/*
Copyright 2014 Google Inc. All rights reserved.

Licensed under the Apache License, Version 2.0 (the "License");
you may not use this file except in compliance with the License.
You may obtain a copy of the License at

    http://www.apache.org/licenses/LICENSE-2.0

Unless required by applicable law or agreed to in writing, software
distributed under the License is distributed on an "AS IS" BASIS,
WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
See the License for the specific language governing permissions and
limitations under the License.
*/

package cmd

import (
	"fmt"
	"io"
	"os"

	"github.com/GoogleCloudPlatform/kubernetes/pkg/api"
	"github.com/GoogleCloudPlatform/kubernetes/pkg/api/latest"
	"github.com/GoogleCloudPlatform/kubernetes/pkg/api/meta"
	"github.com/GoogleCloudPlatform/kubernetes/pkg/api/validation"
	"github.com/GoogleCloudPlatform/kubernetes/pkg/client"
	"github.com/GoogleCloudPlatform/kubernetes/pkg/client/clientcmd"
	"github.com/GoogleCloudPlatform/kubernetes/pkg/kubectl"
	cmdconfig "github.com/GoogleCloudPlatform/kubernetes/pkg/kubectl/cmd/config"
	cmdutil "github.com/GoogleCloudPlatform/kubernetes/pkg/kubectl/cmd/util"
	"github.com/GoogleCloudPlatform/kubernetes/pkg/kubectl/resource"
	"github.com/GoogleCloudPlatform/kubernetes/pkg/runtime"
	"github.com/GoogleCloudPlatform/kubernetes/pkg/util"

	"github.com/spf13/cobra"
	"github.com/spf13/pflag"
)

const (
	FlagMatchBinaryVersion = "match-server-version"
)

// Factory provides abstractions that allow the Kubectl command to be extended across multiple types
// of resources and different API sets.
// TODO: make the functions interfaces
type Factory struct {
	clients *clientCache
	flags   *pflag.FlagSet

	// Returns interfaces for dealing with arbitrary runtime.Objects.
	Object func(cmd *cobra.Command) (meta.RESTMapper, runtime.ObjectTyper)
	// Returns a client for accessing Kubernetes resources or an error.
	Client func(cmd *cobra.Command) (*client.Client, error)
	// Returns a client.Config for accessing the Kubernetes server.
	ClientConfig func(cmd *cobra.Command) (*client.Config, error)
	// Returns a RESTClient for working with the specified RESTMapping or an error. This is intended
	// for working with arbitrary resources and is not guaranteed to point to a Kubernetes APIServer.
	RESTClient func(cmd *cobra.Command, mapping *meta.RESTMapping) (resource.RESTClient, error)
	// Returns a Describer for displaying the specified RESTMapping type or an error.
	Describer func(cmd *cobra.Command, mapping *meta.RESTMapping) (kubectl.Describer, error)
	// Returns a Printer for formatting objects of the given type or an error.
	Printer func(cmd *cobra.Command, mapping *meta.RESTMapping, noHeaders bool) (kubectl.ResourcePrinter, error)
	// Returns a Resizer for changing the size of the specified RESTMapping type or an error
	Resizer func(cmd *cobra.Command, mapping *meta.RESTMapping) (kubectl.Resizer, error)
	// Returns a Reaper for gracefully shutting down resources.
	Reaper func(cmd *cobra.Command, mapping *meta.RESTMapping) (kubectl.Reaper, error)
	// Returns a schema that can validate objects stored on disk.
	Validator func(*cobra.Command) (validation.Schema, error)
	// Returns the default namespace to use in cases where no other namespace is specified
	DefaultNamespace func(cmd *cobra.Command) (string, error)
}

