require 'pathname'

module Uricp
  class Segmenter
    include Methadone::CLILogging
    include Methadone::SH
    include Uricp::CurlPrimitives

    def initialize(options)
      @options = options
      source = options['from']
      if @source = source && open(source)
        @stream = File.pipe?(source) || File.chardev?(source)
      else
        @source = STDIN
        @stream = true
      end
      split_path
    end

    def split_path
      elements = Pathname.new(to.path).enum_for(:each_filename).to_a
      elements.shift
      @account = elements.shift
      @container = elements.shift
      @object_path = File.join(elements)
    end

    def upload
      if large_upload?
        segmented_upload
      else
        sh! curl_upload_from(options['from']),
            on_fail: "Upload to #{to} failed"
      end
    end

    def segment_size
      options['segment-size'].to_i
    end

    def stream?
      @stream
    end

    def large_upload?
      stream? || @source.stat.size > segment_size
    end

    def manifest_suffix
      @manifest_suffix ||= [Time.now.to_f, @source.stat.size, segment_size].join('/')
    end

    def object_manifest
      @object_manifest ||= File.join(@container, @object_path, manifest_suffix) + '/'
    end

    def segmented_upload
      debug "#{self.class.name}: Large upload detected - segmenting into #{segment_size} byte chunks."
      suffix = 0
      until @source.eof?
        debug "#{self.class.name}: Uploading segment #{suffix}"
        upload_segment(suffix)
        suffix = suffix.next
      end
      add_manifest
    end

    def upload_segment(segment_number)
      segment_name = File.join(to.to_s, manifest_suffix, '%08d' % segment_number)
      debug "Uploading with #{curl_upload_from('-', segment_name)}"
      open('|' + curl_upload_from('-', segment_name), 'w') do |destination|
        copy_length = IO.copy_stream(@source, destination, segment_size)
        debug "#{self.class.name}: Uploaded #{copy_length} bytes to #{segment_name}"
      end
    end

    def add_manifest
      debug "Adding DLO object_manifest #{object_manifest}"
      sh! curl_manifest(object_manifest),
          on_fail: "Upload to #{to} failed"
    end
  end
end