/*
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 cloudcfg

import (
	"encoding/json"
	"fmt"
	"io"
	"strings"
	"text/tabwriter"

	"github.com/GoogleCloudPlatform/kubernetes/pkg/api"
	"github.com/GoogleCloudPlatform/kubernetes/pkg/labels"
	"gopkg.in/v1/yaml"
)

// ResourcePrinter is an interface that knows how to print API resources
type ResourcePrinter interface {
	// Print receives an arbitrary JSON body, formats it and prints it to a writer
	Print([]byte, io.Writer) error
	PrintObj(interface{}, io.Writer) error
}

// Identity printer simply copies the body out to the output stream
type IdentityPrinter struct{}

func (i *IdentityPrinter) Print(data []byte, w io.Writer) error {
	_, err := w.Write(data)
	return err
}

func (i *IdentityPrinter) PrintObj(obj interface{}, output io.Writer) error {
	data, err := api.Encode(obj)
	if err != nil {
		return err
	}
	return i.Print(data, output)
}

// YAMLPrinter parses JSON, and re-formats as YAML
type YAMLPrinter struct{}

func (y *YAMLPrinter) Print(data []byte, w io.Writer) error {
	var obj interface{}
	if err := json.Unmarshal(data, &obj); err != nil {
		return err
	}
	output, err := yaml.Marshal(obj)
	if err != nil {
		return err
	}
	_, err = fmt.Fprint(w, string(output))
	return err
}

func (y *YAMLPrinter) PrintObj(obj interface{}, w io.Writer) error {
	output, err := yaml.Marshal(obj)
	if err != nil {
		return err
	}
	_, err = fmt.Fprint(w, string(output))
	return err
}

// HumanReadablePrinter attempts to provide more elegant output
type HumanReadablePrinter struct{}

var podColumns = []string{"Name", "Image(s)", "Host", "Labels"}
var replicationControllerColumns = []string{"Name", "Image(s)", "Selector", "Replicas"}
var serviceColumns = []string{"Name", "Labels", "Selector", "Port"}
var statusColumns = []string{"Status"}

func (h *HumanReadablePrinter) unknown(data []byte, w io.Writer) error {
	_, err := fmt.Fprintf(w, "Unknown object: %s", string(data))
	return err
}

func (h *HumanReadablePrinter) printHeader(columnNames []string, w io.Writer) error {
	if _, err := fmt.Fprintf(w, "%s\n", strings.Join(columnNames, "\t")); err != nil {
		return err
	}
	var lines []string
	for _ = range columnNames {
		lines = append(lines, "----------")
	}
	_, err := fmt.Fprintf(w, "%s\n", strings.Join(lines, "\t"))
	return err
}

func (h *HumanReadablePrinter) makeImageList(manifest api.ContainerManifest) string {
	var images []string
	for _, container := range manifest.Containers {
		images = append(images, container.Image)
	}
	return strings.Join(images, ",")
}

func (h *HumanReadablePrinter) printPod(pod *api.Pod, w io.Writer) error {
	_, err := fmt.Fprintf(w, "%s\t%s\t%s\t%s\n",
		pod.ID, h.makeImageList(pod.DesiredState.Manifest), pod.CurrentState.Host+"/"+pod.CurrentState.HostIP, labels.Set(pod.Labels))
	return err
}

func (h *HumanReadablePrinter) printPodList(podList *api.PodList, w io.Writer) error {
	for _, pod := range podList.Items {
		if err := h.printPod(&pod, w); err != nil {
			return err
		}
	}
	return nil
}

func (h *HumanReadablePrinter) printReplicationController(ctrl *api.ReplicationController, w io.Writer) error {
	_, err := fmt.Fprintf(w, "%s\t%s\t%s\t%d\n",
		ctrl.ID, h.makeImageList(ctrl.DesiredState.PodTemplate.DesiredState.Manifest), labels.Set(ctrl.DesiredState.ReplicaSelector), ctrl.DesiredState.Replicas)
	return err
}

func (h *HumanReadablePrinter) printReplicationControllerList(list *api.ReplicationControllerList, w io.Writer) error {
	for _, ctrl := range list.Items {
		if err := h.printReplicationController(&ctrl, w); err != nil {
			return err
		}
	}
	return nil
}

func (h *HumanReadablePrinter) printService(svc *api.Service, w io.Writer) error {
	_, err := fmt.Fprintf(w, "%s\t%s\t%s\t%d\n", svc.ID, labels.Set(svc.Labels), labels.Set(svc.Selector), svc.Port)
	return err
}

func (h *HumanReadablePrinter) printServiceList(list *api.ServiceList, w io.Writer) error {
	for _, svc := range list.Items {
		if err := h.printService(&svc, w); err != nil {
			return err
		}
	}
	return nil
}

func (h *HumanReadablePrinter) printStatus(status *api.Status, w io.Writer) error {
	err := h.printHeader(statusColumns, w)
	if err != nil {
		return err
	}
	_, err = fmt.Fprintf(w, "%v\n", status.Status)
	return err
}

func (h *HumanReadablePrinter) Print(data []byte, output io.Writer) error {
	var mapObj map[string]interface{}
	if err := json.Unmarshal([]byte(data), &mapObj); err != nil {
		return err
	}

	if _, contains := mapObj["kind"]; !contains {
		return fmt.Errorf("unexpected object with no 'kind' field: %s", data)
	}

	obj, err := api.Decode(data)
	if err != nil {
		return err
	}
	return h.PrintObj(obj, output)
}

func (h *HumanReadablePrinter) PrintObj(obj interface{}, output io.Writer) error {
	w := tabwriter.NewWriter(output, 20, 5, 3, ' ', 0)
	defer w.Flush()
	switch o := obj.(type) {
	case *api.Pod:
		h.printHeader(podColumns, w)
		return h.printPod(o, w)
	case *api.PodList:
		h.printHeader(podColumns, w)
		return h.printPodList(o, w)
	case *api.ReplicationController:
		h.printHeader(replicationControllerColumns, w)
		return h.printReplicationController(o, w)
	case *api.ReplicationControllerList:
		h.printHeader(replicationControllerColumns, w)
		return h.printReplicationControllerList(o, w)
	case *api.Service:
		h.printHeader(serviceColumns, w)
		return h.printService(o, w)
	case *api.ServiceList:
		h.printHeader(serviceColumns, w)
		return h.printServiceList(o, w)
	case *api.Status:
		return h.printStatus(o, w)
	default:
		_, err := fmt.Fprintf(w, "Error: unknown type %#v", obj)
		return err
	}
}