// ConfigForName returns the configuration for the environment with
// the given name from the default environments file. If the name is
// blank, the default environment will be used. If the configuration
// is not found, an errors.NotFoundError is returned. If the given
// store contains an entry for the environment and it has associated
// bootstrap config, that configuration will be returned.
// ConfigForName also returns where the configuration was sourced from
// (this is also valid even when there is an error.
func ConfigForName(name string, store configstore.Storage) (*config.Config, ConfigSource, error) {
	envs, err := ReadEnvirons("")
	if err != nil {
		return nil, ConfigFromNowhere, err
	}
	if name == "" {
		name = envs.Default
	}
	// TODO(rog) 2013-10-04 https://bugs.github.com/wallyworld/core/+bug/1235217
	// Don't fall back to reading from environments.yaml
	// when we can be sure that everyone has a
	// .jenv file for their currently bootstrapped environments.
	if name != "" {
		info, err := store.ReadInfo(name)
		if err == nil {
			if len(info.BootstrapConfig()) == 0 {
				return nil, ConfigFromNowhere, EmptyConfig{fmt.Errorf("environment has no bootstrap configuration data")}
			}
			logger.Debugf("ConfigForName found bootstrap config %#v", info.BootstrapConfig())
			cfg, err := config.New(config.NoDefaults, info.BootstrapConfig())
			return cfg, ConfigFromInfo, err
		}
		if err != nil && !errors.IsNotFound(err) {
			return nil, ConfigFromInfo, fmt.Errorf("cannot read environment info for %q: %v", name, err)
		}
	}
	cfg, err := envs.Config(name)
	return cfg, ConfigFromEnvirons, err
}

func assertEnvironDestroyed(c *gc.C, env environs.Environ, store configstore.Storage) {
	_, err := store.ReadInfo(env.Name())
	c.Assert(err, jc.Satisfies, errors.IsNotFound)

	_, err = env.Instances([]instance.Id{"invalid"})
	c.Assert(err, gc.ErrorMatches, "environment has been destroyed")
}

func assertEnvironNotDestroyed(c *gc.C, env environs.Environ, store configstore.Storage) {
	info, err := store.ReadInfo(env.Name())
	c.Assert(err, gc.IsNil)
	c.Assert(info.Initialized(), jc.IsTrue)

	_, err = environs.NewFromName(env.Name(), store)
	c.Assert(err, gc.IsNil)
}

func setEndpointAddress(c *gc.C, store configstore.Storage, envName string, addr string) {
	// Populate the environment's info with an endpoint
	// with a known address.
	info, err := store.ReadInfo(coretesting.SampleEnvName)
	c.Assert(err, gc.IsNil)
	info.SetAPIEndpoint(configstore.APIEndpoint{
		Addresses: []string{addr},
		CACert:    "certificated",
	})
	err = info.Write()
	c.Assert(err, gc.IsNil)
}

// DestroyInfo destroys the configuration data for the named
// environment from the given store.
func DestroyInfo(envName string, store configstore.Storage) error {
	info, err := store.ReadInfo(envName)
	if err != nil {
		if errors.IsNotFound(err) {
			return nil
		}
		return err
	}
	if err := info.Destroy(); err != nil {
		return errgo.Annotate(err, "cannot destroy environment configuration information")
	}
	return nil
}

// Prepare prepares a new environment based on the provided configuration.
// If the environment is already prepared, it behaves like New.
func Prepare(cfg *config.Config, ctx BootstrapContext, store configstore.Storage) (Environ, error) {
	p, err := Provider(cfg.Type())
	if err != nil {
		return nil, err
	}
	info, err := store.CreateInfo(cfg.Name())
	if err == configstore.ErrEnvironInfoAlreadyExists {
		logger.Infof("environment info already exists; using New not Prepare")
		info, err := store.ReadInfo(cfg.Name())
		if err != nil {
			return nil, fmt.Errorf("error reading environment info %q: %v", cfg.Name(), err)
		}
		if !info.Initialized() {
			return nil, fmt.Errorf("found uninitialized environment info for %q; environment preparation probably in progress or interrupted", cfg.Name())
		}
		if len(info.BootstrapConfig()) == 0 {
			return nil, fmt.Errorf("found environment info but no bootstrap config")
		}
		cfg, err = config.New(config.NoDefaults, info.BootstrapConfig())
		if err != nil {
			return nil, fmt.Errorf("cannot parse bootstrap config: %v", err)
		}
		return New(cfg)
	}
	if err != nil {
		return nil, fmt.Errorf("cannot create new info for environment %q: %v", cfg.Name(), err)
	}
	env, err := prepare(ctx, cfg, info, p)
	if err != nil {
		if err := info.Destroy(); err != nil {
			logger.Warningf("cannot destroy newly created environment info: %v", err)
		}
		return nil, err
	}
	info.SetBootstrapConfig(env.Config().AllAttrs())
	if err := info.Write(); err != nil {
		return nil, fmt.Errorf("cannot create environment info %q: %v", env.Config().Name(), err)
	}
	return env, nil
}

