/*
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/healthz"
	"github.com/GoogleCloudPlatform/kubernetes/pkg/httplog"
	"github.com/GoogleCloudPlatform/kubernetes/pkg/kubelet/dockertools"
	"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 net.IP, port uint, enableDebuggingHandlers bool) {
	glog.V(1).Infof("Starting to listen on %s:%d", address, port)
	handler := NewServer(host, updates, enableDebuggingHandlers)
	s := &http.Server{
		Addr:           net.JoinHostPort(address.String(), 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, uuid, containerName string, req *info.ContainerInfoRequest) (*info.ContainerInfo, error)
	GetRootInfo(req *info.ContainerInfoRequest) (*info.ContainerInfo, error)
	GetMachineInfo() (*info.MachineInfo, error)
	GetPodInfo(name, uuid string) (api.PodInfo, error)
	RunInContainer(name, uuid, container string, cmd []string) ([]byte, error)
	GetKubeletContainerLogs(podFullName, containerName, tail string, follow bool, stdout, stderr io.Writer) 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{}, enableDebuggingHandlers bool) Server {
	server := Server{
		host:    host,
		updates: updates,
		mux:     http.NewServeMux(),
	}
	server.InstallDefaultHandlers()
	if enableDebuggingHandlers {
		server.InstallDebuggingHandlers()
	}
	return server
}

// InstallDefaultHandlers registers the default set of supported HTTP request patterns with the mux.
func (s *Server) InstallDefaultHandlers() {
	healthz.InstallHandler(s.mux)
	s.mux.HandleFunc("/podInfo", s.handlePodInfo)
	s.mux.HandleFunc("/stats/", s.handleStats)
	s.mux.HandleFunc("/spec/", s.handleSpec)
}

// InstallDeguggingHandlers registers the HTTP request patterns that serve logs or run commands/containers
func (s *Server) InstallDebuggingHandlers() {
	// ToDo: /container, /run, and /containers aren't debugging options, should probably be handled separately
	s.mux.HandleFunc("/container", s.handleContainer)
	s.mux.HandleFunc("/containers", s.handleContainers)
	s.mux.HandleFunc("/run/", s.handleRun)

	s.mux.HandleFunc("/logs/", s.handleLogs)
	s.mux.HandleFunc("/containerLogs/", s.handleContainerLogs)
}

// 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)
}

// 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}

}

// handleContainerLogs handles containerLogs request against the Kubelet
func (s *Server) handleContainerLogs(w http.ResponseWriter, req *http.Request) {
	defer req.Body.Close()
	u, err := url.ParseRequestURI(req.RequestURI)
	if err != nil {
		s.error(w, err)
		return
	}
	parts := strings.Split(u.Path, "/")

	var podID, containerName string
	if len(parts) == 4 {
		podID = parts[2]
		containerName = parts[3]
	} else {
		http.Error(w, "Unexpected path for command running", http.StatusBadRequest)
		return
	}

	if len(podID) == 0 {
		http.Error(w, `{"message": "Missing podID."}`, http.StatusBadRequest)
		return
	}
	if len(containerName) == 0 {
		http.Error(w, `{"message": "Missing container name."}`, http.StatusBadRequest)
		return
	}

	uriValues := u.Query()
	follow, _ := strconv.ParseBool(uriValues.Get("follow"))
	tail := uriValues.Get("tail")

	podFullName := GetPodFullName(&Pod{Name: podID, Namespace: "etcd"})

	fw := FlushWriter{writer: w}
	if flusher, ok := w.(http.Flusher); ok {
		fw.flusher = flusher
	}
	w.Header().Set("Transfer-Encoding", "chunked")
	w.WriteHeader(http.StatusOK)
	err = s.host.GetKubeletContainerLogs(podFullName, containerName, tail, follow, &fw, &fw)
	if err != nil {
		s.error(w, err)
		return
	}
}

// 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")
	podUUID := u.Query().Get("UUID")
	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, podUUID)
	if err == dockertools.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)

}

// handleRun handles requests to run a command inside a container.
func (s *Server) handleRun(w http.ResponseWriter, req *http.Request) {
	u, err := url.ParseRequestURI(req.RequestURI)
	if err != nil {
		s.error(w, err)
		return
	}
	parts := strings.Split(u.Path, "/")
	var podID, uuid, container string
	if len(parts) == 4 {
		podID = parts[2]
		container = parts[3]
	} else if len(parts) == 5 {
		podID = parts[2]
		uuid = parts[3]
		container = parts[4]
	} else {
		http.Error(w, "Unexpected path for command running", http.StatusBadRequest)
		return
	}
	podFullName := GetPodFullName(&Pod{Name: podID, Namespace: "etcd"})
	command := strings.Split(u.Query().Get("cmd"), " ")
	data, err := s.host.RunInContainer(podFullName, uuid, container, command)
	if err != nil {
		s.error(w, err)
		return
	}
	w.Header().Add("Content-type", "text/plain")
	w.Write(data)
}

// ServeHTTP responds to HTTP requests on the Kubelet.
func (s *Server) ServeHTTP(w http.ResponseWriter, req *http.Request) {
	defer httplog.NewLogged(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> or /stats/<podfullname>/<uuid>/<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:
		// Backward compatibility without uuid information
		podFullName := GetPodFullName(&Pod{Name: components[1], Namespace: "etcd"})
		stats, err = s.host.GetContainerInfo(podFullName, "", components[2], &query)
	case 4:
		podFullName := GetPodFullName(&Pod{Name: components[1], Namespace: "etcd"})
		stats, err = s.host.GetContainerInfo(podFullName, components[2], 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
}