Pre commit webhook to check if Ecto structure.sql is updated

.overcommit.yml

PreCommit:
  StructureUpToDate:
    enabled: true
    description: 'Checking for schema changes'
    include: 'priv/repo/**/*'

structure_up_to_date.rb

# borrowed from
# https://github.com/brigade/overcommit/blob/master/lib/overcommit/hook/pre_commit/rails_schema_up_to_date.rb
#
# rubocop:disable
module Overcommit::Hook::PreCommit
  # Check to see whether the structure file is in line with the migrations. When a
  # structure file is present but a migration file is not, this is usually a
  # failure. The exception is if the structure is at version 0 (i.e before any
  # migrations have been run). In this case it is OK if there are no migrations.
  class StructureUpToDate < Base
    def run
      if migration_files.any? && structure_files.none?
        return :fail, "It looks like you're adding a migration, but did not update "\
        "the structure file. Please run 'mix do ecto.migrate, ecto.dump' and stage changes"
      elsif migration_files.none? && structure_files.any?
        return :fail, "You're trying to change the structure without adding a migration file"
      elsif migration_files.any? && structure_files.any?
        # Get the latest version from the migration filename. Use
        # `File.basename` to prevent finding numbers that could appear in
        # directories, such as the home directory of a user with a number in
        # their username.
        latest_version = migration_files.map do |file|
          File.basename(file)[/\d+/]
        end.sort.last

        up_to_date = structure.include?(latest_version)

        unless up_to_date
          return :fail, "The latest migration version you're committing is " \
                       "#{latest_version}, but your structure file " \
                       "#{structure_files.join(' or ')} is on a different version." \
                       "Please run 'mix do ecto.migrate, ecto.dump' and stage changes"
        end
      end

      :pass
    end

    private

    def migration_files
      @migration_files ||= applicable_files.select do |file|
        file.match %r{priv/repo/migrations/.*\.exs}
      end
    end

    def structure_files
      @structure_files ||= applicable_files.select do |file|
        file.match %r{priv/repo/structure.*\.sql}
      end
    end

    def structure
      @structure ||= structure_files.map { |file| File.read(file) }.join
    end

    def non_zero_structure_version?
      structure =~ /\d{14}/
    end
  end
end