package storage

import (
	"context"
	"encoding/json"
	"errors"
	"fmt"
	"time"

	"github.com/spf13/viper"
	clientv3 "go.etcd.io/etcd/client/v3"
	"go.etcd.io/etcd/client/v3/namespace"
)

type EtcdKVStore struct {
	Client *clientv3.Client
}

func NewEtcdKVStore(cfg *viper.Viper) (EtcdKVStore, error) {
	var (
		endpoints = cfg.GetStringSlice("storage.kv.etcd.endpoints")
		prefix    = cfg.GetString("storage.kv.etcd.prefix")
	)

	cli, err := clientv3.New(clientv3.Config{
		Endpoints:   endpoints,
		DialTimeout: 5 * time.Second,
	})
	if err != nil {
		return EtcdKVStore{}, err
	}

	cli.KV = namespace.NewKV(cli.KV, prefix)
	cli.Watcher = namespace.NewWatcher(cli.Watcher, prefix)
	cli.Lease = namespace.NewLease(cli.Lease, prefix)

	return EtcdKVStore{
		Client: cli,
	}, nil
}

func (s EtcdKVStore) Put(k string, v any) error {
	data, err := json.Marshal(v)
	if err != nil {
		return err
	}
	ctx, cancel := context.WithTimeout(context.Background(), 5*time.Second)
	_, err = s.Client.KV.Put(ctx, k, string(data))
	cancel()
	if err != nil {
		return err
	}
	return nil
}

func (s EtcdKVStore) PutWithTTL(k string, v any, duration time.Duration) error {
	lease, err := s.Client.Lease.Grant(context.TODO(), int64(duration.Seconds()))
	if err != nil {
		return err
	}

	data, err := json.Marshal(v)
	if err != nil {
		return err
	}
	ctx, cancel := context.WithTimeout(context.Background(), 5*time.Second)
	_, err = s.Client.KV.Put(ctx, k, string(data), clientv3.WithLease(lease.ID))
	cancel()
	if err != nil {
		return err
	}
	return nil
}

func (s EtcdKVStore) Get(k string) (any, error) {
	ctx, cancel := context.WithTimeout(context.Background(), 5*time.Second)
	resp, err := s.Client.KV.Get(ctx, k)
	cancel()
	if err != nil {
		return nil, err
	}
	for _, v := range resp.Kvs {
		var data any
		err := json.Unmarshal([]byte(v.Value), &data)
		if err != nil {
			return nil, err
		}
		// We return directly as we want to last revision of value
		return data, nil
	}
	return nil, errors.New(fmt.Sprintf("no value %v", k))
}

func (s EtcdKVStore) Delete(k string) error {
	ctx, cancel := context.WithTimeout(context.Background(), 5*time.Second)
	_, err := s.Client.KV.Delete(ctx, k)
	cancel()
	if err != nil {
		return err
	}
	return nil
}