package cache

import "sync"

type Cache struct {
	mu  sync.RWMutex
	s2c map[string]string
	c2s map[string]string
}

func NewCache() *Cache {
	return &Cache{
		s2c: make(map[string]string),
		c2s: make(map[string]string),
	}
}

// Set creates or overwrites the pair a -> b and b -> a.
// It ensures any previous mappings involving a or b are removed first.
func (c *Cache) Set(serverId, channelId string) {
	c.mu.Lock()
	defer c.mu.Unlock()

	if old, ok := c.s2c[serverId]; ok && old != channelId {
		delete(c.c2s, old)
	}

	if old, ok := c.c2s[channelId]; ok && old != serverId {
		delete(c.s2c, old)
	}

	c.s2c[serverId] = channelId
	c.c2s[channelId] = serverId
}

func (c *Cache) GetByServerId(serverId string) (string, bool) {
	c.mu.RLock()
	defer c.mu.RUnlock()

	cId, ok := c.s2c[serverId]
	return cId, ok
}

func (c *Cache) GetByChannelId(channelId string) (string, bool) {
	c.mu.RLock()
	defer c.mu.RUnlock()

	sId, ok := c.c2s[channelId]
	return sId, ok
}

func (c *Cache) RemoveByServerId(serverId string) {
	c.mu.RLock()
	defer c.mu.RUnlock()

	if channelId, ok := c.s2c[serverId]; ok {
		delete(c.s2c, serverId)
		delete(c.c2s, channelId)
	}
}

func (c *Cache) RemoveByChannelId(channelId string) {
	c.mu.RLock()
	defer c.mu.RUnlock()

	if serverId, ok := c.s2c[channelId]; ok {
		delete(c.c2s, channelId)
		delete(c.s2c, serverId)
	}
}