text: #!/usr/bin/env python
  # Copyright (c) 2011 Google Inc. All rights reserved.
  #
  # Redistribution and use in source and binary forms, with or without
  # modification, are permitted provided that the following conditions are
  # met:
  #
  #     * Redistributions of source code must retain the above copyright
  # notice, this list of conditions and the following disclaimer.
  #     * Redistributions in binary form must reproduce the above
  # copyright notice, this list of conditions and the following disclaimer
  # in the documentation and/or other materials provided with the
  # distribution.
  #     * Neither the name of Google Inc. nor the names of its
  # contributors may be used to endorse or promote products derived from
  # this software without specific prior written permission.
  #
  # THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
  # "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
  # LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR
  # A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT
  # OWNER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL,
  # SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT
  # LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
  # DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
  # THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
  # (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE
  # OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
  #
  # Inspector protocol validator.
  #
  # Tests that subsequent protocol changes are not breaking backwards compatibility.
  # Following violations are reported:
  #
  #   - Domain has been removed
  #   - Command has been removed
  #   - Required command parameter was added or changed from optional
  #   - Required response parameter was removed or changed to optional
  #   - Event has been removed
  #   - Required event parameter was removed or changed to optional
  #   - Parameter type has changed.
  #
  # For the parameters with composite types the above checks are also applied
  # recursively to every property of the type.
  #
  # Adding --show_changes to the command line prints out a list of valid public API changes.
  
  from __future__ import print_function
  import copy
  import os.path
  import optparse
  import sys
  
  import pdl
  
  try:
      import json
  except ImportError:
      import simplejson as json
  
  
  def list_to_map(items, key):
      result = {}
      for item in items:
          if "experimental" not in item and "hidden" not in item:
              result[item[key]] = item
      return result
  
  
  def named_list_to_map(container, name, key):
      if name in container:
          return list_to_map(container[name], key)
      return {}
  
  
  def removed(reverse):
      if reverse:
          return "added"
      return "removed"
  
  
  def required(reverse):
      if reverse:
          return "optional"
      return "required"
  
  
  def compare_schemas(d_1, d_2, reverse):
      errors = []
      domains_1 = copy.deepcopy(d_1)
      domains_2 = copy.deepcopy(d_2)
      types_1 = normalize_types_in_schema(domains_1)
      types_2 = normalize_types_in_schema(domains_2)
  
      domains_by_name_1 = list_to_map(domains_1, "domain")
      domains_by_name_2 = list_to_map(domains_2, "domain")
  
      for name in domains_by_name_1:
          domain_1 = domains_by_name_1[name]
          if name not in domains_by_name_2:
              errors.append("%s: domain has been %s" % (name, removed(reverse)))
              continue
          compare_domains(domain_1, domains_by_name_2[name], types_1, types_2, errors, reverse)
      return errors
  
  
  def compare_domains(domain_1, domain_2, types_map_1, types_map_2, errors, reverse):
      domain_name = domain_1["domain"]
      commands_1 = named_list_to_map(domain_1, "commands", "name")
      commands_2 = named_list_to_map(domain_2, "commands", "name")
      for name in commands_1:
          command_1 = commands_1[name]
          if name not in commands_2:
              errors.append("%s.%s: command has been %s" % (domain_1["domain"], name, removed(reverse)))
              continue
          compare_commands(domain_name, command_1, commands_2[name], types_map_1, types_map_2, errors, reverse)
  
      events_1 = named_list_to_map(domain_1, "events", "name")
      events_2 = named_list_to_map(domain_2, "events", "name")
      for name in events_1:
          event_1 = events_1[name]
          if name not in events_2:
              errors.append("%s.%s: event has been %s" % (domain_1["domain"], name, removed(reverse)))
              continue
          compare_events(domain_name, event_1, events_2[name], types_map_1, types_map_2, errors, reverse)
  
  
  def compare_commands(domain_name, command_1, command_2, types_map_1, types_map_2, errors, reverse):
      context = domain_name + "." + command_1["name"]
  
      params_1 = named_list_to_map(command_1, "parameters", "name")
      params_2 = named_list_to_map(command_2, "parameters", "name")
      # Note the reversed order: we allow removing but forbid adding parameters.
      compare_params_list(context, "parameter", params_2, params_1, types_map_2, types_map_1, 0, errors, not reverse)
  