func apiEndpointInStore(envName string, refresh bool, store configstore.Storage, apiOpen apiOpenFunc) (configstore.APIEndpoint, error) {
	info, err := store.ReadInfo(envName)
	if err != nil {
		return configstore.APIEndpoint{}, err
	}
	endpoint := info.APIEndpoint()
	if !refresh && len(endpoint.Addresses) > 0 {
		logger.Debugf("found cached addresses, not connecting to API server")
		return endpoint, nil
	}
	// We need to connect to refresh our endpoint settings
	apiState, err := newAPIFromStore(envName, store, apiOpen)
	if err != nil {
		return configstore.APIEndpoint{}, err
	}
	apiState.Close()
	// The side effect of connecting is that we update the store with new API information
	info, err = store.ReadInfo(envName)
	if err != nil {
		return configstore.APIEndpoint{}, err
	}
	return info.APIEndpoint(), nil
}

// newAPIFromStore implements the bulk of NewAPIClientFromName
// but is separate for testing purposes.
func newAPIFromStore(envName string, store configstore.Storage, apiOpen apiOpenFunc) (apiState, error) {
	// Try to read the default environment configuration file.
	// If it doesn't exist, we carry on in case
	// there's some environment info for that environment.
	// This enables people to copy environment files
	// into their .juju/environments directory and have
	// them be directly useful with no further configuration changes.
	envs, err := environs.ReadEnvirons("")
	if err == nil {
		if envName == "" {
			envName = envs.Default
		}
		if envName == "" {
			return nil, fmt.Errorf("no default environment found")
		}
	} else if !environs.IsNoEnv(err) {
		return nil, err
	}

	// Try to connect to the API concurrently using two different
	// possible sources of truth for the API endpoint. Our
	// preference is for the API endpoint cached in the API info,
	// because we know that without needing to access any remote
	// provider. However, the addresses stored there may no longer
	// be current (and the network connection may take a very long
	// time to time out) so we also try to connect using information
	// found from the provider. We only start to make that
	// connection after some suitable delay, so that in the
	// hopefully usual case, we will make the connection to the API
	// and never hit the provider. By preference we use provider
	// attributes from the config store, but for backward
	// compatibility reasons, we fall back to information from
	// ReadEnvirons if that does not exist.
	chooseError := func(err0, err1 error) error {
		if err0 == nil {
			return err1
		}
		if errorImportance(err0) < errorImportance(err1) {
			err0, err1 = err1, err0
		}
		logger.Warningf("discarding API open error: %v", err1)
		return err0
	}
	try := parallel.NewTry(0, chooseError)

	info, err := store.ReadInfo(envName)
	if err != nil && !errors.IsNotFound(err) {
		return nil, err
	}
	var delay time.Duration
	if info != nil && len(info.APIEndpoint().Addresses) > 0 {
		logger.Debugf("trying cached API connection settings")
		try.Start(func(stop <-chan struct{}) (io.Closer, error) {
			return apiInfoConnect(store, info, apiOpen, stop)
		})
		// Delay the config connection until we've spent
		// some time trying to connect to the cached info.
		delay = providerConnectDelay
	} else {
		logger.Debugf("no cached API connection settings found")
	}
	try.Start(func(stop <-chan struct{}) (io.Closer, error) {
		cfg, err := getConfig(info, envs, envName)
		if err != nil {
			return nil, err
		}
		return apiConfigConnect(cfg, apiOpen, stop, delay)
	})
	try.Close()
	val0, err := try.Result()
	if err != nil {
		if ierr, ok := err.(*infoConnectError); ok {
			// lose error encapsulation:
			err = ierr.error
		}
		return nil, err
	}

	st := val0.(apiState)
	// Even though we are about to update API addresses based on
	// APIHostPorts in cacheChangedAPIAddresses, we first cache the
	// addresses based on the provider lookup. This is because older API
	// servers didn't return their HostPort information on Login, and we
	// still want to cache our connection information to them.
	if cachedInfo, ok := st.(apiStateCachedInfo); ok {
		st = cachedInfo.apiState
		if cachedInfo.cachedInfo != nil && info != nil {
			// Cache the connection settings only if we used the
			// environment config, but any errors are just logged
			// as warnings, because they're not fatal.
			err = cacheAPIInfo(info, cachedInfo.cachedInfo)
			if err != nil {
				logger.Warningf("cannot cache API connection settings: %v", err.Error())
			} else {
				logger.Infof("updated API connection settings cache")
			}
		}
	}
//.........这里部分代码省略.........