package websocket

import (
	"net/http"
	"strconv"
	"time"

	"github.com/kataras/iris/context"

	"github.com/iris-contrib/go.uuid"
)

const (
	// DefaultWebsocketWriteTimeout 0, no timeout
	DefaultWebsocketWriteTimeout = 0
	// DefaultWebsocketReadTimeout 0, no timeout
	DefaultWebsocketReadTimeout = 0
	// DefaultWebsocketPingPeriod is 0 but
	// could be 10 * time.Second.
	DefaultWebsocketPingPeriod = 0
	// DefaultWebsocketMaxMessageSize 0
	DefaultWebsocketMaxMessageSize = 0
	// DefaultWebsocketReadBufferSize 0
	DefaultWebsocketReadBufferSize = 0
	// DefaultWebsocketWriterBufferSize 0
	DefaultWebsocketWriterBufferSize = 0
	// DefaultEvtMessageKey is the default prefix of the underline websocket events
	// that are being established under the hoods.
	//
	// Defaults to "iris-websocket-message:".
	// Last character of the prefix should be ':'.
	DefaultEvtMessageKey = "iris-websocket-message:"
)

var (
	// DefaultIDGenerator returns a random unique string for a new connection.
	// Used when config.IDGenerator is nil.
	DefaultIDGenerator = func(context.Context) string {
		id, err := uuid.NewV4()
		if err != nil {
			return strconv.FormatInt(time.Now().Unix(), 10)
		}
		return id.String()
	}
)

// Config contains the websocket server's configuration, optional.
type Config struct {
	// IDGenerator used to create (and later on, set)
	// an ID for each incoming websocket connections (clients).
	// The request is an input parameter which you can use to generate the ID (from headers for example).
	// If empty then the ID is generated by DefaultIDGenerator: randomString(64)
	IDGenerator func(ctx context.Context) string
	// EvtMessagePrefix is the prefix of the underline websocket events that are being established under the hoods.
	// This prefix is visible only to the javascript side (code) and it has nothing to do
	// with the message that the end-user receives.
	// Do not change it unless it is absolutely necessary.
	//
	// If empty then defaults to []byte("iris-websocket-message:").
	EvtMessagePrefix []byte
	// Error is the function that will be fired if any client couldn't upgrade the HTTP connection
	// to a websocket connection, a handshake error.
	Error func(w http.ResponseWriter, r *http.Request, status int, reason error)
	// CheckOrigin a function that is called right before the handshake,
	// if returns false then that client is not allowed to connect with the websocket server.
	CheckOrigin func(r *http.Request) bool
	// HandshakeTimeout specifies the duration for the handshake to complete.
	HandshakeTimeout time.Duration
	// WriteTimeout time allowed to write a message to the connection.
	// 0 means no timeout.
	// Default value is 0
	WriteTimeout time.Duration
	// ReadTimeout time allowed to read a message from the connection.
	// 0 means no timeout.
	// Default value is 0
	ReadTimeout time.Duration
	// PingPeriod send ping messages to the connection repeatedly after this period.
	// The value should be close to the ReadTimeout to avoid issues.
	// Default value is 0.
	PingPeriod time.Duration
	// MaxMessageSize max message size allowed from connection.
	// Default value is 1024
	MaxMessageSize int64
	// BinaryMessages set it to true in order to denotes binary data messages instead of utf-8 text
	// compatible if you wanna use the Connection's EmitMessage to send a custom binary data to the client, like a native server-client communication.
	// Default value is false
	BinaryMessages bool
	// ReadBufferSize and WriteBufferSize specify I/O buffer sizes. If a buffer
	// size is zero, then buffers allocated by the HTTP server are used. The
	// I/O buffer sizes do not limit the size of the messages that can be sent
	// or received.
	//
	// Default value is 0.
	ReadBufferSize, WriteBufferSize int
	// EnableCompression specify if the server should attempt to negotiate per
	// message compression (RFC 7692). Setting this value to true does not
	// guarantee that compression will be supported. Currently only "no context
	// takeover" modes are supported.
	//
	// Defaults to false and it should be remain as it is, unless special requirements.
	EnableCompression bool

	// Subprotocols specifies the server's supported protocols in order of
	// preference. If this field is set, then the Upgrade method negotiates a
	// subprotocol by selecting the first match in this list with a protocol
	// requested by the client.
	Subprotocols []string
}

// Validate validates the configuration
func (c Config) Validate() Config {
	// 0 means no timeout.
	if c.WriteTimeout < 0 {
		c.WriteTimeout = DefaultWebsocketWriteTimeout
	}

	if c.ReadTimeout < 0 {
		c.ReadTimeout = DefaultWebsocketReadTimeout
	}

	if c.PingPeriod <= 0 {
		c.PingPeriod = DefaultWebsocketPingPeriod
	}

	if c.MaxMessageSize <= 0 {
		c.MaxMessageSize = DefaultWebsocketMaxMessageSize
	}

	if c.ReadBufferSize <= 0 {
		c.ReadBufferSize = DefaultWebsocketReadBufferSize
	}

	if c.WriteBufferSize <= 0 {
		c.WriteBufferSize = DefaultWebsocketWriterBufferSize
	}

	if c.Error == nil {
		c.Error = func(w http.ResponseWriter, r *http.Request, status int, reason error) {
			//empty
		}
	}

	if c.CheckOrigin == nil {
		c.CheckOrigin = func(r *http.Request) bool {
			// allow all connections by default
			return true
		}
	}

	if len(c.EvtMessagePrefix) == 0 {
		c.EvtMessagePrefix = []byte(DefaultEvtMessageKey)
	}

	if c.IDGenerator == nil {
		c.IDGenerator = DefaultIDGenerator
	}

	return c
}