      returns_1 = named_list_to_map(command_1, "returns", "name")
      returns_2 = named_list_to_map(command_2, "returns", "name")
      compare_params_list(context, "response parameter", returns_1, returns_2, types_map_1, types_map_2, 0, errors, reverse)
  
  
  def compare_events(domain_name, event_1, event_2, types_map_1, types_map_2, errors, reverse):
      context = domain_name + "." + event_1["name"]
      params_1 = named_list_to_map(event_1, "parameters", "name")
      params_2 = named_list_to_map(event_2, "parameters", "name")
      compare_params_list(context, "parameter", params_1, params_2, types_map_1, types_map_2, 0, errors, reverse)
  
  
  def compare_params_list(context, kind, params_1, params_2, types_map_1, types_map_2, depth, errors, reverse):
      for name in params_1:
          param_1 = params_1[name]
          if name not in params_2:
              if "optional" not in param_1:
                  errors.append("%s.%s: required %s has been %s" % (context, name, kind, removed(reverse)))
              continue
  
          param_2 = params_2[name]
          if param_2 and "optional" in param_2 and "optional" not in param_1:
              errors.append("%s.%s: %s %s is now %s" % (context, name, required(reverse), kind, required(not reverse)))
              continue
          type_1 = extract_type(param_1, types_map_1, errors)
          type_2 = extract_type(param_2, types_map_2, errors)
          compare_types(context + "." + name, kind, type_1, type_2, types_map_1, types_map_2, depth, errors, reverse)
  
  
  def compare_types(context, kind, type_1, type_2, types_map_1, types_map_2, depth, errors, reverse):
      if depth > 5:
          return
  
      base_type_1 = type_1["type"]
      base_type_2 = type_2["type"]
  
      # Binary and string have the same wire representation in JSON.
      if ((base_type_1 == "string" and base_type_2 == "binary") or
          (base_type_2 == "string" and base_type_1 == "binary")):
        return
  
      if base_type_1 != base_type_2:
          errors.append("%s: %s base type mismatch, '%s' vs '%s'" % (context, kind, base_type_1, base_type_2))
      elif base_type_1 == "object":
          params_1 = named_list_to_map(type_1, "properties", "name")
          params_2 = named_list_to_map(type_2, "properties", "name")
          # If both parameters have the same named type use it in the context.
          if "id" in type_1 and "id" in type_2 and type_1["id"] == type_2["id"]:
              type_name = type_1["id"]
          else:
              type_name = "<object>"
          context += " %s->%s" % (kind, type_name)
          compare_params_list(context, "property", params_1, params_2, types_map_1, types_map_2, depth + 1, errors, reverse)
      elif base_type_1 == "array":
          item_type_1 = extract_type(type_1["items"], types_map_1, errors)
          item_type_2 = extract_type(type_2["items"], types_map_2, errors)
          compare_types(context, kind, item_type_1, item_type_2, types_map_1, types_map_2, depth + 1, errors, reverse)
  
  
  def extract_type(typed_object, types_map, errors):
      if "type" in typed_object:
          result = {"id": "<transient>", "type": typed_object["type"]}
          if typed_object["type"] == "object":
              result["properties"] = []
          elif typed_object["type"] == "array":
              result["items"] = typed_object["items"]
          return result
      elif "$ref" in typed_object:
          ref = typed_object["$ref"]
          if ref not in types_map:
              errors.append("Can not resolve type: %s" % ref)
              types_map[ref] = {"id": "<transient>", "type": "object"}
          return types_map[ref]
  
  
  def normalize_types_in_schema(domains):
      types = {}
      for domain in domains:
          domain_name = domain["domain"]
          normalize_types(domain, domain_name, types)
      return types
  
  
  def normalize_types(obj, domain_name, types):
      if isinstance(obj, list):
          for item in obj:
              normalize_types(item, domain_name, types)
      elif isinstance(obj, dict):
          for key, value in obj.items():
              if key == "$ref" and value.find(".") == -1:
                  obj[key] = "%s.%s" % (domain_name, value)
              elif key == "id":
                  obj[key] = "%s.%s" % (domain_name, value)
                  types[obj[key]] = obj
              else:
                  normalize_types(value, domain_name, types)
  
  
  def load_schema(file_name, domains):
      # pylint: disable=W0613
      if not os.path.isfile(file_name):
          return
      input_file = open(file_name, "r")
      parsed_json = pdl.loads(input_file.read(), file_name)
      input_file.close()
      domains += parsed_json["domains"]
      return parsed_json["version"]
  
