# typed: false
# frozen_string_literal: true

module Homebrew
  module Livecheck
    module Strategy
      # The {Gnu} strategy identifies versions of software at gnu.org by
      # checking directory listing pages.
      #
      # GNU URLs use a variety of formats:
      #
      # * Archive file URLs:
      #   * `https://ftp.gnu.org/gnu/example/example-1.2.3.tar.gz`
      #   * `https://ftp.gnu.org/gnu/example/1.2.3/example-1.2.3.tar.gz`
      # * Homepage URLs:
      #   * `https://www.gnu.org/software/example/`
      #   * `https://example.gnu.org`
      #
      # There are other URL formats that this strategy currently doesn't
      # support:
      #
      # * `https://ftp.gnu.org/non-gnu/example/source/feature/1.2.3/example-1.2.3.tar.gz`
      # * `https://savannah.nongnu.org/download/example/example-1.2.3.tar.gz`
      # * `https://download.savannah.gnu.org/releases/example/example-1.2.3.tar.gz`
      # * `https://download.savannah.nongnu.org/releases/example/example-1.2.3.tar.gz`
      #
      # The default regex identifies versions in archive files found in `href`
      # attributes.
      #
      # @api public
      class Gnu
        extend T::Sig

        NICE_NAME = "GNU"

        # The `Regexp` used to determine if the strategy applies to the URL.
        URL_MATCH_REGEX = %r{
          ^https?://
          (?:(?:[^/]+?\.)*gnu\.org/(?:gnu|software)/(?<project_name>[^/]+)/
          |(?<project_name>[^/]+)\.gnu\.org/?$)
        }ix.freeze

        # Whether the strategy can be applied to the provided URL.
        #
        # @param url [String] the URL to match against
        # @return [Boolean]
        def self.match?(url)
          URL_MATCH_REGEX.match?(url) && url.exclude?("savannah.")
        end

        # Generates a URL and regex (if one isn't provided) and passes them
        # to {PageMatch.find_versions} to identify versions in the content.
        #
        # @param url [String] the URL of the content to check
        # @param regex [Regexp] a regex used for matching versions in content
        # @return [Hash]
        sig {
          params(
            url:   String,
            regex: T.nilable(Regexp),
            cask:  T.nilable(Cask::Cask),
            block: T.nilable(T.proc.params(arg0: String).returns(T.any(T::Array[String], String))),
          ).returns(T::Hash[Symbol, T.untyped])
        }
        def self.find_versions(url, regex, cask: nil, &block)
          match = url.match(URL_MATCH_REGEX)

          # The directory listing page for the project's files
          page_url = "http://ftp.gnu.org/gnu/#{match[:project_name]}/?C=M&O=D"

          # The default regex consists of the following parts:
          # * `href=.*?`: restricts matching to URLs in `href` attributes
          # * The project name
          # * `[._-]`: the generic delimiter between project name and version
          # * `v?(\d+(?:\.\d+)*)`: the numeric version
          # * `(?:\.[a-z]+|/)`: the file extension (a trailing delimiter)
          #
          # Example regex: `%r{href=.*?example[._-]v?(\d+(?:\.\d+)*)(?:\.[a-z]+|/)}i`
          regex ||= %r{href=.*?#{match[:project_name]}[._-]v?(\d+(?:\.\d+)*)(?:\.[a-z]+|/)}i

          PageMatch.find_versions(page_url, regex, cask: cask, &block)
        end
      end
    end
  end
end