package store

import (
	"errors"
	"time"
)

// ErrNotFound is returned when a key is not found in the store.
var ErrNotFound = errors.New("key not found")

// Message is the struct for received pub/sub messages.
type Message struct {
	Channel string
	Payload []byte
}

// Subscription represents an active subscription to a pub/sub channel.
type Subscription interface {
	Channel() <-chan *Message
	Close() error
}

// Pipeliner defines an interface for executing a batch of commands.
type Pipeliner interface {
	// General
	Del(keys ...string)
	Expire(key string, expiration time.Duration)

	// HASH
	HSet(key string, values map[string]any)
	HIncrBy(key, field string, incr int64)

	// SET
	SAdd(key string, members ...any)
	SRem(key string, members ...any)

	// LIST
	LPush(key string, values ...any)
	LRem(key string, count int64, value any)

	// Execution
	Exec() error
}

// Store is the master interface for our cache service.
type Store interface {
	// Basic K/V operations
	Set(key string, value []byte, ttl time.Duration) error
	Get(key string) ([]byte, error)
	Del(keys ...string) error
	Exists(key string) (bool, error)
	SetNX(key string, value []byte, ttl time.Duration) (bool, error)

	// HASH operations
	HSet(key string, values map[string]any) error
	HGetAll(key string) (map[string]string, error)
	HIncrBy(key, field string, incr int64) (int64, error)
	HDel(key string, fields ...string) error // [新增]

	// LIST operations
	LPush(key string, values ...any) error
	LRem(key string, count int64, value any) error
	Rotate(key string) (string, error)
	LIndex(key string, index int64) (string, error)

	// SET operations
	SAdd(key string, members ...any) error
	SPopN(key string, count int64) ([]string, error)
	SMembers(key string) ([]string, error)
	SRem(key string, members ...any) error
	SRandMember(key string) (string, error)

	// Pub/Sub operations
	Publish(channel string, message []byte) error
	Subscribe(channel string) (Subscription, error)

	// Pipeline (optional) - 我们在redis实现它，内存版暂时不实现
	Pipeline() Pipeliner

	// Close closes the store and releases any underlying resources.
	Close() error

	// === 新增方法，支持轮询策略 ===
	ZAdd(key string, members map[string]float64) error
	ZRange(key string, start, stop int64) ([]string, error)
	ZRem(key string, members ...any) error
	PopAndCycleSetMember(mainKey, cooldownKey string) (string, error)
}