/*
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.
*/

// A client for the Kubernetes cluster management API
// There are three fundamental objects
//   Task - A single running container
//   TaskForce - A set of co-scheduled Task(s)
//   ReplicationController - A manager for replicating TaskForces
package client

import (
	"bytes"
	"crypto/tls"
	"encoding/json"
	"fmt"
	"io"
	"io/ioutil"
	"log"
	"net/http"
	"net/url"
	"strings"

	"github.com/GoogleCloudPlatform/kubernetes/pkg/api"
)

// ClientInterface holds the methods for clients of Kubenetes, an interface to allow mock testing
type ClientInterface interface {
	ListTasks(labelQuery map[string]string) (api.TaskList, error)
	GetTask(name string) (api.Pod, error)
	DeleteTask(name string) error
	CreateTask(api.Pod) (api.Pod, error)
	UpdateTask(api.Pod) (api.Pod, error)

	GetReplicationController(name string) (api.ReplicationController, error)
	CreateReplicationController(api.ReplicationController) (api.ReplicationController, error)
	UpdateReplicationController(api.ReplicationController) (api.ReplicationController, error)
	DeleteReplicationController(string) error

	GetService(name string) (api.Service, error)
	CreateService(api.Service) (api.Service, error)
	UpdateService(api.Service) (api.Service, error)
	DeleteService(string) error
}

// AuthInfo is used to store authorization information
type AuthInfo struct {
	User     string
	Password string
}

// Client is the actual implementation of a Kubernetes client.
// Host is the http://... base for the URL
type Client struct {
	Host       string
	Auth       *AuthInfo
	httpClient *http.Client
}

// Underlying base implementation of performing a request.
// method is the HTTP method (e.g. "GET")
// path is the path on the host to hit
// requestBody is the body of the request. Can be nil.
// target the interface to marshal the JSON response into.  Can be nil.
func (client Client) rawRequest(method, path string, requestBody io.Reader, target interface{}) ([]byte, error) {
	request, err := http.NewRequest(method, client.makeURL(path), requestBody)
	if err != nil {
		return []byte{}, err
	}
	if client.Auth != nil {
		request.SetBasicAuth(client.Auth.User, client.Auth.Password)
	}
	tr := &http.Transport{
		TLSClientConfig: &tls.Config{InsecureSkipVerify: true},
	}
	var httpClient *http.Client
	if client.httpClient != nil {
		httpClient = client.httpClient
	} else {
		httpClient = &http.Client{Transport: tr}
	}
	response, err := httpClient.Do(request)
	if err != nil {
		return nil, err
	}
	if response.StatusCode != 200 {
		return nil, fmt.Errorf("request [%s %s] failed (%d) %s", method, client.makeURL(path), response.StatusCode, response.Status)
	}
	defer response.Body.Close()
	body, err := ioutil.ReadAll(response.Body)
	if err != nil {
		return body, err
	}
	if target != nil {
		err = json.Unmarshal(body, target)
	}
	if err != nil {
		log.Printf("Failed to parse: %s\n", string(body))
		// FIXME: no need to return err here?
	}
	return body, err
}

func (client Client) makeURL(path string) string {
	return client.Host + "/api/v1beta1/" + path
}

func EncodeLabelQuery(labelQuery map[string]string) string {
	query := make([]string, 0, len(labelQuery))
	for key, value := range labelQuery {
		query = append(query, key+"="+value)
	}
	return url.QueryEscape(strings.Join(query, ","))
}

func DecodeLabelQuery(labelQuery string) map[string]string {
	result := map[string]string{}
	if len(labelQuery) == 0 {
		return result
	}
	parts := strings.Split(labelQuery, ",")
	for _, part := range parts {
		pieces := strings.Split(part, "=")
		if len(pieces) == 2 {
			result[pieces[0]] = pieces[1]
		} else {
			log.Printf("Invalid label query: %s", labelQuery)
		}
	}
	return result
}

