class AssertResponse
  
  # error class, raised when a 404 status but another status was expected
  class Status404 < Exception ; end

  # Hash to collection available content-types (prefilled with the Rack::Mime::MIME_TYPES)
  #
  # @see AssertResponse#method_missing
  CONTENT_TYPES = {}

  # Adds custom content_types to 
  # {AssertResponse::CONTENT_TYPES}. We would then have all the test methods for the content-type
  # @param [Symbol] name name of the content_type
  # @param [String] content_type content_type (mime type, eg. "text/html")
  def AssertResponse.add_content_type(name, content_type)
    CONTENT_TYPES.update(name => content_type)
  end

  # add all Rack::Mime::MIME_TYPES as content_types
  Rack::Mime::MIME_TYPES.each do |fileext,mime|
    AssertResponse.add_content_type fileext.sub(/^\./, '').to_sym, mime
  end

  # add content_type 'text/plain' as :text
  AssertResponse.add_content_type :text, 'text/plain'

  # Creates a new {AssertResponse} Object. Usually you will want to +instance_exec+ some code on it.
  #
  # @param [Object] delegate_to the test object that has all the +assert_equal+, +assert_match+ and +assert+ methods that we need
  # @param [MockResponse, Response] response the response object that is checked
  def initialize(delegate_to, response, &code)
    @delegate_to = delegate_to
    @response = response
    @error = nil
    check_for_error()
  end

  # for each content-type in {AssertResponse::CONTENT_TYPES} these methods are served by method_missing
  # * +is_[content_type]+ that checks if the response has the content-type
  # * +[content_type]+ that checks the content-type and matches the body against the given pattern and checks for status 200
  # * +not_found_[content_type]+ that checks the content-type, matches the body against the pattern and checks for status 404  
  # further unknown methods are delegated to +@delegate_to+
  def method_missing(meth, *args, &code)
    case meth.to_s
    when /^(is|found)_(.+)$/ # is_[content_type] methods
      if ctype = CONTENT_TYPES[$2.to_sym]
        ok()
        return content_type(ctype)
      end
    when /^not_found_(.+)$/ # not_found_[content_type] methods
      if ctype = CONTENT_TYPES[$1.to_sym]
        content_type ctype
        return body(args.first, 404)
      end
    else
      if ctype = CONTENT_TYPES[meth] # [content_type] methods
        ok()
        content_type ctype
        return body(args.first)
      end
    end
    @delegate_to.send meth, *args, &code
  end

  # Checks if status is 200.
  def ok()
    status 200
  end

  # Checks if the status is +status+. For status other then 5xx and error is raised if the response has an error.
  # For status other than 404 an error Status404 is thrown if response status is 404
  #
  # @params [Integer] status the expected status
  def status(status)
    raise_error() unless status =~ /^5/ or @response.errors.empty?
    Kernel.raise(Status404, "not found") unless status == 404 or @response.status != 404
    assert_equal(status, @response.status)
  end

  # Checks if the response status is 404.
  def not_found()
    status 404
  end

  # Checks if the status is 302, and the header "Location" matches the +pattern+
  # 
  # @param [String,Regexp] pattern the pattern to match against.  
  def redirect(pattern)
    status 302
    header 'Location', pattern
  end    

  # Checks if the header +key+ exists and / or if it matches +pattern+.
  # 
  # @param [String] key the key to look for
  # @param [String,Regexp,:exists] pattern the pattern to match against. +:exists+ just checks for existance of +key+.
  def header(key, pattern=:exists)
    if pattern == :exists
      assert !@response.headers[key].to_s.empty?, "Header '#{key}' not found"
    else
      assert_match normalize_pattern(pattern), @response.headers[key].to_s
    end
  end

  # Check if the +Content-Type+ matches +pattern+. Checks also if request is ok (see {#ok}).
  #
  # @param [String,Regexp] pattern the pattern to match against.
  def content_type(pattern)
    header 'Content-Type', pattern
  end

