cachex

type Cache interface {

	// Get retrieves the value for key and deserializes into dest.
	// Returns ErrNotFound if the key does not exist.
	Get(ctx context.Context, key string, dest any) error

	// Set stores value at key with the given TTL.
	// TTL == 0 means no expiration.
	Set(ctx context.Context, key string, value any, ttl time.Duration) error

	// Del removes one or more keys.
	Del(ctx context.Context, keys ...string) error

	// Exists checks if any of the keys exist. Returns count.
	Exists(ctx context.Context, keys ...string) (int64, error)

	// Expire sets a TTL on an existing key. No-op if key doesn't exist.
	Expire(ctx context.Context, key string, ttl time.Duration) error

	// TTL returns the remaining TTL of a key.
	// Returns -1 if key has no expiration.
	// Returns -2 if key does not exist.
	TTL(ctx context.Context, key string) (time.Duration, error)

	// MGet retrieves multiple keys. dest must be *[]T or *[]any.
	// Missing keys appear as nil in the result.
	MGet(ctx context.Context, keys []string, dest any) error

	// MSet sets multiple key-value pairs with the same TTL.
	MSet(ctx context.Context, pairs map[string]any, ttl time.Duration) error

	// GetOrSet retrieves the value for key. If the key is missing, it calls
	// fn to compute the value, caches it with the given TTL, and returns it.
	// This is the standard cache penetration prevention pattern.
	GetOrSet(ctx context.Context, key string, dest any, ttl time.Duration, fn func(ctx context.Context) (any, error)) error

	// SetIfNotExist sets key=value with TTL only if key does not exist.
	// Returns true if the key was set (i.e., acquired).
	SetIfNotExist(ctx context.Context, key string, value any, ttl time.Duration) (bool, error)

	// Incr atomically increments key by 1. Creates the key with value 1 if
	// it doesn't exist. Returns the new value.
	Incr(ctx context.Context, key string) (int64, error)

	// IncrBy atomically increments key by delta. Returns the new value.
	IncrBy(ctx context.Context, key string, delta int64) (int64, error)

	// Decr atomically decrements key by 1. Returns the new value.
	Decr(ctx context.Context, key string) (int64, error)

	// Publish sends a message to a channel. Returns the number of subscribers.
	Publish(ctx context.Context, channel string, message any) (int64, error)

	// Subscribe subscribes to channels and returns a Subscription.
	// Call Subscription.Close() to stop receiving.
	Subscribe(ctx context.Context, channels ...string) (*Subscription, error)

	// HSet sets a field in a hash.
	HSet(ctx context.Context, key, field string, value any) error

	// HGet gets a field from a hash and deserializes into dest.
	// Returns ErrNotFound if the field does not exist.
	HGet(ctx context.Context, key, field string, dest any) error

	// HGetAll returns all fields of a hash as a map.
	// dest must be *map[string]any or *map[string]T.
	HGetAll(ctx context.Context, key string, dest any) error

	// HDel removes fields from a hash.
	HDel(ctx context.Context, key string, fields ...string) error

	// LPush prepends values to a list.
	LPush(ctx context.Context, key string, values ...any) error

	// RPush appends values to a list.
	RPush(ctx context.Context, key string, values ...any) error

	// LPop removes and returns the first element.
	LPop(ctx context.Context, key string, dest any) error

	// RPop removes and returns the last element.
	RPop(ctx context.Context, key string, dest any) error

	// LRange returns a range of elements from a list.
	// dest must be *[]T or *[]any.
	LRange(ctx context.Context, key string, start, stop int64, dest any) error

	// LLen returns the length of a list.
	LLen(ctx context.Context, key string) (int64, error)

	// SAdd adds members to a set.
	SAdd(ctx context.Context, key string, members ...any) error

	// SRem removes members from a set.
	SRem(ctx context.Context, key string, members ...any) error

	// SMembers returns all members of a set.
	// dest must be *[]T or *[]any.
	SMembers(ctx context.Context, key string, dest any) error

	// SIsMember checks if a value is in a set.
	SIsMember(ctx context.Context, key string, member any) (bool, error)

	// Ping verifies the cache is reachable.
	Ping(ctx context.Context) error

	// Close closes the cache connection. Idempotent.
	Close() error

	// DriverName returns the registered driver name.
	DriverName() string
}

type Config struct {
	// Driver selects the registered driver: "redis".
	Driver string `json:"driver"`

	// Addrs is the list of Redis node addresses.
	// Single-node: ["localhost:6379"]
	// Cluster:     ["node1:6379", "node2:6379", "node3:6379"]
	Addrs []string `json:"addrs"`

	// Username for AUTH (Redis 6+ ACL).
	Username string `json:"username"`

	// Password for AUTH.
	Password string `json:"password"`

	// DB selects the Redis database (0-15 for single-node; ignored in cluster).
	DB int `json:"db"`

	// MasterName enables Sentinel mode (non-empty = sentinel).
	MasterName string `json:"master_name"`

	// Cluster enables cluster mode. If true, Addrs are seed nodes.
	Cluster bool `json:"cluster"`

	// PoolSize is the max number of socket connections.
	// Default is 10 * runtime.GOMAXPROCS.
	PoolSize int `json:"pool_size"`

	// MinIdleConns is the minimum number of idle connections.
	MinIdleConns int `json:"min_idle_conns"`

	// DialTimeout is the timeout for establishing connections.
	DialTimeout time.Duration `json:"dial_timeout_ns"`

	// ReadTimeout is the timeout for socket reads.
	ReadTimeout time.Duration `json:"read_timeout_ns"`

	// WriteTimeout is the timeout for socket writes.
	WriteTimeout time.Duration `json:"write_timeout_ns"`

	// KeyPrefix is prepended to all keys (namespace isolation).
	KeyPrefix string `json:"key_prefix"`

	// TLSEnabled enables TLS.
	TLSEnabled bool `json:"tls_enabled"`

	// TLSSkipVerify skips TLS certificate verification.
	TLSSkipVerify bool `json:"tls_skip_verify"`
}

type DriverOpener func(cfg Config) (Cache, error)

type Message struct {
	Channel string
	Pattern string // non-empty if subscribed via pattern
	Payload string
}

type Subscription struct {
	// Channel receives messages from all subscribed channels.
	Channel <-chan *Message

	// internal fields (set by driver implementation)
	UnsubscribeFn func(channels ...string) error
	CloseFn       func() error
}