oauth_handler.go

package fundrive

import (
    "github.com/gofiber/fiber/v2"
    "golang.org/x/oauth2"
    "gorm.io/gorm"
    "log"
    "net/http"
    "net/url"
)

type OAuthHandler struct {
    oauth2Config   *oauth2.Config
    db             *gorm.DB
    tokenEncryptor *TokenEncryption
}

func NewOAuthHandler(
    oauth2Config *oauth2.Config,
    db *gorm.DB,
    tokenEncryptor *TokenEncryption,
) OAuthHandler {
    return OAuthHandler{
        oauth2Config:   oauth2Config,
        db:             db,
        tokenEncryptor: tokenEncryptor,
    }
}

func (handler *OAuthHandler) Route(app *fiber.App) {
    app.Get("/auth/google/authorize", handler.AuthorizeHandler)
    app.Get("/google-drive", handler.AuthorizeCallbackHandler)
}

func (handler *OAuthHandler) Run(app *fiber.App, port string) {
    log.Println("Listening on port 3000")
    err := app.Listen(":" + port)
    if err != nil {
        log.Fatal(err)
    }
}

type AuthorizeResponse struct {
    URL string `json:"url"`
}

func (handler *OAuthHandler) AuthorizeHandler(c *fiber.Ctx) error {
    redirectURL := c.Query("redirect_url", "http://localhost:3000/google-drive")

    queryParams := url.Values{
        "redirect_url": {redirectURL},
    }

    // https://medium.com/starthinker/google-oauth-2-0-access-token-and-refresh-token-explained-cccf2fc0a6d9
    authCodeOpt := []oauth2.AuthCodeOption{
        oauth2.AccessTypeOffline, // obtain the refresh token
        oauth2.ApprovalForce,     // forces the users to view the consent dialog
    }

    loginUrl := handler.oauth2Config.AuthCodeURL(queryParams.Encode(), authCodeOpt...)
    return c.Redirect(loginUrl, http.StatusFound)
}

func (handler *OAuthHandler) AuthorizeCallbackHandler(c *fiber.Ctx) error {
    code := c.Query("code")

    token, err := handler.oauth2Config.Exchange(c.Context(), code)
    if err != nil {
        return c.Status(500).JSON(fiber.Map{
            "code":    http.StatusInternalServerError,
            "success": false,
            "message": http.StatusText(http.StatusInternalServerError),
            "details": err.Error(),
        })
    }

    oAuthConfig := OAuthConfig{
        DB:             handler.db,
        OAuth2Config:   handler.oauth2Config,
        TokenEncryptor: handler.tokenEncryptor,
    }

    oauthService, err := NewOAuthService(&oAuthConfig)
    if err != nil {
        return c.Status(500).JSON(fiber.Map{
            "code":    http.StatusInternalServerError,
            "success": false,
            "message": http.StatusText(http.StatusInternalServerError),
            "details": err.Error(),
        })
    }

    userInfo, err := oauthService.GetGoogleUserInfo(c.Context(), &GetUserInfoRequest{Token: token})
    if err != nil {
        return c.Status(500).JSON(fiber.Map{
            "code":    http.StatusInternalServerError,
            "success": false,
            "message": http.StatusText(http.StatusInternalServerError),
            "details": err.Error(),
        })
    }

    userInfo.ID = "user-dev" // dummy user, simulate multiple email with same ID

    saveTokenReq := SaveTokenRequest{
        UserID: userInfo.ID,
        Email:  userInfo.Email,
        Token:  token,
    }

    err = oauthService.SaveToken(c.Context(), &saveTokenReq)
    if err != nil {
        return c.Status(500).JSON(fiber.Map{
            "code":    http.StatusInternalServerError,
            "success": false,
            "message": http.StatusText(http.StatusInternalServerError),
            "details": err.Error(),
        })
    }

    return c.Status(200).JSON(fiber.Map{
        "code":    http.StatusOK,
        "success": true,
        "message": http.StatusText(http.StatusOK),
        "details": userInfo,
    })
}