CHANGELOG.md application version bump script suitable for ruby, Rails, npm and Flutter projects

bump-version.rb

#!/usr/bin/env ruby

tag_prefix = "version/"
changelog_path = "CHANGELOG.md"

changelog = File.read(changelog_path)
if changelog.empty?
  puts "No changelog found in #{changelog_path}"
  exit
end

version = changelog.scan(/^##\s*(\S+)/).first&.first
if version.nil?
  puts "No version found in #{changelog_path}"
  exit
end

`git fetch --tags`

current_tag = "#{tag_prefix}#{version}"
current_tag_exists = !`git tag -l "#{current_tag}"`.empty?
git_log = if current_tag_exists
  `git log --pretty=format:"%h %s" #{current_tag}..HEAD`
end

next_version_parts = version.split(".")
3.times { |idx| next_version_parts[idx] = next_version_parts[idx].to_i }

git_log_lines_count = git_log&.lines&.size || 0
if git_log_lines_count < 100
  next_version_parts[2] += 1
else
  next_version_parts[1] += 1
  next_version_parts[2] = 0
end
next_version = next_version_parts.join(".")
next_version_tag = "#{tag_prefix}#{next_version}"

puts "Next version will be #{next_version} (based on #{git_log_lines_count} commits since #{version})"
puts "Do you want to continue? (y/n)"
if gets.chomp.downcase != "y"
  puts "Exiting"
  exit
end

puts "Updating CHANGELOG.md"
File.open("CHANGELOG.md", "w") do |file|
  file.puts "# CHANGELOG\n\n"
  file.puts "## #{next_version}\n\n"
  file.puts "Diff ref: #{current_tag}...#{next_version_tag}\n"
  file.puts git_log.lines.map { |line| "  * #{line}" }.join if git_log
  file.puts changelog.lines[1..].join
end

puts "Updating webapp/package.json"
require "json"
webapp_package_json_path = "webapp/package.json"
webapp_package_json = JSON.parse(File.read(webapp_package_json_path))
webapp_package_json["version"] = next_version
File.open(webapp_package_json_path, "w") do |file|
  file.puts JSON.pretty_generate(webapp_package_json)
end

puts "Updating flutter_app/pubspec.yaml"
flutter_app_pubspec_yaml_path = "flutter_app/pubspec.yaml"
flutter_app_pubspec_yaml = YAML.load_file(flutter_app_pubspec_yaml_path)
flutter_app_pubspec_yaml["version"] = next_version
File.open(flutter_app_pubspec_yaml_path, "w") do |file|
  file.puts YAML.dump(flutter_app_pubspec_yaml)
end

puts "Creating git tag #{next_version_tag}"
`git tag "#{next_version_tag}" && git push --tags`