feat: enhance OAuth2 authentication for Google and GitHub

[ssk033]

Enhanced OAuth2 Authentication for Google and GitHub

Summary

This PR enhances the existing OAuth2 authentication implementations for Google and GitHub with improved error handling, comprehensive logging, and user-friendly error messages. Additionally, it includes comprehensive setup documentation to help users configure OAuth2 authentication.

Changes

1. Enhanced Google OAuth2 Authentication

• Added comprehensive logging (info, warn, error levels) throughout the authentication flow
• Improved error messages with user-friendly feedback
• Enhanced domain validation with clearer error messages
• Better error handling for email-related issues
• Preserved existing error types for proper handling

2. Enhanced GitHub OAuth2 Authentication

• Added comprehensive logging throughout the authentication flow
• Email availability validation with warning logs
• Improved error messages with actionable feedback
• Better error handling for email-related issues
• Preserved existing error types for proper handling

3. Comprehensive Setup Documentation

• Step-by-step Google OAuth2 setup guide
• Step-by-step GitHub OAuth2 setup guide
• GitHub Enterprise setup instructions
• Troubleshooting section with common issues and solutions
• Security best practices
• Advanced configuration options

Benefits

1. Better Debugging: Comprehensive logging makes it easier to troubleshoot authentication issues
2. Improved User Experience: User-friendly error messages help users understand what went wrong
3. Enhanced Maintainability: Better code structure and error handling
4. Documentation: Complete setup guide helps users configure OAuth2 easily

Files Changed

• server/modules/authentication/google/authentication.js
• server/modules/authentication/github/authentication.js
• OAUTH2_SETUP.md (new file)

Testing

• ✅ Tested error handling with various scenarios
• ✅ Verified logging output
• ✅ Confirmed backward compatibility
• ✅ Checked code style and linting

Backward Compatibility

✅ All changes are backward compatible - existing configurations will continue to work without modification.

Screenshots/Examples

The enhanced logging will output messages like:

Google OAuth: Processing profile for user 123456789
Google OAuth: Successfully authenticated user user@example.com

Error messages are now more descriptive:

• Before: Generic error
• After: "Google authentication failed: Email address is required but not available. Please ensure your Google account has a verified email address."