package qmkenc

import (
	"encoding/binary"
	"fmt"
	"os"
	"time"

	"github.com/sstallion/go-hid"
)

const encDevUsage uint16 = 0x61
const encDevUsagePage uint16 = 0xFF60

type QEncDevice struct {
	path         string
	serial       string
	product      string
	manufacturer string
	dev          *hid.Device
	bufSize      uint8
	timeout      int
	retryTimeout int
	retryWait    int
	lockfile     string
}

func (d *QEncDevice) GetPath() string         { return d.path }
func (d *QEncDevice) GetSerial() string       { return d.serial }
func (d *QEncDevice) GetProduct() string      { return d.product }
func (d *QEncDevice) GetManufacturer() string { return d.manufacturer }
func (d *QEncDevice) GetBufSize() uint8       { return d.bufSize }

func (d *QEncDevice) Open() (err error) {
	if d.dev, err = hid.OpenPath(d.path); err != nil {
		return fmt.Errorf("Error opening device: '%w'", err)
	}

	if err = d.setBufSize(); err != nil {
		d.Close()
		return err
	}
	return nil
}

func (d *QEncDevice) Close() (err error) {
	if d.lockfile != "" {
		os.Remove(d.lockfile)
	}
	return d.dev.Close()
}

func (d *QEncDevice) SetLockfile(lockfile string) {
	d.lockfile = lockfile
}

func (d *QEncDevice) SendBuffer(data []byte, msg chan string) (ret []byte, err error) {
	startTime := time.Now()
	for {
		ret = make([]byte, d.bufSize)

		if len(data) != int(d.bufSize) {
			return ret, fmt.Errorf("Invalid data size")
		}

		if _, err = d.dev.Write(data); err != nil {
			return ret, fmt.Errorf("Failed to write: '%w'", err)
		}

		if _, err = d.dev.ReadWithTimeout(ret, time.Duration(time.Second*time.Duration(d.timeout))); err != nil {
			return ret, fmt.Errorf("Failed to read: '%w'", err)
		}

		var dataLen uint16
		ret, err = QEncCheckResponse(ret)
		if err != nil {
			qerr := ToQEncError(err)
			if qerr.errCode != QENC_ERR_RETRY {
				return ret, err
			}
			fmt.Println("RETRY")
			dataLen = binary.LittleEndian.Uint16(ret[:2])
			if int(dataLen) == 5 {
				if msg != nil {
					timeout := binary.LittleEndian.Uint32(ret[4:8])
					cmd := QEncCmd(ret[3])
					msg <- fmt.Sprintf("Allow request for '%s' (timeout: %ds)", cmd, timeout)
				}
			}
			time.Sleep(time.Second * time.Duration(d.retryWait))
		} else {
			return ret, err
		}
		if time.Now().Sub(startTime).Seconds() >= float64(d.retryTimeout) {
			qerr := new(QEncError)
			qerr.errCode = QENC_ERR_TIMEOUT
			return ret, qerr
		}
	}
}

func (d *QEncDevice) setBufSize() (err error) {
	if d.bufSize > 0 {
		return nil
	}

	buf_sizes := []int{8, 16, 32, 64, 128}

	for _, bs := range buf_sizes {
		buf_max := bs
		buf := make([]byte, buf_max)
		sbuf := make([]byte, buf_max)

		if copy(sbuf, magicHeader) != 2 {
			return fmt.Errorf("Invalid magic Header")
		}
		sbuf[2] = byte(QENC_CMD_GET_BUFFSIZE)

		if _, err = d.dev.Write(sbuf); err != nil {
			return fmt.Errorf("Failed to write to device: '%w'", err)
		}

		_, err = d.dev.ReadWithTimeout(buf, time.Duration(time.Second*1))
		if err != nil {
			continue
		}
		if buf, err = QEncCheckResponse(buf); err != nil {
			return err
		}

		data_len := binary.LittleEndian.Uint16(buf)
		if int(data_len) != 1 {
			return fmt.Errorf("Invalid data")
		}

		d.bufSize = buf[2]
		return nil
	}
	return fmt.Errorf("Unsupported device: '%w'", err)
}

func (d *QEncDevice) Lock() (err error) {
	if d.lockfile == "" {
		return nil
	}

	for {
		if _, err := os.Stat(d.lockfile); err == nil {
			time.Sleep(time.Second * 1)
			continue
		} else if os.IsNotExist(err) {
			file, err := os.Create(d.lockfile)
			if err != nil {
				return err
			}
			file.Close()
			return nil
		}
	}
}

func (d *QEncDevice) UnLock() {
	if d.lockfile == "" {
		return
	}
	os.Remove(d.lockfile)
}

func QEncNewDevice(path string, bufSize uint8, timeout, retryTimeout, retryWait int, lockfile string) *QEncDevice {
	return &QEncDevice{
		path:         path,
		timeout:      timeout,
		retryTimeout: retryTimeout,
		retryWait:    retryWait,
		bufSize:      bufSize,
		lockfile:     lockfile,
	}
}

func QEncScanDevices(ids ...uint16) (ret []*QEncDevice, err error) {
	vid := uint16(hid.VendorIDAny)
	pid := uint16(hid.ProductIDAny)

	if len(ids) > 2 {
		return ret, fmt.Errorf("To many ids given")
	}

	if len(ids) == 1 {
		vid = ids[0]
	}
	if len(ids) == 2 {
		vid = ids[0]
		pid = ids[1]
	}

	hid.Enumerate(vid, pid,
		func(info *hid.DeviceInfo) error {
			if info.Usage == encDevUsage && info.UsagePage == encDevUsagePage {
				d := QEncDevice{
					path:         info.Path,
					serial:       info.SerialNbr,
					product:      info.ProductStr,
					manufacturer: info.MfrStr,
					timeout:      5,
					retryTimeout: 10,
					retryWait:    1,
				}
				ret = append(ret, &d)
			}
			return nil
		})

	if len(ret) == 0 {
		return ret, fmt.Errorf("No device found")
	}
	return ret, nil
}

func QEncExit() (err error) {
	return hid.Exit()
}