package resource

import (
	"bufio"
	"context"
	"fmt"
	"strconv"
	"time"

	"github.com/derailed/k9s/internal/k8s"
	"github.com/rs/zerolog/log"
	v1 "k8s.io/api/core/v1"
)

const (
	defaultTimeout = 1 * time.Second
)

type (
	// Container represents a resource that encompass multiple containers.
	Container interface {
		Containers(path string, includeInit bool) ([]string, error)
	}

	// Tailable represents a resource with tailable logs.
	Tailable interface {
		Logs(c chan<- string, ns, na, co string, lines int64, prev bool) (context.CancelFunc, error)
	}

	// TailableResource is a resource that have tailable logs.
	TailableResource interface {
		Resource
		Tailable
	}

	// Pod that can be displayed in a table and interacted with.
	Pod struct {
		*Base
		instance      *v1.Pod
		MetricsServer MetricsServer
		metrics       k8s.PodMetrics
	}
)

// NewPodList returns a new resource list.
func NewPodList(c Connection, mx MetricsServer, ns string) List {
	return NewList(
		ns,
		"po",
		NewPod(c, mx),
		AllVerbsAccess|DescribeAccess,
	)
}

// NewPod instantiates a new Pod.
func NewPod(c Connection, mx MetricsServer) *Pod {
	p := &Pod{&Base{Connection: c, Resource: k8s.NewPod(c)}, nil, mx, k8s.PodMetrics{}}
	p.Factory = p

	return p
}

// New builds a new Pod instance from a k8s resource.
func (r *Pod) New(i interface{}) Columnar {
	c := NewPod(r.Connection, r.MetricsServer)
	switch instance := i.(type) {
	case *v1.Pod:
		c.instance = instance
	case v1.Pod:
		c.instance = &instance
	case *interface{}:
		ptr := *instance
		po := ptr.(v1.Pod)
		c.instance = &po
	default:
		log.Fatal().Msgf("unknown Pod type %#v", i)
	}
	c.path = c.namespacedName(c.instance.ObjectMeta)

	return c
}

// Metrics retrieves cpu/mem resource consumption on a pod.
func (r *Pod) Metrics() k8s.PodMetrics {
	return r.metrics
}

// SetMetrics set the current k8s resource metrics on a given pod.
func (r *Pod) SetMetrics(m k8s.PodMetrics) {
	r.metrics = m
}

// Marshal resource to yaml.
func (r *Pod) Marshal(path string) (string, error) {
	ns, n := namespaced(path)
	i, err := r.Resource.Get(ns, n)
	if err != nil {
		return "", err
	}

	po := i.(*v1.Pod)
	po.TypeMeta.APIVersion = "v1"
	po.TypeMeta.Kind = "Pod"

	return r.marshalObject(po)
}

// Containers lists out all the docker contrainers name contained in a pod.
func (r *Pod) Containers(path string, includeInit bool) ([]string, error) {
	ns, po := namespaced(path)

	return r.Resource.(k8s.Loggable).Containers(ns, po, includeInit)
}

// Logs tails a given container logs
func (r *Pod) Logs(c chan<- string, ns, n, co string, lines int64, prev bool) (context.CancelFunc, error) {
	req := r.Resource.(k8s.Loggable).Logs(ns, n, co, lines, prev)
	ctx, cancel := context.WithCancel(context.TODO())
	req.Context(ctx)

	blocked := true
	go func() {
		select {
		case <-time.After(defaultTimeout):
			if blocked {
				close(c)
				cancel()
			}
		}
	}()
	// This call will block if nothing is in the stream!!
	stream, err := req.Stream()
	blocked = false
	if err != nil {
		log.Error().Msgf("Tail logs failed `%s/%s:%s -- %v", ns, n, co, err)
		return cancel, fmt.Errorf("%v", err)
	}

	go func() {
		defer func() {
			stream.Close()
			cancel()
			close(c)
		}()

		scanner := bufio.NewScanner(stream)
		for scanner.Scan() {
			c <- scanner.Text()
		}
	}()

	return cancel, nil
}

// List resources for a given namespace.
func (r *Pod) List(ns string) (Columnars, error) {
	pods, err := r.Resource.List(ns)
	if err != nil {
		return nil, err
	}

	mx := make(k8s.PodsMetrics, len(pods))
	if r.MetricsServer.HasMetrics() {
		pmx, _ := r.MetricsServer.FetchPodsMetrics(ns)
		r.MetricsServer.PodsMetrics(pmx, mx)
	}

	cc := make(Columnars, 0, len(pods))
	for i := range pods {
		po := r.New(&pods[i]).(*Pod)
		if err == nil {
			po.metrics = mx[po.Name()]
		}
		cc = append(cc, po)
	}

	return cc, nil
}

// Header return resource header.
func (*Pod) Header(ns string) Row {
	hh := Row{}
	if ns == AllNamespaces {
		hh = append(hh, "NAMESPACE")
	}
	return append(hh,
		"NAME",
		"READY",
		"STATUS",
		"RS",
		"CPU",
		"MEM",
		"IP",
		"NODE",
		"QOS",
		"AGE",
	)
}

// Fields retrieves displayable fields.
func (r *Pod) Fields(ns string) Row {
	ff := make(Row, 0, len(r.Header(ns)))
	i := r.instance

	if ns == AllNamespaces {
		ff = append(ff, i.Namespace)
	}

	ss := i.Status.ContainerStatuses
	cr, _, rc := r.statuses(ss)

	return append(ff,
		i.ObjectMeta.Name,
		strconv.Itoa(cr)+"/"+strconv.Itoa(len(ss)),
		r.phase(i.Status),
		strconv.Itoa(rc),
		ToMillicore(r.metrics.CurrentCPU),
		ToMi(r.metrics.CurrentMEM),
		i.Status.PodIP,
		i.Spec.NodeName,
		r.mapQOS(i.Status.QOSClass),
		toAge(i.ObjectMeta.CreationTimestamp),
	)
}

// ----------------------------------------------------------------------------
// Helpers...

func (*Pod) mapQOS(class v1.PodQOSClass) string {
	switch class {
	case v1.PodQOSGuaranteed:
		return "GA"
	case v1.PodQOSBurstable:
		return "BU"
	default:
		return "BE"
	}
}

func (r *Pod) statuses(ss []v1.ContainerStatus) (cr, ct, rc int) {
	for _, c := range ss {
		if c.State.Terminated != nil {
			ct++
		}
		if c.Ready {
			cr = cr + 1
		}
		rc += int(c.RestartCount)
	}

	return
}

func (*Pod) phase(s v1.PodStatus) string {
	status := "Pending"
	for _, cs := range s.ContainerStatuses {
		switch {
		case cs.State.Running != nil:
			status = "Running"
		case cs.State.Waiting != nil:
			status = cs.State.Waiting.Reason
		case cs.State.Terminated != nil:
			status = "Terminating"
			if len(cs.State.Terminated.Reason) != 0 {
				status = cs.State.Terminated.Reason
			}
		}
	}

	return status
}