package gws

import (
	"bufio"
	"crypto/tls"
	"net"
	"net/http"
	"time"

	"github.com/klauspost/compress/flate"
	"github.com/lxzan/gws/internal"
)

const (
	defaultParallelGolimit     = 8
	defaultCompressLevel       = flate.BestSpeed
	defaultReadMaxPayloadSize  = 16 * 1024 * 1024
	defaultWriteMaxPayloadSize = 16 * 1024 * 1024
	defaultCompressThreshold   = 512
	defaultCompressorPoolSize  = 32
	defaultReadBufferSize      = 4 * 1024
	defaultWriteBufferSize     = 4 * 1024
	defaultHandshakeTimeout    = 5 * time.Second
	defaultDialTimeout         = 5 * time.Second
)

type (
	// PermessageDeflate 压缩拓展配置
	// 对于gws client, 建议开启上下文接管, 不修改滑动窗口指数, 提供最好的兼容性.
	// 对于gws server, 如果开启上下文接管, 每个连接会占用更多内存, 合理配置滑动窗口指数.
	// For gws client, it is recommended to enable contextual takeover and not modify the sliding window index to provide the best compatibility.
	// For gws server, if you turn on context-side takeover, each connection takes up more memory, configure the sliding window index appropriately.
	PermessageDeflate struct {
		// 是否开启压缩
		// Whether to turn on compression
		Enabled bool

		// 压缩级别
		// Compress level
		Level int

		// 压缩阈值, 长度小于阈值的消息不会被压缩
		// Compression threshold, messages below the threshold will not be compressed
		Threshold int

		// 压缩器内存池大小
		// 数值越大竞争的概率越小, 但是会耗费大量内存
		// Compressor memory pool size
		// The higher the value the lower the probability of competition, but it will consume a lot of memory
		PoolSize int

		// 服务端上下文接管
		// Server side context takeover
		ServerContextTakeover bool

		// 客户端上下文接管
		// Client side context takeover
		ClientContextTakeover bool

		// 服务端滑动窗口指数
		// 取值范围 8<=n<=15, 表示pow(2,n)个字节
		// The server-side sliding window index
		// Range 8<=n<=15, means pow(2,n) bytes.
		ServerMaxWindowBits int

		// 客户端滑动窗口指数
		// 取值范围 8<=x<=15, 表示pow(2,n)个字节
		// The client-side sliding window index
		// Range 8<=n<=15, means pow(2,n) bytes.
		ClientMaxWindowBits int
	}

	Config struct {
		// bufio.Reader内存池
		brPool *internal.Pool[*bufio.Reader]

		// 压缩器滑动窗口内存池
		cswPool *internal.Pool[[]byte]

		// 解压器滑动窗口内存池
		dswPool *internal.Pool[[]byte]

		// 是否开启并行消息处理
		// Whether to enable parallel message processing
		ParallelEnabled bool

		// (单个连接)用于并行消息处理的协程数量限制
		// Limit on the number of concurrent goroutine used for parallel message processing (single connection)
		ParallelGolimit int

		// 最大读取的消息内容长度
		// Maximum read message content length
		ReadMaxPayloadSize int

		// 读缓冲区的大小
		// Size of the read buffer
		ReadBufferSize int

		// 最大写入的消息内容长度
		// Maximum length of written message content
		WriteMaxPayloadSize int

		// 写缓冲区的大小, v1.4.5版本此参数被废弃
		// Deprecated: Size of the write buffer, v1.4.5 version of this parameter is deprecated
		WriteBufferSize int

		// 是否检查文本utf8编码, 关闭性能会好点
		// Whether to check the text utf8 encoding, turn off the performance will be better
		CheckUtf8Enabled bool

		// 消息回调(OnMessage)的恢复程序
		// Message callback (OnMessage) recovery program
		Recovery func(logger Logger)

		// 日志工具
		// Logging tools
		Logger Logger
	}

	ServerOption struct {
		config *Config

		// 写缓冲区的大小, v1.4.5版本此参数被废弃
		// Deprecated: Size of the write buffer, v1.4.5 version of this parameter is deprecated
		WriteBufferSize int

		PermessageDeflate   PermessageDeflate
		ParallelEnabled     bool
		ParallelGolimit     int
		ReadMaxPayloadSize  int
		ReadBufferSize      int
		WriteMaxPayloadSize int
		CheckUtf8Enabled    bool
		Logger              Logger
		Recovery            func(logger Logger)

		// TLS设置
		TlsConfig *tls.Config

		// 握手超时时间
		HandshakeTimeout time.Duration

		// WebSocket子协议, 握手失败会断开连接
		// WebSocket sub-protocol, handshake failure disconnects the connection
		SubProtocols []string

