package network

import (
	"fmt"
	"net"
	"time"
)

const (
	udpClientReceiveBufferSize = 1024
)

// UDPClientResponseCallback 响应回调
// 参数：
// dataReader: 响应数据DataReader
type UDPClientResponseCallback func(dataReader *DataReader)

type UDPClientOption func(opt *UDPClientOptions)

func WithUDPClientRequestNonBlockCount(count int) UDPClientOption {
	return func(opt *UDPClientOptions) {
		opt.requestNonBlockCount = count
	}
}

func WithUDPClientReceiveBufferSize(receiveBufferSize int) UDPClientOption {
	return func(opt *UDPClientOptions) {
		opt.receiveBufferSize = receiveBufferSize
	}
}

func WithUDPClientWriteTimeout(timeout time.Duration) UDPClientOption {
	return func(opt *UDPClientOptions) {
		opt.writeTimeout = timeout
	}
}

func WithUDPClientReadTimeout(timeout time.Duration) UDPClientOption {
	return func(opt *UDPClientOptions) {
		opt.readTimeout = timeout
	}
}

func WithUDPClientResponseCallback(responseCallback UDPClientResponseCallback) UDPClientOption {
	return func(opt *UDPClientOptions) {
		opt.responseCallback = responseCallback
	}
}

type UDPClientOptions struct {
	// 不阻塞的请求数量，默认为阻塞
	requestNonBlockCount int

	// 默认1024字节，一般保证足够收取一个数据包
	receiveBufferSize int

	// 写超时，不设置就是阻塞写
	writeTimeout time.Duration

	// 读超时，不设置就是阻塞读
	readTimeout time.Duration

	// 响应数据回调
	responseCallback UDPClientResponseCallback
}

func NewUDPClientOptions(opts ...UDPClientOption) *UDPClientOptions {
	options := new(UDPClientOptions)

	for _, opt := range opts {
		opt(options)
	}

	if options.receiveBufferSize == 0 {
		options.receiveBufferSize = udpClientReceiveBufferSize
	}

	return options
}

type UDPClient struct {
	options     *UDPClientOptions
	conn        *net.UDPConn
	requestChan chan []byte
	doneChan    chan any
}

// Connect 建立连接
func (client *UDPClient) Connect(serverAddress string, options *UDPClientOptions) error {
	serverAddr, err := net.ResolveUDPAddr("udp", serverAddress)
	if err != nil {
		panic(err)
	}

	conn, err := net.DialUDP("udp", nil, serverAddr)
	if err != nil {
		panic(err)
	}

	client.options = options
	client.conn = conn
	client.requestChan = make(chan []byte, options.requestNonBlockCount)
	client.doneChan = make(chan any)

	// 启动发送请求协程
	go client.sendRequest()

	return nil
}

// Disconnect 断开连接
func (client *UDPClient) Disconnect() {
	client.doneChan <- nil
	close(client.doneChan)
	client.doneChan = nil

	close(client.requestChan)
	client.requestChan = nil

	closeConnection(client.conn)
	client.conn = nil
}

// Send 发送数据包，data应该为大端字节序
func (client *UDPClient) Send(data []byte) {
	client.requestChan <- data
}

func (client *UDPClient) sendRequest() {
	dealRequestDoneChannels := make([]chan any, 0)

	for {
		select {
		case <-client.doneChan:
			for _, dealRequestDoneChan := range dealRequestDoneChannels {
				dealRequestDoneChan <- nil
				close(dealRequestDoneChan)
			}

			return
		case data := <-client.requestChan:
			err := writeUDP(client.conn, data, withWriteDeadline(client.options.writeTimeout))
			if err != nil {
				fmt.Println(err)
				continue
			}

			if client.options.responseCallback != nil {
				responseBytes, _, err := readUDP(client.conn, client.options.receiveBufferSize, withReadDeadline(client.options.readTimeout))
				if err != nil {
					fmt.Println(err)
					continue
				}

				go client.options.responseCallback(NewDataReader(responseBytes))
			}
		}
	}
}