// NewFactory creates a factory with the default Kubernetes resources defined
// if optionalClientConfig is nil, then flags will be bound to a new clientcmd.ClientConfig.
// if optionalClientConfig is not nil, then this factory will make use of it.
func NewFactory(optionalClientConfig clientcmd.ClientConfig) *Factory {
	mapper := kubectl.ShortcutExpander{latest.RESTMapper}

	flags := pflag.NewFlagSet("", pflag.ContinueOnError)

	clientConfig := optionalClientConfig
	if optionalClientConfig == nil {
		clientConfig = DefaultClientConfig(flags)
	}

	clients := &clientCache{
		clients: make(map[string]*client.Client),
		loader:  clientConfig,
	}

	return &Factory{
		clients: clients,
		flags:   flags,

		Object: func(cmd *cobra.Command) (meta.RESTMapper, runtime.ObjectTyper) {
			cfg, err := clientConfig.ClientConfig()
			cmdutil.CheckErr(err)
			cmdApiVersion := cfg.Version

			return kubectl.OutputVersionMapper{mapper, cmdApiVersion}, api.Scheme
		},
		Client: func(cmd *cobra.Command) (*client.Client, error) {
			return clients.ClientForVersion("")
		},
		ClientConfig: func(cmd *cobra.Command) (*client.Config, error) {
			return clients.ClientConfigForVersion("")
		},
		RESTClient: func(cmd *cobra.Command, mapping *meta.RESTMapping) (resource.RESTClient, error) {
			client, err := clients.ClientForVersion(mapping.APIVersion)
			if err != nil {
				return nil, err
			}
			return client.RESTClient, nil
		},
		Describer: func(cmd *cobra.Command, mapping *meta.RESTMapping) (kubectl.Describer, error) {
			client, err := clients.ClientForVersion(mapping.APIVersion)
			if err != nil {
				return nil, err
			}
			describer, ok := kubectl.DescriberFor(mapping.Kind, client)
			if !ok {
				return nil, fmt.Errorf("no description has been implemented for %q", mapping.Kind)
			}
			return describer, nil
		},
		Printer: func(cmd *cobra.Command, mapping *meta.RESTMapping, noHeaders bool) (kubectl.ResourcePrinter, error) {
			return kubectl.NewHumanReadablePrinter(noHeaders), nil
		},
		Resizer: func(cmd *cobra.Command, mapping *meta.RESTMapping) (kubectl.Resizer, error) {
			client, err := clients.ClientForVersion(mapping.APIVersion)
			if err != nil {
				return nil, err
			}
			return kubectl.ResizerFor(mapping.Kind, client)
		},
		Reaper: func(cmd *cobra.Command, mapping *meta.RESTMapping) (kubectl.Reaper, error) {
			client, err := clients.ClientForVersion(mapping.APIVersion)
			if err != nil {
				return nil, err
			}
			return kubectl.ReaperFor(mapping.Kind, client)
		},
		Validator: func(cmd *cobra.Command) (validation.Schema, error) {
			if cmdutil.GetFlagBool(cmd, "validate") {
				client, err := clients.ClientForVersion("")
				if err != nil {
					return nil, err
				}
				return &clientSwaggerSchema{client, api.Scheme}, nil
			}
			return validation.NullSchema{}, nil
		},
		DefaultNamespace: func(cmd *cobra.Command) (string, error) {
			return clientConfig.Namespace()
		},
	}
}

// BindFlags adds any flags that are common to all kubectl sub commands.
func (f *Factory) BindFlags(flags *pflag.FlagSet) {
	// any flags defined by external projects (not part of pflags)
	util.AddAllFlagsToPFlagSet(flags)

	// This is necessary as github.com/spf13/cobra doesn't support "global"
	// pflags currently.  See https://github.com/spf13/cobra/issues/44.
	util.AddPFlagSetToPFlagSet(pflag.CommandLine, flags)

	if f.flags != nil {
		f.flags.VisitAll(func(flag *pflag.Flag) {
			flags.AddFlag(flag)
		})
	}

	// Globally persistent flags across all subcommands.
	// TODO Change flag names to consts to allow safer lookup from subcommands.
	// TODO Add a verbose flag that turns on glog logging. Probably need a way
	// to do that automatically for every subcommand.
	flags.BoolVar(&f.clients.matchVersion, FlagMatchBinaryVersion, false, "Require server version to match client version")
	flags.Bool("validate", false, "If true, use a schema to validate the input before sending it")
}

// NewKubectlCommand creates the `kubectl` command and its nested children.
func (f *Factory) NewKubectlCommand(in io.Reader, out, err io.Writer) *cobra.Command {
	// Parent command to which all subcommands are added.
	cmds := &cobra.Command{
		Use:   "kubectl",
		Short: "kubectl controls the Kubernetes cluster manager",
		Long: `kubectl controls the Kubernetes cluster manager.

