package update

import (
	"encoding/binary"
	"encoding/hex"
	"errors"
	"fmt"
	"github.com/albenik/go-serial/v2"
	"github.com/go-playground/log/v7"
	"github.com/schollz/progressbar/v3"
	"io/ioutil"
	"os"
	"path"
	"regexp"
	"strings"
	"time"
)

const CHUNKSIZE = 256

type modem struct {
	port serial.Port
}

func initmodem(serport string, baudrate int) (*modem, error) {
	p, err := serial.Open(serport,
		serial.WithBaudrate(baudrate),
		serial.WithDataBits(8),
		serial.WithParity(serial.NoParity),
		serial.WithStopBits(serial.OneStopBit),
		serial.WithReadTimeout(70),
		serial.WithWriteTimeout(70)) // 50 was not stable, bump to 70
	if err != nil {
		fmt.Printf("ERROR: File %s could not be opened\n", serport)
		return nil, err
	}
	m := &modem{*p}
	return m, nil
}

func (m *modem) write(out string, nolog ...bool) ([]byte, error) {
	if len(nolog) == 0 {
		log.Debug("Sending " + out)
	} else {
		if len(out) < 200 { // in other cases it's the firmware!
			log.Debugf("Sending %d byte(s)", len(out))
		}
	}
	_, err := m.port.Write([]byte(out))
	if err != nil {
		log.Errorf("ERROR while sending serial command: %s\n", out)
		log.Error(err)
		return []byte(""), err
	}
	buff := make([]byte, 1024)
	if len(nolog) == 0 {
		time.Sleep(50 * time.Millisecond) // give the PTC some time to answer, no needed with binary
	}
	n, err := m.port.Read(buff)
	// fmt.Printf("Read %d bytes\n", n)
	if err != nil {
		log.Errorf("ERROR: cannot read answer from command: %s\n", out)
		return []byte(""), err
	}
	// TODO: Handle EOF
	return buff[:n], nil

}

func (m *modem) getSerNum() (string, error) {
	answer, err := m.write("\rsys sern\r")
	if err != nil {
		return "", err
	}
	re := regexp.MustCompile(`Serial number: \w{2,16}`)
	sn := strings.ReplaceAll(string(re.Find(answer)), "Serial number: ", "")
	return sn, nil
}

func (m *modem) setDateTime() error {
	ct := time.Now()
	answer, err := m.write("DATE " + ct.Format("020106\r"))
	if err != nil {
		return err
	}
	if strings.Contains(string(answer), "BAD ARGUMENT") {
		return errors.New("setting DATE returns a BAD ARGUMENT error!")
	}
	answer, err = m.write("TIME " + ct.Format("150405\r"))
	if strings.Contains(string(answer), "BAD ARGUMENT") {
		return errors.New("setting TIME returns a BAD ARGUMENT error!")
	}
	return nil
}

func (m *modem) writeUpdate(fwfile string) error {
	_, err := m.write("UPDATE\r")
	if err != nil {
		_, _ = m.write("\033", true) // send ESC to cancel the update
		return err
	}
	answer, err := m.write("\006", true)
	if err != nil {
		_, _ = m.write("\033", true) // send ESC to cancel the update
		return err
	}

	log.Debugf("flash stamp: % X", binary.LittleEndian.Uint32(answer[2:6]))
	flashId := binary.LittleEndian.Uint16(answer[0:2])
	log.Debugf("flash id: % X", flashId)
	if flashId != 0xa41f && flashId != 0x5b1f && flashId != 0xda1f {
		_, _ = m.write("\033", true) // send ESC to cancel the update
		return errors.New("wrong flash id")
	}
	r, err := os.Open(fwfile)
	if err != nil {
		_, _ = m.write("\033", true) // send ESC to cancel the update
		return err
	}
	fstat, _ := r.Stat()
	fsize := fstat.Size()
	_ = r.Close()

	fwblob, err := ioutil.ReadFile(fwfile)
	if err != nil {
		_, _ = m.write("\033", true) // send ESC to cancel the update
		return err
	}
	//	fmt.Println(fsize)
	chunks := uint16(fsize / 256)
	if fsize%256 != 0 {
		chunks++
	}

