from fbp import outport, inport, state, EOS


# Decorators

@inport('filename', type=str, description='the file path to be read')
@outport('line', type=str, description='a single line read from the file, END-OF-STREAM when the content is over')
@state  # tipo il @pass_context di click
async def cat(filename, line, state):
    """ Read a file one line at a time. """
    async with aiofiles.open(await filename.pop(), mode='r') as f:
        # restore state if present
        fpos = state.get('fpos', 0)
        await f.seek(fpos)
        async for fline in f:
            await line.push(fline)
            # save state
            state['fpos'] = await f.tell()
        await line.push(EOS)


@component
async def cat(filename, line, state):
    """ Read a file one line at a time.

    Parameters
    ----------
    filename: inport(type=str)
        the file path to be read
    line: outport(type=str)
        a single line read from the file, END-OF-STREAM when the content is over
    state: state
    """
    async with aiofiles.open(await filename.pop(), mode='r') as f:
        # restore state if present
        fpos = state.get('fpos', 0)
        await f.seek(fpos)
        async for fline in f:
            await line.push(fline)
            # save state
            state['fpos'] = await f.tell()
        await line.push(EOS)