Find more information at https://github.com/GoogleCloudPlatform/kubernetes.`,
		Run: runHelp,
	}

	f.BindFlags(cmds.PersistentFlags())

	cmds.AddCommand(f.NewCmdVersion(out))
	cmds.AddCommand(f.NewCmdClusterInfo(out))
	cmds.AddCommand(f.NewCmdProxy(out))

	cmds.AddCommand(f.NewCmdGet(out))
	cmds.AddCommand(f.NewCmdDescribe(out))
	cmds.AddCommand(f.NewCmdCreate(out))
	cmds.AddCommand(f.NewCmdUpdate(out))
	cmds.AddCommand(f.NewCmdDelete(out))

	cmds.AddCommand(cmdconfig.NewCmdConfig(out))
	cmds.AddCommand(NewCmdNamespace(out))
	cmds.AddCommand(f.NewCmdLog(out))
	cmds.AddCommand(f.NewCmdRollingUpdate(out))
	cmds.AddCommand(f.NewCmdResize(out))

	cmds.AddCommand(f.NewCmdExec(in, out, err))
	cmds.AddCommand(f.NewCmdPortForward())

	cmds.AddCommand(f.NewCmdRunContainer(out))
	cmds.AddCommand(f.NewCmdStop(out))
	cmds.AddCommand(f.NewCmdExposeService(out))

	cmds.AddCommand(f.NewCmdLabel(out))

	return cmds
}

// PrintObject prints an api object given command line flags to modify the output format
func (f *Factory) PrintObject(cmd *cobra.Command, obj runtime.Object, out io.Writer) error {
	mapper, _ := f.Object(cmd)
	_, kind, err := api.Scheme.ObjectVersionAndKind(obj)
	if err != nil {
		return err
	}

	mapping, err := mapper.RESTMapping(kind)
	if err != nil {
		return err
	}

	printer, err := f.PrinterForMapping(cmd, mapping)
	if err != nil {
		return err
	}
	return printer.PrintObj(obj, out)
}

// PrinterForMapping returns a printer suitable for displaying the provided resource type.
// Requires that printer flags have been added to cmd (see AddPrinterFlags).
func (f *Factory) PrinterForMapping(cmd *cobra.Command, mapping *meta.RESTMapping) (kubectl.ResourcePrinter, error) {
	printer, ok, err := cmdutil.PrinterForCommand(cmd)
	if err != nil {
		return nil, err
	}
	if ok {
		clientConfig, err := f.ClientConfig(cmd)
		if err != nil {
			return nil, err
		}
		defaultVersion := clientConfig.Version

		version := cmdutil.OutputVersion(cmd, defaultVersion)
		if len(version) == 0 {
			version = mapping.APIVersion
		}
		if len(version) == 0 {
			return nil, fmt.Errorf("you must specify an output-version when using this output format")
		}
		printer = kubectl.NewVersionedPrinter(printer, mapping.ObjectConvertor, version)
	} else {
		printer, err = f.Printer(cmd, mapping, cmdutil.GetFlagBool(cmd, "no-headers"))
		if err != nil {
			return nil, err
		}
	}
	return printer, nil
}

// ClientMapperForCommand returns a ClientMapper for the given command and factory.
func (f *Factory) ClientMapperForCommand(cmd *cobra.Command) resource.ClientMapper {
	return resource.ClientMapperFunc(func(mapping *meta.RESTMapping) (resource.RESTClient, error) {
		return f.RESTClient(cmd, mapping)
	})
}

