package main

import (
	"crypto/sha256"
	"encoding/base64"
	"fmt"
	"io/ioutil"
	"log"
	"net/http"
	"os"
	"path/filepath"
	"text/template"

	"gocv.io/x/gocv"
)

// StreamURL Unexported
type StreamURL struct {
	URL string
}

func index(w http.ResponseWriter, r *http.Request) {
	if r.FormValue("URL") == "" {
		indexTemplate, err := template.ParseFiles(filepath.Join("templates", "index.html"))
		if err != nil {
			log.Fatal(err)
		}
		indexTemplate.Execute(w, nil)
		return
	}
	streamURL := StreamURL{
		URL: r.FormValue("URL"),
	}
	streamTemplate, err := template.ParseFiles(filepath.Join("templates", "stream.html"))

	if err != nil {
		log.Fatal(err)
	}

	streamTemplate.Execute(w, streamURL)
}

func stream(w http.ResponseWriter, r *http.Request) {
	if r.FormValue("URL") == "" {
		return
	}
	w.Header().Set("Content-Type", "image/jpeg")
	URL := r.FormValue("URL")
	resp, err := http.Get(URL)
	if err != nil {
		log.Fatal(err)
	}
	img, err := ioutil.ReadAll(resp.Body)
	defer resp.Body.Close()

	// TODO async for this?
	saveStreamInstant(URL, img)

	w.Write([]byte(img))

	gocvImg := gocv.IMRead(filepath.Join(".", "streams", "vERFlpF_5Y-AgJ06PjD8-LtylFJXEjbqJp0g3he5Ngs=", "current.jpg"), gocv.IMReadColor)
	fmt.Println(gocvImg.Empty())
}

func saveStreamInstant(URL string, img []byte) {
	h := sha256.New()
	h.Write([]byte(URL))
	streamDir := base64.URLEncoding.EncodeToString(h.Sum(nil))
	streamStoreDir := filepath.Join(".", "streams", string(streamDir))
	os.MkdirAll(streamStoreDir, os.ModePerm)

	currentStreamInstantPath := filepath.Join(streamStoreDir, "current.jpg")
	_, err := os.Stat(currentStreamInstantPath)
	swap := !os.IsNotExist(err)

	if swap {
		currentStreamInstantPath = filepath.Join(streamStoreDir, "next.jpg")
	}
	err = ioutil.WriteFile(currentStreamInstantPath, img, os.ModePerm)
	if err != nil {
		log.Fatal("Can't write latest stream instant.")
	}
	if swap {
		previousStreamInstantPath := filepath.Join(streamStoreDir, "previous.jpg")
		nextStreamInstantPath := currentStreamInstantPath
		currentStreamInstantPath = filepath.Join(streamStoreDir, "current.jpg")

		err = os.Rename(currentStreamInstantPath, previousStreamInstantPath)
		err = os.Rename(nextStreamInstantPath, currentStreamInstantPath)
	}
}

func main() {
	staticFileServer := http.FileServer(http.Dir("./static"))
	http.Handle("/static/", http.StripPrefix("/static/", staticFileServer))

	http.HandleFunc("/", index)
	http.HandleFunc("/stream", stream)
	log.Fatal(http.ListenAndServe(":8080", nil))
}