# frozen_string_literal: true

module FileStore

  class BaseStore

    def store_upload(file, upload, content_type = nil)
      path = get_path_for_upload(upload)
      store_file(file, path)
    end

    def store_optimized_image(file, optimized_image, content_type = nil, secure: false)
      path = get_path_for_optimized_image(optimized_image)
      store_file(file, path)
    end

    def store_file(file, path, opts = {})
      not_implemented
    end

    def remove_upload(upload)
      remove_file(upload.url, get_path_for_upload(upload))
    end

    def remove_optimized_image(optimized_image)
      remove_file(optimized_image.url, get_path_for_optimized_image(optimized_image))
    end

    def remove_file(url, path)
      not_implemented
    end

    def upload_path
      path = File.join("uploads", RailsMultisite::ConnectionManagement.current_db)
      return path unless Discourse.is_parallel_test?

      n = ENV['TEST_ENV_NUMBER'].presence || '1'
      File.join(path, n)
    end

    def has_been_uploaded?(url)
      not_implemented
    end

    def download_url(upload)
      not_implemented
    end

    def cdn_url(url)
      not_implemented
    end

    def absolute_base_url
      not_implemented
    end

    def relative_base_url
      not_implemented
    end

    def s3_upload_host
      not_implemented
    end

    def external?
      not_implemented
    end

    def internal?
      !external?
    end

    def path_for(upload)
      not_implemented
    end

    def list_missing_uploads(skip_optimized: false)
      not_implemented
    end

    def download(upload)
      DistributedMutex.synchronize("download_#{upload.sha1}") do
        filename = "#{upload.sha1}#{File.extname(upload.original_filename)}"
        file = get_from_cache(filename)

        if !file
          max_file_size_kb = [SiteSetting.max_image_size_kb, SiteSetting.max_attachment_size_kb].max.kilobytes

          url = upload.secure? ?
            Discourse.store.signed_url_for_path(upload.url) :
            Discourse.store.cdn_url(upload.url)

          url = SiteSetting.scheme + ":" + url if url =~ /^\/\//
          file = FileHelper.download(
            url,
            max_file_size: max_file_size_kb,
            tmp_file_name: "discourse-download",
            follow_redirect: true
          )
          cache_file(file, filename)
          file = get_from_cache(filename)
        end

        file
      end
    end

    def purge_tombstone(grace_period)
    end

    def get_path_for(type, id, sha, extension)
      depth = get_depth_for(id)
      tree = File.join(*sha[0, depth].chars, "")
      "#{type}/#{depth + 1}X/#{tree}#{sha}#{extension}"
    end

    def get_path_for_upload(upload)
      extension =
        if upload.extension
          ".#{upload.extension}"
        else
          # Maintain backward compatibility before Jobs::MigrateUploadExtensions runs
          File.extname(upload.original_filename)
        end

      get_path_for("original".freeze, upload.id, upload.sha1, extension)
    end

    def get_path_for_optimized_image(optimized_image)
      upload = optimized_image.upload
      version = optimized_image.version || 1
      extension = "_#{version}_#{optimized_image.width}x#{optimized_image.height}#{optimized_image.extension}"
      get_path_for("optimized".freeze, upload.id, upload.sha1, extension)
    end

    CACHE_DIR ||= "#{Rails.root}/tmp/download_cache/"
    CACHE_MAXIMUM_SIZE ||= 500

    def get_cache_path_for(filename)
      "#{CACHE_DIR}#{filename}"
    end

    def get_from_cache(filename)
      path = get_cache_path_for(filename)
      File.open(path) if File.exists?(path)
    end

    def cache_file(file, filename)
      path = get_cache_path_for(filename)
      dir = File.dirname(path)
      FileUtils.mkdir_p(dir) unless Dir.exist?(dir)
      FileUtils.cp(file.path, path)

      # Keep latest 500 files
      processes = Open3.pipeline(
        ["ls -t #{CACHE_DIR}", err: "/dev/null"],
        "tail -n +#{CACHE_MAXIMUM_SIZE + 1}",
        "awk '$0=\"#{CACHE_DIR}\"$0'",
        "xargs rm -f"
      )

      ls = processes.shift

      # Exit status `1` in `ls` occurs when e.g. "listing a directory
      # in which entries are actively being removed or renamed".
      # It's safe to ignore it here.
      if ![0, 1].include?(ls.exitstatus) || !processes.all?(&:success?)
        raise "Error clearing old cache"
      end
    end

    private

    def not_implemented
      raise "Not implemented."
    end

    def get_depth_for(id)
      depths = [0]
      depths << Math.log(id / 1_000.0, 16).ceil if id.positive?
      depths.max
    end

  end

end