package storage

import (
	"context"
	"encoding/base64"
	"encoding/json"
	"errors"
	"fmt"
	"log"
	"net/http"
	"time"

	"github.com/mailgun/groupcache/v2"
	"github.com/spf13/viper"
)

type EtcdGroupCacheHandler struct {
	EtcdHandler *EtcdHandler
	Group       *groupcache.Group
}

func NewEtcdGroupCacheHandler(cfg *viper.Viper) (*EtcdGroupCacheHandler, error) {
	var endpoint = cfg.GetString("storage.kv.groupcache.endpoint")
	etcdHandler, err := NewEtcdHandler(cfg)
	if err != nil {
		return nil, err
	}
	pool := groupcache.NewHTTPPoolOpts("http://"+endpoint, &groupcache.HTTPPoolOptions{})
	server := http.Server{
		Addr:    endpoint,
		Handler: pool,
	}
	go func() {
		log.Printf("Serving....\n")
		if err := server.ListenAndServe(); err != nil {
			log.Fatal(err)
		}
	}()
	group := groupcache.NewGroup("data", 3000000, groupcache.GetterFunc(
		func(ctx context.Context, key string, dest groupcache.Sink) error {

			resp, err := etcdHandler.Get(key)
			if err != nil {
				return err
			}
			if resp == nil {
				return errors.New("key not found in ETCD")
			}
			decoded, err := base64.StdEncoding.DecodeString(resp.(string))
			if err != nil {
				return fmt.Errorf("failed to decode value for key %s: %v", key, err)
			}
			dest.SetString(string(decoded), time.Now().Add(time.Minute*5))
			return nil
		},
	))

	return &EtcdGroupCacheHandler{
		EtcdHandler: etcdHandler,
		Group:       group,
	}, nil
}

func (h *EtcdGroupCacheHandler) Put(k string, v interface{}) error {
	value, err := json.Marshal(v)
	if err != nil {
		return err
	}
	return h.EtcdHandler.Put(k, value)
}

func (h *EtcdGroupCacheHandler) PutWithTTL(k string, v interface{}, duration time.Duration) error {
	value, err := json.Marshal(v)
	if err != nil {
		return err
	}
	return h.EtcdHandler.PutWithTTL(k, value, duration)
}

func (h *EtcdGroupCacheHandler) Get(k string) (interface{}, error) {
	var value []byte
	err := h.Group.Get(nil, k, groupcache.AllocatingByteSliceSink(&value))
	if err != nil {
		return nil, err
	}
	return value, nil
}

func (h *EtcdGroupCacheHandler) Delete(k string) error {
	err := h.EtcdHandler.Delete(k)
	if err != nil {
		return err
	}
	err = h.Group.Remove(context.Background(), k)
	if err != nil {
		return err
	}
	return nil
}