package main

import (
	"bytes"
	"encoding/json"
	"flag"
	"fmt"
	"image/png"
	"net/http"
	"os"
	"path"
	"strings"

	"github.com/kettek/apng"
)

var cacheDirectory string

func handleUpload(w http.ResponseWriter, r *http.Request) {
	inf, header, err := r.FormFile("image")
	if err != nil {
		http.Error(w, err.Error(), http.StatusInternalServerError)
		return
	}
	defer inf.Close()

	if !strings.HasSuffix(header.Filename, ".pixil") {
		http.Error(w, "Invalid file type", http.StatusBadRequest)
		return
	}

	var pixil Pixil
	if err := json.NewDecoder(inf).Decode(&pixil); err != nil {
		http.Error(w, err.Error(), http.StatusInternalServerError)
		return
	}

	if pixil.Width != 8 || pixil.Height != 8 {
		http.Error(w, "Invalid image size", http.StatusBadRequest)
		return
	}

	outRaw, err := os.Create(path.Join(cacheDirectory, "wallart.bin"))
	if err != nil {
		http.Error(w, err.Error(), http.StatusInternalServerError)
		return
	}
	defer outRaw.Close()

	outPng, err := os.Create(path.Join(cacheDirectory, "wallart.png"))
	if err != nil {
		http.Error(w, err.Error(), http.StatusInternalServerError)
		return
	}
	defer outPng.Close()

	// You only get 8 frames max
	numFrames := len(pixil.Frames)
	if numFrames > 8 {
		numFrames = 8
	}

	outImage := apng.APNG{
		Frames: make([]apng.Frame, len(pixil.Frames)),
	}

	for i := 0; i < numFrames; i++ {
		frame := pixil.Frames[i]
		preview := frame.GetPreview()
		if preview == nil {
			http.Error(w, "Invalid frame", http.StatusBadRequest)
			return
		}
		img, err := png.Decode(bytes.NewReader(preview))
		if err != nil {
			http.Error(w, err.Error(), http.StatusInternalServerError)
			return
		}

		// Dump it to the raw file
		for y := 0; y < 8; y++ {
			for x := 0; x < 8; x++ {
				r, g, b, _ := img.At(x, y).RGBA()
				outRaw.Write([]byte{
					byte(r >> 8),
					byte(g >> 8),
					byte(b >> 8),
				})
			}
		}

		outImage.Frames[i] = apng.Frame{
			Image:            img,
			DelayNumerator:   1,
			DelayDenominator: 2,
		}
	}

	if err := apng.Encode(outPng, outImage); err != nil {
		http.Error(w, err.Error(), http.StatusInternalServerError)
		return
	}

	fmt.Fprintln(w, "It worked")
}

func main() {
	listen := flag.String("listen", ":8080", "listen address")
	web := flag.String("web", "web", "web directory")
	flag.StringVar(&cacheDirectory, "cache", "cache", "cache directory")
	flag.Parse()

	cacheDir := http.Dir(cacheDirectory)
	http.HandleFunc("/upload", handleUpload)
	http.Handle("/wallart.bin", http.FileServer(cacheDir))
	http.Handle("/wallart.png", http.FileServer(cacheDir))
	http.Handle("/", http.FileServer(http.Dir(*web)))
	http.ListenAndServe(*listen, nil)
}