	// send ACK
	_, err = m.write("\006", true)
	if err != nil {
		_, _ = m.write("\033", true) // send ESC to cancel the update
		return err
	}

	// send number of chunks
	a := make([]byte, 2)
	binary.BigEndian.PutUint16(a, chunks)
	res, err := m.write(string(a), true)
	if err != nil || string(res) != "\006" { //no ACK
		_, _ = m.write("\033", true) // send ESC to cancel the update
		return err
	}

	bar := progressbar.Default(int64(chunks), "flashing chunk")
	var sendbuff string = ""
	for i := 0; i < int(chunks); i++ {
		_ = bar.Add(1)
		//log.Debugf("Sending chunk %d", i)
		if i*CHUNKSIZE+CHUNKSIZE > len(fwblob) {
			nullbytes := make([]byte, CHUNKSIZE-len(fwblob[(i*CHUNKSIZE):]))
			sendbuff = string(append(fwblob[(i*CHUNKSIZE):], nullbytes...))
		} else {
			sendbuff = string(fwblob[i*CHUNKSIZE : i*CHUNKSIZE+CHUNKSIZE])
		}
		res, err = m.write(sendbuff, true)
		if err != nil || string(res) != "\006" { //no ACK
			_, _ = m.write("\033", true) // send ESC to cancel the update
			log.Errorf("Error in Handshake! Rx: %s", hex.EncodeToString(res))
			return err
		}
	}
	log.Infof("Firmware file %s successfully written", fwfile)
	_, err = m.write("\r", true)
	if err != nil {
		log.Error("Error in Handshake: cannot send final cr")
	}
	return nil
}

func (m *modem) checkFirmwareFits(fwfile string) error {
	answer, err := m.write("ver ##\r")
	if err != nil {
		log.Errorf("Error while reading the modem version: %s", err)
		return err
	}
	re := regexp.MustCompile(`\w#1`)
	version := strings.ReplaceAll(string(re.Find(answer)), "#1", "")
	type modemtype struct {
		ext, modem string
	}
	var extensions = map[string]modemtype{
		"A": {".pt2", "PTC-II"},
		"B": {".pro", "PTC-IIpro"},
		"C": {".pte", "PTC-IIe"},
		"D": {".pex", "PTC-IIex"},
		"E": {".ptu", "PTC-IIusb"},
		"F": {".ptn", "PTC-IInet"},
		"H": {".dr7", "DR-7800"},
		"I": {".dr7", "DR-7400"},
		"K": {".pr7", "DR-7000"},
		"L": {".p3u", "PTC-IIIusb"},
		"T": {".ptx", "PTC-IIItrx"},
	}

	modem, exists := extensions[version]
	if exists {
		if modem.ext == path.Ext(fwfile) {
			log.Infof("Firmware %s matches detected modem type %s.", fwfile, modem.modem)
			return nil
		} else {
			log.Fatalf("Firmware %s does NOT match detected modem type %s.", fwfile, modem.modem)
			return errors.New("Firmware and modem type do not match")
		}
	} else {
		log.Fatal("Cannot detect modem type.")
		return errors.New("Cannot detect modem type")
	}

}

func Update(serport string, baudrate int, fwfile string) error {
	m, err := initmodem(serport, baudrate)
	defer m.port.Close()
	if err != nil {
		return errors.New("FEHLER in Update")
	}
	sn, err := m.getSerNum()
	if len(sn) < 6 {
		// can't be a valid serial number, something's wrong, bump out here
		log.Errorf("ERROR: got invalid serial number: %s", sn)
		return err
	} else {
		log.Infof("Serial number of your modem is: %s", sn)
	}
	if m.setDateTime() != nil {
		return err
	}
	if m.checkFirmwareFits(fwfile) != nil {
		return err
	}
	if m.writeUpdate(fwfile) != nil {
		return err
	}

	return nil
}