github.com/mmatczuk/gohan@v0.0.0-20170206152520-30e45d9bdb69/extension/extension.go (about)

     1  // Copyright (C) 2015 NTT Innovation Institute, Inc.
     2  //
     3  // Licensed under the Apache License, Version 2.0 (the "License");
     4  // you may not use this file except in compliance with the License.
     5  // You may obtain a copy of the License at
     6  //
     7  //    http://www.apache.org/licenses/LICENSE-2.0
     8  //
     9  // Unless required by applicable law or agreed to in writing, software
    10  // distributed under the License is distributed on an "AS IS" BASIS,
    11  // WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or
    12  // implied.
    13  // See the License for the specific language governing permissions and
    14  // limitations under the License.
    15  
    16  package extension
    17  
    18  import (
    19  	"fmt"
    20  
    21  	"github.com/cloudwan/gohan/schema"
    22  )
    23  
    24  //Environment is a interface for extension environment
    25  type Environment interface {
    26  	LoadExtensionsForPath(extensions []*schema.Extension, path string) error
    27  	HandleEvent(event string, context map[string]interface{}) error
    28  	Clone() Environment
    29  }
    30  
    31  var manager *Manager
    32  
    33  //Manager takes care of mapping schemas to Environments.
    34  //This is a singleton class.
    35  type Manager struct {
    36  	environments map[string]Environment
    37  }
    38  
    39  //RegisterEnvironment registers a new environment for the given schema ID
    40  func (manager *Manager) RegisterEnvironment(schemaID string, env Environment) error {
    41  	if _, ok := manager.environments[schemaID]; ok {
    42  		return fmt.Errorf("Environment already registered for this schema")
    43  	}
    44  	manager.environments[schemaID] = env
    45  	return nil
    46  }
    47  
    48  //UnRegisterEnvironment removes an environment registered for the given schema ID
    49  func (manager *Manager) UnRegisterEnvironment(schemaID string) error {
    50  	if _, ok := manager.environments[schemaID]; !ok {
    51  		return fmt.Errorf("No environment registered for this schema")
    52  	}
    53  	delete(manager.environments, schemaID)
    54  	return nil
    55  }
    56  
    57  //GetEnvironment returns the environment registered for the given schema ID
    58  func (manager *Manager) GetEnvironment(schemaID string) (env Environment, ok bool) {
    59  	env, ok = manager.environments[schemaID]
    60  	if ok {
    61  		env = env.Clone()
    62  	}
    63  	return
    64  }
    65  
    66  //GetManager gets manager
    67  func GetManager() *Manager {
    68  	if manager == nil {
    69  		manager = &Manager{
    70  			environments: map[string]Environment{},
    71  		}
    72  	}
    73  	return manager
    74  }
    75  
    76  //ClearManager clears manager
    77  func ClearManager() {
    78  	manager = nil
    79  }
    80  
    81  // Error is created when a problem has occurred during event handling. It contains the information
    82  // required to reraise the javascript exception that caused this error.
    83  type Error struct {
    84  	error
    85  	ExceptionInfo map[string]interface{}
    86  }
    87  
    88  //HandleEvent handles the event in the given environment
    89  func HandleEvent(context map[string]interface{}, environment Environment, event string) error {
    90  	if err := environment.HandleEvent(event, context); err != nil {
    91  		return err
    92  	}
    93  	exceptionInfoRaw, ok := context["exception"]
    94  	if !ok {
    95  		return nil
    96  	}
    97  	exceptionInfo, ok := exceptionInfoRaw.(map[string]interface{})
    98  	if !ok {
    99  		return fmt.Errorf("extension returned invalid error information")
   100  	}
   101  	exceptionMessage := context["exception_message"]
   102  	return Error{fmt.Errorf("%v", exceptionMessage), exceptionInfo}
   103  }
   104  
   105  //Errorf makes extension error
   106  func Errorf(code int, name, message string) Error {
   107  	return Error{fmt.Errorf("%v", message),
   108  		map[string]interface{}{
   109  			"code":    code,
   110  			"name":    name,
   111  			"message": message,
   112  		}}
   113  }