// Package uc8151 implements a driver for e-ink displays controlled by UC8151
//
// Inspired by https://github.com/pimoroni/pimoroni-pico/blob/main/drivers/uc8151/uc8151.cpp
// Datasheet: https://www.buydisplay.com/download/ic/UC8151C.pdf
package uc8151 // import "tinygo.org/x/drivers/uc8151"

import (
	"errors"
	"image/color"
	"machine"
	"time"

	"tinygo.org/x/drivers"
)

type Config struct {
	Width    int16
	Height   int16
	Rotation Rotation // Rotation is clock-wise
	Speed    Speed    // Value from DEFAULT, MEDIUM, FAST, TURBO
	Blocking bool
}

type Device struct {
	bus          drivers.SPI
	cs           machine.Pin
	dc           machine.Pin
	rst          machine.Pin
	busy         machine.Pin
	width        int16
	height       int16
	buffer       []uint8
	bufferLength uint32
	rotation     Rotation
	speed        Speed
	blocking     bool
}

type Rotation uint8
type Speed uint8

// New returns a new epd2in13x driver. Pass in a fully configured SPI bus.
func New(bus drivers.SPI, csPin, dcPin, rstPin, busyPin machine.Pin) Device {
	csPin.Configure(machine.PinConfig{Mode: machine.PinOutput})
	dcPin.Configure(machine.PinConfig{Mode: machine.PinOutput})
	rstPin.Configure(machine.PinConfig{Mode: machine.PinOutput})
	busyPin.Configure(machine.PinConfig{Mode: machine.PinInput})
	return Device{
		bus:  bus,
		cs:   csPin,
		dc:   dcPin,
		rst:  rstPin,
		busy: busyPin,
	}
}

// Configure sets up the device.
func (d *Device) Configure(cfg Config) {
	if cfg.Width != 0 {
		d.width = cfg.Width
	} else {
		d.width = EPD_WIDTH
	}
	if cfg.Height != 0 {
		d.height = cfg.Height
	} else {
		d.height = EPD_HEIGHT
	}
	d.rotation = cfg.Rotation
	d.speed = cfg.Speed
	d.blocking = cfg.Blocking
	d.bufferLength = (uint32(d.width) * uint32(d.height)) / 8
	d.buffer = make([]uint8, d.bufferLength)
	for i := uint32(0); i < d.bufferLength; i++ {
		d.buffer[i] = 0xFF
	}

	d.Reset()

	d.SendCommand(PSR)
	if d.speed == 0 {
		d.SendData(RES_128x296 | LUT_OTP | FORMAT_BW | SHIFT_RIGHT | BOOSTER_ON | RESET_NONE | SCAN_UP)
	} else {
		d.SendData(RES_128x296 | LUT_REG | FORMAT_BW | SHIFT_RIGHT | BOOSTER_ON | RESET_NONE | SCAN_UP)
	}

	d.SetLUT(d.speed)

	d.SendCommand(PWR)
	d.SendData(VDS_INTERNAL | VDG_INTERNAL)
	d.SendData(VCOM_VG | VGHL_16V)
	d.SendData(0x2B)
	d.SendData(0x2B)
	d.SendData(0x2B)

	d.SendCommand(PON)
	d.WaitUntilIdle()

	d.SendCommand(BTST)
	d.SendData(START_10MS | STRENGTH_3 | OFF_6_58US)
	d.SendData(START_10MS | STRENGTH_3 | OFF_6_58US)
	d.SendData(START_10MS | STRENGTH_3 | OFF_6_58US)

	d.SendCommand(PFS)
	d.SendData(FRAMES_1)

	d.SendCommand(TSE)
	d.SendData(TEMP_INTERNAL | OFFSET_0)

	d.SendCommand(TCON)
	d.SendData(0x22)

	d.SendCommand(CDI)
	d.SendData(0x4C) // 4C  //5C

	d.SendCommand(PLL)
	d.SendData(HZ_100)

	d.SendCommand(POF)
	d.WaitUntilIdle()

}

// Reset resets the device
func (d *Device) Reset() {
	d.rst.Low()
	time.Sleep(10 * time.Millisecond)
	d.rst.High()
	time.Sleep(10 * time.Millisecond)
	d.WaitUntilIdle()
}

