from smbus import SMBus
from time import sleep


ALIGN_FUNC = {"left": "ljust", "right": "rjust", "center": "center"}
CLEAR_DISPLAY = 0x01
ENABLE_BIT = 0b00000100
LINES = {1: 0x80, 2: 0xC0, 3: 0x94, 4: 0xD4}

LCD_BACKLIGHT = 0x08
LCD_NOBACKLIGHT = 0x00


class LCD(object):

    def __init__(self, address=0x27, bus=1, width=20, rows=4, backlight=True):
        self.address = address
        self.bus = SMBus(bus)
        self.delay = 0.0005
        self.rows = rows
        self.width = width
        self.backlight_status = backlight

        self.write(0x33)
        self.write(0x32)
        self.write(0x06)
        self.write(0x0C)
        self.write(0x28)
        self.write(CLEAR_DISPLAY)
        sleep(self.delay)

    def _write_byte(self, byte):
        self.bus.write_byte(self.address, byte)
        self.bus.write_byte(self.address, (byte | ENABLE_BIT))
        sleep(self.delay)
        self.bus.write_byte(self.address, (byte & ~ENABLE_BIT))
        sleep(self.delay)

    def write(self, byte, mode=0):
        backlight_mode = LCD_BACKLIGHT if self.backlight_status else LCD_NOBACKLIGHT
        self._write_byte(mode | (byte & 0xF0) | backlight_mode)
        self._write_byte(mode | ((byte << 4) & 0xF0) | backlight_mode)

    def text(self, text, line, align="left"):
        self.write(LINES.get(line, LINES[1]))
        text, other_lines = self.get_text_line(text)
        text = getattr(text, ALIGN_FUNC.get(align, "ljust"))(self.width)
        for char in text:
            self.write(ord(char), mode=1)
        if other_lines and line <= self.rows - 1:
            self.text(other_lines, line + 1, align=align)

    def backlight(self, turn_on=True):
        self.backlight_status = turn_on
        self.write(0)

    def get_text_line(self, text):
        line_break = self.width
        if len(text) > self.width:
            line_break = text[: self.width + 1].rfind(" ")
        if line_break < 0:
            line_break = self.width
        return text[:line_break], text[line_break:].strip()

    def clear(self):
        self.write(CLEAR_DISPLAY)