// Package is31fl3731 provides a driver for the Lumissil IS31FL3731 matrix LED
// driver.
//
// Driver supports following layouts:
//   - any custom LED matrix layout
//   - Adafruit 15x7 CharliePlex LED Matrix FeatherWing (CharlieWing)
//     https://www.adafruit.com/product/3163
//
// Datasheet:
//
//	https://www.lumissil.com/assets/pdf/core/IS31FL3731_DS.pdf
//
// This driver inspired by Adafruit Python driver:
//
//	https://github.com/adafruit/Adafruit_CircuitPython_IS31FL3731
package is31fl3731

import (
	"fmt"
	"time"

	"tinygo.org/x/drivers"
	"tinygo.org/x/drivers/internal/legacy"
)

// Device implements TinyGo driver for Lumissil IS31FL3731 matrix LED driver
type Device struct {
	Address uint8
	bus     drivers.I2C

	// Currently selected command register (one of the frame registers or the
	// function register)
	selectedCommand uint8
}

// Configure chip for operating as a LED matrix display
func (d *Device) Configure() (err error) {
	// Shutdown software
	err = d.writeFunctionRegister(SET_SHUTDOWN, []byte{SOFTWARE_OFF})
	if err != nil {
		return fmt.Errorf("failed to shutdown: %w", err)
	}

	time.Sleep(time.Millisecond * 10)

	// Wake up software
	err = d.writeFunctionRegister(SET_SHUTDOWN, []byte{SOFTWARE_ON})
	if err != nil {
		return fmt.Errorf("failed to wake up: %w", err)
	}

	// Set display to a picture mode ("auto frame play mode" and "audio frame play
	// mode" are not supported in this version of the driver)
	err = d.writeFunctionRegister(SET_DISPLAY_MODE, []byte{DISPLAY_MODE_PICTURE})
	if err != nil {
		return fmt.Errorf("failed to switch to a picture move: %w", err)
	}

	// Enable LEDs that are present (soldered) on the board. From the datasheet:
	// LEDs which are no connected must be off by LED Control Register (Frame
	// Registers) or it will affect other LEDs
	err = d.enableLEDs()
	if err != nil {
		return fmt.Errorf("failed to enable LEDs: %w", err)
	}

	// Disable audiosync
	err = d.writeFunctionRegister(SET_AUDIOSYNC, []byte{AUDIOSYNC_OFF})
	if err != nil {
		return fmt.Errorf("failed to disable audiosync: %w", err)
	}

	// Clear all frames
	for frame := FRAME_0; frame <= FRAME_7; frame++ {
		err = d.Clear(frame)
		if err != nil {
			return fmt.Errorf("failed to clear frame %d: %w", frame, err)
		}
	}

	// 1st frame is displayed by default
	err = d.SetActiveFrame(FRAME_0)
	if err != nil {
		return fmt.Errorf("failed to set active frame: %w", err)
	}

	return nil
}

// selectCommand selects command register, can be:
// - frame registers 0-7
// - function register
func (d *Device) selectCommand(command uint8) (err error) {
	if command != d.selectedCommand {
		d.selectedCommand = command
		return legacy.WriteRegister(d.bus, d.Address, COMMAND, []byte{command})
	}

	return nil
}

// writeFunctionRegister selects the function register and writes data into it
func (d *Device) writeFunctionRegister(operation uint8, data []byte) (err error) {
	err = d.selectCommand(FUNCTION)
	if err != nil {
		return err
	}

	return legacy.WriteRegister(d.bus, d.Address, operation, data)
}

// enableLEDs enables only LEDs that are soldered on the set board. Enabled
// all 16x9 LEDs by default
func (d *Device) enableLEDs() (err error) {
	for frame := FRAME_0; frame <= FRAME_7; frame++ {
		err = d.selectCommand(frame)
		if err != nil {
			return err
		}

		// Enable every LED (16 columns x 9 rows)
		for i := uint8(0); i < 16; i++ {
			err = legacy.WriteRegister(d.bus, d.Address, i, []byte{0xFF})
			if err != nil {
				return err
			}
		}
	}

	return nil
}

// setPixelPWD sets individual pixel's PWM value [0-255] on the selected frame
func (d *Device) setPixelPWD(frame, n, value uint8) (err error) {
	err = d.selectCommand(frame)
	if err != nil {
		return err
	}

	return legacy.WriteRegister(d.bus, d.Address, LED_PWM_OFFSET+n, []byte{value})
}

// SetActiveFrame sets frame to display with LEDs
func (d *Device) SetActiveFrame(frame uint8) (err error) {
	if frame > FRAME_7 {
		return fmt.Errorf("frame %d is out of valid range [0-7]", frame)
	}

	return d.writeFunctionRegister(SET_ACTIVE_FRAME, []byte{frame})
}

// Fill the whole frame with provided PWM value [0-255]
func (d *Device) Fill(frame, value uint8) (err error) {
	if frame > FRAME_7 {
		return fmt.Errorf("frame %d is out of valid range [0-7]", frame)
	}

	err = d.selectCommand(frame)
	if err != nil {
		return err
	}

	data := make([]byte, 24)
	for i := range data {
		data[i] = value
	}

	for i := uint8(0); i < 6; i++ {
		err = legacy.WriteRegister(d.bus, d.Address, LED_PWM_OFFSET+i*24, data)
		if err != nil {
			return err
		}
	}

	return nil
}

// Clear the whole frame
func (d *Device) Clear(frame uint8) (err error) {
	return d.Fill(frame, 0x00)
}

// DrawPixelIndex draws a single pixel on the selected frame by its index with
// provided PWM value [0-255]
func (d *Device) DrawPixelIndex(frame, index, value uint8) (err error) {
	if frame > FRAME_7 {
		return fmt.Errorf("frame %d is out of valid range [0-7]", frame)
	}

	return d.setPixelPWD(frame, index, value)
}

// DrawPixelXY draws a single pixel on the selected frame by its XY coordinates
// with provided PWM value [0-255]. Raw LEDs layout assumed to be a 16x9 matrix,
// and can be used with any custom board that has IS31FL3731 driver.
func (d *Device) DrawPixelXY(frame, x, y, value uint8) (err error) {
	return d.setPixelPWD(frame, 16*x+y, value)
}

// New creates a raw driver w/o any preset board layout.
// Addresses:
// - 0x74 (AD pin connected to GND)
// - 0x75 (AD pin connected to SCL)
// - 0x76 (AD pin connected to SDA)
// - 0x77 (AD pin connected to VCC)
func New(bus drivers.I2C, address uint8) Device {
	return Device{
		Address: address,
		bus:     bus,
	}
}