codeowners_to_database.rb

#!/usr/bin/env ruby
require 'bundler/inline'

gemfile do
  source 'https://rubygems.org'
  gem 'pathspec', require: 'pathspec'
  gem 'pry'
end

module CodeownersToDatabase

  module_function
  def patterns_with_owners
    @patterns_with_owners ||=
      File.readlines('.github/CODEOWNERS').map do |line|
        line = line.strip.chomp
        next if line.empty?
        next if line.start_with?('#')
        pattern, *owners = line.split ' '
        [PathSpec.from_lines(pattern), owners]
    end.compact
  end

  def import(file)
    target = patterns_with_owners.find do |spec, owners|
      spec.match(file)
    end
    owners = target ? target.last : []
    insert_database(file, owners)
  end

  def insert_database(file, owners)
    puts "INSERT INTO owners (file, owners) values ('#{file}', '#{owners.join(', ')}');"
  end
  def import_all!(files=Dir.glob('**/*'))
    puts <<~SQL
      CREATE TABLE owners (file TEXT, owners TEXT);
      CREATE VIEW expanded_owners AS
        SELECT unnest(regexp_split_to_array(file, '/')) AS fragment,
          owners FROM owners;
      CREATE VIEW keyword_map AS SELECT COUNT(1) AS occurrences, fragment, owners
         from expanded_owners
         where fragment !~ '\.'
         group by fragment, owners order by 2;
    SQL
    files.each(&method(:import))
    puts "select * from keyword_map;"
  end
end
CodeownersToDatabase.import_all!