# typed: true
# frozen_string_literal: true

require "cli/parser"
require "erb"

SOURCE_PATH = (HOMEBREW_LIBRARY_PATH/"manpages").freeze
TARGET_MAN_PATH = (HOMEBREW_REPOSITORY/"manpages").freeze
TARGET_DOC_PATH = (HOMEBREW_REPOSITORY/"docs").freeze
module Homebrew
  # Helper functions for generating homebrew manual.
  #
  # @api private
  module Manpages
    extend T::Sig

    Variables = Struct.new(
      :alumni,
      :commands,
      :developer_commands,
      :environment_variables,
      :global_cask_options,
      :global_options,
      :lead,
      :maintainers,
      :official_external_commands,
      :plc,
      :tsc,
      keyword_init: true,
    )

    module_function

    def regenerate_man_pages(quiet:)
      Homebrew.install_bundler_gems!

      markup = build_man_page(quiet: quiet)
      convert_man_page(markup, TARGET_DOC_PATH/"Manpage.md")
      convert_man_page(markup, TARGET_MAN_PATH/"brew.1")
    end

    def build_man_page(quiet:)
      template = (SOURCE_PATH/"brew.1.md.erb").read
      readme = HOMEBREW_REPOSITORY/"README.md"
      variables = Variables.new(
        commands:                   generate_cmd_manpages(Commands.internal_commands_paths),
        developer_commands:         generate_cmd_manpages(Commands.internal_developer_commands_paths),
        official_external_commands: generate_cmd_manpages(Commands.official_external_commands_paths(quiet: quiet)),
        global_cask_options:        global_cask_options_manpage,
        global_options:             global_options_manpage,
        environment_variables:      env_vars_manpage,
        lead:                       readme.read[/(Homebrew's \[Project Leader.*\.)/, 1]
                                      .gsub(/\[([^\]]+)\]\([^)]+\)/, '\1'),
        plc:                        readme.read[/(Homebrew's \[Project Leadership Committee.*\.)/, 1]
                                      .gsub(/\[([^\]]+)\]\([^)]+\)/, '\1'),
        tsc:                        readme.read[/(Homebrew's \[Technical Steering Committee.*\.)/, 1]
                                      .gsub(/\[([^\]]+)\]\([^)]+\)/, '\1'),
        maintainers:                readme.read[/(Homebrew's maintainers .*\.)/, 1]
                                      .gsub(/\[([^\]]+)\]\([^)]+\)/, '\1'),
        alumni:                     readme.read[/(Former maintainers .*\.)/, 1]
                                      .gsub(/\[([^\]]+)\]\([^)]+\)/, '\1'),
      )

      ERB.new(template, trim_mode: ">").result(variables.instance_eval { binding })
    end

    def sort_key_for_path(path)
      # Options after regular commands (`~` comes after `z` in ASCII table).
      path.basename.to_s.sub(/\.(rb|sh)$/, "").sub(/^--/, "~~")
    end

    def convert_man_page(markup, target)
      manual = target.basename(".1")
      organisation = "Homebrew"

      # Set the manpage date to the existing one if we're updating.
      # This avoids the only change being e.g. a new date.
      date = if target.extname == ".1" && target.exist?
        /"(\d{1,2})" "([A-Z][a-z]+) (\d{4})" "#{organisation}" "#{manual}"/ =~ target.read
        Date.parse("#{Regexp.last_match(1)} #{Regexp.last_match(2)} #{Regexp.last_match(3)}")
      else
        Date.today
      end
      date = date.strftime("%Y-%m-%d")

      shared_args = %W[
        --pipe
        --organization=#{organisation}
        --manual=#{target.basename(".1")}
        --date=#{date}
      ]

      format_flag, format_desc = target_path_to_format(target)

      puts "Writing #{format_desc} to #{target}"
      Utils.popen(["ronn", format_flag] + shared_args, "rb+") do |ronn|
        ronn.write markup
        ronn.close_write
        ronn_output = ronn.read
        odie "Got no output from ronn!" if ronn_output.blank?
        ronn_output = case format_flag
        when "--markdown"
          ronn_output.gsub(%r{<var>(.*?)</var>}, "*`\\1`*")
                     .gsub(/\n\n\n+/, "\n\n")
                     .gsub(/^(- `[^`]+`):/, "\\1") # drop trailing colons from definition lists
                     .gsub(/(?<=\n\n)([\[`].+):\n/, "\\1\n<br>") # replace colons with <br> on subcommands
        when "--roff"
          ronn_output.gsub(%r{<code>(.*?)</code>}, "\\fB\\1\\fR")
                     .gsub(%r{<var>(.*?)</var>}, "\\fI\\1\\fR")
                     .gsub(/(^\[?\\fB.+): /, "\\1\n    ")
        end
        target.atomic_write ronn_output
      end
    end