		// 额外的响应头(可能不受客户端支持)
		// Additional response headers (may not be supported by the client)
		// https://www.rfc-editor.org/rfc/rfc6455.html#section-1.3
		ResponseHeader http.Header

		// 鉴权
		// Authentication of requests for connection establishment
		Authorize func(r *http.Request, session SessionStorage) bool

		// 创建session存储空间
		// 用于自定义SessionStorage实现
		// For custom SessionStorage implementations
		NewSession func() SessionStorage
	}
)

// 设置压缩阈值
// 开启上下文接管时, 必须不论长短压缩全部消息, 否则浏览器会报错
// when context takeover is enabled, all messages must be compressed regardless of length,
// otherwise the browser will report an error.
func (c *PermessageDeflate) setThreshold(isServer bool) {
	if (isServer && c.ServerContextTakeover) || (!isServer && c.ClientContextTakeover) {
		c.Threshold = 0
	}
}

func (c *ServerOption) deleteProtectedHeaders() {
	c.ResponseHeader.Del(internal.Upgrade.Key)
	c.ResponseHeader.Del(internal.Connection.Key)
	c.ResponseHeader.Del(internal.SecWebSocketAccept.Key)
	c.ResponseHeader.Del(internal.SecWebSocketExtensions.Key)
	c.ResponseHeader.Del(internal.SecWebSocketProtocol.Key)
}

func initServerOption(c *ServerOption) *ServerOption {
	if c == nil {
		c = new(ServerOption)
	}
	if c.ReadMaxPayloadSize <= 0 {
		c.ReadMaxPayloadSize = defaultReadMaxPayloadSize
	}
	if c.ParallelGolimit <= 0 {
		c.ParallelGolimit = defaultParallelGolimit
	}
	if c.ReadBufferSize <= 0 {
		c.ReadBufferSize = defaultReadBufferSize
	}
	if c.WriteMaxPayloadSize <= 0 {
		c.WriteMaxPayloadSize = defaultWriteMaxPayloadSize
	}
	if c.WriteBufferSize <= 0 {
		c.WriteBufferSize = defaultWriteBufferSize
	}
	if c.Authorize == nil {
		c.Authorize = func(r *http.Request, session SessionStorage) bool { return true }
	}
	if c.NewSession == nil {
		c.NewSession = func() SessionStorage { return newSmap() }
	}
	if c.ResponseHeader == nil {
		c.ResponseHeader = http.Header{}
	}
	if c.HandshakeTimeout <= 0 {
		c.HandshakeTimeout = defaultHandshakeTimeout
	}
	if c.Logger == nil {
		c.Logger = defaultLogger
	}
	if c.Recovery == nil {
		c.Recovery = func(logger Logger) {}
	}

	if c.PermessageDeflate.Enabled {
		if c.PermessageDeflate.ServerMaxWindowBits < 8 || c.PermessageDeflate.ServerMaxWindowBits > 15 {
			c.PermessageDeflate.ServerMaxWindowBits = internal.SelectValue(c.PermessageDeflate.ServerContextTakeover, 12, 15)
		}
		if c.PermessageDeflate.ClientMaxWindowBits < 8 || c.PermessageDeflate.ClientMaxWindowBits > 15 {
			c.PermessageDeflate.ClientMaxWindowBits = internal.SelectValue(c.PermessageDeflate.ClientContextTakeover, 12, 15)
		}
		if c.PermessageDeflate.Threshold <= 0 {
			c.PermessageDeflate.Threshold = defaultCompressThreshold
		}
		if c.PermessageDeflate.Level == 0 {
			c.PermessageDeflate.Level = defaultCompressLevel
		}
		if c.PermessageDeflate.PoolSize <= 0 {
			c.PermessageDeflate.PoolSize = defaultCompressorPoolSize
		}
		c.PermessageDeflate.PoolSize = internal.ToBinaryNumber(c.PermessageDeflate.PoolSize)
	}

	c.deleteProtectedHeaders()

	c.config = &Config{
		ParallelEnabled:     c.ParallelEnabled,
		ParallelGolimit:     c.ParallelGolimit,
		ReadMaxPayloadSize:  c.ReadMaxPayloadSize,
		ReadBufferSize:      c.ReadBufferSize,
		WriteMaxPayloadSize: c.WriteMaxPayloadSize,
		WriteBufferSize:     c.WriteBufferSize,
		CheckUtf8Enabled:    c.CheckUtf8Enabled,
		Recovery:            c.Recovery,
		Logger:              c.Logger,
		brPool: internal.NewPool(func() *bufio.Reader {
			return bufio.NewReaderSize(nil, c.ReadBufferSize)
		}),
	}

