1 files changed, 149 insertions, 0 deletions
diff --git a/actionpack/lib/action_dispatch/middleware/exception_wrapper.rb b/actionpack/lib/action_dispatch/middleware/exception_wrapper.rb
new file mode 100644
index 0000000000..3b61824cc9
--- /dev/null
+++ b/actionpack/lib/action_dispatch/middleware/exception_wrapper.rb
@@ -0,0 +1,149 @@
+require 'action_controller/metal/exceptions'
+require 'active_support/core_ext/module/attribute_accessors'
+require 'rack/utils'
+
+module ActionDispatch
+  class ExceptionWrapper
+    cattr_accessor :rescue_responses
+    @@rescue_responses = Hash.new(:internal_server_error)
+    @@rescue_responses.merge!(
+      'ActionController::RoutingError'                => :not_found,
+      'AbstractController::ActionNotFound'            => :not_found,
+      'ActionController::MethodNotAllowed'            => :method_not_allowed,
+      'ActionController::UnknownHttpMethod'           => :method_not_allowed,
+      'ActionController::NotImplemented'              => :not_implemented,
+      'ActionController::UnknownFormat'               => :not_acceptable,
+      'ActionController::InvalidAuthenticityToken'    => :unprocessable_entity,
+      'ActionController::InvalidCrossOriginRequest'   => :unprocessable_entity,
+      'ActionDispatch::ParamsParser::ParseError'      => :bad_request,
+      'ActionController::BadRequest'                  => :bad_request,
+      'ActionController::ParameterMissing'            => :bad_request,
+      'Rack::Utils::ParameterTypeError'               => :bad_request,
+      'Rack::Utils::InvalidParameterError'            => :bad_request
+    )
+
+    cattr_accessor :rescue_templates
+    @@rescue_templates = Hash.new('diagnostics')
+    @@rescue_templates.merge!(
+      'ActionView::MissingTemplate'         => 'missing_template',
+      'ActionController::RoutingError'      => 'routing_error',
+      'AbstractController::ActionNotFound'  => 'unknown_action',
+      'ActionView::Template::Error'         => 'template_error'
+    )
+
+    attr_reader :backtrace_cleaner, :exception, :line_number, :file
+
+    def initialize(backtrace_cleaner, exception)
+      @backtrace_cleaner = backtrace_cleaner
+      @exception = original_exception(exception)
+
+      expand_backtrace if exception.is_a?(SyntaxError) || exception.cause.is_a?(SyntaxError)
+    end
+
+    def rescue_template
+      @@rescue_templates[@exception.class.name]
+    end
+
+    def status_code
+      self.class.status_code_for_exception(@exception.class.name)
+    end
+
+    def application_trace
+      clean_backtrace(:silent)
+    end
+
+    def framework_trace
+      clean_backtrace(:noise)
+    end
+
+    def full_trace
+      clean_backtrace(:all)
+    end
+
+    def traces
+      application_trace_with_ids = []
+      framework_trace_with_ids = []
+      full_trace_with_ids = []
+
+      full_trace.each_with_index do |trace, idx|
+        trace_with_id = { id: idx, trace: trace }
+
+        if application_trace.include?(trace)
+          application_trace_with_ids << trace_with_id
+        else
+          framework_trace_with_ids << trace_with_id
+        end
+
+        full_trace_with_ids << trace_with_id
+      end
+
+      {
+        "Application Trace" => application_trace_with_ids,
+        "Framework Trace" => framework_trace_with_ids,
+        "Full Trace" => full_trace_with_ids
+      }
+    end
+
+    def self.status_code_for_exception(class_name)
+      Rack::Utils.status_code(@@rescue_responses[class_name])
+    end
+
+    def source_extracts
+      backtrace.map do |trace|
+        file, line_number = extract_file_and_line_number(trace)
+
+        {
+          code: source_fragment(file, line_number),
+          line_number: line_number
+        }
+      end
+    end
+
+    private
+
+    def backtrace
+      Array(@exception.backtrace)
+    end
+
+    def original_exception(exception)
+      if @@rescue_responses.has_key?(exception.cause.class.name)
+        exception.cause
+      else
+        exception
+      end
+    end
+
+    def clean_backtrace(*args)
+      if backtrace_cleaner
+        backtrace_cleaner.clean(backtrace, *args)
+      else
+        backtrace
+      end
+    end
+
+    def source_fragment(path, line)
+      return unless Rails.respond_to?(:root) && Rails.root
+      full_path = Rails.root.join(path)
+      if File.exist?(full_path)
+        File.open(full_path, "r") do |file|
+          start = [line - 3, 0].max
+          lines = file.each_line.drop(start).take(6)
+          Hash[*(start+1..(lines.count+start)).zip(lines).flatten]
+        end
+      end
+    end
+
+    def extract_file_and_line_number(trace)
+      # Split by the first colon followed by some digits, which works for both
+      # Windows and Unix path styles.
+      file, line = trace.match(/^(.+?):(\d+).*$/, &:captures) || trace
+      [file, line.to_i]
+    end
+
+    def expand_backtrace
+      @exception.backtrace.unshift(
+        @exception.to_s.split("\n")
+      ).flatten!
+    end
+  end
+end