// Copyright 2018 DREP Foundation Ltd.
// This file is part of the drep-cli library.
//
// The drep-cli library is free software: you can redistribute it and/or modify
// it under the terms of the GNU Lesser General Public License as published by
// the Free Software Foundation, either version 3 of the License, or
// (at your option) any later version.
//
// The drep-cli library is distributed in the hope that it will be useful,
// but WITHOUT ANY WARRANTY; without even the implied warranty of
// MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
// GNU Lesser General Public License for more details.
//
// You should have received a copy of the GNU Lesser General Public License
// along with the drep-cli library. If not, see <http://www.gnu.org/licenses/>.

package component

import (
	"context"
	"crypto/tls"
	"encoding/base64"
	"net"
	"net/http"
	"net/url"
	"os"
	"strings"
	"time"

	"golang.org/x/net/websocket"

	rpcTypes "github.com/drep-project/drepcli/rpc/types"
)

// NewWSServer creates a new websocket RPC server around an API provider.
// Deprecated: use Server.WebsocketHandler
func NewWSServer(allowedOrigins []string, srv *rpcTypes.Server) *http.Server {
	return &http.Server{Handler: srv.WebsocketHandler(allowedOrigins)}
}

func wsGetConfig(endpoint, origin string) (*websocket.Config, error) {
	if origin == "" {
		var err error
		if origin, err = os.Hostname(); err != nil {
			return nil, err
		}
		if strings.HasPrefix(endpoint, "wss") {
			origin = "https://" + strings.ToLower(origin)
		} else {
			origin = "http://" + strings.ToLower(origin)
		}
	}
	config, err := websocket.NewConfig(endpoint, origin)
	if err != nil {
		return nil, err
	}

	if config.Location.User != nil {
		b64auth := base64.StdEncoding.EncodeToString([]byte(config.Location.User.String()))
		config.Header.Add("Authorization", "Basic "+b64auth)
		config.Location.User = nil
	}
	return config, nil
}

// DialWebsocket creates a new RPC client that communicates with a JSON-RPC server
// that is listening on the given endpoint.
//
// The context is used for the initial connection establishment. It does not
// affect subsequent interactions with the client.
func DialWebsocket(ctx context.Context, endpoint, origin string) (*Client, error) {
	config, err := wsGetConfig(endpoint, origin)
	if err != nil {
		return nil, err
	}

	return newClient(ctx, func(ctx context.Context) (net.Conn, error) {
		return wsDialContext(ctx, config)
	})
}

func wsDialContext(ctx context.Context, config *websocket.Config) (*websocket.Conn, error) {
	var conn net.Conn
	var err error
	switch config.Location.Scheme {
	case "ws":
		conn, err = dialContext(ctx, "tcp", wsDialAddress(config.Location))
	case "wss":
		dialer := contextDialer(ctx)
		conn, err = tls.DialWithDialer(dialer, "tcp", wsDialAddress(config.Location), config.TlsConfig)
	default:
		err = websocket.ErrBadScheme
	}
	if err != nil {
		return nil, err
	}
	ws, err := websocket.NewClient(config, conn)
	if err != nil {
		conn.Close()
		return nil, err
	}
	return ws, err
}

var wsPortMap = map[string]string{"ws": "80", "wss": "443"}

func wsDialAddress(location *url.URL) string {
	if _, ok := wsPortMap[location.Scheme]; ok {
		if _, _, err := net.SplitHostPort(location.Host); err != nil {
			return net.JoinHostPort(location.Host, wsPortMap[location.Scheme])
		}
	}
	return location.Host
}

func dialContext(ctx context.Context, network, addr string) (net.Conn, error) {
	d := &net.Dialer{KeepAlive: tcpKeepAliveInterval}
	return d.DialContext(ctx, network, addr)
}

func contextDialer(ctx context.Context) *net.Dialer {
	dialer := &net.Dialer{Cancel: ctx.Done(), KeepAlive: tcpKeepAliveInterval}
	if deadline, ok := ctx.Deadline(); ok {
		dialer.Deadline = deadline
	} else {
		dialer.Deadline = time.Now().Add(defaultDialTimeout)
	}
	return dialer
}