// PowerOff power off the device
func (d *Device) PowerOff() {
	d.SendCommand(POF)
}

// SendCommand sends a command to the display
func (d *Device) SendCommand(command uint8) {
	d.sendDataCommand(true, command)
}

// SendData sends a data byte to the display
func (d *Device) SendData(data uint8) {
	d.sendDataCommand(false, data)
}

// sendDataCommand sends image data or a command to the screen
func (d *Device) sendDataCommand(isCommand bool, data uint8) {
	if isCommand {
		d.dc.Low()
	} else {
		d.dc.High()
	}
	d.cs.Low()
	d.bus.Transfer(data)
	d.cs.High()
}

// SetPixel modifies the internal buffer in a single pixel.
// The display have 2 colors: black and white
// We use RGBA(0,0,0, 255) as white (transparent)
// Anything else as black
func (d *Device) SetPixel(x int16, y int16, c color.RGBA) {
	x, y = d.xy(x, y)

	if x < 0 || x >= d.width || y < 0 || y >= d.height {
		return
	}
	byteIndex := x/8 + y*(d.width/8)
	if c.R == 0 && c.G == 0 && c.B == 0 { // TRANSPARENT / WHITE
		d.buffer[byteIndex] &^= 0x80 >> uint8(x%8)
	} else { // WHITE / EMPTY
		d.buffer[byteIndex] |= 0x80 >> uint8(x%8)
	}
}

// Display sends the buffer to the screen.
func (d *Device) Display() error {
	if d.blocking {
		d.WaitUntilIdle()
	}
	d.SendCommand(PON)
	d.SendCommand(PTOU)
	d.SendCommand(DTM2)
	for i := uint32(0); i < d.bufferLength; i++ {
		d.SendData(d.buffer[i])
	}

	d.SendCommand(DSP)
	d.SendCommand(DRF)
	if d.blocking {
		d.WaitUntilIdle()
		d.PowerOff()
	}
	return nil
}

// DisplayRect sends only an area of the buffer to the screen.
// The rectangle points need to be a multiple of 8 in the screen.
// They might not work as expected if the screen is rotated.
func (d *Device) DisplayRect(x int16, y int16, width int16, height int16) error {
	if d.blocking {
		d.WaitUntilIdle()
	}

	x, y = d.xy(x, y)
	if x < 0 || y < 0 || x >= d.width || y >= d.height || width < 0 || height < 0 {
		return errors.New("wrong rectangle")
	}
	if d.rotation == ROTATION_90 {
		width, height = height, width
		x -= width
	} else if d.rotation == ROTATION_180 {
		x -= width - 1
		y -= height - 1
	} else if d.rotation == ROTATION_270 {
		width, height = height, width
		y -= height
	}
	x &= 0xF8
	width &= 0xF8
	width = x + width // reuse variables
	if width >= d.width {
		width = d.width
	}
	height = y + height
	if height > d.height {
		height = d.height
	}

	d.SendCommand(PON)
	d.SendCommand(PTIN)
	d.SendCommand(PTL)

	d.SendData(uint8(x))
	d.SendData(uint8(x+width-1) | 0x07)
	d.SendData(uint8(y >> 8))
	d.SendData(uint8(y))
	d.SendData(uint8((y + height - 1) >> 8))
	d.SendData(uint8(y + height - 1))
	d.SendData(0x01)

	d.SendCommand(DTM2)
	x = x / 8
	width = width / 8
	for ; y < height; y++ {
		for i := x; i < width; i++ {
			d.SendData(d.buffer[i+y*(d.width/8)])
		}
	}

	d.SendCommand(DSP)
	d.SendCommand(DRF)

	if d.blocking {
		d.WaitUntilIdle()
		d.PowerOff()
	}
	return nil
}

// ClearDisplay erases the device SRAM
func (d *Device) ClearDisplay() {
	d.ClearBuffer()
	d.Display()
}

// WaitUntilIdle waits until the display is ready
func (d *Device) WaitUntilIdle() {
	for !d.busy.Get() {
		time.Sleep(100 * time.Millisecond)
	}
}

