brew/Library/Homebrew/dev-cmd/cat.rb

# typed: false
# frozen_string_literal: true

require "cli/parser"

module Homebrew
  extend T::Sig

  module_function

  sig { returns(CLI::Parser) }
  def cat_args
    Homebrew::CLI::Parser.new do
      description <<~EOS
        Display the source of a <formula> or <cask>.
      EOS

      switch "--formula", "--formulae",
             description: "Treat all named arguments as formulae."
      switch "--cask", "--casks",
             description: "Treat all named arguments as casks."

      conflicts "--formula", "--cask"

      named_args [:formula, :cask], min: 1
    end
  end

  def cat
    args = cat_args.parse

    cd HOMEBREW_REPOSITORY
    pager = if Homebrew::EnvConfig.bat?
      ENV["BAT_CONFIG_PATH"] = Homebrew::EnvConfig.bat_config_path
      ENV["BAT_THEME"] = Homebrew::EnvConfig.bat_theme
      ensure_formula_installed!(
        "bat",
        reason:           "displaying <formula>/<cask> source",
        # The user might want to capture the output of `brew cat ...`
        # Redirect stdout to stderr
        output_to_stderr: true,
      ).opt_bin/"bat"
    else
      "cat"
    end

    args.named.to_paths.each do |path|
      next path if path.exist?

      path = path.basename(".rb") if args.cask?

      ofail "#{path}'s source doesn't exist on disk."
    end

    if Homebrew.failed?
      $stderr.puts "The name may be wrong, or the tap hasn't been tapped. Instead try:"
      treat_as = "--cask " if args.cask?
      treat_as = "--formula " if args.formula?
      $stderr.puts "  brew info --github #{treat_as}#{args.named.join(" ")}"
      return
    end

    safe_system pager, *args.named.to_paths
  end
end