package main

import (
	"bytes"
	"context"
	"flag"
	"fmt"
	"github.com/bakape/thumbnailer"
	"golang.org/x/net/webdav"
	"log"
	"net/http"
	"os"
	"path"
	"path/filepath"
	"strconv"
)

type Handler struct {
	webdav.Handler
}

func (h *Handler) ServeHTTP(w http.ResponseWriter, req *http.Request) {
	width, _ := strconv.Atoi(req.FormValue("w"))
	height, _ := strconv.Atoi(req.FormValue("h"))

	if (width > 0) || (height > 0) {
		h.ServeThumbnail(w, req, uint(width), uint(height))
		return
	}

	h.Handler.ServeHTTP(w, req)
}

func (h *Handler) ServeThumbnail(w http.ResponseWriter, req *http.Request, width uint, height uint) {
	srcPath := path.Clean(req.URL.Path)
	srcFile, err := h.FileSystem.OpenFile(context.Background(), srcPath, os.O_RDONLY, 0664)
	if err != nil {
		http.NotFound(w, req)
		return
	}
	defer srcFile.Close()
	srcFileInfo, err := srcFile.Stat()
	if err != nil {
		http.NotFound(w, req)
		return
	}

	var opts thumbnailer.Options
	opts.ThumbDims.Width = width
	opts.ThumbDims.Height = height
	_, thumb, err := thumbnailer.Process(srcFile, opts)
	if err != nil {
		http.Error(w, err.Error(), http.StatusInternalServerError)
		return
	}
	ext := "jpeg"
	if thumb.IsPNG {
		ext = "png"
	}
	fileName := filepath.Base(srcPath)
	thumbFileName := fmt.Sprintf("%s.thumb.%s", fileName, ext)
	thumbRs := bytes.NewReader(thumb.Image.Data)
	http.ServeContent(w, req, thumbFileName, srcFileInfo.ModTime(), thumbRs)
}

func main() {
	address := flag.String("a", "localhost:8080", "Address to listen to.")
	flag.Parse()

	handler := &Handler{}
	handler.FileSystem = webdav.Dir(".")
	handler.LockSystem = webdav.NewMemLS()

	log.Println("Listening on", *address)
	http.ListenAndServe(*address, handler)
}