//
// icache.go
// Copyright (C) 2023 tiglog <me@tiglog.com>
//
// Distributed under terms of the MIT license.
//

package gcache

import "time"

// ExpiredCallback Callback the function when the key-value pair expires
// Note that it is executed after expiration
type ExpiredCallback func(k string, v interface{}) error

type ICache interface {
	//Set key to hold the string value. If key already holds a value, it is overwritten, regardless of its type.
	//Any previous time to live associated with the key is discarded on successful SET operation.
	//Example:
	//c.Set("demo", 1)
	//c.Set("demo", 1, WithEx(10*time.Second))
	//c.Set("demo", 1, WithEx(10*time.Second), WithNx())
	Set(k string, v interface{}, opts ...SetIOption) bool
	//Get the value of key.
	//If the key does not exist the special value nil,false is returned.
	//Example:
	//c.Get("demo") //nil, false
	//c.Set("demo", "value")
	//c.Get("demo") //"value", true
	Get(k string) (interface{}, bool)
	//GetSet Atomically sets key to value and returns the old value stored at key.
	//Returns nil,false when key not exists.
	//Example:
	//c.GetSet("demo", 1) //nil,false
	//c.GetSet("demo", 2) //1,true
	GetSet(k string, v interface{}, opts ...SetIOption) (interface{}, bool)
	//GetDel Get the value of key and delete the key.
	//This command is similar to GET, except for the fact that it also deletes the key on success.
	//Example:
	//c.Set("demo", "value")
	//c.GetDel("demo") //"value", true
	//c.GetDel("demo") //nil, false
	GetDel(k string) (interface{}, bool)
	//Del Removes the specified keys. A key is ignored if it does not exist.
	//Return the number of keys that were removed.
	//Example:
	//c.Set("demo1", "1")
	//c.Set("demo2", "1")
	//c.Del("demo1", "demo2", "demo3") //2
	Del(keys ...string) int
	//DelExpired Only delete when key expires
	//Example:
	//c.Set("demo1", "1")
	//c.Set("demo2", "1", WithEx(1*time.Second))
	//time.Sleep(1*time.Second)
	//c.DelExpired("demo1", "demo2") //true
	DelExpired(k string) bool
	//Exists Returns if key exists.
	//Return the number of exists keys.
	//Example:
	//c.Set("demo1", "1")
	//c.Set("demo2", "1")
	//c.Exists("demo1", "demo2", "demo3") //2
	Exists(keys ...string) bool
	//Expire Set a timeout on key.
	//After the timeout has expired, the key will automatically be deleted.
	//Return false if the key not exist.
	//Example:
	//c.Expire("demo", 1*time.Second) // false
	//c.Set("demo", "1")
	//c.Expire("demo", 1*time.Second) // true
	Expire(k string, d time.Duration) bool
	//ExpireAt has the same effect and semantic as Expire, but instead of specifying the number of seconds representing the TTL (time to live),
	//it takes an absolute Unix Time (seconds since January 1, 1970). A Time in the past will delete the key immediately.
	//Return false if the key not exist.
	//Example:
	//c.ExpireAt("demo", time.Now().Add(10*time.Second)) // false
	//c.Set("demo", "1")
	//c.ExpireAt("demo", time.Now().Add(10*time.Second)) // true
	ExpireAt(k string, t time.Time) bool
	//Persist Remove the existing timeout on key.
	//Return false if the key not exist.
	//Example:
	//c.Persist("demo") // false
	//c.Set("demo", "1")
	//c.Persist("demo") // true
	Persist(k string) bool
	//Ttl Returns the remaining time to live of a key that has a timeout.
	//Returns 0,false if the key does not exist or if the key exist but has no associated expire.
	//Example:
	//c.Set("demo", "1")
	//c.Ttl("demo") // 0,false
	//c.Set("demo", "1", WithEx(10*time.Second))
	//c.Ttl("demo") // 10*time.Second,true
	Ttl(k string) (time.Duration, bool)
}

type IItem interface {
	Expired() bool
	CanExpire() bool
	SetExpireAt(t time.Time)
}

type Item struct {
	v      interface{}
	expire time.Time
}

func (i *Item) Expired() bool {
	if !i.CanExpire() {
		return false
	}
	return time.Now().After(i.expire)
}

func (i *Item) CanExpire() bool {
	return !i.expire.IsZero()
}

func (i *Item) SetExpireAt(t time.Time) {
	i.expire = t
}