package main

import (
	"bytes"
	"crypto/sha1"
	"crypto/tls"
	"fmt"
	"io"
	"io/ioutil"
	"log"
	"net/http"
	"net/url"
	"path/filepath"
	"strings"

	"github.com/yookoala/gofast"
)

type fakeResponseWriter struct {
	io.WriteCloser
	header http.Header
}

func newFakeResponseWriter(out io.WriteCloser) *fakeResponseWriter {
	return &fakeResponseWriter{
		WriteCloser: out,
		header:      make(http.Header),
	}
}

func (w *fakeResponseWriter) Header() http.Header {
	return w.header
}

func (w *fakeResponseWriter) WriteHeader(statusCode int) {
	// Do nothing
}

func serveFastCGI(c *tls.Conn, connFactory gofast.ConnFactory, u *url.URL, filePath string) {
	header := map[string][]string{
		"Accept": {"*/*"},
		"Host":   {u.Hostname()},
	}

	r := &http.Request{
		Method:     "GET",
		URL:        u,
		Proto:      "HTTP/1.1",
		ProtoMajor: 1,
		ProtoMinor: 1,
		Header:     header,
		Body:       ioutil.NopCloser(bytes.NewReader(nil)),
		Host:       u.Host,
		RemoteAddr: c.RemoteAddr().String(),
	}

	req := gofast.NewRequest(r)
	req.Params["CONTENT_TYPE"] = r.Header.Get("Content-Type")
	req.Params["CONTENT_LENGTH"] = r.Header.Get("Content-Length")
	req.Params["HTTP_HOST"] = r.Host
	req.Params["HTTPS"] = "on"
	req.Params["GATEWAY_INTERFACE"] = "CGI/1.1"
	req.Params["REMOTE_ADDR"] = strings.SplitN(c.RemoteAddr().String(), ":", 2)[0]
	req.Params["REMOTE_PORT"] = "1965"
	req.Params["SERVER_PORT"] = "1965"
	req.Params["SERVER_NAME"] = r.Host
	req.Params["SERVER_PROTOCOL"] = r.Proto
	req.Params["SERVER_SOFTWARE"] = "twins"
	req.Params["REDIRECT_STATUS"] = "200"
	req.Params["REQUEST_METHOD"] = r.Method
	req.Params["REQUEST_URI"] = r.RequestURI
	req.Params["QUERY_STRING"] = r.URL.RawQuery
	req.Params["DOCUMENT_ROOT"] = filepath.Dir(filePath)
	req.Params["DOCUMENT_URI"] = r.URL.Path
	req.Params["SCRIPT_FILENAME"] = filePath
	req.Params["SCRIPT_NAME"] = filepath.Base(filePath)

	certLabel := 'A'
	clientCerts := c.ConnectionState().PeerCertificates
	for i := 0; i < len(clientCerts) && i < 26; i++ {
		req.Params["CLIENT_CERT_"+string(certLabel+rune(i))] = fmt.Sprintf("%x", sha1.Sum(clientCerts[i].Raw))
	}

	w := newFakeResponseWriter(c)

	client, err := gofast.SimpleClientFactory(connFactory, 0)()
	if err != nil {
		log.Printf("FastCGI Error: %s", err)
		http.Error(w, "Failed to connect to FastCGI server", http.StatusInternalServerError)
		return
	}

	resp, err := client.Do(req)
	if err != nil {
		log.Printf("FastCGI Error: %s", err)
		http.Error(w, "Failed to connect to FastCGI server", http.StatusInternalServerError)
		return
	}

	errBuffer := new(bytes.Buffer)
	err = resp.WriteTo(w, errBuffer)
	if err != nil {
		log.Printf("FastCGI Error: %s", err)
		http.Error(w, "Failed to connect to FastCGI server", http.StatusInternalServerError)
		return
	} else if errBuffer.Len() > 0 {
		log.Printf("FastCGI Error: %s", errBuffer.String())
		http.Error(w, "Failed to connect to FastCGI server", http.StatusInternalServerError)
	}
}