Google API + Python Integration: A General Setup Tutorial

This tutorial provides a generalized guide for integrating Google APIs with Python, applicable to Google Sheets, Drive, Gmail, Calendar, and more. You will learn how to:
✔ Enable and authenticate a Google API
✔ Set up API credentials
✔ Install and use the `google-auth` and `gspread` libraries
✔ Access Google services using Python

Step 1: Enable the Google API

1. Go to the Google Cloud Console (https://console.cloud.google.com/). (You may need to create account) 

2. Create a new project or select an existing one.

3. Navigate to APIs & Services > Library.

4. Search for the API you want to use (e.g., Google Sheets API, Google Drive API, Gmail API, etc.).

5. Click Enable.

Step 2: Create API Credentials

1. Go to APIs & Services > Credentials.

2. Click Create Credentials > Service Account.

3. Enter a name (e.g., `MyPythonAppService`).

4. Assign a role (Editor, Viewer, or Owner, depending on permissions needed).

5. Click Continue > Done.

6. Open the new service account and go to the Keys tab.

7. Click Add Key > JSON. This will download a `credentials.json` file.

Step 3: Grant API Access (If Required)

Some APIs (like Google Sheets or Google Drive) require you to share access with your service account.

For example, if using Google Sheets:

1. Open Google Sheets and create a new spreadsheet.

2. Click Share in the top-right corner.

3. Copy the service account email from Google Cloud Console.

4. Paste it in the Add people and groups field and grant Editor access.

Step 4: Install Required Python Libraries

To use Google APIs in Python, install the necessary libraries:

```sh
pip install google-auth google-auth-oauthlib google-auth-httplib2 google-api-python-client gspread
```

Step 5: Authenticate & Connect to Google API

For most Google APIs, use service account authentication:

```python
from google.oauth2 import service_account
from googleapiclient.discovery import build

SCOPES = ["https://www.googleapis.com/auth/drive", "https://www.googleapis.com/auth/spreadsheets"]
creds = service_account.Credentials.from_service_account_file("credentials.json", scopes=SCOPES)

# Connect to Google Drive API
drive_service = build("drive", "v3", credentials=creds)

# Connect to Google Sheets API
sheets_service = build("sheets", "v4", credentials=creds)

print("Google API connection successful!")
```

Step 6: API-Specific Usage

### Example: Google Drive API (List Files)

```python
results = drive_service.files().list().execute()
files = results.get("files", [])
for file in files:
print(f"File name: {file['name']} (ID: {file['id']})")
```

### Example: Google Sheets API (Write Data)

```python
spreadsheet_id = "your_google_sheet_id_here"
range_name = "Sheet1!A1:C1"
values = [["Timestamp", "Metric", "Value"]]

body = {"values": values}
sheets_service.spreadsheets().values().update(
spreadsheetId=spreadsheet_id, range=range_name,
valueInputOption="RAW", body=body).execute()

print("Data written to Google Sheets")
```

Step 7: Running the Script

To test your setup, run:

```sh
python google_api_test.py
```

If everything is set up correctly, you should see data fetched or updated.

Troubleshooting & Common Errors

### 1️⃣ Permission Denied (403 Error)

✔ Ensure the service account email has been added to Google Sheets/Drive with the correct access.

### 2️⃣ Quota Exceeded (429 Error)

✔ Add a short delay (`time.sleep(0.1)`) between requests.
✔ Avoid sending too many API calls in a short time.

### 3️⃣ `google.auth.exceptions.DefaultCredentialsError`

✔ Ensure `credentials.json` is in the correct directory.
✔ Verify that the path in `from_service_account_file()` is correct.

Expanding to Other Google APIs

This setup works for various Google APIs. To integrate with other services:
- **Google Calendar API** → Schedule events
- **Gmail API** → Send & read emails
- **Google Maps API** → Geolocation & directions
- **YouTube Data API** → Retrieve video analytics