git_worktree.rb

# frozen_string_literal: true
# Helper for Git worktree-aware behavior
module GitWorktree
  PROJECT_ROOT = File.expand_path("..", __dir__)

  def self.name
    return @_name if defined?(@_name)

    git_dir = `git rev-parse --git-dir 2>/dev/null`.strip
    return @_name = nil if git_dir.empty? || git_dir.exclude?("/.git/worktrees/")

    # Conductor renames the branch after setup runs, so use the worktree directory
    # name (set at worktree creation) for a stable identifier during setup.
    @_name = normalize(File.basename(git_dir))
  end

  def self.normalize(text)
    text.gsub(/[^a-zA-Z0-9_]/, "_").squeeze("_").downcase
  end
  private_class_method :normalize

  def self.db_suffix
    value = name
    return "" if value.blank?

    "_#{value.first(30)}"
  end

  # Returns a deterministic integer from +range+ based on the current worktree branch name.
  # Returns +range.first+ when not in a worktree (e.g. main branch).
  #
  # +stride+ reserves a block of consecutive integers per worktree so callers can add an
  # offset without colliding with adjacent worktrees. For example, Capybara system tests
  # use stride equal to PARALLEL_TEST_GROUPS and add TEST_ENV_NUMBER on top:
  #
  #   GitWorktree.integer(4000..4990, stride: ENV.fetch("PARALLEL_TEST_GROUPS", 1).to_i) + ENV.fetch("TEST_ENV_NUMBER", 0).to_i
  #   # worktree A (PARALLEL_TEST_GROUPS=4) => 4000, 4001, 4002, 4003
  #   # worktree B (PARALLEL_TEST_GROUPS=4) => 4020, 4021, 4022, 4023  (never overlaps A)
  def self.integer(range, stride: 1)
    value = name
    return range.first if value.nil?

    require "zlib"
    slots = range.size / stride
    range.first + ((Zlib.crc32(value) % slots) * stride)
  end
end