// IsBusy returns the busy status of the display
func (d *Device) IsBusy() bool {
	return d.busy.Get()
}

// ClearBuffer sets the buffer to 0xFF (white)
func (d *Device) ClearBuffer() {
	for i := uint32(0); i < d.bufferLength; i++ {
		d.buffer[i] = 0x00
	}
}

// Size returns the current size of the display.
func (d *Device) Size() (w, h int16) {
	if d.rotation == ROTATION_90 || d.rotation == ROTATION_270 {
		return d.height, d.width
	}
	return d.width, d.height
}

// SetRotation changes the rotation (clock-wise) of the device
func (d *Device) SetRotation(rotation Rotation) {
	d.rotation = rotation
}

// SetBlocking changes the blocking flag of the device
func (d *Device) SetBlocking(blocking bool) {
	d.blocking = blocking
}

// xy chages the coordinates according to the rotation
func (d *Device) xy(x, y int16) (int16, int16) {
	switch d.rotation {
	case NO_ROTATION:
		return x, y
	case ROTATION_90:
		return d.width - y - 1, x
	case ROTATION_180:
		return d.width - x - 1, d.height - y - 1
	case ROTATION_270:
		return y, d.height - x - 1
	}
	return x, y
}

// SetSpeed changes the refresh speed of the device (the display needs to re-configure)
func (d *Device) SetSpeed(speed Speed) {
	d.Configure(Config{
		Width:    d.width,
		Height:   d.height,
		Rotation: d.rotation,
		Speed:    speed,
		Blocking: d.blocking,
	})
}

// Invert sets the display' invert mode
func (d *Device) Invert(invert bool) {
	if invert {
		d.SendData(0x5C)
	} else {
		d.SendData(0x4C)
	}
}

// SetLUT sets the look up tables for full or partial updates
func (d *Device) SetLUT(speed Speed) {
	switch speed {
	case MEDIUM:
		var lut = [44]uint8{
			0x00, 0x16, 0x16, 0x0d, 0x00, 0x01,
			0x00, 0x23, 0x23, 0x00, 0x00, 0x02,
			0x00, 0x16, 0x16, 0x0d, 0x00, 0x01,
			0x00, 0x00, 0x00, 0x00, 0x00, 0x00,
			0x00, 0x00, 0x00, 0x00, 0x00, 0x00,
			0x00, 0x00, 0x00, 0x00, 0x00, 0x00,
			0x00, 0x00, 0x00, 0x00, 0x00, 0x00,
			0x00, 0x00,
		}
		d.SendCommand(LUT_VCOM)
		for i := 0; i < 44; i++ {
			d.SendData(lut[i])
		}
		lut = [44]uint8{
			0x54, 0x16, 0x16, 0x0d, 0x00, 0x01,
			0x60, 0x23, 0x23, 0x00, 0x00, 0x02,
			0xa8, 0x16, 0x16, 0x0d, 0x00, 0x01,
			0x00, 0x00, 0x00, 0x00, 0x00, 0x00,
			0x00, 0x00, 0x00, 0x00, 0x00, 0x00,
			0x00, 0x00, 0x00, 0x00, 0x00, 0x00,
			0x00, 0x00, 0x00, 0x00, 0x00, 0x00}
		d.SendCommand(LUT_WW)
		// do not send last two bytes
		for i := 0; i < 42; i++ {
			d.SendData(lut[i])
		}

		lut = [44]uint8{
			0x54, 0x16, 0x16, 0x0d, 0x00, 0x01,
			0x60, 0x23, 0x23, 0x00, 0x00, 0x02,
			0xa8, 0x16, 0x16, 0x0d, 0x00, 0x01,
			0x00, 0x00, 0x00, 0x00, 0x00, 0x00,
			0x00, 0x00, 0x00, 0x00, 0x00, 0x00,
			0x00, 0x00, 0x00, 0x00, 0x00, 0x00,
			0x00, 0x00, 0x00, 0x00, 0x00, 0x00}
		d.SendCommand(LUT_BW)
		// do not send last two bytes
		for i := 0; i < 42; i++ {
			d.SendData(lut[i])
		}

