rails_schema_up_to_date.rb

# frozen_string_literal: true

module Overcommit::Hook::PreCommit
  # Check to see whether the schema file is in line with the migrations. When a
  # schema file is present but a migration file is not, this is usually a
  # failure. The exception is if the schema is at version 0 (i.e before any
  # migrations have been run). In this case it is OK if there are no migrations.
  class RailsSchemaUpToDate < Base
    def run # rubocop:disable CyclomaticComplexity, PerceivedComplexity
      if migration_files.any? && schema_files.none?
        return :fail, "It looks like you're adding a migration, but did not update the schema file"
      elsif migration_files.none? && schema_files.any? && non_zero_schema_version?
        return :fail, "You're trying to change the schema without adding a migration file"
      elsif migration_files.any? && schema_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 = schema.include?(latest_version)

        unless up_to_date
          return :fail, "The latest migration version you're committing is " \
                       "#{latest_version}, but your schema file " \
                       "#{schema_files.join(' or ')} is on a different version."
        end
      end

      :pass
    end

    private

    def migration_files
      @migration_files ||= applicable_files.select do |file|
        file.match %r{db/migrate/.*\.rb}
      end
    end

    def schema_files
      @schema_files ||= applicable_files.select do |file|
        file.match %r{db/schema\.rb|db/structure.*\.sql}
      end
    end

    def schema
      @schema ||= schema_files.map { |file| File.read(file) }.join
      @schema.tr('_', '')
    end

    def non_zero_schema_version?
      schema =~ /\d{14}/
    end
  end
end