feat: enhance UI with file statistics and changes preview

[DFanso]

Description

This PR enhances the user interface of the commit message generator by adding comprehensive file statistics and a visual preview of changes. The improvements provide users with clear, colorful feedback about their Git repository state before generating commit messages.

Type of Change

• Bug fix (non-breaking change which fixes an issue)
• New feature (non-breaking change which adds functionality)
• Breaking change (fix or feature that would cause existing functionality to not work as expected)
• Documentation update
• Code refactoring
• Performance improvement
• Other (please describe):

Related Issue

Fixes #(issue number)

Changes Made

UI Enhancements

• File Statistics Display: Added a comprehensive changes summary showing:

  • ✅ Staged files count with file names (displays first 5)
  • ⚠️ Unstaged files count with file names (displays first 3)
  • 📝 Untracked files count with file names (displays first 3)
  • Collapsible view showing "... and X more" for additional files

• Visual Changes Preview: Implemented a table-based preview showing:

  • Lines added (displayed in green with + prefix)
  • Lines deleted (displayed in red with - prefix)
  • Total files affected

• Enhanced Header: Added a full-width styled header "🚀 Commit Message Generator"

• Improved Commit Message Display:

  • Commit messages now displayed in a styled bordered box
  • Uses custom box characters (┌─┐│└┘) for a polished look
  • Light green color scheme for better visibility

• Better Spinner Feedback:

  • Custom spinner sequence for generating animation
  • Success message: "✅ Commit message generated successfully!"
  • Failure handling with appropriate error messages

Code Improvements

• New Data Structure: Added FileStatistics struct to track:

  • Staged files
  • Unstaged files
  • Untracked files
  • Total file count
  • Lines added/deleted

• Helper Functions:

  • getFileStatistics(): Collects comprehensive file statistics from Git
  • displayFileStatistics(): Renders file stats with pterm styling
  • displayCommitMessage(): Shows commit message in a styled panel
  • displayChangesPreview(): Displays line change statistics
  • filterEmpty(): Utility to clean up file lists

• Import Organization: Reordered imports for better code organization

Dependency Updates

• Added github.com/openai/openai-go/v3 v3.0.1 to support ChatGPT integration
• Updated go.mod and go.sum with new dependencies and reordered entries

Testing

• Tested with Gemini API
• Tested with Grok API
• Tested on Windows
• Tested on Linux
• Tested on macOS
• Added/updated tests (if applicable)

Test Scenarios Verified

1. ✅ Repository with staged files only
2. ✅ Repository with unstaged files only
3. ✅ Repository with untracked files only
4. ✅ Repository with mixed file states
5. ✅ Repository with no changes (displays warning)
6. ✅ Large number of files (collapse functionality works)
7. ✅ Line statistics calculation for staged changes

Checklist

• My code follows the project's code style
• I have performed a self-review of my code
• I have commented my code, particularly in hard-to-understand areas
• I have made corresponding changes to the documentation
• My changes generate no new warnings or errors
• I have tested this in a real Git repository
• I have read the CONTRIBUTING.md guidelines

Screenshots (if applicable)

Before

No changes detected in the Git repository.

After

┏━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━┓
┃                  🚀 Commit Message Generator                    ┃
┗━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━┛

📊 Changes Summary

  ✅ Staged files: 3
    • src/main.go
    • go.mod
    • go.sum
  
  ⚠️ Unstaged files: 1
    • README.md

🤖 Generating commit message...
✅ Commit message generated successfully!

📝 Generated Commit Message

┌─────────────────── Commit Message ───────────────────┐
│  feat: enhance UI with file statistics and preview   │
│                                                       │
│  - Add file statistics display                       │
│  - Implement changes preview                         │
│  - Update dependencies                               │
└───────────────────────────────────────────────────────┘

🔍 Changes Preview

  Lines Added    | +254
  Lines Deleted  | -32
  Total Files    | 3

Additional Notes

Technical Details

• Uses pterm library extensively for styled terminal output
• File statistics are collected before fetching full Git changes for better performance
• Implements early exit when no changes are detected
• Statistics calculation only processes staged changes for accuracy
• Binary and large files are excluded from detailed analysis

Future Enhancements

• Add line statistics for unstaged changes
• Include file type breakdown (e.g., Go files, Markdown, etc.)
• Add option to toggle detailed/summary view
• Support for displaying modified lines context

Breaking Changes

None. This is a pure UI enhancement that doesn't change any existing functionality or API.

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For Hacktoberfest Participants

• This PR is submitted as part of Hacktoberfest 2025

Thank you for your contribution! 🎉