		lut = [44]uint8{
			0xa8, 0x16, 0x16, 0x0d, 0x00, 0x01,
			0x60, 0x23, 0x23, 0x00, 0x00, 0x02,
			0x54, 0x16, 0x16, 0x0d, 0x00, 0x01,
			0x00, 0x00, 0x00, 0x00, 0x00, 0x00,
			0x00, 0x00, 0x00, 0x00, 0x00, 0x00,
			0x00, 0x00, 0x00, 0x00, 0x00, 0x00,
			0x00, 0x00, 0x00, 0x00, 0x00, 0x00}
		d.SendCommand(LUT_WB)
		// do not send last two bytes
		for i := 0; i < 42; i++ {
			d.SendData(lut[i])
		}

		lut = [44]uint8{
			0xa8, 0x16, 0x16, 0x0d, 0x00, 0x01,
			0x60, 0x23, 0x23, 0x00, 0x00, 0x02,
			0x54, 0x16, 0x16, 0x0d, 0x00, 0x01,
			0x00, 0x00, 0x00, 0x00, 0x00, 0x00,
			0x00, 0x00, 0x00, 0x00, 0x00, 0x00,
			0x00, 0x00, 0x00, 0x00, 0x00, 0x00,
			0x00, 0x00, 0x00, 0x00, 0x00, 0x00}
		d.SendCommand(LUT_BB)
		// do not send last two bytes
		for i := 0; i < 42; i++ {
			d.SendData(lut[i])
		}

		break
	case FAST:
		var lut = [44]uint8{
			0x00, 0x04, 0x04, 0x07, 0x00, 0x01,
			0x00, 0x0c, 0x0c, 0x00, 0x00, 0x02,
			0x00, 0x04, 0x04, 0x07, 0x00, 0x02,
			0x00, 0x00, 0x00, 0x00, 0x00, 0x00,
			0x00, 0x00, 0x00, 0x00, 0x00, 0x00,
			0x00, 0x00, 0x00, 0x00, 0x00, 0x00,
			0x00, 0x00, 0x00, 0x00, 0x00, 0x00,
			0x00, 0x00,
		}
		d.SendCommand(LUT_VCOM)
		for i := 0; i < 44; i++ {
			d.SendData(lut[i])
		}
		lut = [44]uint8{
			0x54, 0x04, 0x04, 0x07, 0x00, 0x01,
			0x60, 0x0c, 0x0c, 0x00, 0x00, 0x02,
			0xa8, 0x04, 0x04, 0x07, 0x00, 0x02,
			0x00, 0x00, 0x00, 0x00, 0x00, 0x00,
			0x00, 0x00, 0x00, 0x00, 0x00, 0x00,
			0x00, 0x00, 0x00, 0x00, 0x00, 0x00,
			0x00, 0x00, 0x00, 0x00, 0x00, 0x00}
		d.SendCommand(LUT_WW)
		// do not send last two bytes
		for i := 0; i < 42; i++ {
			d.SendData(lut[i])
		}

		lut = [44]uint8{
			0x54, 0x04, 0x04, 0x07, 0x00, 0x01,
			0x60, 0x0c, 0x0c, 0x00, 0x00, 0x02,
			0xa8, 0x04, 0x04, 0x07, 0x00, 0x02,
			0x00, 0x00, 0x00, 0x00, 0x00, 0x00,
			0x00, 0x00, 0x00, 0x00, 0x00, 0x00,
			0x00, 0x00, 0x00, 0x00, 0x00, 0x00,
			0x00, 0x00, 0x00, 0x00, 0x00, 0x00}
		d.SendCommand(LUT_BW)
		// do not send last two bytes
		for i := 0; i < 42; i++ {
			d.SendData(lut[i])
		}

		lut = [44]uint8{
			0xa8, 0x04, 0x04, 0x07, 0x00, 0x01,
			0x60, 0x0c, 0x0c, 0x00, 0x00, 0x02,
			0x54, 0x04, 0x04, 0x07, 0x00, 0x02,
			0x00, 0x00, 0x00, 0x00, 0x00, 0x00,
			0x00, 0x00, 0x00, 0x00, 0x00, 0x00,
			0x00, 0x00, 0x00, 0x00, 0x00, 0x00,
			0x00, 0x00, 0x00, 0x00, 0x00, 0x00}
		d.SendCommand(LUT_WB)
		// do not send last two bytes
		for i := 0; i < 42; i++ {
			d.SendData(lut[i])
		}

