import asyncio
from LCD import LCD

alloc_lock = asyncio.Lock()

class display:
    def __init__(self, width=20, height=4, i2c_addr=0x27):
        self.width = width
        self.height = height
        self.device = LCD(2, i2c_addr, True)
        self.contents = [" " * width] * self.height
        self.custom_char_allocations = [False] * 8
    
    async def redraw(self, row = None):
        if row == None:
            for row, line in enumerate(self.contents):
                await self.device.async_message(line, row + 1)
        else:
            await self.device.async_message(self.contents[row - 1], row)
    
    async def alloc_cchar(self):
        async with alloc_lock:
            new_alloc = self.custom_char_allocations.index(False)
            self.custom_char_allocations[new_alloc] = True
        return new_alloc
        
    async def free_cchar(self, cchar):
        self.custom_char_allocations[cchar] = False
    
    async def read(self, row):
        return self.contents[row]
    
    async def write(self, row, data, offset = 0):
        self.contents[row - 1] = f'{self.contents[row - 1][:offset]}{data}{self.contents[row - 1][offset+len(data):]}'
        await self.redraw(row)