#!/usr/bin/env python3
# SPDX-License-Identifier: GPL-2.0-or-later
# SPDX-FileCopyrightText: 2023 Kent Gibson <warthog618@gmail.com>

"""Minimal example of watching for edges on a single line."""

from datetime import timedelta

import gpiod
from gpiod.edge_event import EdgeEvent
from gpiod.line import Bias, Edge


def edge_type_str(event: EdgeEvent) -> str:
    if event.event_type is event.Type.RISING_EDGE:
        return "Rising"
    if event.event_type is event.Type.FALLING_EDGE:
        return "Falling"
    return "Unknown"


def watch_line_value(chip_path: str, line_offset: int) -> None:
    # Assume a button connecting the pin to ground,
    # so pull it up and provide some debounce.
    with gpiod.request_lines(
        chip_path,
        consumer="watch-line-value",
        config={
            line_offset: gpiod.LineSettings(
                edge_detection=Edge.BOTH,
                bias=Bias.PULL_UP,
                debounce_period=timedelta(milliseconds=10),
            )
        },
    ) as request:
        while True:
            # Blocks until at least one event is available
            for event in request.read_edge_events():
                print(
                    f"line: {event.line_offset}"
                    f"  type: {edge_type_str(event):<7}"
                    f"  event #{event.line_seqno}"
                )


if __name__ == "__main__":
    try:
        watch_line_value("/dev/gpiochip0", 5)
    except OSError as ex:
        print(ex, "\nCustomise the example configuration to suit your situation")