package main

import (
	"fmt"
	"sync"
	"time"
)
type Item struct {
	Value any
	ExpiresAt *time.Time
}

type RedisDB struct {
	mu   sync.Mutex
	shards []*Shard
}

type SimpleString string

func (db *RedisDB) Execute(key string, fn func(*Shard) interface{}) interface{} {
    shard := db.getShard(key)
    shard.mu.Lock()
    defer shard.mu.Unlock()
    return fn(shard)
}

func serializeRESP(v any) []byte {
    switch val := v.(type) {
    case string:
		bulkString := fmt.Sprintf("$%d\r\n%s\r\n", len(val), val)
        return []byte(bulkString)
    case int:
		integerString := fmt.Sprintf(":%d\r\n",val)
        return []byte(integerString)
    case nil:
		return []byte("$-1\r\n")
    case error:
        errorString := fmt.Sprintf("-ERR %s\r\n",val.Error())
		return []byte(errorString)
    case []string:
        size := len(val)
		result := []byte(fmt.Sprintf("*%d\r\n", size))
		for i := 0; i < size; i++ {
			result = append(result, serializeRESP(val[i])...)
		}
		return result
	case map[string]string:
		size := len(val)
		result := []byte(fmt.Sprintf("*%d\r\n", size*2))
		for key, value := range val {
			result = append(result, serializeRESP(key)...)
			result = append(result, serializeRESP(value)...)
		}
		return result
	case SimpleString:
		simpleStr := fmt.Sprintf("+%s\r\n", val)
		return []byte(simpleStr)
    default:
        return []byte("-ERR internal server error: unknown type\r\n")
    }
}