package store

import (
	"context"
	"crypto/rand"
	"encoding/hex"
	"fmt"
	"time"

	"github.com/redis/go-redis/v9"
)

// TTL is how long any stored file lives in Redis before automatic deletion.
const TTL = 2 * time.Hour

type Store struct {
	rdb *redis.Client
}

func New(addr string) (*Store, error) {
	rdb := redis.NewClient(&redis.Options{Addr: addr})
	if err := rdb.Ping(context.Background()).Err(); err != nil {
		return nil, fmt.Errorf("redis connect %s: %w", addr, err)
	}
	return &Store{rdb: rdb}, nil
}

// Set stores binary data under key with the global TTL.
func (s *Store) Set(ctx context.Context, key string, data []byte) error {
	return s.rdb.Set(ctx, key, data, TTL).Err()
}

// Get retrieves binary data by key.
func (s *Store) Get(ctx context.Context, key string) ([]byte, error) {
	return s.rdb.Get(ctx, key).Bytes()
}

// Delete removes a key immediately (called after download).
func (s *Store) Delete(ctx context.Context, key string) {
	s.rdb.Del(ctx, key)
}

// NewID generates a random hex ID for use as a Redis key suffix.
func NewID() string {
	b := make([]byte, 16)
	rand.Read(b)
	return hex.EncodeToString(b)
}