my_uploader.rb

# An uploader for merb, stored in app/uploaders/my_uploader.rb
#
# Usage:
#
#     identifier = "some_string_probably_filename.png"
#     uploader = MyUploader.new(identifier)
#
# Storing files to the filesystem
#     uploader.storage = :file
#
# Filename defaults to the same as identifier, but can be overridden 
#     uploader.filename # => uploader.identifier
#
# Path for storage defaults to store_dir plus filename, but can be overridden 
#     uploader.path # => uploader.store_dir / uploader.filename
#
# Read contents
#     uploader.read # => nil (file is empty)
#
# Upload a file.
#     uploader.upload!(file)
#
# Identical to:
#     uploader.storage.upload!(file)
#
# Read contents
#     uploader.read # => "..." (contents of file)
#
# Processing the files when they are uploaded:
#     class MyUploader
#       process :shrink!
#       process :inflate!
#       process :grow!
#     end
# this will call uploader.shrink!, uploader.inflate!, uploader.grow! after calling
# uploader.upload!
# 
#     class MyUploader
#       process :shrink!
#       process :inflate! => "original size"
#       process :grow! => [200, 400]
#     end
# this will call uploader.shrink!, uploader.inflate!("original size"), uploader.grow!(200, 400)
#
# those methods can then be done whatever we want. Plugins can use this, for example RMagick:
#
#     class MyUploader
#       include Merb::Uploader::RMagick
#       process :crop_resized => [300, 300]
#       process :desaturate
#       process :awesomerize
#
#       def awesomerize
#         manipulate do |img|
#           # do something
#         end
#       end
#     end
class MyUploader
  
  # Provided by merb-uploader
  include Merb::Uploader
  
  # Provided by merb_rmagick, merb_image_science, etc...
  include Merb::Uploader::RMagick

  # This is done for all versions
  process :resize => '800x600'

  # It's possible to create versions of uploaded files (maybe?)
  version :thumb do
    # Multiple instructions for a single process, maybe the plugins can take advantage of this
    # somehow in order to perform all this simultaneously and save memory?
    process :crop_resized => '100x60', :convert => 'png'
  end
  
  version :backup do
    # We can redefine most stuff for versions
    include Merb::Uploader::ImageScience
    storage :s3
    process :resize => '400x300'
  end
  
  # Most things should be overridable
  def filename
    "#{basename}.#{extension}"
  end
  
  # Like so.
  def extension
    options[:extension] || "png"
  end
  
  # This thing is a DataMapper type, so we can use it as such, to get DataMapper backed uploads
  # for free ;)
  def self.load(string)
    self.retrieve(string)
  end
  
  def self.dump(file)
    self.upload!(file.original_filename, file)
  end

end