fix: improve authentication flow and session handling

[hrntknr]

Summary

Improves the authentication flow and session handling in the auth router by adding proper authorization checks, fixing redirect URL management, and refactoring template rendering for better maintainability.

Type of Change

• fix: A bug fix

Related Issues

Changes Made

• Added authorization check after user authentication to ensure authenticated users are also authorized
• Fixed redirect URL handling by properly deleting redirect URL from session after use
• Refactored template rendering into dedicated methods (renderLogin and renderUnauthorized) for better code organization
• Improved logout behavior to redirect users to login page instead of showing plain text
• Enhanced session management by deleting specific keys instead of clearing all session data
• Renamed template field to loginTemplate for clarity

Testing

• Manual testing of login flow
• Manual testing of logout flow
• Manual testing of authorization checks
• Manual testing of redirect URL handling

[codecov]

Codecov Report

❌ Patch coverage is 33.89831% with 39 lines in your changes missing coverage. Please review.

Files with missing lines	Patch %	Lines
pkg/auth/auth.go	33.89%	35 Missing and 4 partials ⚠️

📢 Thoughts on this report? Let us know!

[Copilot]

Pull Request Overview

This PR improves the authentication flow and session handling by adding proper authorization checks after authentication, fixing redirect URL management, and refactoring template rendering methods for better code organization.

• Added authorization verification in the OAuth callback handler to ensure authenticated users are also authorized
• Fixed session management by properly deleting specific session keys and handling redirect URLs correctly
• Refactored template rendering into dedicated methods for better maintainability

Reviewed Changes

Copilot reviewed 2 out of 2 changed files in this pull request and generated 2 comments.

File	Description
pkg/auth/auth.go	Added authorization checks, improved session handling, refactored template rendering methods, and enhanced logout behavior
pkg/auth/auth_test.go	Updated test expectations to reflect authorization flow changes and moved mock setup for better organization

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[Copilot]

The redirect URL is deleted from the session before checking if it's nil, but the check happens after the session is saved. This could cause issues if the session save fails. Consider moving the session.Save() call after the redirect logic.

[Copilot]

Same issue as in the OAuth callback: the redirect URL is deleted and session saved before the redirect logic. If session.Save() fails, the redirect URL would be lost but the redirect might not happen correctly.