/*
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 kubelet

import (
	"encoding/json"
	"errors"
	"fmt"
	"io"
	"io/ioutil"
	"net"
	"net/http"
	"net/url"
	"path"
	"strconv"
	"strings"
	"time"

	"github.com/GoogleCloudPlatform/kubernetes/pkg/api"
	"github.com/GoogleCloudPlatform/kubernetes/pkg/httplog"
	"github.com/golang/glog"
	"github.com/google/cadvisor/info"
	"gopkg.in/v1/yaml"
)

// Server is a http.Handler which exposes kubelet functionality over HTTP.
type Server struct {
	host    HostInterface
	updates chan<- interface{}
	mux     *http.ServeMux
}

// ListenAndServeKubeletServer initializes a server to respond to HTTP network requests on the Kubelet
func ListenAndServeKubeletServer(host HostInterface, updates chan<- interface{}, address string, port uint) {
	glog.Infof("Starting to listen on %s:%d", address, port)
	handler := NewServer(host, updates)
	s := &http.Server{
		Addr:           net.JoinHostPort(address, strconv.FormatUint(uint64(port), 10)),
		Handler:        &handler,
		ReadTimeout:    10 * time.Second,
		WriteTimeout:   10 * time.Second,
		MaxHeaderBytes: 1 << 20,
	}
	s.ListenAndServe()
}

// HostInterface contains all the kubelet methods required by the server.
// For testablitiy.
type HostInterface interface {
	GetContainerInfo(podFullName, containerName string, req *info.ContainerInfoRequest) (*info.ContainerInfo, error)
	GetRootInfo(req *info.ContainerInfoRequest) (*info.ContainerInfo, error)
	GetMachineInfo() (*info.MachineInfo, error)
	GetPodInfo(name string) (api.PodInfo, error)
	ServeLogs(w http.ResponseWriter, req *http.Request)
}

// NewServer initializes and configures a kubelet.Server object to handle HTTP requests
func NewServer(host HostInterface, updates chan<- interface{}) Server {
	server := Server{
		host:    host,
		updates: updates,
		mux:     http.NewServeMux(),
	}
	server.InstallDefaultHandlers()
	return server
}

// InstallDefaultHandlers registers the set of supported HTTP request patterns with the mux
func (s *Server) InstallDefaultHandlers() {
	s.mux.HandleFunc("/healthz", s.handleHealth)
	s.mux.HandleFunc("/container", s.handleContainer)
	s.mux.HandleFunc("/containers", s.handleContainers)
	s.mux.HandleFunc("/podInfo", s.handlePodInfo)
	s.mux.HandleFunc("/stats/", s.handleStats)
	s.mux.HandleFunc("/logs/", s.handleLogs)
	s.mux.HandleFunc("/spec/", s.handleSpec)
}

// error serializes an error object into an HTTP response
func (s *Server) error(w http.ResponseWriter, err error) {
	http.Error(w, fmt.Sprintf("Internal Error: %v", err), http.StatusInternalServerError)
}

// handleHealth handles health checking requests against the Kubelet
func (s *Server) handleHealth(w http.ResponseWriter, req *http.Request) {
}

// handleContainer handles container requests against the Kubelet
func (s *Server) handleContainer(w http.ResponseWriter, req *http.Request) {
	defer req.Body.Close()
	data, err := ioutil.ReadAll(req.Body)
	if err != nil {
		s.error(w, err)
		return
	}
	// This is to provide backward compatibility. It only supports a single manifest
	var pod Pod
	err = yaml.Unmarshal(data, &pod.Manifest)
	if err != nil {
		s.error(w, err)
		return
	}
	//TODO: sha1 of manifest?
	pod.Name = "1"
	s.updates <- PodUpdate{[]Pod{pod}, SET}

