# frozen_string_literal: true

# Copyright, 2018, by Samuel G. D. Williams. <http://www.codeotaku.com>
# 
# Permission is hereby granted, free of charge, to any person obtaining a copy
# of this software and associated documentation files (the "Software"), to deal
# in the Software without restriction, including without limitation the rights
# to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
# copies of the Software, and to permit persons to whom the Software is
# furnished to do so, subject to the following conditions:
# 
# The above copyright notice and this permission notice shall be included in
# all copies or substantial portions of the Software.
# 
# THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
# IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
# FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
# AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
# LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
# OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN
# THE SOFTWARE.

require 'protocol/http/body/readable'
require 'protocol/http/body/file'

module Falcon
	module Adapters
		# Wraps the rack response body.
		#
		# The `rack` body must respond to `each` and must only yield `String` values. If the body responds to `close`, it will be called after iteration. If the body is replaced by a middleware after action, the original body must be closed first, if it responds to `close`. If the body responds to `to_path`, it must return a String identifying the location of a file whose contents are identical to that produced by calling `each`; this may be used by the server as an alternative, possibly more efficient way to transport the response. The body commonly is an `Array` of strings, the application instance itself, or a `File`-like object.
		class Output < ::Protocol::HTTP::Body::Readable
			CONTENT_LENGTH = 'content-length'.freeze
			
			# Wraps an array into a buffered body.
			# @parameter status [Integer] The response status.
			# @parameter headers [Protocol::HTTP::Headers] The response headers.
			# @parameter body [Object] The `rack` response body.
			def self.wrap(status, headers, body, request = nil)
				# In no circumstance do we want this header propagating out:
				if length = headers.delete(CONTENT_LENGTH)
					# We don't really trust the user to provide the right length to the transport.
					length = Integer(length)
				end
				
				# If we have an Async::HTTP body, we return it directly:
				if body.is_a?(::Protocol::HTTP::Body::Readable)
					# warn "Returning #{body.class} as body is falcon-specific and may be removed in the future!"
					return body
				end
				
				# Otherwise, we have a more typical response body:
				if status == 200 and body.respond_to?(:to_path)
					begin
						# Don't mangle partial responses (206)
						return ::Protocol::HTTP::Body::File.open(body.to_path).tap do
							body.close if body.respond_to?(:close) # Close the original body.
						end
					rescue Errno::ENOENT
						# If the file is not available, ignore.
					end
				end
				
				# If we have a streaming body, we hijack the connection:
				unless body.respond_to?(:each)
					return Async::HTTP::Body::Hijack.new(body, request&.body)
				end
				
				if body.is_a?(Array)
					length ||= body.sum(&:bytesize)
					return self.new(body, length)
				else
					return self.new(body, length)
				end
			end
			
			# Initialize the output wrapper.
			# @parameter body [Object] The rack response body.
			# @parameter length [Integer] The rack response length.
			def initialize(body, length)
				@length = length
				@body = body
				
				@chunks = nil
			end
			
			# The rack response body.
			attr :body
			
			# The content length of the rack response body.
			attr :length
			
			# Whether the body is empty.
			def empty?
				@length == 0 or (@body.respond_to?(:empty?) and @body.empty?)
			end
			
			# Whether the body can be read immediately.
			def ready?
				body.is_a?(Array) or body.respond_to?(:to_ary)
			end
			
			# Close the response body.
			def close(error = nil)
				if @body and @body.respond_to?(:close)
					@body.close
				end
				
				@body = nil
				@chunks = nil
				
				super
			end
			
			# Enumerate the response body.
			# @yields {|chunk| ...}
			# 	@parameter chunk [String]
			def each(&block)
				@body.each(&block)
			ensure
				self.close($!)
			end
			
			# Read the next chunk from the response body.
			# @returns [String | Nil]
			def read
				@chunks ||= @body.to_enum(:each)
				
				return @chunks.next
			rescue StopIteration
				return nil
			end
			
			def inspect
				"\#<#{self.class} length=#{@length.inspect} body=#{@body.class}>"
			end
		end
	end
end