  
  def self_test():
      def create_test_schema_1():
          return [
              {
                  "domain": "Network",
                  "types": [
                      {
                          "id": "LoaderId",
                          "type": "string"
                      },
                      {
                          "id": "Headers",
                          "type": "object"
                      },
                      {
                          "id": "Request",
                          "type": "object",
                          "properties": [
                              {"name": "url", "type": "string"},
                              {"name": "method", "type": "string"},
                              {"name": "headers", "$ref": "Headers"},
                              {"name": "becameOptionalField", "type": "string"},
                              {"name": "removedField", "type": "string"},
                          ]
                      }
                  ],
                  "commands": [
                      {
                          "name": "removedCommand",
                      },
                      {
                          "name": "setExtraHTTPHeaders",
                          "parameters": [
                              {"name": "headers", "$ref": "Headers"},
                              {"name": "mismatched", "type": "string"},
                              {"name": "becameOptional", "$ref": "Headers"},
                              {"name": "removedRequired", "$ref": "Headers"},
                              {"name": "becameRequired", "$ref": "Headers", "optional": True},
                              {"name": "removedOptional", "$ref": "Headers", "optional": True},
                          ],
                          "returns": [
                              {"name": "mimeType", "type": "string"},
                              {"name": "becameOptional", "type": "string"},
                              {"name": "removedRequired", "type": "string"},
                              {"name": "becameRequired", "type": "string", "optional": True},
                              {"name": "removedOptional", "type": "string", "optional": True},
                          ]
                      }
                  ],
                  "events": [
                      {
                          "name": "requestWillBeSent",
                          "parameters": [
                              {"name": "frameId", "type": "string", "experimental": True},
                              {"name": "request", "$ref": "Request"},
                              {"name": "becameOptional", "type": "string"},
                              {"name": "removedRequired", "type": "string"},
                              {"name": "becameRequired", "type": "string", "optional": True},
                              {"name": "removedOptional", "type": "string", "optional": True},
                          ]
                      },
                      {
                          "name": "removedEvent",
                          "parameters": [
                              {"name": "errorText", "type": "string"},
                              {"name": "canceled", "type": "boolean", "optional": True}
                          ]
                      }
                  ]
              },
              {
                  "domain":  "removedDomain"
              }
          ]
  
      def create_test_schema_2():
          return [
              {
                  "domain": "Network",
                  "types": [
                      {
                          "id": "LoaderId",
                          "type": "string"
                      },
                      {
                          "id": "Request",
                          "type": "object",
                          "properties": [
                              {"name": "url", "type": "string"},
                              {"name": "method", "type": "string"},
                              {"name": "headers", "type": "object"},
                              {"name": "becameOptionalField", "type": "string", "optional": True},
                          ]
                      }
                  ],
                  "commands": [
                      {
                          "name": "addedCommand",
                      },
                      {
                          "name": "setExtraHTTPHeaders",
                          "parameters": [
                              {"name": "headers", "type": "object"},
                              {"name": "mismatched", "type": "object"},
                              {"name": "becameOptional", "type": "object", "optional": True},
                              {"name": "addedRequired", "type": "object"},
                              {"name": "becameRequired", "type": "object"},
                              {"name": "addedOptional", "type": "object", "optional": True},
                          ],
                          "returns": [
                              {"name": "mimeType", "type": "string"},
                              {"name": "becameOptional", "type": "string", "optional": True},
                              {"name": "addedRequired", "type": "string"},
                              {"name": "becameRequired", "type": "string"},
                              {"name": "addedOptional", "type": "string", "optional": True},
                          ]
                      }
                  ],
                  "events": [
                      {
                          "name": "requestWillBeSent",
                          "parameters": [
                              {"name": "request", "$ref": "Request"},
                              {"name": "becameOptional", "type": "string", "optional": True},
                              {"name": "addedRequired", "type": "string"},
                              {"name": "becameRequired", "type": "string"},
                              {"name": "addedOptional", "type": "string", "optional": True},
                          ]
                      },
                      {
                          "name": "addedEvent"
                      }
                  ]
              },
              {
                  "domain": "addedDomain"
              }
          ]
  