// ListTasks takes a label query, and returns the list of tasks that match that query
func (client Client) ListTasks(labelQuery map[string]string) (api.TaskList, error) {
	path := "tasks"
	if labelQuery != nil && len(labelQuery) > 0 {
		path += "?labels=" + EncodeLabelQuery(labelQuery)
	}
	var result api.TaskList
	_, err := client.rawRequest("GET", path, nil, &result)
	return result, err
}

// GetTask takes the name of the task, and returns the corresponding Task object, and an error if it occurs
func (client Client) GetTask(name string) (api.Pod, error) {
	var result api.Pod
	_, err := client.rawRequest("GET", "tasks/"+name, nil, &result)
	return result, err
}

// DeleteTask takes the name of the task, and returns an error if one occurs
func (client Client) DeleteTask(name string) error {
	_, err := client.rawRequest("DELETE", "tasks/"+name, nil, nil)
	return err
}

// CreateTask takes the representation of a task.  Returns the server's representation of the task, and an error, if it occurs
func (client Client) CreateTask(task api.Pod) (api.Pod, error) {
	var result api.Pod
	body, err := json.Marshal(task)
	if err == nil {
		_, err = client.rawRequest("POST", "tasks", bytes.NewBuffer(body), &result)
	}
	return result, err
}

// UpdateTask takes the representation of a task to update.  Returns the server's representation of the task, and an error, if it occurs
func (client Client) UpdateTask(task api.Pod) (api.Pod, error) {
	var result api.Pod
	body, err := json.Marshal(task)
	if err == nil {
		_, err = client.rawRequest("PUT", "tasks/"+task.ID, bytes.NewBuffer(body), &result)
	}
	return result, err
}

// GetReplicationController returns information about a particular replication controller
func (client Client) GetReplicationController(name string) (api.ReplicationController, error) {
	var result api.ReplicationController
	_, err := client.rawRequest("GET", "replicationControllers/"+name, nil, &result)
	return result, err
}

// CreateReplicationController creates a new replication controller
func (client Client) CreateReplicationController(controller api.ReplicationController) (api.ReplicationController, error) {
	var result api.ReplicationController
	body, err := json.Marshal(controller)
	if err == nil {
		_, err = client.rawRequest("POST", "replicationControllers", bytes.NewBuffer(body), &result)
	}
	return result, err
}

// UpdateReplicationController updates an existing replication controller
func (client Client) UpdateReplicationController(controller api.ReplicationController) (api.ReplicationController, error) {
	var result api.ReplicationController
	body, err := json.Marshal(controller)
	if err == nil {
		_, err = client.rawRequest("PUT", "replicationControllers/"+controller.ID, bytes.NewBuffer(body), &result)
	}
	return result, err
}

func (client Client) DeleteReplicationController(name string) error {
	_, err := client.rawRequest("DELETE", "replicationControllers/"+name, nil, nil)
	return err
}

// GetReplicationController returns information about a particular replication controller
func (client Client) GetService(name string) (api.Service, error) {
	var result api.Service
	_, err := client.rawRequest("GET", "services/"+name, nil, &result)
	return result, err
}

// CreateReplicationController creates a new replication controller
func (client Client) CreateService(svc api.Service) (api.Service, error) {
	var result api.Service
	body, err := json.Marshal(svc)
	if err == nil {
		_, err = client.rawRequest("POST", "services", bytes.NewBuffer(body), &result)
	}
	return result, err
}

// UpdateReplicationController updates an existing replication controller
func (client Client) UpdateService(svc api.Service) (api.Service, error) {
	var result api.Service
	body, err := json.Marshal(svc)
	if err == nil {
		_, err = client.rawRequest("PUT", "services/"+svc.ID, bytes.NewBuffer(body), &result)
	}
	return result, err
}

func (client Client) DeleteService(name string) error {
	_, err := client.rawRequest("DELETE", "services/"+name, nil, nil)
	return err
}