Change Log Generator

# Changes since last tag
git log $(git describe --tags --abbrev=0)..HEAD --oneline

# Changes between two tags
git log v1.2.0..v1.3.0 --oneline

# Changes in last N commits
git log -n 50 --oneline

# Changes since specific date
git log --since="2024-01-01" --oneline

# Changes in current branch vs main
git log main..HEAD --oneline

# Full commit messages
git log v1.2.0..HEAD --format="%H|%an|%ad|%s|%b" --date=short

# With file changes
git log v1.2.0..HEAD --name-status

# With diff stats
git log v1.2.0..HEAD --stat

# Using GitHub CLI
gh pr list --state merged --base main --limit 50

# Get PR details
gh pr view 123 --json title,body,labels,mergedAt

<type>[optional scope]: <description>

[optional body]

[optional footer(s)]

feat(auth): add OAuth2 authentication

Implements OAuth2 authentication flow using Google provider.
Users can now sign in with their Google accounts.

Closes #45

fix(api): prevent race condition in user creation

Race condition occurred when multiple requests tried to create
the same user simultaneously. Added database constraint and
retry logic.

Fixes #123

docs: update installation instructions

Added troubleshooting section for Windows users.

BREAKING CHANGE: remove deprecated API endpoints

The /api/v1/users endpoint has been removed. Use /api/v2/users instead.

import re

def parse_conventional_commit(message):
    """Parse conventional commit message."""
    # Pattern: type(scope): description
    pattern = r'^(\w+)(\(([^)]+)\))?:\s*(.+)$'
    match = re.match(pattern, message)

    if match:
        return {
            'type': match.group(1),
            'scope': match.group(3),
            'description': match.group(4),
            'breaking': 'BREAKING CHANGE' in message
        }
    else:
        return {
            'type': 'other',
            'scope': None,
            'description': message,
            'breaking': 'BREAKING CHANGE' in message
        }

# Example
commit = "feat(auth): add OAuth2 authentication"
parsed = parse_conventional_commit(commit)
# Returns: {'type': 'feat', 'scope': 'auth', 'description': 'add OAuth2 authentication', 'breaking': False}

CATEGORIES = {
    'feat': {
        'title': 'Features',
        'emoji': '✨',
        'description': 'New features and capabilities'
    },
    'fix': {
        'title': 'Bug Fixes',
        'emoji': '🐛',
        'description': 'Bug fixes and corrections'
    },
    'perf': {
        'title': 'Performance',
        'emoji': '⚡',
        'description': 'Performance improvements'
    },
    'refactor': {
        'title': 'Refactoring',
        'emoji': '♻️',
        'description': 'Code refactoring'
    },
    'docs': {
        'title': 'Documentation',
        'emoji': '📚',
        'description': 'Documentation updates'
    },
    'test': {
        'title': 'Testing',
        'emoji': '✅',
        'description': 'Test additions and updates'
    },
    'build': {
        'title': 'Build System',
        'emoji': '🏗️',
        'description': 'Build and dependency changes'
    },
    'ci': {
        'title': 'CI/CD',
        'emoji': '👷',
        'description': 'CI/CD changes'
    },
    'style': {
        'title': 'Code Style',
        'emoji': '💄',
        'description': 'Code style and formatting'
    },
    'chore': {
        'title': 'Chores',
        'emoji': '🔧',
        'description': 'Maintenance and chores'
    }
}

def categorize_commits(commits):
    """Categorize commits by type."""
    categorized = {}

    for commit in commits:
        parsed = parse_conventional_commit(commit['message'])
        commit_type = parsed['type']

        if commit_type not in categorized:
            categorized[commit_type] = []

        categorized[commit_type].append({
            'description': parsed['description'],
            'scope': parsed['scope'],
            'sha': commit['sha'][:7],
            'author': commit['author'],
            'breaking': parsed['breaking']
        })

    return categorized

# Changelog

All notable changes to this project will be documented in this file.

The format is based on [Keep a Changelog](https://keepachangelog.com/),
and this project adheres to [Semantic Versioning](https://semver.org/).

## [Unreleased]

### Added
- New feature A
- New feature B

### Changed
- Updated component X
- Improved performance of Y

### Deprecated
- Old API endpoint will be removed in v2.0

### Removed
- Deprecated feature Z

### Fixed
- Bug in authentication flow
- Memory leak in processor

### Security
- Fixed XSS vulnerability in input validation

def generate_changelog_entry(version, date, categorized_commits):
    """Generate changelog entry for a version."""
    lines = []

    # Header
    lines.append(f"## [{version}] - {date}\n")

    # Breaking Changes (if any)
    breaking_changes = []
    for category, commits in categorized_commits.items():
        for commit in commits:
            if commit.get('breaking'):
                breaking_changes.append(commit)

    if breaking_changes:
        lines.append("### ⚠️ BREAKING CHANGES\n")
        for change in breaking_changes:
            scope_str = f"**{change['scope']}**: " if change['scope'] else ""
            lines.append(f"- {scope_str}{change['description']} ({change['sha']})")
        lines.append("")

