package ingress

import (
	"fmt"
	"net"
	"net/http"
	"net/url"
	"strings"

	"github.com/cloudflare/cloudflared/h2mux"
	"github.com/cloudflare/cloudflared/websocket"
	"github.com/pkg/errors"
)

var (
	switchingProtocolText = fmt.Sprintf("%d %s", http.StatusSwitchingProtocols, http.StatusText(http.StatusSwitchingProtocols))
)

// HTTPOriginProxy can be implemented by origin services that want to proxy http requests.
type HTTPOriginProxy interface {
	// RoundTrip is how cloudflared proxies eyeball requests to the actual origin services
	http.RoundTripper
}

// StreamBasedOriginProxy can be implemented by origin services that want to proxy ws/TCP.
type StreamBasedOriginProxy interface {
	EstablishConnection(r *http.Request) (OriginConnection, *http.Response, error)
}

func (o *unixSocketPath) RoundTrip(req *http.Request) (*http.Response, error) {
	return o.transport.RoundTrip(req)
}

func (o *httpService) RoundTrip(req *http.Request) (*http.Response, error) {
	// Rewrite the request URL so that it goes to the origin service.
	req.URL.Host = o.url.Host
	req.URL.Scheme = o.url.Scheme
	if o.hostHeader != "" {
		// For incoming requests, the Host header is promoted to the Request.Host field and removed from the Header map.
		req.Host = o.hostHeader
	}
	return o.transport.RoundTrip(req)
}

func (o *httpService) EstablishConnection(req *http.Request) (OriginConnection, *http.Response, error) {
	req.URL.Host = o.url.Host
	req.URL.Scheme = websocket.ChangeRequestScheme(o.url)
	if o.hostHeader != "" {
		// For incoming requests, the Host header is promoted to the Request.Host field and removed from the Header map.
		req.Host = o.hostHeader
	}
	return newWSConnection(o.transport.TLSClientConfig, req)
}

func (o *helloWorld) RoundTrip(req *http.Request) (*http.Response, error) {
	// Rewrite the request URL so that it goes to the Hello World server.
	req.URL.Host = o.server.Addr().String()
	req.URL.Scheme = "https"
	return o.transport.RoundTrip(req)
}

func (o *helloWorld) EstablishConnection(req *http.Request) (OriginConnection, *http.Response, error) {
	req.URL.Host = o.server.Addr().String()
	req.URL.Scheme = "wss"
	return newWSConnection(o.transport.TLSClientConfig, req)
}

func (o *statusCode) RoundTrip(_ *http.Request) (*http.Response, error) {
	return o.resp, nil
}

func (o *rawTCPService) EstablishConnection(r *http.Request) (OriginConnection, *http.Response, error) {
	dest, err := getRequestHost(r)
	if err != nil {
		return nil, nil, err
	}
	conn, err := net.Dial("tcp", dest)
	if err != nil {
		return nil, nil, err
	}

	originConn := &tcpConnection{
		conn: conn,
	}
	resp := &http.Response{
		Status:        switchingProtocolText,
		StatusCode:    http.StatusSwitchingProtocols,
		ContentLength: -1,
	}
	return originConn, resp, nil
}

// getRequestHost returns the host of the http.Request.
func getRequestHost(r *http.Request) (string, error) {
	if r.Host != "" {
		return r.Host, nil
	}
	if r.URL != nil {
		return r.URL.Host, nil
	}
	return "", errors.New("host not found")
}

func (o *tcpOverWSService) EstablishConnection(r *http.Request) (OriginConnection, *http.Response, error) {
	var err error
	dest := o.dest
	if o.isBastion {
		dest, err = o.bastionDest(r)
		if err != nil {
			return nil, nil, err
		}
	}

	conn, err := net.Dial("tcp", dest)
	if err != nil {
		return nil, nil, err
	}
	originConn := &tcpOverWSConnection{
		conn:          conn,
		streamHandler: o.streamHandler,
	}
	resp := &http.Response{
		Status:        switchingProtocolText,
		StatusCode:    http.StatusSwitchingProtocols,
		Header:        websocket.NewResponseHeader(r),
		ContentLength: -1,
	}
	return originConn, resp, nil

}

func (o *tcpOverWSService) bastionDest(r *http.Request) (string, error) {
	jumpDestination := r.Header.Get(h2mux.CFJumpDestinationHeader)
	if jumpDestination == "" {
		return "", fmt.Errorf("Did not receive final destination from client. The --destination flag is likely not set on the client side")
	}
	// Strip scheme and path set by client. Without a scheme
	// Parsing a hostname and path without scheme might not return an error due to parsing ambiguities
	if jumpURL, err := url.Parse(jumpDestination); err == nil && jumpURL.Host != "" {
		return removePath(jumpURL.Host), nil
	}
	return removePath(jumpDestination), nil
}

func removePath(dest string) string {
	return strings.SplitN(dest, "/", 2)[0]
}

func (o *socksProxyOverWSService) EstablishConnection(r *http.Request) (OriginConnection, *http.Response, error) {
	originConn := o.conn
	resp := &http.Response{
		Status:        switchingProtocolText,
		StatusCode:    http.StatusSwitchingProtocols,
		Header:        websocket.NewResponseHeader(r),
		ContentLength: -1,
	}
	return originConn, resp, nil
}