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require 'u3d/utils'
require 'u3d/download_validator'

module U3d
  # Take care of downloading files and packages
  module Downloader
    # Name of the directory for the package downloading
    DOWNLOAD_DIRECTORY = 'Unity_Packages'
    # Path to the directory for the package downloading
    DOWNLOAD_PATH = "#{ENV['HOME']}/Downloads"
    # Regex to get the name of a localization asset
    UNITY_LANGUAGE_FILE_REGEX = %r{/\d+/[0-9.]+/([\w-]+)$}.freeze
    # Regex to get the name of a package out of its file name
    UNITY_MODULE_FILE_REGEX = %r{/([\w\-_.+]+\.(?:pkg|dmg|exe|zip|sh|deb|msi|xz))[^/]*$}.freeze

    class << self
      def download_directory
        File.expand_path(ENV['U3D_DOWNLOAD_PATH'] || File.join(DOWNLOAD_PATH, DOWNLOAD_DIRECTORY))
      end

      # fetch modules and put them in local cache
      def fetch_modules(definition, packages: [], download: nil)
        if download
          download_modules(definition, packages: packages)
        else
          local_files(definition, packages: packages)
        end
      end

      # download packages
      def download_modules(definition, packages: [])
        files = []
        validator, downloader = setup_os(definition.os)

        packages.each do |package|
          get_package(downloader, validator, package, definition, files)
        end
        files
      end

      # find already downloaded packages
      def local_files(definition, packages: [])
        files = []
        validator, downloader = setup_os(definition.os)

        packages.each do |package|
          path = downloader.destination_for(package, definition)
          if File.file?(path)
            if validator.validate(package, path, definition)
              files << [package, path, definition[package]]
            else
              UI.important "File present at #{path} is not correct, will not be used. Skipping #{package}"
            end
          else
            UI.error "No file has been downloaded for #{package}, or it has been moved from #{path}"
          end
        end

        files
      end

      private #-----------------------------------------------------------------

      def setup_os(os)
        # downloader = Downloader::StandardPackageDownloader.new
        case os
        when :linux
          validator = LinuxValidator.new
          downloader = Downloader::LinuxDownloader.new
        when :mac
          validator = MacValidator.new
          downloader = Downloader::MacDownloader.new
        when :win
          validator = WindowsValidator.new
          downloader = Downloader::WindowsDownloader.new
        else
          raise ArgumentError, "Operating system #{os.id2name} is not recognized"
        end
        return validator, downloader
      end

      def get_package(downloader, validator, package, definition, files)
        path, url = downloader.destination_and_url_for(package, definition)
        package_info = definition[package]
        if File.file?(path)
          UI.verbose "Installer file for #{package_info.name} seems to be present at #{path}"
          if validator.validate(package, path, definition)
            UI.message "#{package_info.name} is already downloaded"
            files << [package, path, package_info]
            return
          else
            extension = File.extname(path)
            new_path = File.join(File.dirname(path), "#{File.basename(path, extension)}_CORRUPTED#{extension}")
            UI.important "File present at #{path} is not correct, it has been renamed to #{new_path}"
            File.rename(path, new_path)
          end
        end

        UI.header "Downloading #{package_info.name} version #{definition.version}"
        UI.message "Downloading from #{url.to_s.cyan.underline}"
        UI.message "Download will be found at #{path}"
        download_package(path, url, size: package_info.download_size)

        if validator.validate(package, path, definition)
          UI.success "Successfully downloaded #{package}."
          files << [package, path, package_info]
        else
          UI.error "Failed to download #{package}"
        end
      end

      def download_package(path, url, size: nil)
        Utils.download_file(path, url, size: size)
      rescue Interrupt => e
        # Ensure that the file is deleted if download is aborted
        File.delete path
        raise e
      end
    end

    class StandardPackageDownloader
      # for backward compatibility
      def destination_for(package, definition)
        destination_and_url_for(package, definition)[0]
      end

      def destination_and_url_for(package, definition)
        final_url = url_for(package, definition)

        dir = File.join(Downloader.download_directory, definition.version)
        Utils.ensure_dir(dir)

        file_name = if (language_match = UNITY_LANGUAGE_FILE_REGEX.match(final_url))
                      "#{language_match[1]}.po" # Unity uses PO (Portable object files) for localization
                    elsif (module_match = UNITY_MODULE_FILE_REGEX.match(final_url))
                      module_match[1]
                    else
                      raise "Unable to download file at #{final_url}. Please report it to the u3d issues on Github: https://github.com/DragonBox/u3d/issues/new"
                    end

        destination = File.expand_path(file_name, dir)

        [destination, final_url]
      end

      def url_for(package, definition)
        url = definition[package].url
        if url
          if url =~ /^http/
            Utils.final_url(url)
          else
            definition.url + url
          end
        else
          definition.url
        end
      end
    end

    # for backward compatibility
    class MacDownloader < StandardPackageDownloader
    end

    class LinuxDownloader < StandardPackageDownloader
    end

    class WindowsDownloader < StandardPackageDownloader
    end
  end
end