================================================================================
GMAIL CLEANUP - CHALLENGE 2 SOLUTION
Chapter 2: Configuration Management
Challenge: Configuration Validation
================================================================================

PROBLEM:
Extend Config.validate() to check:
1. GMAIL_USER is not empty
2. GMAIL_USER contains @ symbol (valid email)
3. API_REQUEST_TIMEOUT is positive number
4. Return True if all valid, False otherwise

SOLUTION:
================================================================================

File: config.py (updated)

import os
import re
from pathlib import Path
from dotenv import load_dotenv

ENV_FILE = Path(__file__).parent / ".env"
load_dotenv(ENV_FILE)

class Config:
    """Application configuration with validation."""

    def __init__(self):
        self.gmail_user = os.environ.get('GMAIL_USER')
        self.api_timeout = int(os.environ.get('API_REQUEST_TIMEOUT', '10'))
        self.max_results = int(os.environ.get('MAX_RESULTS', '100'))
        self.days_old = int(os.environ.get('DELETE_OLDER_THAN_DAYS', '365'))
        self.min_attachment_mb = int(os.environ.get('MIN_ATTACHMENT_SIZE_MB', '10'))

    def validate(self) -> bool:
        """Validate all configuration values."""

        # Check GMAIL_USER is not empty
        if not self.gmail_user:
            print("❌ GMAIL_USER is empty!")
            print("   Fix: Set GMAIL_USER in .env")
            return False

        # Check GMAIL_USER is not just whitespace
        if not self.gmail_user.strip():
            print("❌ GMAIL_USER is just whitespace!")
            print("   Fix: Remove spaces from GMAIL_USER")
            return False

        # Check email format (has @)
        if '@' not in self.gmail_user:
            print(f"❌ GMAIL_USER '{self.gmail_user}' is not a valid email!")
            print("   Fix: Use format: user@gmail.com")
            return False

        # Check email format (regex)
        email_pattern = r'^[a-zA-Z0-9._%+-]+@[a-zA-Z0-9.-]+\.[a-zA-Z]{2,}$'
        if not re.match(email_pattern, self.gmail_user):
            print(f"❌ GMAIL_USER '{self.gmail_user}' doesn't look like a valid email!")
            print("   Fix: Use format: user@example.com")
            return False

        # Check API timeout is positive
        if self.api_timeout <= 0:
            print(f"❌ API_REQUEST_TIMEOUT must be positive! Got: {self.api_timeout}")
            print("   Fix: Set API_REQUEST_TIMEOUT to positive number (e.g., 10)")
            return False

        # Check MAX_RESULTS is positive
        if self.max_results <= 0:
            print(f"❌ MAX_RESULTS must be positive! Got: {self.max_results}")
            print("   Fix: Set MAX_RESULTS to positive number (e.g., 100)")
            return False

        # Check days_old is positive
        if self.days_old < 0:
            print(f"❌ DELETE_OLDER_THAN_DAYS must be >= 0! Got: {self.days_old}")
            print("   Fix: Set to positive number (e.g., 365)")
            return False

        print("✅ All configuration values are valid!")
        return True


TESTING
================================================================================

Test 1: Valid configuration (should pass)
Config with GMAIL_USER=emubantam@gmail.com, API_REQUEST_TIMEOUT=10

Result:
✅ All configuration values are valid!


Test 2: Missing GMAIL_USER (should fail)
Config with GMAIL_USER="" (empty)

Result:
❌ GMAIL_USER is empty!
   Fix: Set GMAIL_USER in .env


Test 3: Invalid email (should fail)
Config with GMAIL_USER=notanemail

Result:
❌ GMAIL_USER 'notanemail' is not a valid email!
   Fix: Use format: user@gmail.com


Test 4: Negative timeout (should fail)
Config with API_REQUEST_TIMEOUT=-5

Result:
❌ API_REQUEST_TIMEOUT must be positive! Got: -5
   Fix: Set API_REQUEST_TIMEOUT to positive number (e.g., 10)


KEY IMPROVEMENTS
================================================================================

✅ Multiple validation checks
✅ Clear error messages
✅ Helpful hints for fixing errors
✅ Email format validation (regex)
✅ Range checking for numbers

================================================================================