// Copyright 2019 fatedier, fatedier@gmail.com
//
// Licensed under the Apache License, Version 2.0 (the "License");
// you may not use this file except in compliance with the License.
// You may obtain a copy of the License at
//
//     http://www.apache.org/licenses/LICENSE-2.0
//
// Unless required by applicable law or agreed to in writing, software
// distributed under the License is distributed on an "AS IS" BASIS,
// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
// See the License for the specific language governing permissions and
// limitations under the License.

package proxy

import (
	"io"
	"net"
	"reflect"
	"strings"

	libio "github.com/fatedier/golib/io"

	"github.com/fatedier/frp/pkg/config"
	"github.com/fatedier/frp/pkg/util/limit"
	utilnet "github.com/fatedier/frp/pkg/util/net"
	"github.com/fatedier/frp/pkg/util/util"
	"github.com/fatedier/frp/pkg/util/vhost"
	"github.com/fatedier/frp/server/metrics"
)

func init() {
	RegisterProxyFactory(reflect.TypeOf(&config.HTTPProxyConf{}), NewHTTPProxy)
}

type HTTPProxy struct {
	*BaseProxy
	cfg *config.HTTPProxyConf

	closeFuncs []func()
}

func NewHTTPProxy(baseProxy *BaseProxy, cfg config.ProxyConf) Proxy {
	unwrapped, ok := cfg.(*config.HTTPProxyConf)
	if !ok {
		return nil
	}
	return &HTTPProxy{
		BaseProxy: baseProxy,
		cfg:       unwrapped,
	}
}

func (pxy *HTTPProxy) Run() (remoteAddr string, err error) {
	xl := pxy.xl
	routeConfig := vhost.RouteConfig{
		RewriteHost:     pxy.cfg.HostHeaderRewrite,
		RouteByHTTPUser: pxy.cfg.RouteByHTTPUser,
		Headers:         pxy.cfg.Headers,
		Username:        pxy.cfg.HTTPUser,
		Password:        pxy.cfg.HTTPPwd,
		CreateConnFn:    pxy.GetRealConn,
	}

	locations := pxy.cfg.Locations
	if len(locations) == 0 {
		locations = []string{""}
	}

	defer func() {
		if err != nil {
			pxy.Close()
		}
	}()

	addrs := make([]string, 0)
	for _, domain := range pxy.cfg.CustomDomains {
		if domain == "" {
			continue
		}

		routeConfig.Domain = domain
		for _, location := range locations {
			routeConfig.Location = location

			tmpRouteConfig := routeConfig

			// handle group
			if pxy.cfg.Group != "" {
				err = pxy.rc.HTTPGroupCtl.Register(pxy.name, pxy.cfg.Group, pxy.cfg.GroupKey, routeConfig)
				if err != nil {
					return
				}

				pxy.closeFuncs = append(pxy.closeFuncs, func() {
					pxy.rc.HTTPGroupCtl.UnRegister(pxy.name, pxy.cfg.Group, tmpRouteConfig)
				})
			} else {
				// no group
				err = pxy.rc.HTTPReverseProxy.Register(routeConfig)
				if err != nil {
					return
				}
				pxy.closeFuncs = append(pxy.closeFuncs, func() {
					pxy.rc.HTTPReverseProxy.UnRegister(tmpRouteConfig)
				})
			}
			addrs = append(addrs, util.CanonicalAddr(routeConfig.Domain, pxy.serverCfg.VhostHTTPPort))
			xl.Info("http proxy listen for host [%s] location [%s] group [%s], routeByHTTPUser [%s]",
				routeConfig.Domain, routeConfig.Location, pxy.cfg.Group, pxy.cfg.RouteByHTTPUser)
		}
	}

	if pxy.cfg.SubDomain != "" {
		routeConfig.Domain = pxy.cfg.SubDomain + "." + pxy.serverCfg.SubDomainHost
		for _, location := range locations {
			routeConfig.Location = location

			tmpRouteConfig := routeConfig

			// handle group
			if pxy.cfg.Group != "" {
				err = pxy.rc.HTTPGroupCtl.Register(pxy.name, pxy.cfg.Group, pxy.cfg.GroupKey, routeConfig)
				if err != nil {
					return
				}

				pxy.closeFuncs = append(pxy.closeFuncs, func() {
					pxy.rc.HTTPGroupCtl.UnRegister(pxy.name, pxy.cfg.Group, tmpRouteConfig)
				})
			} else {
				err = pxy.rc.HTTPReverseProxy.Register(routeConfig)
				if err != nil {
					return
				}
				pxy.closeFuncs = append(pxy.closeFuncs, func() {
					pxy.rc.HTTPReverseProxy.UnRegister(tmpRouteConfig)
				})
			}
			addrs = append(addrs, util.CanonicalAddr(tmpRouteConfig.Domain, pxy.serverCfg.VhostHTTPPort))

			xl.Info("http proxy listen for host [%s] location [%s] group [%s], routeByHTTPUser [%s]",
				routeConfig.Domain, routeConfig.Location, pxy.cfg.Group, pxy.cfg.RouteByHTTPUser)
		}
	}
	remoteAddr = strings.Join(addrs, ",")
	return
}

func (pxy *HTTPProxy) GetConf() config.ProxyConf {
	return pxy.cfg
}

func (pxy *HTTPProxy) GetRealConn(remoteAddr string) (workConn net.Conn, err error) {
	xl := pxy.xl
	rAddr, errRet := net.ResolveTCPAddr("tcp", remoteAddr)
	if errRet != nil {
		xl.Warn("resolve TCP addr [%s] error: %v", remoteAddr, errRet)
		// we do not return error here since remoteAddr is not necessary for proxies without proxy protocol enabled
	}

	tmpConn, errRet := pxy.GetWorkConnFromPool(rAddr, nil)
	if errRet != nil {
		err = errRet
		return
	}

	var rwc io.ReadWriteCloser = tmpConn
	if pxy.cfg.UseEncryption {
		rwc, err = libio.WithEncryption(rwc, []byte(pxy.serverCfg.Token))
		if err != nil {
			xl.Error("create encryption stream error: %v", err)
			return
		}
	}
	if pxy.cfg.UseCompression {
		var releaseFn func()
		rwc, releaseFn = libio.WithCompressionFromPool(rwc)
		defer releaseFn()
	}

	if pxy.GetLimiter() != nil {
		rwc = libio.WrapReadWriteCloser(limit.NewReader(rwc, pxy.GetLimiter()), limit.NewWriter(rwc, pxy.GetLimiter()), func() error {
			return rwc.Close()
		})
	}

	workConn = utilnet.WrapReadWriteCloserToConn(rwc, tmpConn)
	workConn = utilnet.WrapStatsConn(workConn, pxy.updateStatsAfterClosedConn)
	metrics.Server.OpenConnection(pxy.GetName(), pxy.GetConf().GetBaseConfig().ProxyType)
	return
}

func (pxy *HTTPProxy) updateStatsAfterClosedConn(totalRead, totalWrite int64) {
	name := pxy.GetName()
	proxyType := pxy.GetConf().GetBaseConfig().ProxyType
	metrics.Server.CloseConnection(name, proxyType)
	metrics.Server.AddTrafficIn(name, proxyType, totalWrite)
	metrics.Server.AddTrafficOut(name, proxyType, totalRead)
}

func (pxy *HTTPProxy) Close() {
	pxy.BaseProxy.Close()
	for _, closeFn := range pxy.closeFuncs {
		closeFn()
	}
}