    # Regular categories
    category_order = ['feat', 'fix', 'perf', 'refactor', 'docs', 'test', 'build', 'ci', 'style', 'chore']

    for cat_type in category_order:
        if cat_type in categorized_commits:
            category_info = CATEGORIES.get(cat_type, {'title': cat_type.title()})
            lines.append(f"### {category_info['title']}\n")

            for commit in categorized_commits[cat_type]:
                if commit.get('breaking'):
                    continue  # Already listed in breaking changes

                scope_str = f"**{commit['scope']}**: " if commit['scope'] else ""
                lines.append(f"- {scope_str}{commit['description']} ([`{commit['sha']}`](link/to/commit/{commit['sha']}))")

            lines.append("")

    return "\n".join(lines)

## [1.3.0] - 2024-02-15

### ⚠️ BREAKING CHANGES

- **api**: remove deprecated /v1/users endpoint (a1b2c3d)

### Features

- **auth**: add OAuth2 authentication support ([`d4e5f6g`](link))
- **dashboard**: add real-time metrics visualization ([`h7i8j9k`](link))
- **api**: implement rate limiting for API endpoints ([`l0m1n2o`](link))

### Bug Fixes

- **auth**: prevent race condition in user creation ([`p3q4r5s`](link))
- **ui**: fix button alignment on mobile devices ([`t6u7v8w`](link))
- **api**: handle null values in request validation ([`x9y0z1a`](link))

### Performance

- **database**: optimize user query with indexes ([`b2c3d4e`](link))
- **api**: implement caching for frequently accessed data ([`f5g6h7i`](link))

### Documentation

- update installation instructions ([`j8k9l0m`](link))
- add troubleshooting guide ([`n1o2p3q`](link))

def categorize_non_conventional(message):
    """Categorize commits that don't follow conventional format."""
    message_lower = message.lower()

    # Keyword-based categorization
    if any(word in message_lower for word in ['add', 'implement', 'create']):
        return 'feat'
    elif any(word in message_lower for word in ['fix', 'resolve', 'correct', 'patch']):
        return 'fix'
    elif any(word in message_lower for word in ['update', 'improve', 'enhance']):
        return 'refactor'
    elif any(word in message_lower for word in ['doc', 'readme', 'comment']):
        return 'docs'
    elif any(word in message_lower for word in ['test', 'spec']):
        return 'test'
    else:
        return 'other'

# Exclude merge commits
git log --no-merges v1.2.0..HEAD

# Or include merge commits with special handling
git log --first-parent v1.2.0..HEAD

def extract_pr_info(commit_message):
    """Extract PR number from commit message."""
    # Pattern: (#123) or Merge pull request #123
    import re
    match = re.search(r'#(\d+)', commit_message)
    if match:
        return match.group(1)
    return None

def enhance_with_pr_data(commit, pr_number):
    """Enhance commit with PR metadata."""
    # Use gh CLI or GitHub API
    import subprocess
    import json

    result = subprocess.run(
        ['gh', 'pr', 'view', pr_number, '--json', 'title,labels,author'],
        capture_output=True,
        text=True
    )

    if result.returncode == 0:
        pr_data = json.loads(result.stdout)
        commit['pr_title'] = pr_data.get('title')
        commit['pr_labels'] = pr_data.get('labels', [])
        commit['pr_author'] = pr_data.get('author', {}).get('login')

    return commit

## [1.3.0] - 2024-02-15

[Full Changelog](https://github.com/user/repo/compare/v1.2.0...v1.3.0)

### Features
...

# Get unique contributors
git log v1.2.0..v1.3.0 --format="%an <%ae>" | sort | uniq

## [1.3.0] - 2024-02-15

**Contributors:** @alice, @bob, @charlie

### Features
...

def extract_issue_refs(message):
    """Extract issue references from commit message."""
    import re
    # Patterns: #123, Closes #123, Fixes #123
    patterns = [
        r'#(\d+)',
        r'[Cc]loses?\s+#(\d+)',
        r'[Ff]ixes?\s+#(\d+)',
        r'[Rr]esolves?\s+#(\d+)'
    ]

    issues = set()
    for pattern in patterns:
        matches = re.findall(pattern, message)
        issues.update(matches)

    return list(issues)

# Format in changelog
# - Fix authentication bug (closes #123, #124)

# Prepend new entry to existing CHANGELOG.md
cat new_entry.md CHANGELOG.md > temp.md
mv temp.md CHANGELOG.md

# Commit the changelog
git add CHANGELOG.md
git commit -m "docs: update changelog for v1.3.0"

# Using gh CLI
gh release create v1.3.0 \
  --title "Version 1.3.0" \
  --notes-file new_entry.md

# Or manually via GitHub web interface