  # Check if body matches +pattern+ and status is +status+.
  #
  # @param [String,Regexp] pattern the pattern to match against.
  # @params [Integer] status the expected status (default 200, see {#ok})
  def body(pattern, status=200)
    status(status)
    assert_match normalize_pattern(pattern), @response.body
  end

  # Check if an error was raised. 
  #
  # @param [Class] exception_class also check if error is_a? +exception_class+
  # @param [String,Regexp] pattern also check if the error message matches +pattern+
  def raises(exception_class=nil, pattern=nil)
    assert_equal exception_class, @error.class if exception_class
    assert_match normalize_pattern(pattern), @error.message if pattern
    assert !@error.nil?
  end

  private

  def normalize_pattern(pattern)
    pattern.is_a?(Regexp) ? pattern : /#{Regexp.escape(pattern.to_s)}/
  end

  def check_for_error
    normalize_error unless @response.errors.to_s.empty?
  end

  def normalize_error
    message, backtrace = @response.errors.split "\n", 2
    backtrace = backtrace.split
    err_klass, message = message.split '-', 2
    @error = Module.const_get(err_klass.strip.to_sym).new(message.strip)
    @error.set_backtrace backtrace
    @error
  end  

  def raise_error()     
    Kernel.raise @error
  end      

  # these methods are included in Rack::Test::Methods to be used in a Test Class
  #
  # call assert_response with a code block to use the DSL (methods from {AssertResponse})
  # or use a method like assert_response_xxx where xxx is the name of the method from {AssertResponse} you want to call
  # @see AssertResponse
  #
  # @example with Test::Unit, simple
  #     require 'rack/test'
  #     require 'assert-response'
  #
  #     class TestMe < Test::Unit::Testcase
  #       include Rack::Test::Methods
  #       def app
  #         MyApp
  #       end
  #
  #       def test_something
  #         get '/works'
  #         assert_response_html "should really work"
  #       end
  #     end
  #
  # @example without including +Rack::Test::Methods+
  #     require 'rack/test'
  #     require 'assert-response'
  #
  #     class AppWrapper
  #       include Rack::Test::Methods
  #       def app
  #         MyApp
  #       end
  #     end
  #
  #     class TestMe < Test::Unit::Testcase
  #       include AssertResponse::Methods
  #
  #       def test_something
  #         server = AppWrapper.new
  #         server.get '/works'
  #         assert_response server.last_response do
  #           html "should really work"
  #         end
  #       end
  #     end
  #
  # @example with *Minitest*, simple
  #     require 'rack/test'
  #     require 'assert-response'
  #     include Rack::Test::Methods
  #
  #     # write your tests here
  #     it "should work" do
  #       get '/works'
  #       assert_response_html "should really work"
  #     end
  #
  # @example without including +Rack::Test::Methods+
  #     require 'rack/test'
  #     require 'assert-response'
  #
  #     class AppWrapper
  #       include Rack::Test::Methods
  #       def app
  #         MyApp
  #       end
  #     end
  #
  #     include AssertResponse::Methods
  #
  #     describe "my app" do
  #       before do
  #         @app = AppWrapper.new
  #       end
  #
  #       it "should work" do
  #         @app.get '/works'
  #         assert_response(@app.last_response) do
  #           html "should really work"
  #         end
  #       end
  #     end
  module Methods
    # route assert_response_ methods to {AssertResponse}
    # @see AssertResponse
    def method_missing(meth, *args, &code)
      if meth.to_s =~ /^assert_response_(.+)$/
        AssertResponse.new(self, last_response).send($1.to_sym, *args)
      else
        super
      end
    end

    # creates an {AssertResponse} Object and +instance_exec+ the code (DSL) in it  
    # @see AssertResponse
    def assert_response(response=last_response, &code) 
      file, line, rest = caller[0].split(':', 3)
      AssertResponse.new(self, response).instance_exec(file, line.to_i, &code)
    end
  end
end

module Rack::Test::Methods
  include AssertResponse::Methods
end