cache

type Cacher interface {
	// Closer closes the cache, cleaning up any stale entries. A closed cache is
	// no longer valid and attempts to call methods should return an error or
	// (less preferred) panic.
	io.Closer

	// Fetch retrieves the named item from the cache. If the item does not exist,
	// it calls FetchFunc to create the item. If FetchFunc returns an error, the
	// error is bubbled up the stack and no value is cached. If FetchFunc
	// succeeds, the value is cached for the provided TTL.
	Fetch(context.Context, string, interface{}, time.Duration, FetchFunc) error

	// Read gets an item from the cache and reads it into the provided interface.
	// If it does not exist, it returns ErrNotFound.
	Read(context.Context, string, interface{}) error

	// Write adds an item to the cache, overwriting if it already exists, caching
	// for TTL. It returns any errors that occur on writing.
	Write(context.Context, string, interface{}, time.Duration) error

	// Delete removes an item from the cache, returning any errors that occur.
	Delete(context.Context, string) error
}

type CacherType string

type Config struct {
	Type CacherType `env:"TYPE, default=IN_MEMORY"`

	// Redis options
	RedisAddress  string `env:"REDIS_ADDRESS"`
	RedisUsername string `env:"REDIS_USERNAME"`
	RedisPassword string `env:"REDIS_PASSWORD"`
}

type FetchFunc func() (interface{}, error)

type InMemoryConfig struct {
	// KeyFunc is the key function.
	KeyFunc KeyFunc

	// GCInterval is how frequently to purge stale entries from the cache.
	GCInterval time.Duration
}

type KeyFunc func(string) (string, error)

type RedisConfig struct {
	// Address is the redis address and port. The default value is 127.0.0.1:6379.
	Address string

	// Username and Password are used for authentication.
	Username, Password string

	// KeyFunc is the key function.
	KeyFunc KeyFunc
}