package parallel8bit

import (
	"fmt"
	"log"
	"time"

	"github.com/stianeikeland/go-rpio/v4"
)

const (
	adressWriteTimeout = 50 * time.Nanosecond   // 40
	dataStrobeTimeout  = 200 * time.Nanosecond  // (Data transfer) 160
	dataReadTimeout    = 400 * time.Nanosecond  // 300
	gapTimeout         = 2000 * time.Nanosecond // TIM // 2000
	maxWaitCycles      = 100
)

// Interface for MT displays (do not set cristals bits)
type Device interface {
	Reset()
	WriteByte(b byte, cd rpio.State)
	WriteBytes(b []byte, cd rpio.State)
	ReadByte(cd rpio.State) byte

	Pins() DevicePins

	WaitReady() error
}

type DevicePins struct {
	// GPIO pins
	PinA0  rpio.Pin
	PinRW  rpio.Pin
	PinE   rpio.Pin
	PinDB0 rpio.Pin
	PinDB1 rpio.Pin
	PinDB2 rpio.Pin
	PinDB3 rpio.Pin
	PinDB4 rpio.Pin
	PinDB5 rpio.Pin
	PinDB6 rpio.Pin
	PinDB7 rpio.Pin
}

type device struct {
	logger *log.Logger

	isBusOutput bool
	DevicePins
}

func New(logger *log.Logger, pins DevicePins) Device {
	return &device{
		logger:     logger,
		DevicePins: pins,
	}
}

func (d *device) Pins() DevicePins {
	return d.DevicePins
}

func (d *device) Reset() {
	d.PinA0.Output()
	d.PinRW.Output()
	d.PinE.Output()
	d.busOutput()
	d.PinA0.Low()
	d.PinRW.Low()
	d.PinE.High()
	d.PinDB0.Low()
	d.PinDB1.Low()
	d.PinDB2.Low()
	d.PinDB3.Low()
	d.PinDB4.Low()
	d.PinDB5.Low()
	d.PinDB6.Low()
	d.PinDB7.Low()
}

func (d *device) WriteByte(b byte, cd rpio.State) {
	d.busOutput()
	d.PinRW.Low() // We write
	d.PinA0.Write(cd)

	// Write bus
	d.PinDB0.Write(rpio.State((b >> 0) & 1))
	d.PinDB1.Write(rpio.State((b >> 1) & 1))
	d.PinDB2.Write(rpio.State((b >> 2) & 1))
	d.PinDB3.Write(rpio.State((b >> 3) & 1))
	d.PinDB4.Write(rpio.State((b >> 4) & 1))
	d.PinDB5.Write(rpio.State((b >> 5) & 1))
	d.PinDB6.Write(rpio.State((b >> 6) & 1))
	d.PinDB7.Write(rpio.State((b >> 7) & 1))

	time.Sleep(adressWriteTimeout)

	d.PinE.Low() // Strobe start
	time.Sleep(dataStrobeTimeout)
	d.PinE.High() // Strobe end

	time.Sleep(gapTimeout - dataStrobeTimeout - adressWriteTimeout)
}

func (d *device) WriteBytes(b []byte, cd rpio.State) {
	d.busOutput()
	d.PinRW.Low() // We write
	d.PinA0.Write(cd)

	// Write bus
	d.PinDB0.Write(rpio.State(b[0]))
	d.PinDB1.Write(rpio.State(b[1]))
	d.PinDB2.Write(rpio.State(b[2]))
	d.PinDB3.Write(rpio.State(b[3]))
	d.PinDB4.Write(rpio.State(b[4]))
	d.PinDB5.Write(rpio.State(b[5]))
	d.PinDB6.Write(rpio.State(b[6]))
	d.PinDB7.Write(rpio.State(b[7]))

	time.Sleep(adressWriteTimeout)

	d.PinE.Low() // Strobe start
	time.Sleep(dataStrobeTimeout)
	d.PinE.High() // Strobe end

	time.Sleep(gapTimeout - dataStrobeTimeout - adressWriteTimeout)
}

func (d *device) ReadByte(cd rpio.State) byte {
	// Setup
	var b byte
	d.PinA0.Write(cd)
	d.PinRW.High() // We read
	d.busInput()

	// Strobe start
	time.Sleep(adressWriteTimeout)
	d.PinE.Low()
	time.Sleep(dataReadTimeout)

	// Read
	b = uint8(d.PinDB0.Read()) |
		(uint8(d.PinDB1.Read()) << 1) |
		(uint8(d.PinDB2.Read()) << 2) |
		(uint8(d.PinDB3.Read()) << 3) |
		(uint8(d.PinDB4.Read()) << 4) |
		(uint8(d.PinDB5.Read()) << 5) |
		(uint8(d.PinDB6.Read()) << 6) |
		(uint8(d.PinDB7.Read()) << 7)

	// Strobe end
	d.PinE.High()
	time.Sleep(gapTimeout - dataReadTimeout - adressWriteTimeout)
	return b
}

func (d *device) WaitReady() error {
	d.busInput()   // Set bus to input
	d.PinA0.Low()  // Status
	d.PinRW.High() // We read
	time.Sleep(adressWriteTimeout)

	// Strobe start
	d.PinE.Low()
	time.Sleep(dataReadTimeout)

	// Wait status flag drop
	ok := false
	for counter := 0; counter < maxWaitCycles; counter++ {
		if d.PinDB7.Read() != rpio.High {
			//d.logger.Printf("BUS:%d%d%d%d%d%d%d%d\n", d.PinDB0.Read(), d.PinDB1.Read(), d.PinDB2.Read(), d.PinDB3.Read(), d.PinDB4.Read(), d.PinDB5.Read(), d.PinDB6.Read(), d.PinDB7.Read())
			ok = true
			break
		}
		fmt.Print(".")
	}
	if !ok {
		return fmt.Errorf("busy timeout")
	}

	// Strobe end
	d.PinE.High()
	time.Sleep(gapTimeout - dataReadTimeout - adressWriteTimeout)
	// d.logger.Println("Ready")
	return nil
}

// Set bus Pins to output
func (d *device) busOutput() {
	if d.isBusOutput {
		return
	}
	d.PinDB0.Output()
	d.PinDB1.Output()
	d.PinDB2.Output()
	d.PinDB3.Output()
	d.PinDB4.Output()
	d.PinDB5.Output()
	d.PinDB6.Output()
	d.PinDB7.Output()
	d.isBusOutput = true
}

func (d *device) busInput() {
	if !d.isBusOutput {
		return
	}
	d.PinDB0.Input()
	d.PinDB1.Input()
	d.PinDB2.Input()
	d.PinDB3.Input()
	d.PinDB4.Input()
	d.PinDB5.Input()
	d.PinDB6.Input()
	d.PinDB7.Input()
	d.isBusOutput = false
}