1 files changed, 147 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..d1b4508378
--- /dev/null
+++ b/actionpack/lib/action_dispatch/middleware/exception_wrapper.rb
@@ -0,0 +1,147 @@
+# frozen_string_literal: true
+
+require "active_support/core_ext/module/attribute_accessors"
+require "rack/utils"
+
+module ActionDispatch
+  class ExceptionWrapper
+    cattr_accessor :rescue_responses, default: Hash.new(:internal_server_error).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::Http::Parameters::ParseError" => :bad_request,
+      "ActionController::BadRequest"                 => :bad_request,
+      "ActionController::ParameterMissing"           => :bad_request,
+      "Rack::QueryParser::ParameterTypeError"        => :bad_request,
+      "Rack::QueryParser::InvalidParameterError"     => :bad_request
+    )
+
+    cattr_accessor :rescue_templates, default: Hash.new("diagnostics").merge!(
+      "ActionView::MissingTemplate"         => "missing_template",
+      "ActionController::RoutingError"      => "routing_error",
+      "AbstractController::ActionNotFound"  => "unknown_action",
+      "ActiveRecord::StatementInvalid"      => "invalid_statement",
+      "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