// DefaultClientConfig creates a clientcmd.ClientConfig with the following hierarchy:
//   1.  Use the kubeconfig builder.  The number of merges and overrides here gets a little crazy.  Stay with me.
//       1.  Merge together the kubeconfig itself.  This is done with the following hierarchy and merge rules:
//           1.  CommandLineLocation - this parsed from the command line, so it must be late bound
//           2.  EnvVarLocation
//           3.  CurrentDirectoryLocation
//           4.  HomeDirectoryLocation
//           Empty filenames are ignored.  Files with non-deserializable content produced errors.
//           The first file to set a particular value or map key wins and the value or map key is never changed.
//           This means that the first file to set CurrentContext will have its context preserved.  It also means
//           that if two files specify a "red-user", only values from the first file's red-user are used.  Even
//           non-conflicting entries from the second file's "red-user" are discarded.
//       2.  Determine the context to use based on the first hit in this chain
//           1.  command line argument - again, parsed from the command line, so it must be late bound
//           2.  CurrentContext from the merged kubeconfig file
//           3.  Empty is allowed at this stage
//       3.  Determine the cluster info and auth info to use.  At this point, we may or may not have a context.  They
//           are built based on the first hit in this chain.  (run it twice, once for auth, once for cluster)
//           1.  command line argument
//           2.  If context is present, then use the context value
//           3.  Empty is allowed
//       4.  Determine the actual cluster info to use.  At this point, we may or may not have a cluster info.  Build
//           each piece of the cluster info based on the chain:
//           1.  command line argument
//           2.  If cluster info is present and a value for the attribute is present, use it.
//           3.  If you don't have a server location, bail.
//       5.  Auth info is build using the same rules as cluster info, EXCEPT that you can only have one authentication
//           technique per auth info.  The following conditions result in an error:
//           1.  If there are two conflicting techniques specified from the command line, fail.
//           2.  If the command line does not specify one, and the auth info has conflicting techniques, fail.
//           3.  If the command line specifies one and the auth info specifies another, honor the command line technique.
//   2.  Use default values and potentially prompt for auth information
func DefaultClientConfig(flags *pflag.FlagSet) clientcmd.ClientConfig {
	loadingRules := clientcmd.NewClientConfigLoadingRules()
	loadingRules.EnvVarPath = os.Getenv(clientcmd.RecommendedConfigPathEnvVar)
	flags.StringVar(&loadingRules.CommandLinePath, "kubeconfig", "", "Path to the kubeconfig file to use for CLI requests.")

	overrides := &clientcmd.ConfigOverrides{}
	flagNames := clientcmd.RecommendedConfigOverrideFlags("")
	// short flagnames are disabled by default.  These are here for compatibility with existing scripts
	flagNames.AuthOverrideFlags.AuthPathShort = "a"
	flagNames.ClusterOverrideFlags.APIServerShort = "s"

	clientcmd.BindOverrideFlags(overrides, flags, flagNames)
	clientConfig := clientcmd.NewInteractiveDeferredLoadingClientConfig(loadingRules, overrides, os.Stdin)

	return clientConfig
}

func runHelp(cmd *cobra.Command, args []string) {
	cmd.Help()
}

type clientSwaggerSchema struct {
	c *client.Client
	t runtime.ObjectTyper
}

func (c *clientSwaggerSchema) ValidateBytes(data []byte) error {
	version, _, err := c.t.DataVersionAndKind(data)
	if err != nil {
		return err
	}
	schemaData, err := c.c.RESTClient.Get().
		AbsPath("/swaggerapi/api", version).
		Do().
		Raw()
	if err != nil {
		return err
	}
	schema, err := validation.NewSwaggerSchemaFromBytes(schemaData)
	if err != nil {
		return err
	}
	return schema.ValidateBytes(data)
}

// clientCache caches previously loaded clients for reuse, and ensures MatchServerVersion
// is invoked only once
type clientCache struct {
	loader        clientcmd.ClientConfig
	clients       map[string]*client.Client
	defaultConfig *client.Config
	matchVersion  bool
}

// ClientConfigForVersion returns the correct config for a server
func (c *clientCache) ClientConfigForVersion(version string) (*client.Config, error) {
	if c.defaultConfig == nil {
		config, err := c.loader.ClientConfig()
		if err != nil {
			return nil, err
		}
		c.defaultConfig = config
		if c.matchVersion {
			if err := client.MatchesServerVersion(config); err != nil {
				return nil, err
			}
		}
	}
	// TODO: have a better config copy method
	config := *c.defaultConfig
	if len(version) != 0 {
		config.Version = version
	}
	client.SetKubernetesDefaults(&config)

	return &config, nil
}

// ClientForVersion initializes or reuses a client for the specified version, or returns an
// error if that is not possible
func (c *clientCache) ClientForVersion(version string) (*client.Client, error) {
	config, err := c.ClientConfigForVersion(version)
	if err != nil {
		return nil, err
	}

	if client, ok := c.clients[config.Version]; ok {
		return client, nil
	}

	client, err := client.New(config)
	if err != nil {
		return nil, err
	}

	c.clients[config.Version] = client
	return client, nil
}