package main

import (
	"bufio"
	"crypto/sha1"
	"encoding/hex"
	"fmt"
	"github.com/boombuler/barcode"
	"github.com/boombuler/barcode/codabar"
	"github.com/boombuler/barcode/code128"
	"github.com/boombuler/barcode/code39"
	"github.com/boombuler/barcode/datamatrix"
	"github.com/boombuler/barcode/ean"
	"github.com/boombuler/barcode/qr"
	"github.com/boombuler/barcode/twooffive"
	"github.com/julienschmidt/httprouter"
	"image/png"
	"log"
	"net/http"
	"os"
	"strconv"
)

func IdToPath(id string) string {
	hasher := sha1.New()
	hasher.Write([]byte(id))
	hash := hex.EncodeToString(hasher.Sum(nil))
	path := fmt.Sprintf("%s/%s/%s.png", hash[0:2], hash[2:4], hash)
	os.MkdirAll(fmt.Sprintf("public/%s/%s", hash[0:2], hash[2:4]), 0755)
	return path
}

func Get(w http.ResponseWriter, r *http.Request, p httprouter.Params) {
	bartype := p.ByName("type")
	content := r.URL.Query().Get("content")

	swidth := r.URL.Query().Get("width")
	sheight := r.URL.Query().Get("height")

	if swidth == "" {
		swidth = "0"
	}
	if sheight == "" {
		sheight = "0"
	}

	width, werr := strconv.Atoi(swidth)
	if werr != nil {
		log.Println(werr)
		w.WriteHeader(http.StatusBadRequest)
		fmt.Fprintf(w, "Error: %s", werr)
		return
	}
	height, herr := strconv.Atoi(sheight)
	if herr != nil {
		log.Println(herr)
		w.WriteHeader(http.StatusBadRequest)
		fmt.Fprintf(w, "Error: %s", herr)
		return
	}

	id := fmt.Sprintf("%s:%s:%d:%d", bartype, content, width, height)
	path := IdToPath(id)
	realPath := fmt.Sprintf("public/%s", path)

	if _, err := os.Stat(realPath); err == nil {
		http.Redirect(w, r, fmt.Sprintf("/%s", path), 307)
		return
	}

	var err error
	var initialBarcode barcode.Barcode

	switch bartype {
	case "datamatrix":
		initialBarcode, err = datamatrix.Encode(content)
		if width == 0 {
			width = 256
		}
		if height == 0 {
			height = 256
		}
	case "qr":
		initialBarcode, err = qr.Encode(content, qr.Q, qr.Auto)
		if width == 0 {
			width = 256
		}
		if height == 0 {
			height = 256
		}
	case "codabar":
		initialBarcode, err = codabar.Encode(content)
		if width == 0 {
			width = 256
		}
		if height == 0 {
			height = 50
		}
	case "code128":
		initialBarcode, err = code128.Encode(content)
		if width == 0 {
			width = 256
		}
		if height == 0 {
			height = 25
		}
	case "code39":
		initialBarcode, err = code39.Encode(content, true, true)
		if width == 0 {
			width = 256
		}
		if height == 0 {
			height = 25
		}
	case "ean":
		initialBarcode, err = ean.Encode(content)
		if width == 0 {
			width = 256
		}
		if height == 0 {
			height = 25
		}
	case "2of5":
		initialBarcode, err = twooffive.Encode(content, true)
		if width == 0 {
			width = 256
		}
		if height == 0 {
			height = 25
		}
	case "twooffive":
		initialBarcode, err = twooffive.Encode(content, true)
		if width == 0 {
			width = 256
		}
		if height == 0 {
			height = 25
		}
	}

	if err != nil {
		log.Println(err)
		w.WriteHeader(http.StatusInternalServerError)
		fmt.Fprintf(w, "Error: %s", err)
		return
	} else if bartype == "" || initialBarcode == nil {
		log.Println("Bad type")
		w.WriteHeader(http.StatusBadRequest)
		fmt.Fprintf(w, "Error: %s", "Bad bar type")
		return
	} else {
		var serr error
		var finalBarcode barcode.Barcode
		if width != 0 && height != 0 {
			finalBarcode, serr = barcode.Scale(initialBarcode, width, height)
		} else {
			finalBarcode = initialBarcode
		}
		if serr != nil {
			log.Println(serr)
			w.WriteHeader(http.StatusInternalServerError)
			fmt.Fprintf(w, "Error: %s", serr)
			return
		}

		file, ferr := os.Create(realPath)
		if ferr != nil {
			log.Println(ferr)
			w.WriteHeader(http.StatusInternalServerError)
			fmt.Fprintf(w, "Error: %s", ferr)
			return
		}
		defer file.Close()

		writer := bufio.NewWriter(file)
		perr := png.Encode(writer, finalBarcode)
		if perr != nil {
			log.Println(perr)
			w.WriteHeader(http.StatusInternalServerError)
			fmt.Fprintf(w, "Error: %s", perr)
			return
		}
		writer.Flush()

		http.Redirect(w, r, fmt.Sprintf("/%s", path), 307)
	}
}

func main() {
	sport := os.Getenv("PORT")
	var port string
	if len(sport) > 2 {
		port = sport
	} else {
		port = "8080"
	}

	log.Printf("Binding at 0.0.0.0:%s", port)

	router := httprouter.New()
	router.NotFound = http.FileServer(http.Dir("public"))

	router.GET("/", Get)
	router.GET("/:type", Get)

	log.Fatal(http.ListenAndServe(fmt.Sprintf(":%s", port), router))
}