	if c.PermessageDeflate.Enabled {
		if c.PermessageDeflate.ServerContextTakeover {
			windowSize := internal.BinaryPow(c.PermessageDeflate.ServerMaxWindowBits)
			c.config.cswPool = internal.NewPool[[]byte](func() []byte {
				return make([]byte, 0, windowSize)
			})
		}
		if c.PermessageDeflate.ClientContextTakeover {
			windowSize := internal.BinaryPow(c.PermessageDeflate.ClientMaxWindowBits)
			c.config.dswPool = internal.NewPool[[]byte](func() []byte {
				return make([]byte, 0, windowSize)
			})
		}
	}

	return c
}

// 获取通用配置
func (c *ServerOption) getConfig() *Config { return c.config }

type ClientOption struct {
	// 写缓冲区的大小, v1.4.5版本此参数被废弃
	// Deprecated: Size of the write buffer, v1.4.5 version of this parameter is deprecated
	WriteBufferSize int

	PermessageDeflate   PermessageDeflate
	ParallelEnabled     bool
	ParallelGolimit     int
	ReadMaxPayloadSize  int
	ReadBufferSize      int
	WriteMaxPayloadSize int
	CheckUtf8Enabled    bool
	Logger              Logger
	Recovery            func(logger Logger)

	// 连接地址, 例如 wss://example.com/connect
	// server address, eg: wss://example.com/connect
	Addr string

	// 额外的请求头
	// extra request header
	RequestHeader http.Header

	// 握手超时时间
	HandshakeTimeout time.Duration

	// TLS设置
	TlsConfig *tls.Config

	// 拨号器
	// 默认是返回net.Dialer实例, 也可以用于设置代理.
	// The default is to return the net.Dialer instance
	// Can also be used to set a proxy, for example
	// NewDialer: func() (proxy.Dialer, error) {
	//		return proxy.SOCKS5("tcp", "127.0.0.1:1080", nil, nil)
	// },
	NewDialer func() (Dialer, error)

	// 创建session存储空间
	// 用于自定义SessionStorage实现
	// For custom SessionStorage implementations
	NewSession func() SessionStorage
}

func initClientOption(c *ClientOption) *ClientOption {
	if c == nil {
		c = new(ClientOption)
	}
	if c.ReadMaxPayloadSize <= 0 {
		c.ReadMaxPayloadSize = defaultReadMaxPayloadSize
	}
	if c.ParallelGolimit <= 0 {
		c.ParallelGolimit = defaultParallelGolimit
	}
	if c.ReadBufferSize <= 0 {
		c.ReadBufferSize = defaultReadBufferSize
	}
	if c.WriteMaxPayloadSize <= 0 {
		c.WriteMaxPayloadSize = defaultWriteMaxPayloadSize
	}
	if c.WriteBufferSize <= 0 {
		c.WriteBufferSize = defaultWriteBufferSize
	}
	if c.HandshakeTimeout <= 0 {
		c.HandshakeTimeout = defaultHandshakeTimeout
	}
	if c.RequestHeader == nil {
		c.RequestHeader = http.Header{}
	}
	if c.NewDialer == nil {
		c.NewDialer = func() (Dialer, error) { return &net.Dialer{Timeout: defaultDialTimeout}, nil }
	}
	if c.NewSession == nil {
		c.NewSession = func() SessionStorage { return newSmap() }
	}
	if c.Logger == nil {
		c.Logger = defaultLogger
	}
	if c.Recovery == nil {
		c.Recovery = func(logger Logger) {}
	}
	if c.PermessageDeflate.Enabled {
		if c.PermessageDeflate.ServerMaxWindowBits < 8 || c.PermessageDeflate.ServerMaxWindowBits > 15 {
			c.PermessageDeflate.ServerMaxWindowBits = 15
		}
		if c.PermessageDeflate.ClientMaxWindowBits < 8 || c.PermessageDeflate.ClientMaxWindowBits > 15 {
			c.PermessageDeflate.ClientMaxWindowBits = 15
		}
		if c.PermessageDeflate.Threshold <= 0 {
			c.PermessageDeflate.Threshold = defaultCompressThreshold
		}
		if c.PermessageDeflate.Level == 0 {
			c.PermessageDeflate.Level = defaultCompressLevel
		}
		c.PermessageDeflate.PoolSize = 1
	}
	return c
}

func (c *ClientOption) getConfig() *Config {
	config := &Config{
		ParallelEnabled:     c.ParallelEnabled,
		ParallelGolimit:     c.ParallelGolimit,
		ReadMaxPayloadSize:  c.ReadMaxPayloadSize,
		ReadBufferSize:      c.ReadBufferSize,
		WriteMaxPayloadSize: c.WriteMaxPayloadSize,
		WriteBufferSize:     c.WriteBufferSize,
		CheckUtf8Enabled:    c.CheckUtf8Enabled,
		Recovery:            c.Recovery,
		Logger:              c.Logger,
	}
	return config
}