lighttroupe/luz

# ImageThumbnailer doesn't thumbnail images (yet?), instead it looks for existing desktop thumbnails
# as per FreeDesktop spec: http://specifications.freedesktop.org/thumbnail-spec/thumbnail-spec-latest.html

require 'digest'

class ImageThumbnailer
    def add(path, &proc)
        file_name = thumbnail_file_name_for_path(path)
        thumbnail_directory_paths.each do |thumbnail_directory_path|
            full_path = File.join(thumbnail_directory_path, file_name)
            if File.exists?(full_path)
                proc.call(full_path)
                return
            end
        end

        p "Thumbnail not found for #{path} (looked in #{thumbnail_directory_paths.join(', ')} with hash #{file_name})"
    end

private

    def thumbnail_directory_paths
        [
            File.join(Dir.home, '.thumbnails/normal'),
            File.join(Dir.home, '.cache/thumbnails/normal'),        # new as of ubuntu 15.04
        ]
    end

    def thumbnail_file_name_for_path(path)
        thumbnail_hash_for_path(path)+'.png'
    end

    def thumbnail_hash_for_path(path)
        absolute_path = 'file://'+File.absolute_path(path)        # "absolute canonical URI"        TODO: more proper way to do this?
        Digest::MD5.hexdigest(absolute_path)
    end
end