		lut = [44]uint8{
			0xa8, 0x04, 0x04, 0x07, 0x00, 0x01,
			0x60, 0x0c, 0x0c, 0x00, 0x00, 0x02,
			0x54, 0x04, 0x04, 0x07, 0x00, 0x02,
			0x00, 0x00, 0x00, 0x00, 0x00, 0x00,
			0x00, 0x00, 0x00, 0x00, 0x00, 0x00,
			0x00, 0x00, 0x00, 0x00, 0x00, 0x00,
			0x00, 0x00, 0x00, 0x00, 0x00, 0x00}
		d.SendCommand(LUT_BB)
		// do not send last two bytes
		for i := 0; i < 42; i++ {
			d.SendData(lut[i])
		}

		break
	case TURBO:
		var lut = [44]uint8{
			0x00, 0x01, 0x01, 0x02, 0x00, 0x01,
			0x00, 0x02, 0x02, 0x00, 0x00, 0x02,
			0x00, 0x02, 0x02, 0x03, 0x00, 0x02,
			0x00, 0x00, 0x00, 0x00, 0x00, 0x00,
			0x00, 0x00, 0x00, 0x00, 0x00, 0x00,
			0x00, 0x00, 0x00, 0x00, 0x00, 0x00,
			0x00, 0x00, 0x00, 0x00, 0x00, 0x00,
			0x00, 0x00,
		}
		d.SendCommand(LUT_VCOM)
		for i := 0; i < 44; i++ {
			d.SendData(lut[i])
		}
		lut = [44]uint8{
			0x54, 0x01, 0x01, 0x02, 0x00, 0x01,
			0x60, 0x02, 0x02, 0x00, 0x00, 0x02,
			0xa8, 0x02, 0x02, 0x03, 0x00, 0x02,
			0x00, 0x00, 0x00, 0x00, 0x00, 0x00,
			0x00, 0x00, 0x00, 0x00, 0x00, 0x00,
			0x00, 0x00, 0x00, 0x00, 0x00, 0x00,
			0x00, 0x00, 0x00, 0x00, 0x00, 0x00}
		d.SendCommand(LUT_WW)
		// do not send last two bytes
		for i := 0; i < 42; i++ {
			d.SendData(lut[i])
		}

		lut = [44]uint8{
			0x54, 0x01, 0x01, 0x02, 0x00, 0x01,
			0x60, 0x02, 0x02, 0x00, 0x00, 0x02,
			0xa8, 0x02, 0x02, 0x03, 0x00, 0x02,
			0x00, 0x00, 0x00, 0x00, 0x00, 0x00,
			0x00, 0x00, 0x00, 0x00, 0x00, 0x00,
			0x00, 0x00, 0x00, 0x00, 0x00, 0x00,
			0x00, 0x00, 0x00, 0x00, 0x00, 0x00}
		d.SendCommand(LUT_BW)
		// do not send last two bytes
		for i := 0; i < 42; i++ {
			d.SendData(lut[i])
		}

		lut = [44]uint8{
			0xa8, 0x01, 0x01, 0x02, 0x00, 0x01,
			0x60, 0x02, 0x02, 0x00, 0x00, 0x02,
			0x54, 0x02, 0x02, 0x03, 0x00, 0x02,
			0x00, 0x00, 0x00, 0x00, 0x00, 0x00,
			0x00, 0x00, 0x00, 0x00, 0x00, 0x00,
			0x00, 0x00, 0x00, 0x00, 0x00, 0x00,
			0x00, 0x00, 0x00, 0x00, 0x00, 0x00}
		d.SendCommand(LUT_WB)
		// do not send last two bytes
		for i := 0; i < 42; i++ {
			d.SendData(lut[i])
		}

