package display

import (
	"context"
	"fmt"
	"image"
	"log"
	"math/rand"
	"sync"
	"sync/atomic"
	"time"

	"gitea.unprism.ru/yotia/display-test/pkg/mt12232a"
)

var _ = rand.Int() // for import existance

const (
	mt12232aW    = 122
	mt12232aH    = 32
	flushChanCap = 24 // Flush channel capacity

	flushUpdateTimeout = 5 * time.Millisecond
)

type displayMt12232a struct {
	logger *log.Logger

	// Some state flags
	isTurnedOn bool

	// Image
	img      *image.Gray
	imgMutex sync.Mutex

	// GPIO pins
	dev mt12232a.Device

	// Flush goroutine
	flushCancel     context.CancelFunc
	pagesFlushFlags atomic.Uint32 // (!use only 8 bits) Every bit corresponds to page/crystal with this number
	flushDone       chan struct{}
}

func newMt12232a(logger *log.Logger) (Display, error) {
	dev, err := mt12232a.New(log.New(logger.Writer(), "display-mt12864 : ", log.LstdFlags))
	if err != nil {
		return nil, fmt.Errorf("mt12864 create: %w", err)
	}
	// Allocate bits
	bits := make([][]byte, 32)
	for i := 0; i < 32; i++ {
		bits[i] = make([]byte, 122)
	}

	ctx, cancel := context.WithCancel(context.Background())
	// Setup submit goroutine
	d := displayMt12232a{
		logger:      logger,
		dev:         dev,
		flushCancel: cancel,
		img:         image.NewGray(image.Rect(0, 0, mt12232aW, mt12232aH)),
		flushDone:   make(chan struct{}), // For waiting flush to finish before exiting
	}
	go d.flushLoop(ctx)

	// Temp debug draw
	//if st0, st1 := d.dev.ReadStatus(0), d.dev.ReadStatus(1); false { //st0&0x20 == 0 && st1&0x20 == 0 {
	//	d.logger.Println("Display is already on")
	//} else {
	d.status("Setup start")
	if err := d.dev.Reset(); err != nil {
		return nil, fmt.Errorf("reset: %w", err)
	}
	d.status("After reset")
	time.Sleep(200 * time.Millisecond)
	if st0, st1 := d.dev.ReadStatus(0), d.dev.ReadStatus(1); st0 == 0 && st1 == 0 {
		return nil, fmt.Errorf("No status response from dysplay")
	}
	if err := d.powerOn(); err != nil {
		return nil, fmt.Errorf("power on: %w", err)
	}
	d.status("Setup end")
	return &d, nil
}

func (d *displayMt12232a) status(label string) {
	//d.logger.Printf("STATUS %s -- L: %08b R: %08b\n", label, d.dev.ReadStatus(0)&0xFF, d.dev.ReadStatus(1)&0xFF)
}

func (d *displayMt12232a) powerOn() error {
	// Reset
	if err := d.dev.WriteCode(0, 0xE2); err != nil {
		return fmt.Errorf("reset: %w", err)
	}
	if err := d.dev.WriteCode(1, 0xE2); err != nil {
		return fmt.Errorf("reset: %w", err)
	}
	// ReadModifyWrite off
	if err := d.dev.WriteCode(0, 0xEE); err != nil {
		return fmt.Errorf("RMW off: %w", err)
	}
	if err := d.dev.WriteCode(1, 0xEE); err != nil {
		return fmt.Errorf("RMW off: %w", err)
	}
	// Turn on common mode
	if err := d.dev.WriteCode(0, 0xA4); err != nil {
		return fmt.Errorf("turn on common mode: %w", err)
	}
	if err := d.dev.WriteCode(1, 0xA4); err != nil {
		return fmt.Errorf("turn on common mode: %w", err)
	}
	// Multiplex 1/32
	if err := d.dev.WriteCode(0, 0xA9); err != nil {
		return fmt.Errorf("multiplex 1/32: %w", err)
	}
	if err := d.dev.WriteCode(1, 0xA9); err != nil {
		return fmt.Errorf("multiplex 1/32: %w", err)
	}
	// Top line to 0
	if err := d.dev.WriteCode(0, 0xC0); err != nil {
		return fmt.Errorf("top line to 0: %w", err)
	}
	if err := d.dev.WriteCode(1, 0xC0); err != nil {
		return fmt.Errorf("top line to 0: %w", err)
	}
	// Invert scan RAM
	if err := d.dev.WriteCode(0, 0xA1); err != nil {
		return fmt.Errorf("inver scan RAM: %w", err)
	}
	if err := d.dev.WriteCode(1, 0xA0); err != nil {
		return fmt.Errorf("inver scan RAM: %w", err)
	}
	// Display on
	if err := d.dev.WriteCode(0, 0xAF); err != nil {
		return fmt.Errorf("display on: %w", err)
	}
	if err := d.dev.WriteCode(1, 0xAF); err != nil {
		return fmt.Errorf("display on: %w", err)
	}

	//time.Sleep(time.Second)

