Custom google oauth docs (#153)

Co-authored-by: Miljan <noreply.mn@aleksic.es>

src/essentials-for-yootheme-pro/auths/custom-google-dev-app.md

@@ -0,0 +1,95 @@
+# Custom Google Dev App
+
+Learn how to create a custom Google Dev App and get your own oAuth credentials. Once ready, you can use the resulting _Access Token_ into the respective [Google Auth](./drivers#google-auth-driver) driver to authenticate.
+
+This process is covered in great extens by the [Google official guide](https://developers.google.com/identity/protocols/oauth2/web-server) while next step will try to summarize it.
+
+## 1. Create Google Cloud Project
+
+Login with your Google account to the [Google Cloud Console](https://cloud.google.com/cloud-console/) and create and/or choose a project where to manage the custom oAuth credentials.
+
+![Google Cloud Console](./assets/google/google-cloud-console.png)
+
+## 2. Enable Google APIs
+
+Go to the [Google Cloud Console API Libraries](https://console.cloud.google.com/apis/library) and enable the APIs you need. For example, for Google Sheets enable the _Google Sheets API_, for YouTube the _YouTube Data API_, etc.
+
+![Choose project](./assets/google/google-choose-project.png)
+
+![Enable APIs](./assets/google/google-enable-apis.png)
+
+::: tip
+You can either create one project for each API, or a single-project for every API. It's up to you and your security policies.
+:::
+
+## 3. Create oAuth Consent Screen
+
+Go to the console [oAuth Consent Screen Page](https://console.developers.google.com/apis/credentials/consent) and choose _Internal_ as the User Type. Follow through the form to fullfill all the necessary data.
+
+![Google oAuth Consent Screen](./assets/google/google-oauth-consent-screen.png)
+
+In the scopes section you would usually match the scopes for the APIs you have enabled previously. Refer to the following table as the scopes required by Essential addons.
+
+| Scope  | Addon |
+|--------|-------|
+| https://www.googleapis.com/auth/youtube.readonly | Youtube Source |
+| https://www.googleapis.com/auth/business.manage | Google Business Profile Source. |
+| https://www.googleapis.com/auth/drive.readonly | Google Sheets Source and Google Sheets Form Action |
+| https://www.googleapis.com/auth/spreadsheets | Google Sheets Source and Google Sheets Form Action |
+| https://www.googleapis.com/auth/calendar.readonly | Google Calendar Source |
+| https://www.googleapis.com/auth/calendar.events.readonly | Google Calendar Source |
+| https://www.googleapis.com/auth/photoslibrary.readonly | Google Photos Source |
+
+## 4. Create oAuth Client ID
+
+Go to the console [Credentials Page](https://console.developers.google.com/apis/credentials) and create an _oAuth Client ID_. Select _Web Application_ and set a name. For the URL, input your site one or any URL you want to set as authorized.
+
+Once created, copy the `Redirect URI`, `Client ID` and `Client Secret` parameters.
+
+![Google oAuth Client ID](./assets/google/google-oauth-client-id.png)
+
+## 5. Generate Refresh Token
+
+Through your browser, visit the following URL, replacing the placeholders with parameters from the previous steps.
+
+```html
+https://accounts.google.com/o/oauth2/v2/auth?client_id={CLIENT_ID}&redirect_uri={REDIRECT_URI}&response_type=code&access_type=offline&state=state&scope={LIST_OF_SCOPES}
+```
+
+::: tip
+If there are multiple scopes, separate them with a comma.
+:::
+
+You will get redirected back to the _REDIRECT_URI_ with a `code` parameter in the URL, for example `https://example.com/?code=4/P7q7W91a-oMsCeLvIaQm6bTrgtp7`. Copy that `code` value.
+
+Through an HTTP client like [Postman](https://www.postman.com/), or your terminal using CURL, make a post request like the following one, once again, replacing the placeholders.
+
+```curl
+POST /token HTTP/1.1
+Host: oauth2.googleapis.com
+Content-Type: application/x-www-form-urlencoded
+
+code={CODE}
+client_id={CLIENT_ID}&
+client_secret={CLIENT_SECRET}&
+redirect_uri={REDIRECT_URI}&
+grant_type=authorization_code
+```
+
+You should get back a JSON response that contains the `refresh_token` you need, for example:
+
+```json
+{
+  "access_token": "1/fFAGRNJru1FTz70BzhT3Zg",
+  "expires_in": 3920,
+  "token_type": "Bearer",
+  "scope": "https://www.googleapis.com/auth/drive.metadata.readonly",
+  "refresh_token": "1//xEoDL4iW3cxlI7yDbSRFYNG01kVKM2C-259HOF2aQbI"
+}
+```
+
+## 6. Authenticate
+
+When creating a Source or Action that requires Google Authentication choose Custom App and fill in the details using the `Client ID`, `Client Secret` and `Refresh Token` obtained in the previous steps.
+
+![Google Custom OAuth](./assets/google/google-custom-oauth.webp)

src/essentials-for-yootheme-pro/sidebar.json

@@ -204,6 +204,10 @@
                 "text": "Custom Facebook Dev App",
                 "link": "/auths/custom-facebook-dev-app"
             },
+            {
+                "text": "Custom Google Dev App",
+                "link": "/auths/custom-google-dev-app"
+            },
             {
                 "text": "Form Events",
                 "link": "/addons/forms/form-events"