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rack-thumb-proxy.rb
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rack-thumb-proxy.rb
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require 'CGI'
require 'open-uri'
require 'tempfile'
require 'rack-thumb-proxy/version'
require 'rack-thumb-proxy/configuration'
module Rack
module Thumb
class Proxy
class << self
attr_writer :configuration
def configure(&block)
configuration.instance_eval(&block)
configuration
end
def configuration
@configuration ||= Configuration.new
end
def call(env)
new(env).call
end
end
def initialize(env)
@env = env
@path = env['PATH_INFO']
end
def call
if request_matches?
validate_signature! &&
retreive_upstream! &&
transform_image! &&
format_response!
response.finish
else
[404, {'Content-Length' => 9.to_s, 'Content-Type' => 'text/plain'}, ['Not Found']]
end
end
private
def validate_signature!
true
end
def retreive_upstream!
begin
open(request_url, 'rb') do |f|
tempfile.binmode
tempfile.write(f.read)
tempfile.flush
end
rescue
write_error_to_response!
return false
end
return true
end
def format_response!
response.status = 200
response.headers["Content-Type"] = mime_type_from_request_url
response.headers["Content-Length"] = transformed_image_file_size_in_bytes.to_s
response.body << read_tempfile
true
end
def read_tempfile
tempfile.rewind
tempfile.read
end
def tempfile
@_tempfile ||= Tempfile.new('rack_thumb_proxy')
end
def tempfile_path
tempfile.path
end
def transform_image!
return true unless should_resize?
begin
require 'mapel'
width, height = dimensions_from_request_options
owidth, oheight = dimensions_from_tempfile
width = [width, owidth].min if width
height = [height, oheight].min if height
cmd = Mapel(tempfile_path)
if should_apply_gravity?
cmd.gravity(request_gravity)
end
if width && height
cmd.resize!(width, height)
else
cmd.resize(width, height, 0, 0, '>')
end
cmd.to(tempfile_path).run
rescue
puts $!, $@
write_error_to_response!
return false
end
true
end
def should_resize?
!request_options.empty?
end
def should_apply_gravity?
!!request_gravity_shorthand
end
def should_verify_hash_signature?
configuration.hash_signatures_in_use?
end
def configuration
self.class.configuration
end
def request_hash_signature
@_request_match_data["hash_signature"]
end
def request_options
@_request_match_data["options"]
end
def request_gravity
{
'nw' => :northwest,
'n' => :north,
'ne' => :northeast,
'w' => :west,
'c' => :center,
'e' => :east,
'sw' => :southwest,
's' => :south,
'se' => :southeast
}.fetch(request_gravity_shorthand).to_s if request_gravity_shorthand
end
def request_gravity_shorthand
g = @_request_match_data["gravity"]
g.empty? ? nil : g
end
def request_url
CGI.unescape(escaped_request_url)
end
def escaped_request_url
@_request_match_data["escaped_url"]
end
def request_matches?
@_request_match_data = @path.match(routing_pattern)
end
def witdh_from_tempfile
dimensions_from_tempfile.first
end
def height_from_tempfile
dimensions_from_tempfile.last
end
def dimensions_from_tempfile
require 'mapel' unless defined?(Mapel)
Mapel.info(tempfile_path)[:dimensions]
end
def width_from_request_options
dimensions_from_request_options.first
end
def height_from_request_options
dimensions_from_request_options.last
end
def dimensions_from_request_options
width, height = request_options.split('x').map(&:to_i).collect { |dim| dim == 0 ? nil : dim }
[width, height]
end
def transformed_image_file_size_in_bytes
::File.size(tempfile_path)
end
# Examples: http://rubular.com/r/oPRK1t31yv
def routing_pattern
/^\/(?<hash_signature>[a-z0-9]{10}|)\/?(?<options>(:?[0-9]*x+[0-9]*|))(?<gravity>c|n|ne|e|s|sw|w|nw|)\/?(?<escaped_url>https?.*)$/
end
def response
@_response ||= Rack::Response.new
end
def write_error_to_response!
response.status = 500
response.headers['Content-Type'] = 'text/plain'
response.body << $!.message
response.body << "\n\n"
response.body << $!.backtrace.join("\n")
end
def request_url_file_extension
::File.extname(request_url)
end
def mime_type_from_request_url
{
'.png' => 'image/png',
'.gif' => 'image/gif',
'.jpg' => 'image/jpg',
'.jpeg' => 'image/jpeg'
}.fetch(request_url_file_extension)
end
end
end
end