}

// handleContainers handles containers requests against the Kubelet
func (s *Server) handleContainers(w http.ResponseWriter, req *http.Request) {
	defer req.Body.Close()
	data, err := ioutil.ReadAll(req.Body)
	if err != nil {
		s.error(w, err)
		return
	}
	var manifests []api.ContainerManifest
	err = yaml.Unmarshal(data, &manifests)
	if err != nil {
		s.error(w, err)
		return
	}
	pods := make([]Pod, len(manifests))
	for i := range manifests {
		pods[i].Name = fmt.Sprintf("%d", i+1)
		pods[i].Manifest = manifests[i]
	}
	s.updates <- PodUpdate{pods, SET}

}

// handlePodInfo handles podInfo requests against the Kubelet
func (s *Server) handlePodInfo(w http.ResponseWriter, req *http.Request) {
	u, err := url.ParseRequestURI(req.RequestURI)
	if err != nil {
		s.error(w, err)
		return
	}
	podID := u.Query().Get("podID")
	if len(podID) == 0 {
		w.WriteHeader(http.StatusBadRequest)
		http.Error(w, "Missing 'podID=' query entry.", http.StatusBadRequest)
		return
	}
	// TODO: backwards compatibility with existing API, needs API change
	podFullName := GetPodFullName(&Pod{Name: podID, Namespace: "etcd"})
	info, err := s.host.GetPodInfo(podFullName)
	if err == ErrNoContainersInPod {
		http.Error(w, "Pod does not exist", http.StatusNotFound)
		return
	}
	if err != nil {
		s.error(w, err)
		return
	}
	data, err := json.Marshal(info)
	if err != nil {
		s.error(w, err)
		return
	}
	w.WriteHeader(http.StatusOK)
	w.Header().Add("Content-type", "application/json")
	w.Write(data)
}

// handleStats handles stats requests against the Kubelet
func (s *Server) handleStats(w http.ResponseWriter, req *http.Request) {
	s.serveStats(w, req)
}

// handleLogs handles logs requests against the Kubelet
func (s *Server) handleLogs(w http.ResponseWriter, req *http.Request) {
	s.host.ServeLogs(w, req)
}

// handleSpec handles spec requests against the Kubelet
func (s *Server) handleSpec(w http.ResponseWriter, req *http.Request) {
	info, err := s.host.GetMachineInfo()
	if err != nil {
		s.error(w, err)
		return
	}
	data, err := json.Marshal(info)
	if err != nil {
		s.error(w, err)
		return
	}
	w.Header().Add("Content-type", "application/json")
	w.Write(data)

}

// ServeHTTP responds to HTTP requests on the Kubelet
func (s *Server) ServeHTTP(w http.ResponseWriter, req *http.Request) {
	defer httplog.MakeLogged(req, &w).StacktraceWhen(
		httplog.StatusIsNot(
			http.StatusOK,
			http.StatusNotFound,
		),
	).Log()
	s.mux.ServeHTTP(w, req)
}

// serveStats implements stats logic
func (s *Server) serveStats(w http.ResponseWriter, req *http.Request) {
	// /stats/<podfullname>/<containerName>
	components := strings.Split(strings.TrimPrefix(path.Clean(req.URL.Path), "/"), "/")
	var stats *info.ContainerInfo
	var err error
	var query info.ContainerInfoRequest
	err = json.NewDecoder(req.Body).Decode(&query)
	if err != nil && err != io.EOF {
		s.error(w, err)
		return
	}
	switch len(components) {
	case 1:
		// Machine stats
		stats, err = s.host.GetRootInfo(&query)
	case 2:
		// pod stats
		// TODO(monnand) Implement this
		errors.New("pod level status currently unimplemented")
	case 3:
		stats, err = s.host.GetContainerInfo(components[1], components[2], &query)
	default:
		http.Error(w, "unknown resource.", http.StatusNotFound)
		return
	}
	if err != nil {
		s.error(w, err)
		return
	}
	if stats == nil {
		w.WriteHeader(http.StatusOK)
		fmt.Fprint(w, "{}")
		return
	}
	data, err := json.Marshal(stats)
	if err != nil {
		s.error(w, err)
		return
	}
	w.WriteHeader(http.StatusOK)
	w.Header().Add("Content-type", "application/json")
	w.Write(data)
	return
}