	// Check that crystals are turned on

	// The same but with error
	if d.dev.ReadStatus(0)&0x20 != 0 {
		return fmt.Errorf("Left cristal is off")
	}
	if d.dev.ReadStatus(1)&0x20 != 0 {
		return fmt.Errorf("Right cristal is off")
	}
	d.isTurnedOn = true
	return nil
}

func (d *displayMt12232a) IsReady() error {
	if !d.isTurnedOn {
		return fmt.Errorf("display is turned off")
	}
	return nil
}

func (d *displayMt12232a) Test(ctx context.Context) error {
	start := time.Now()

	for p := 0; p < 4; p++ {
		d.dev.WriteCode(0, byte(p)|0xB8)
		d.dev.WriteCode(0, 0x13)
		for c := 0; c < 61; c++ {
			d.dev.WriteData(0, byte(rand.Int()))
		}
		d.dev.WriteCode(1, byte(p)|0xB8)
		d.dev.WriteCode(1, 0x00)
		for c := 0; c < 61; c++ {
			d.dev.WriteData(1, byte(rand.Int()))
		}
	}

	end := time.Now()
	d.logger.Println(end.Sub(start))
	return nil

}

func (d *displayMt12232a) GetBounds() image.Rectangle {
	return image.Rect(0, 0, 122, 32)
}

func (d *displayMt12232a) FlushFull(img *image.Gray) error {
	st := time.Now()

	for p := byte(0); p < 4; p++ {
		d.dev.WriteCode(0, (3-p)|0xB8)
		d.dev.WriteCode(0, 0x13)
		for c := 0; c < 61; c++ {
			d.dev.WriteDatas(0, []byte{
				img.Pix[int(p<<3+7)*122+c],
				img.Pix[int(p<<3+6)*122+c],
				img.Pix[int(p<<3+5)*122+c],
				img.Pix[int(p<<3+4)*122+c],
				img.Pix[int(p<<3+3)*122+c],
				img.Pix[int(p<<3+2)*122+c],
				img.Pix[int(p<<3+1)*122+c],
				img.Pix[int(p<<3+0)*122+c],
			})
		}
		d.dev.WriteCode(1, (3-p)|0xB8)
		d.dev.WriteCode(1, 0x00)
		for c := 61; c < 122; c++ {
			d.dev.WriteDatas(1, []byte{
				img.Pix[int(p<<3+7)*122+c],
				img.Pix[int(p<<3+6)*122+c],
				img.Pix[int(p<<3+5)*122+c],
				img.Pix[int(p<<3+4)*122+c],
				img.Pix[int(p<<3+3)*122+c],
				img.Pix[int(p<<3+2)*122+c],
				img.Pix[int(p<<3+1)*122+c],
				img.Pix[int(p<<3+0)*122+c],
			})
		}
	}
	d.logger.Println("Flush time:", time.Since(st))
	return nil
}

func (d *displayMt12232a) Flush(crystal, page byte) {
	// !!! TODO Need to update GO to 1.23 to use .Or !!!
	bit := uint32(1 << (crystal*4 + page))
	d.pagesFlushFlags.Store(d.pagesFlushFlags.Load() | bit)
}

func (d *displayMt12232a) FlushByMask(mask uint32) {
	// !!! TODO Need to update GO to 1.23 to use .Or !!!
	d.pagesFlushFlags.Store(d.pagesFlushFlags.Load() | mask)
}

func (d *displayMt12232a) GetFlushMaskBit(crystal, page byte) uint32 {
	return uint32(1 << (crystal*4 + page))
}

func (d *displayMt12232a) Close() error {
	if d.flushCancel != nil {
		d.flushCancel()
		d.flushCancel = nil
		<-d.flushDone
	}
	d.isTurnedOn = false
	return d.dev.Close()
}

func (d *displayMt12232a) flushLoop(ctx context.Context) {

	for {
		select {
		case <-ctx.Done():
			close(d.flushDone)
			return
		case <-time.After(flushUpdateTimeout):
			forUpdate := d.pagesFlushFlags.Swap(0)
			checkBit := uint32(1)
			//st := time.Now()
			d.LockImg()
			for p := byte(0); p < 4; p++ {
				if forUpdate&(checkBit) != 0 {
					d.dev.WriteCode(0, (3-p)|0xB8)
					d.dev.WriteCode(0, 0x13)
					for c := 0; c < 61; c++ {
						d.dev.WriteDatas(0, []byte{
							d.img.Pix[int(p<<3+7)*122+c],
							d.img.Pix[int(p<<3+6)*122+c],
							d.img.Pix[int(p<<3+5)*122+c],
							d.img.Pix[int(p<<3+4)*122+c],
							d.img.Pix[int(p<<3+3)*122+c],
							d.img.Pix[int(p<<3+2)*122+c],
							d.img.Pix[int(p<<3+1)*122+c],
							d.img.Pix[int(p<<3+0)*122+c],
						})
					}
				}
				checkBit = checkBit << 1
			}
			//d.logger.Printf("%08b - %s\n", forUpdate, time.Since(st))
			for p := byte(0); p < 4; p++ {
				if forUpdate&(checkBit) != 0 {
					d.dev.WriteCode(1, (3-p)|0xB8)
					d.dev.WriteCode(1, 0x00)
					for c := 61; c < 122; c++ {
						d.dev.WriteDatas(1, []byte{
							d.img.Pix[int(p<<3+7)*122+c],
							d.img.Pix[int(p<<3+6)*122+c],
							d.img.Pix[int(p<<3+5)*122+c],
							d.img.Pix[int(p<<3+4)*122+c],
							d.img.Pix[int(p<<3+3)*122+c],
							d.img.Pix[int(p<<3+2)*122+c],
							d.img.Pix[int(p<<3+1)*122+c],
							d.img.Pix[int(p<<3+0)*122+c],
						})
					}
				}
				checkBit = checkBit << 1
			}
			d.UnlockImg()
		}
	}
}

func (d *displayMt12232a) GetImg() *image.Gray {
	return d.img
}
func (d *displayMt12232a) LockImg() {
	d.imgMutex.Lock()
}
func (d *displayMt12232a) UnlockImg() {
	d.imgMutex.Unlock()
}