feat: add .gitignore pattern support for repository analysis

[e2720pjk]

This PR splits out a feature from the fork branch referenced in #28 as an initial contribution🙏
Welcome to review and provide suggestions. I'm happy to make adjustments as needed

PR report(from DeepWiki team): https://app.devin.ai/review/FSoft-AI4Code/CodeWiki/pull/35

TLDR

Adds support for respecting .gitignore patterns during repository analysis. Uses git check-ignore when available with fallback to pathspec library.

Examples:

# Enable gitignore respect
codewiki generate --respect-gitignore

# Save as default setting
codewiki config set --respect-gitignore

Dive Deeper

Key Changes

repo_analyzer.py

• Added _user_exclude_patterns to distinguish user-specified vs default excludes
• Implemented three-tier priority logic for respect_gitignore:
  1. Git ignores (returns True) → exclude file
  2. Git doesn't ignore (returns False) → check user-specified excludes, then DEFAULT_IGNORE_PATTERNS
  3. Git unavailable (returns None) → fallback to .gitignore file via pathspec
• Modified _should_include_file to use pathspec matching for include patterns
• Bug fix: Ensure DEFAULT_IGNORE_PATTERNS are checked when git returns False (line 188)

analysis_service.py

• Added None checks in analyze_local_repository and _analyze_structure
• Returns empty structure on failure/exclusion to prevent crashes

How It Works

1. Git available: Uses git check-ignore command for full recursive accuracy
2. Git unavailable: Falls back to pathspec library for root-only .gitignore matching
3. Features: Handles nested .gitignore files, pattern negation (!pattern), and complex patterns
4. DEFAULT_IGNORE_PATTERNS: Always checked for patterns like .git, *.pyc, __pycache__/, node_modules/, etc.

Exclusion priority:

1. Git ignore (if --respect-gitignore enabled and git says ignored) → exclude
2. User-specified excludes (CLI --exclude) → exclude
3. .gitignore file (if --respect-gitignore enabled) → exclude
4. DEFAULT_IGNORE_PATTERNS (always checked) → exclude

Use cases:

• Node.js projects: Excludes node_modules/, build/, .env, *.log
• Python projects: Excludes __pycache__/, *.pyc, .venv/, *.egg-info/
• Custom patterns: All patterns in your .gitignore file are respected
• Default exclusions: Git internals (.git/), caches, logs, and other standard patterns always excluded

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Reviewer Test Plan Suggestions

1. Check Documentation

You can review the changes in README.md to verify accuracy and clarity:

git show HEAD -- README.md

2. Verify Gitignore Behavior

You can run this script to verify hybrid strategy and priority logic:

python tests/test_gitignore_verification.py

The test script verifies:

• Basic gitignore patterns (*.log)
• Multiple log files excluded by DEFAULT_IGNORE_PATTERNS
• Nested .gitignore files
• CLI --exclude overrides Git tracking

Output:

Details

3. Runtime Check

You can verify the CLI configuration loads the flag correctly:

codewiki config show
# Should show: "Respect Gitignore: True" when set

codewiki generate --help | grep -i "gitignore"
# Should show the --respect-gitignore option

Output:

Details