
{
    var calculator = app.Services.GetService<Calculator>();

    try
    {
        calculator.Divide(10, 2);
        calculator.Divide(20, 1);
        calculator.Divide(10, 0);
    }catch (Exception ex)