# MicroPython ST7789 display driver, currently only has an SPI interface

import micropython

from micropython import const
from time import sleep_ms

# register definitions
_SWRESET            = const(0x01)
_SLPIN              = const(0x10)
_SLPOUT             = const(0x11)
_NORON              = const(0x13)
_INVOFF             = const(0x20)
_INVON              = const(0x21)
_DISPON             = const(0x29)
_CASET              = const(0x2a)
_RASET              = const(0x2b)
_RAMWR              = const(0x2c)
_COLMOD             = const(0x3a)
_MADCTL             = const(0x36)

class ST7789(object):
    def __init__(self, width, height):
        self.width = width
        self.height = height
        self.linebuffer = bytearray(2 * width)
        self.init_display()

    def init_display(self):
        self.reset()

        self.write_cmd(_SLPOUT)
        sleep_ms(10)

        for cmd in (
            (_COLMOD,   b'\x05'), # MCU will send 16-bit RGB565
            (_MADCTL,   b'\x00'), # Left to right, top to bottom
            #(_INVOFF,   None), # Results in odd palette
            (_INVON,   None),
            (_NORON,   None),
        ):
            self.write_cmd(cmd[0])
            if cmd[1]:
                self.write_data(cmd[1])
        self.fill(0)
        self.write_cmd(_DISPON)

        # From the point we sent the SLPOUT there must be a
        # 120ms gap before any subsequent SLPIN. In most cases
        # (i.e. wen the SPI baud rate is slower than 8M then
        # that time already elapsed as we zeroed the RAM).
        #sleep_ms(125)

    def poweroff(self):
        self.write_cmd(_SLPIN)
        sleep_ms(125)

    def poweron(self):
        self.write_cmd(_SLPOUT)
        sleep_ms(125)

    def contrast(self, contrast):
        pass

    def invert(self, invert):
        if invert:
            self.write_cmd(_INVON)
        else:
            self.write_cmd(_INVOFF)

    def set_window(self, x=0, y=0, width=None, height=None):
        if not width:
            width = self.width
        if not height:
            height = self.height

        xp = x + width - 1
        yp = y + height - 1

        self.write_cmd(_CASET)
        self.write_data(bytearray([x >> 8, x & 0xff, xp >> 8, xp & 0xff]))
        self.write_cmd(_RASET)
        self.write_data(bytearray([y >> 8, y & 0xff, yp >> 8, yp & 0xff]))
        self.write_cmd(_RAMWR)

    def fill(self, bg):
        self.set_window()

        # Populate the line buffer
        for x in range(0, 2 * self.width, 2):
            self.linebuffer[x] = bg >> 8
            self.linebuffer[x+1] = bg & 0xff
        for y in range(self.height):
            self.write_data(self.linebuffer)

    @micropython.native
    def rleblit(self, image, pos=(0, 0), fg=0xffff, bg=0):
        (sx, sy, rle) = image
        self.set_window(pos[0], pos[1], sx, sy)

        # TODO: rework algorithm to allow us to reuse the line buffer
        buf = bytearray(2*sx)
        bp = 0
        color = bg

        for rl in rle:
            while rl:
                buf[bp] = color >> 8
                buf[bp+1] = color & 0xff
                bp += 2
                rl -= 1

                if bp >= (2*sx):
                    self.write_data(buf)
                    bp = 0

            if color == bg:
                color = fg
            else:
                color = bg

class ST7789_SPI(ST7789):
    def __init__(self, width, height, spi, cs, dc, res=None, rate=8000000):
        self.spi = spi
        self.dc = dc
        self.res = res
        self.cs = cs
        self.rate = rate

        #self.spi.init(baudrate=self.rate, polarity=1, phase=1)
        cs.init(cs.OUT, value=1)
        dc.init(dc.OUT, value=0)
        if res:
            res.init(res.OUT, value=0)

        super().__init__(width, height)

    def reset(self):
        if self.res:
            self.res(0)
            sleep_ms(10)
            self.res(1)
        else:
            self.write_cmd(_SWRESET)
        sleep_ms(125)

    def write_cmd(self, cmd):
        self.dc(0)
        self.cs(0)
        self.spi.write(bytearray([cmd]))
        self.cs(1)

    def write_data(self, buf):
        self.dc(1)
        self.cs(0)
        self.spi.write(buf)
        self.cs(1)