/*
tofuproxy -- flexible HTTP proxy, TLS terminator, X.509 certificates
             manager, WARC/Gemini browser
Copyright (C) 2021 Sergey Matveev <stargrave@stargrave.org>

This program is free software: you can redistribute it and/or modify
it under the terms of the GNU General Public License as published by
the Free Software Foundation, version 3 of the License.

This program 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 General Public License for more details.

You should have received a copy of the GNU General Public License
along with this program.  If not, see <http://www.gnu.org/licenses/>.
*/

package rounds

import (
	"fmt"
	"io"
	"io/ioutil"
	"log"
	"net/http"
	"os"
	"os/exec"
	"strings"

	"go.stargrave.org/tofuproxy/fifos"
)

const CmdDWebP = "dwebp"

func isXombrero(req *http.Request) bool {
	return strings.Contains(req.Header.Get("User-Agent"), "AppleWebKit/538.15")
}

func RoundTranscodeWebP(
	host string,
	resp *http.Response,
	w http.ResponseWriter,
	req *http.Request,
) (bool, error) {
	if resp.Header.Get("Content-Type") != "image/webp" || isXombrero(req) {
		return true, nil
	}
	tmpFd, err := ioutil.TempFile("", "tofuproxy.*.webp")
	if err != nil {
		log.Fatalln(err)
	}
	defer os.Remove(tmpFd.Name())
	defer tmpFd.Close()
	defer resp.Body.Close()
	if _, err = io.Copy(tmpFd, resp.Body); err != nil {
		log.Printf("Error during %s: %+v\n", req.URL, err)
		return false, err
	}
	tmpFd.Close()
	cmd := exec.Command(CmdDWebP, tmpFd.Name(), "-o", "-")
	data, err := cmd.Output()
	if err != nil {
		return false, err
	}
	w.Header().Add("Content-Type", "image/png")
	w.WriteHeader(http.StatusOK)
	w.Write(data)
	fifos.LogVarious <- fmt.Sprintf("%s %s\tWebP transcoded to PNG", req.Method, req.URL)
	return false, nil
}