		lut = [44]uint8{
			0xa8, 0x01, 0x01, 0x02, 0x00, 0x01,
			0x60, 0x02, 0x02, 0x00, 0x00, 0x02,
			0x54, 0x02, 0x02, 0x03, 0x00, 0x02,
			0x00, 0x00, 0x00, 0x00, 0x00, 0x00,
			0x00, 0x00, 0x00, 0x00, 0x00, 0x00,
			0x00, 0x00, 0x00, 0x00, 0x00, 0x00,
			0x00, 0x00, 0x00, 0x00, 0x00, 0x00}
		d.SendCommand(LUT_BB)
		// do not send last two bytes
		for i := 0; i < 42; i++ {
			d.SendData(lut[i])
		}

		break
	default:
		var lut = [44]uint8{
			0x00, 0x64, 0x64, 0x37, 0x00, 0x01,
			0x00, 0x8c, 0x8c, 0x00, 0x00, 0x04,
			0x00, 0x64, 0x64, 0x37, 0x00, 0x01,
			0x00, 0x00, 0x00, 0x00, 0x00, 0x00,
			0x00, 0x00, 0x00, 0x00, 0x00, 0x00,
			0x00, 0x00, 0x00, 0x00, 0x00, 0x00,
			0x00, 0x00, 0x00, 0x00, 0x00, 0x00,
			0x00, 0x00,
		}
		d.SendCommand(LUT_VCOM)
		for i := 0; i < 44; i++ {
			d.SendData(lut[i])
		}
		lut = [44]uint8{
			0x54, 0x64, 0x64, 0x37, 0x00, 0x01,
			0x60, 0x8c, 0x8c, 0x00, 0x00, 0x04,
			0xa8, 0x64, 0x64, 0x37, 0x00, 0x01,
			0x00, 0x00, 0x00, 0x00, 0x00, 0x00,
			0x00, 0x00, 0x00, 0x00, 0x00, 0x00,
			0x00, 0x00, 0x00, 0x00, 0x00, 0x00,
			0x00, 0x00, 0x00, 0x00, 0x00, 0x00}
		d.SendCommand(LUT_WW)
		// do not send last two bytes
		for i := 0; i < 42; i++ {
			d.SendData(lut[i])
		}

		lut = [44]uint8{
			0x54, 0x64, 0x64, 0x37, 0x00, 0x01,
			0x60, 0x8c, 0x8c, 0x00, 0x00, 0x04,
			0xa8, 0x64, 0x64, 0x37, 0x00, 0x01,
			0x00, 0x00, 0x00, 0x00, 0x00, 0x00,
			0x00, 0x00, 0x00, 0x00, 0x00, 0x00,
			0x00, 0x00, 0x00, 0x00, 0x00, 0x00,
			0x00, 0x00, 0x00, 0x00, 0x00, 0x00}
		d.SendCommand(LUT_BW)
		// do not send last two bytes
		for i := 0; i < 42; i++ {
			d.SendData(lut[i])
		}

		lut = [44]uint8{
			0xa8, 0x64, 0x64, 0x37, 0x00, 0x01,
			0x60, 0x8c, 0x8c, 0x00, 0x00, 0x04,
			0x54, 0x64, 0x64, 0x37, 0x00, 0x01,
			0x00, 0x00, 0x00, 0x00, 0x00, 0x00,
			0x00, 0x00, 0x00, 0x00, 0x00, 0x00,
			0x00, 0x00, 0x00, 0x00, 0x00, 0x00,
			0x00, 0x00, 0x00, 0x00, 0x00, 0x00}
		d.SendCommand(LUT_WB)
		// do not send last two bytes
		for i := 0; i < 42; i++ {
			d.SendData(lut[i])
		}

		lut = [44]uint8{
			0xa8, 0x64, 0x64, 0x37, 0x00, 0x01,
			0x60, 0x8c, 0x8c, 0x00, 0x00, 0x04,
			0x54, 0x64, 0x64, 0x37, 0x00, 0x01,
			0x00, 0x00, 0x00, 0x00, 0x00, 0x00,
			0x00, 0x00, 0x00, 0x00, 0x00, 0x00,
			0x00, 0x00, 0x00, 0x00, 0x00, 0x00,
			0x00, 0x00, 0x00, 0x00, 0x00, 0x00}
		d.SendCommand(LUT_BB)
		// do not send last two bytes
		for i := 0; i < 42; i++ {
			d.SendData(lut[i])
		}

		break
	}
}