module ReactOnRails::GitUtils

def self.dirty_worktree_error_message
  <<~MSG.strip
    You have uncommitted changes. Please commit or stash them before continuing.
    The React on Rails generator creates many new files and it's important to keep
    your existing changes separate from the generated code for easier review.
  MSG
end

def self.missing_git_error_message
  <<~MSG.strip
    Git is not installed. Please install Git and commit your changes before continuing.
    The React on Rails generator creates many new files and version control helps
    track what was generated versus your existing code.
  MSG
end

def self.not_a_git_repository_error_message
  <<~MSG.strip
    Git is installed, but this directory is not a Git repository yet. Initialize Git
    and commit or stash your changes before continuing.
    The React on Rails generator creates many new files and version control helps
    track what was generated versus your existing code.
  MSG
end

def self.report_worktree_issues(message_handler, git_installed:, as_error:)
  return false if skip_worktree_check?
  status = git_installed ? worktree_status : :git_not_installed
  return false if status == :clean
  msg = worktree_message(status, as_error: as_error)
  as_error ? message_handler.add_error(msg) : message_handler.add_warning(msg)
  true
end

def self.skip_worktree_check?
  truthy_env?(ENV.fetch("CI", nil)) || truthy_env?(ENV.fetch("COVERAGE", nil))
end

def self.truthy_env?(value)
  CI_TRUTHY_VALUES.include?(value.to_s.strip.downcase)
end

def self.uncommitted_changes?(message_handler, git_installed: true)
  report_worktree_issues(message_handler, git_installed: git_installed, as_error: true)
end

def self.warn_if_uncommitted_changes(message_handler, git_installed: true)
  report_worktree_issues(message_handler, git_installed: git_installed, as_error: false)
end

def self.worktree_message(status, as_error:)
  case status
  when :not_a_git_repository
    as_error ? not_a_git_repository_error_message : NOT_A_GIT_REPOSITORY_WARNING
  when :git_not_installed
    as_error ? missing_git_error_message : MISSING_GIT_WARNING
  else
    as_error ? dirty_worktree_error_message : DIRTY_WORKTREE_WARNING
  end
end

def self.worktree_status
  output, status = Open3.capture2e("git", "status", "--porcelain")
  return :clean if status.success? && output.strip.empty?
  # Exit code 128 is git's standard fatal error (e.g., not a git repository)
  return :not_a_git_repository if status.exitstatus == 128
  :dirty
rescue Errno::ENOENT
  # git binary not found despite passing the cli_exists? check
  :git_not_installed
end