    def target_path_to_format(target)
      case target.basename
      when /\.md$/    then ["--markdown", "markdown"]
      when /\.\d$/    then ["--roff", "man page"]
      else
        odie "Failed to infer output format from '#{target.basename}'."
      end
    end

    def generate_cmd_manpages(cmd_paths)
      man_page_lines = []

      # preserve existing manpage order
      cmd_paths.sort_by(&method(:sort_key_for_path))
               .each do |cmd_path|
        cmd_man_page_lines = if (cmd_parser = Homebrew::CLI::Parser.from_cmd_path(cmd_path))
          next if cmd_parser.hide_from_man_page

          cmd_parser_manpage_lines(cmd_parser).join
        else
          cmd_comment_manpage_lines(cmd_path)
        end

        man_page_lines << cmd_man_page_lines
      end

      man_page_lines.compact.join("\n")
    end

    def cmd_parser_manpage_lines(cmd_parser)
      lines = [format_usage_banner(cmd_parser.usage_banner_text)]
      lines += cmd_parser.processed_options.map do |short, long, _, desc, hidden|
        next if hidden

        if long.present?
          next if Homebrew::CLI::Parser.global_options.include?([short, long, desc])
          next if Homebrew::CLI::Parser.global_cask_options.any? do |_, option, description:, **|
                    [long, "#{long}="].include?(option) && description == desc
                  end
        end

        generate_option_doc(short, long, desc)
      end.compact
      lines
    end

    def cmd_comment_manpage_lines(cmd_path)
      comment_lines = cmd_path.read.lines.grep(/^#:/)
      return if comment_lines.empty?
      return if comment_lines.first.include?("@hide_from_man_page")

      lines = [format_usage_banner(comment_lines.first).chomp]
      comment_lines.slice(1..-1)
                   .each do |line|
        line = line.slice(4..-2)
        unless line
          lines.last << "\n"
          next
        end

        # Omit the common global_options documented separately in the man page.
        next if line.match?(/--(debug|help|quiet|verbose) /)

        # Format one option or a comma-separated pair of short and long options.
        lines << line.gsub(/^ +(-+[a-z-]+), (-+[a-z-]+) +/, "* `\\1`, `\\2`:\n  ")
                     .gsub(/^ +(-+[a-z-]+) +/, "* `\\1`:\n  ")
      end
      lines.last << "\n"
      lines
    end

    sig { returns(String) }
    def global_cask_options_manpage
      lines = ["These options are applicable to the `install`, `reinstall`, and `upgrade` " \
               "subcommands with the `--cask` flag.\n"]
      lines += Homebrew::CLI::Parser.global_cask_options.map do |_, long, description:, **|
        generate_option_doc(nil, long.chomp("="), description)
      end
      lines.join("\n")
    end

    sig { returns(String) }
    def global_options_manpage
      lines = ["These options are applicable across multiple subcommands.\n"]
      lines += Homebrew::CLI::Parser.global_options.map do |short, long, desc|
        generate_option_doc(short, long, desc)
      end
      lines.join("\n")
    end

    sig { returns(String) }
    def env_vars_manpage
      lines = Homebrew::EnvConfig::ENVS.flat_map do |env, hash|
        entry = "- `#{env}`:\n  <br>#{hash[:description]}\n"
        default = hash[:default_text]
        default ||= "`#{hash[:default]}`." if hash[:default]
        entry += "\n\n  *Default:* #{default}\n" if default

        entry
      end
      lines.join("\n")
    end

    def format_opt(opt)
      "`#{opt}`" unless opt.nil?
    end

    def generate_option_doc(short, long, desc)
      comma = (short && long) ? ", " : ""
      <<~EOS
        * #{format_opt(short)}#{comma}#{format_opt(long)}:
          #{desc}
      EOS
    end

    def format_usage_banner(usage_banner)
      usage_banner&.sub(/^(#: *\* )?/, "### ")
    end
  end
end