/*
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 (
	"fmt"
	"strconv"
	"strings"
	"sync"
	"time"

	"github.com/GoogleCloudPlatform/kubernetes/pkg/api"
	"github.com/GoogleCloudPlatform/kubernetes/pkg/kubelet/dockertools"
	"github.com/GoogleCloudPlatform/kubernetes/pkg/probe"
	execprobe "github.com/GoogleCloudPlatform/kubernetes/pkg/probe/exec"
	httprobe "github.com/GoogleCloudPlatform/kubernetes/pkg/probe/http"
	tcprobe "github.com/GoogleCloudPlatform/kubernetes/pkg/probe/tcp"
	"github.com/GoogleCloudPlatform/kubernetes/pkg/util"
	"github.com/GoogleCloudPlatform/kubernetes/pkg/util/exec"
	"github.com/fsouza/go-dockerclient"

	"github.com/golang/glog"
)

const maxProbeRetries = 3

// probeContainer probes the liveness/readiness of the given container.
// If the container's liveness probe is unsuccessful, set readiness to false.
// If liveness is successful, do a readiness check and set readiness accordingly.
func (kl *Kubelet) probeContainer(pod *api.Pod, status api.PodStatus, container api.Container, dockerContainer *docker.APIContainers) (probe.Result, error) {
	// Probe liveness.
	live, err := kl.probeContainerLiveness(pod, status, container, dockerContainer)
	if err != nil {
		glog.V(1).Infof("Liveness probe errored: %v", err)
		kl.readiness.set(dockerContainer.ID, false)
		return probe.Unknown, err
	}
	if live != probe.Success {
		glog.V(1).Infof("Liveness probe unsuccessful: %v", live)
		kl.readiness.set(dockerContainer.ID, false)
		return live, nil
	}

	// Probe readiness.
	ready, err := kl.probeContainerReadiness(pod, status, container, dockerContainer)
	if err == nil && ready == probe.Success {
		glog.V(3).Infof("Readiness probe successful: %v", ready)
		kl.readiness.set(dockerContainer.ID, true)
		return probe.Success, nil
	}

	glog.V(1).Infof("Readiness probe failed/errored: %v, %v", ready, err)
	kl.readiness.set(dockerContainer.ID, false)

	containerID := dockertools.DockerID(dockerContainer.ID)
	ref, ok := kl.getRef(containerID)
	if !ok {
		glog.Warningf("No ref for pod '%v' - '%v'", containerID, container.Name)
	} else {
		kl.recorder.Eventf(ref, "unhealthy", "Liveness Probe Failed %v - %v", containerID, container.Name)
	}
	return ready, err
}

// probeContainerLiveness probes the liveness of a container.
// If the initalDelay since container creation on liveness probe has not passed the probe will return probe.Success.
func (kl *Kubelet) probeContainerLiveness(pod *api.Pod, status api.PodStatus, container api.Container, dockerContainer *docker.APIContainers) (probe.Result, error) {
	p := container.LivenessProbe
	if p == nil {
		return probe.Success, nil
	}
	if time.Now().Unix()-dockerContainer.Created < p.InitialDelaySeconds {
		return probe.Success, nil
	}
	return kl.runProbeWithRetries(p, pod, status, container, maxProbeRetries)
}

// probeContainerLiveness probes the readiness of a container.
// If the initial delay on the readiness probe has not passed the probe will return probe.Failure.
func (kl *Kubelet) probeContainerReadiness(pod *api.Pod, status api.PodStatus, container api.Container, dockerContainer *docker.APIContainers) (probe.Result, error) {
	p := container.ReadinessProbe
	if p == nil {
		return probe.Success, nil
	}
	if time.Now().Unix()-dockerContainer.Created < p.InitialDelaySeconds {
		return probe.Failure, nil
	}
	return kl.runProbeWithRetries(p, pod, status, container, maxProbeRetries)
}

