feat: Adding CHANGELOG auto generation script

changes.py

@@ -0,0 +1,153 @@
+#!/usr/bin/python
+"""
+Small python script that, when run, will update the CHANGELOG with information
+about all merged pull requests since the previous release.
+
+This script must be run after tagging the latest version
+It checks the log of commits since the previous tag and parses it
+"""
+import re
+import subprocess
+import sys
+from datetime import datetime
+
+# Regex patterns
+RELEASE_MD_PATTERN = re.compile(r'## \[(\d+\.\d+\.\d+)\]')
+MERGED_PR_PATTERN = re.compile(
+    r'([0-9a-f]{7}) Merge pull request #(\d+) from (.+)/.+'
+)
+TAG_PATTERN = re.compile(
+    r'refs/tags/v(\d+\.\d+\.\d+) (\w{3} \w{3} \d{1,2} \d{2}:\d{2}:\d{2} \d{4})'
+)
+
+# PR Type terms
+FIX_TERMS = ['fix', 'change', 'update']
+
+
+# Helper functions
+def generate_pr_link(pr_num):
+    """
+    Returns a markdown link to a PR in this repo given its number
+    """
+    return (
+        '[PR #{0}](https://github.com/sendgrid/smtpapi-python/pulls/{0})'
+    ).format(pr_num)
+
+
+def generate_user_link(user):
+    """
+    Returns a markdown link to a user
+    """
+    return '[@{0}](https://github.com/{0})'.format(user)
+
+
+# Get latest tag
+command = ['git', 'tag', '--format=%(refname) %(creatordate)']
+res = subprocess.run(command, capture_output=True, text=True)
+if res.returncode != 0:
+    print('Error occurred when running git tag command:', str(res.stderr))
+    sys.exit(1)
+# Get the last line and get the tag number
+latest_release_match = TAG_PATTERN.match(
+    list(filter(None, res.stdout.split('\n')))[-1],
+)
+latest_release = latest_release_match[1]
+latest_release_date = datetime.strptime(
+    latest_release_match[2], '%a %b %d %H:%M:%S %Y',
+)
+print('Generating CHANGELOG for', latest_release)
+
+# Read in the CHANGELOG file first
+with open('CHANGELOG.md') as f:
+    # Read the text in as a list of lines
+    old_text = f.readlines()
+    # Get the latest release (top of the CHANGELOG)
+    for line in old_text:
+        match = RELEASE_MD_PATTERN.match(line)
+        if match:
+            prev_release = match[1]
+            break
+
+if latest_release == prev_release:
+    print(
+        'The latest git tag matches the last release in the CHANGELOG. '
+        'Please tag the repository before running this script.'
+    )
+    sys.exit(1)
+
+# Use git log to list all commits between that tag and HEAD
+command = 'git log --oneline v{}..@'.format(prev_release).split(' ')
+res = subprocess.run(command, capture_output=True, text=True)
+if res.returncode != 0:
+    print('Error occurred when running git log command:', str(res.stderr))
+    sys.exit(1)
+
+# Parse the output from the above command to find all commits for merged PRs
+merge_commits = []
+for line in res.stdout.split('\n'):
+    match = MERGED_PR_PATTERN.match(line)
+    if match:
+        merge_commits.append(match)
+
+# Determine the type of PR from the commit message
+added, fixes = [], []
+for commit in merge_commits:
+    # Get the hash of the commit and get the message of it
+    commit_sha = commit[1]
+    command = 'git show {} --format=format:%B'.format(commit_sha).split(' ')
+    res = subprocess.run(command, capture_output=True, text=True)
+    out = res.stdout.lower()
+    is_added = True
+
+    # When storing we need the PR title, number and user
+    data = {
+        # 3rd line of the commit message is the PR title
+        'title': out.split('\n')[2],
+        'number': commit[2],
+        'user': commit[3],
+    }
+
+    for term in FIX_TERMS:
+        if term in out:
+            fixes.append(data)
+            is_added = False
+            break
+    if is_added:
+        added.append(data)
+
+# Now we need to write out the CHANGELOG again
+with open('CHANGELOG.md', 'w') as f:
+    # Write out the header lines first
+    for i in range(0, 3):
+        f.write(old_text[i])
+
+    # Create and write out the new version information
+    latest_release_date_string = latest_release_date.strftime('%Y-%m-%d')
+    f.write('## [{}] - {} ##\n'.format(
+        latest_release,
+        latest_release_date_string,
+    ))
+    # Add the stuff that was added
+    f.write('### Added\n')
+    for commit in added:
+        f.write('- {}: {}{} (via {})\n'.format(
+            generate_pr_link(commit['number']),
+            commit['title'],
+            '.' if commit['title'][-1] != '.' else '',
+            generate_user_link(commit['user'])
+        ))
+    f.write('\n')
+    # Add the fixes
+    f.write('### Fixes\n')
+    for commit in fixes:
+        f.write('- {}: {}{} (via {})\n'.format(
+            generate_pr_link(commit['number']),
+            commit['title'],
+            '.' if commit['title'][-1] != '.' else '',
+            generate_user_link(commit['user'])
+        ))
+    f.write('\n')
+
+    # Add the old stuff
+    for i in range(3, len(old_text)):
+        f.write(old_text[i])