package noise

import (
	"net"
	"sync"
	"time"

	"github.com/xtls/xray-core/common/crypto"
)

type noiseConn struct {
	net.PacketConn
	config *Config
	m      map[string]time.Time
	stop   chan struct{}
	once   sync.Once
	mutex  sync.RWMutex
}

func NewConnClient(c *Config, raw net.PacketConn) (net.PacketConn, error) {
	conn := &noiseConn{
		PacketConn: raw,
		config:     c,
		m:          make(map[string]time.Time),
		stop:       make(chan struct{}),
	}

	if conn.config.ResetMax > 0 {
		go conn.reset()
	}

	return conn, nil
}

func NewConnServer(c *Config, raw net.PacketConn) (net.PacketConn, error) {
	return NewConnClient(c, raw)
}

func (c *noiseConn) reset() {
	ticker := time.NewTicker(1 * time.Second)
	defer ticker.Stop()
	for {
		select {
		case <-ticker.C:
			c.mutex.RLock()
			now := time.Now()
			timeOut := make([]string, 0, len(c.m))
			for key, last := range c.m {
				if now.After(last) {
					timeOut = append(timeOut, key)
				}
			}
			c.mutex.RUnlock()

			for _, key := range timeOut {
				c.mutex.Lock()
				delete(c.m, key)
				c.mutex.Unlock()
			}
		case <-c.stop:
			return
		}
	}
}

func (c *noiseConn) WriteTo(p []byte, addr net.Addr) (n int, err error) {
	c.mutex.RLock()
	_, ready := c.m[addr.String()]
	c.mutex.RUnlock()

	if !ready {
		c.mutex.Lock()
		_, ready = c.m[addr.String()]
		if !ready {
			for _, item := range c.config.Items {
				if item.RandMax > 0 {
					item.Packet = make([]byte, crypto.RandBetween(item.RandMin, item.RandMax))
					crypto.RandBytesBetween(item.Packet, byte(item.RandRangeMin), byte(item.RandRangeMax))
				}
				c.PacketConn.WriteTo(item.Packet, addr)
				time.Sleep(time.Duration(crypto.RandBetween(item.DelayMin, item.DelayMax)) * time.Millisecond)
			}
			c.m[addr.String()] = time.Now().Add(time.Duration(crypto.RandBetween(c.config.ResetMin, c.config.ResetMax)) * time.Second)
		}
		c.mutex.Unlock()
	}

	return c.PacketConn.WriteTo(p, addr)
}

func (c *noiseConn) Close() error {
	c.once.Do(func() {
		close(c.stop)
	})
	return c.PacketConn.Close()
}