      expected_errors = [
          "removedDomain: domain has been removed",
          "Network.removedCommand: command has been removed",
          "Network.removedEvent: event has been removed",
          "Network.setExtraHTTPHeaders.mismatched: parameter base type mismatch, 'object' vs 'string'",
          "Network.setExtraHTTPHeaders.addedRequired: required parameter has been added",
          "Network.setExtraHTTPHeaders.becameRequired: optional parameter is now required",
          "Network.setExtraHTTPHeaders.removedRequired: required response parameter has been removed",
          "Network.setExtraHTTPHeaders.becameOptional: required response parameter is now optional",
          "Network.requestWillBeSent.removedRequired: required parameter has been removed",
          "Network.requestWillBeSent.becameOptional: required parameter is now optional",
          "Network.requestWillBeSent.request parameter->Network.Request.removedField: required property has been removed",
          "Network.requestWillBeSent.request parameter->Network.Request.becameOptionalField: required property is now optional",
      ]
  
      expected_errors_reverse = [
          "addedDomain: domain has been added",
          "Network.addedEvent: event has been added",
          "Network.addedCommand: command has been added",
          "Network.setExtraHTTPHeaders.mismatched: parameter base type mismatch, 'string' vs 'object'",
          "Network.setExtraHTTPHeaders.removedRequired: required parameter has been removed",
          "Network.setExtraHTTPHeaders.becameOptional: required parameter is now optional",
          "Network.setExtraHTTPHeaders.addedRequired: required response parameter has been added",
          "Network.setExtraHTTPHeaders.becameRequired: optional response parameter is now required",
          "Network.requestWillBeSent.becameRequired: optional parameter is now required",
          "Network.requestWillBeSent.addedRequired: required parameter has been added",
      ]
  
      def is_subset(subset, superset, message):
          for i in range(len(subset)):
              if subset[i] not in superset:
                  sys.stderr.write("%s error: %s\n" % (message, subset[i]))
                  return False
          return True
  
      def errors_match(expected, actual):
          return (is_subset(actual, expected, "Unexpected") and
                  is_subset(expected, actual, "Missing"))
  
      return (errors_match(expected_errors,
                           compare_schemas(create_test_schema_1(), create_test_schema_2(), False)) and
              errors_match(expected_errors_reverse,
                           compare_schemas(create_test_schema_2(), create_test_schema_1(), True)))
  
  
  def load_domains_and_baselines(file_name, domains, baseline_domains):
      version = load_schema(os.path.normpath(file_name), domains)
      suffix = "-%s.%s.json" % (version["major"], version["minor"])
      baseline_file = file_name.replace(".json", suffix)
      baseline_file = file_name.replace(".pdl", suffix)
      load_schema(os.path.normpath(baseline_file), baseline_domains)
      return version
  
  
  def main():
      if not self_test():
          sys.stderr.write("Self-test failed")
          return 1
  
      cmdline_parser = optparse.OptionParser()
      cmdline_parser.add_option("--show_changes")
      cmdline_parser.add_option("--expected_errors")
      cmdline_parser.add_option("--stamp")
      arg_options, arg_values = cmdline_parser.parse_args()
  
      if len(arg_values) < 1:
          sys.stderr.write("Usage: %s [--show_changes] <protocol-1> [, <protocol-2>...]\n" % sys.argv[0])
          return 1
  
      domains = []
      baseline_domains = []
      version = load_domains_and_baselines(arg_values[0], domains, baseline_domains)
      for dependency in arg_values[1:]:
          load_domains_and_baselines(dependency, domains, baseline_domains)
  
      expected_errors = []
      if arg_options.expected_errors:
          expected_errors_file = open(arg_options.expected_errors, "r")
          expected_errors = json.loads(expected_errors_file.read())["errors"]
          expected_errors_file.close()
  
      errors = compare_schemas(baseline_domains, domains, False)
      unexpected_errors = []
      for i in range(len(errors)):
          if errors[i] not in expected_errors:
              unexpected_errors.append(errors[i])
      if len(unexpected_errors) > 0:
          sys.stderr.write("  Compatibility checks FAILED\n")
          for error in unexpected_errors:
              sys.stderr.write("    %s\n" % error)
          return 1
  
      if arg_options.show_changes:
          changes = compare_schemas(domains, baseline_domains, True)
          if len(changes) > 0:
              print("  Public changes since %s:" % version)
              for change in changes:
                  print("    %s" % change)
  
      if arg_options.stamp:
          with open(arg_options.stamp, 'a') as _:
              pass
  
  if __name__ == '__main__':
      sys.exit(main())
  