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# frozen_string_literal: true
require 'stringio'
module FaradayMiddleware
# Wraps a handler originally written for Rack for Faraday compatibility.
#
# Experimental. Only handles changes in request headers.
class RackCompatible
def initialize(app, rack_handler, *args)
# tiny middleware that decomposes a Faraday::Response to standard Rack
# array: [status, headers, body]
compatible_app = lambda do |rack_env|
env = restore_env(rack_env)
response = app.call(env)
[response.status, response.headers, Array(response.body)]
end
@rack = rack_handler.new(compatible_app, *args)
end
def call(env)
rack_env = prepare_env(env)
rack_response = @rack.call(rack_env)
finalize_response(env, rack_response)
end
NON_PREFIXED_HEADERS = %w[CONTENT_LENGTH CONTENT_TYPE].freeze
# faraday to rack-compatible
def prepare_env(faraday_env)
env = headers_to_rack(faraday_env)
url = faraday_env[:url]
env['rack.url_scheme'] = url.scheme
env['PATH_INFO'] = url.path
env['SERVER_PORT'] = if url.respond_to?(:inferred_port)
url.inferred_port
else
url.port
end
env['QUERY_STRING'] = url.query
env['REQUEST_METHOD'] = faraday_env[:method].to_s.upcase
env['rack.errors'] ||= StringIO.new
env['faraday'] = faraday_env
env
end
def headers_to_rack(env)
rack_env = {}
env[:request_headers].each do |name, value|
name = name.upcase.tr('-', '_')
name = "HTTP_#{name}" unless NON_PREFIXED_HEADERS.include? name
rack_env[name] = value
end
rack_env
end
# rack to faraday-compatible
def restore_env(rack_env)
env = rack_env.fetch('faraday')
headers = env[:request_headers]
headers.clear
rack_env.each do |name, value|
next unless name.is_a?(String) && value.is_a?(String)
if NON_PREFIXED_HEADERS.include?(name) || name.start_with?('HTTP_')
name = name.sub(/^HTTP_/, '').downcase.tr('_', '-')
headers[name] = value
end
end
env[:method] = rack_env['REQUEST_METHOD'].downcase.to_sym
env[:rack_errors] = rack_env['rack.errors']
env
end
def finalize_response(env, rack_response)
status, headers, body = rack_response
body = body.inject { |str, part| str << part }
headers = Faraday::Utils::Headers.new(headers) unless headers.is_a?(Faraday::Utils::Headers)
env.update status: status.to_i,
body: body,
response_headers: headers
env[:response] ||= Faraday::Response.new(env)
env[:response]
end
end
end
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