package smartconfig

import (
	"context"
	"fmt"
	"os"
	"strings"
	"time"

	clientv3 "go.etcd.io/etcd/client/v3"
)

// EtcdResolver retrieves values from etcd.
// Usage: ${ETCD:/myapp/config/key}
// Requires ETCD_ENDPOINTS environment variable or defaults to localhost:2379
type EtcdResolver struct{}

// Resolve retrieves the value from etcd.
func (r *EtcdResolver) Resolve(value string) (string, error) {
	// Default to localhost:2379 if ETCD_ENDPOINTS is not set
	endpoints := strings.Split(os.Getenv("ETCD_ENDPOINTS"), ",")
	if len(endpoints) == 1 && endpoints[0] == "" {
		endpoints = []string{"localhost:2379"}
	}

	cli, err := clientv3.New(clientv3.Config{
		Endpoints:   endpoints,
		DialTimeout: 5 * time.Second,
	})
	if err != nil {
		return "", fmt.Errorf("failed to create etcd client: %w", err)
	}
	defer func() {
		_ = cli.Close()
	}()

	ctx, cancel := context.WithTimeout(context.Background(), 5*time.Second)
	defer cancel()

	resp, err := cli.Get(ctx, value)
	if err != nil {
		return "", fmt.Errorf("failed to get key %s from etcd: %w", value, err)
	}

	if len(resp.Kvs) == 0 {
		return "", fmt.Errorf("key %s not found in etcd", value)
	}

	return string(resp.Kvs[0].Value), nil
}