package main

import (
	"bytes"
	"io"
	"io/ioutil"
	"log"
	"net"
	"net/http"
	"net/url"
	"os"
	"os/signal"
	"strconv"
	"sync"
	"syscall"
	"time"

	"github.com/gorilla/handlers"
	"github.com/inconshreveable/log15"
	"github.com/prometheus/client_golang/prometheus"
	"github.com/prometheus/client_golang/prometheus/promauto"
	"github.com/prometheus/client_golang/prometheus/promhttp"

	"github.com/sourcegraph/sourcegraph/internal/debugserver"
	"github.com/sourcegraph/sourcegraph/internal/env"
	"github.com/sourcegraph/sourcegraph/internal/logging"
	"github.com/sourcegraph/sourcegraph/internal/trace"
	"github.com/sourcegraph/sourcegraph/internal/tracer"
)

var logRequests, _ = strconv.ParseBool(env.Get("LOG_REQUESTS", "", "log HTTP requests"))

const port = "3180"

// requestMu ensures we only do one request at a time to prevent tripping abuse detection.
var requestMu sync.Mutex

var metricWaitingRequestsGauge = promauto.NewGauge(prometheus.GaugeOpts{
	Name: "github_proxy_waiting_requests",
	Help: "Number of proxy requests waiting on the mutex",
})

// list obtained from httputil of headers not to forward.
var hopHeaders = map[string]struct{}{
	"Connection":          {},
	"Proxy-Connection":    {}, // non-standard but still sent by libcurl and rejected by e.g. google
	"Keep-Alive":          {},
	"Proxy-Authenticate":  {},
	"Proxy-Authorization": {},
	"Te":                  {}, // canonicalized version of "TE"
	"Trailer":             {}, // not Trailers per URL above; http://www.rfc-editor.org/errata_search.php?eid=4522
	"Transfer-Encoding":   {},
	"Upgrade":             {},
}

func main() {
	env.Lock()
	env.HandleHelpFlag()
	logging.Init()
	tracer.Init()
	trace.Init(true)

	go func() {
		c := make(chan os.Signal, 1)
		signal.Notify(c, syscall.SIGINT, syscall.SIGHUP)