package main

import (
	"fmt"
	"strings"

	"github.com/prometheus/client_golang/prometheus"
	"github.com/prometheus/client_golang/prometheus/promauto"
)

func (id CartId) String() string {
	return strings.Trim(string(id[:]), "\x00")
}

type CartIdPayload struct {
	Id   CartId
	Data []byte
}

func MakeCartInnerFrame(id CartId, payload []byte) []byte {
	if payload == nil {
		return id[:]
	}
	return append(id[:], payload...)
}

func GetCartFrame(data []byte) (*CartIdPayload, error) {
	if len(data) < 16 {
		return nil, fmt.Errorf("data too short")
	}
	return &CartIdPayload{
		Id:   CartId(data[:16]),
		Data: data[16:],
	}, nil
}

func ToCartId(id string) CartId {
	var result [16]byte
	copy(result[:], []byte(id))
	return result
}

type RemoteGrain struct {
	*Connection
	Id   CartId
	Host string
}

func NewRemoteGrain(id CartId, host string) (*RemoteGrain, error) {
	return &RemoteGrain{
		Id:         id,
		Host:       host,
		Connection: NewConnection(fmt.Sprintf("%s:1337", host)),
	}, nil
}

var (
	remoteCartLatency = promauto.NewCounter(prometheus.CounterOpts{
		Name: "cart_remote_grain_calls_total_latency",
		Help: "The total latency of remote grains",
	})
	remoteCartCallsTotal = promauto.NewCounter(prometheus.CounterOpts{
		Name: "cart_remote_grain_calls_total",
		Help: "The total number of calls to remote grains",
	})
)

// var start time.Time

// func MeasureLatency(fn func() (*CallResult, error)) (*CallResult, error) {
// 	start = time.Now()
// 	data, err := fn()
// 	if err != nil {
// 		return data, err
// 	}
// 	elapsed := time.Since(start).Milliseconds()
// 	go func() {
// 		remoteCartLatency.Add(float64(elapsed))
// 		remoteCartCallsTotal.Inc()
// 	}()
// 	return data, nil
// }

func (g *RemoteGrain) HandleMessage(message *Message, isReplay bool) (*FrameWithPayload, error) {

	data, err := GetData(message.Write)
	if err != nil {
		return nil, err
	}
	return g.Call(RemoteHandleMutation, MakeCartInnerFrame(g.Id, data))
}

func (g *RemoteGrain) GetId() CartId {
	return g.Id
}

func (g *RemoteGrain) GetCurrentState() (*FrameWithPayload, error) {
	return g.Call(RemoteGetState, MakeCartInnerFrame(g.Id, nil))
}