// runProbeWithRetries tries to probe the container in a finite loop, it returns the last result
// if it never succeeds.
func (kl *Kubelet) runProbeWithRetries(p *api.Probe, pod *api.Pod, status api.PodStatus, container api.Container, retires int) (probe.Result, error) {
	var err error
	var result probe.Result
	for i := 0; i < retires; i++ {
		result, err = kl.runProbe(p, pod, status, container)
		if result == probe.Success {
			return probe.Success, nil
		}
	}
	return result, err
}

func (kl *Kubelet) runProbe(p *api.Probe, pod *api.Pod, status api.PodStatus, container api.Container) (probe.Result, error) {
	timeout := time.Duration(p.TimeoutSeconds) * time.Second
	if p.Exec != nil {
		return kl.prober.exec.Probe(kl.newExecInContainer(pod, container))
	}
	if p.HTTPGet != nil {
		port, err := extractPort(p.HTTPGet.Port, container)
		if err != nil {
			return probe.Unknown, err
		}
		host, port, path := extractGetParams(p.HTTPGet, status, port)
		return kl.prober.http.Probe(host, port, path, timeout)
	}
	if p.TCPSocket != nil {
		port, err := extractPort(p.TCPSocket.Port, container)
		if err != nil {
			return probe.Unknown, err
		}
		return kl.prober.tcp.Probe(status.PodIP, port, timeout)
	}
	glog.Warningf("Failed to find probe builder for %s %+v", container.Name, container.LivenessProbe)
	return probe.Unknown, nil
}

func extractGetParams(action *api.HTTPGetAction, status api.PodStatus, port int) (string, int, string) {
	host := action.Host
	if host == "" {
		host = status.PodIP
	}
	return host, port, action.Path
}

func extractPort(param util.IntOrString, container api.Container) (int, error) {
	port := -1
	var err error
	switch param.Kind {
	case util.IntstrInt:
		port := param.IntVal
		if port > 0 && port < 65536 {
			return port, nil
		}
		return port, fmt.Errorf("invalid port number: %v", port)
	case util.IntstrString:
		port = findPortByName(container, param.StrVal)
		if port == -1 {
			// Last ditch effort - maybe it was an int stored as string?
			if port, err = strconv.Atoi(param.StrVal); err != nil {
				return port, err
			}
		}
		if port > 0 && port < 65536 {
			return port, nil
		}
		return port, fmt.Errorf("invalid port number: %v", port)
	default:
		return port, fmt.Errorf("IntOrString had no kind: %+v", param)
	}
}

// findPortByName is a helper function to look up a port in a container by name.
// Returns the HostPort if found, -1 if not found.
func findPortByName(container api.Container, portName string) int {
	for _, port := range container.Ports {
		if port.Name == portName {
			return port.HostPort
		}
	}
	return -1
}

type execInContainer struct {
	run func() ([]byte, error)
}

func (kl *Kubelet) newExecInContainer(pod *api.Pod, container api.Container) exec.Cmd {
	uid := pod.UID
	podFullName := GetPodFullName(pod)
	return execInContainer{func() ([]byte, error) {
		return kl.RunInContainer(podFullName, uid, container.Name, container.LivenessProbe.Exec.Command)
	}}
}

func (eic execInContainer) CombinedOutput() ([]byte, error) {
	return eic.run()
}

func (eic execInContainer) SetDir(dir string) {
	//unimplemented
}

// This will eventually maintain info about probe results over time
// to allow for implementation of health thresholds
func newReadinessStates() *readinessStates {
	return &readinessStates{states: make(map[string]bool)}
}

type readinessStates struct {
	// guards states
	sync.RWMutex
	states map[string]bool
}

func (r *readinessStates) IsReady(c api.ContainerStatus) bool {
	if c.State.Running == nil {
		return false
	}
	return r.get(strings.TrimPrefix(c.ContainerID, "docker://"))
}

func (r *readinessStates) get(key string) bool {
	r.RLock()
	defer r.RUnlock()
	state, found := r.states[key]
	return state && found
}

func (r *readinessStates) set(key string, value bool) {
	r.Lock()
	defer r.Unlock()
	r.states[key] = value
}

func (r *readinessStates) remove(key string) {
	r.Lock()
	defer r.Unlock()
	delete(r.states, key)
}

func newProbeHolder() probeHolder {
	return probeHolder{
		exec: execprobe.New(),
		http: httprobe.New(),
		tcp:  tcprobe.New(),
	}
}

type probeHolder struct {
	exec execprobe.ExecProber
	http httprobe.HTTPProber
	tcp  tcprobe.TCPProber
}