#!/usr/bin/env python3
#
# kitchentext: Read text from stdin and put it on the Kitchenlight.
#
# Author: Shy
#
# This program is free software: you can redistribute it and/or modify it under
# the terms of the GNU General Public License as published by the Free Software
# Foundation, either version 3 of the License, or (at your option) any later
# version.
#
# This program is distributed in the hope that it will be useful, but WITHOUT
# ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or FITNESS
# FOR A PARTICULAR PURPOSE.  See the GNU General Public License for more
# details.
#
# You should have received a copy of the GNU General Public License along with
# this program.  If not, see <http://www.gnu.org/licenses/>.

def kitchentext(delay=200, skip_if_off=False, poweron=False, restore=False,
                wait=False, verbose=False, debug=False):

    import sys, signal
    from c4ctrl import C4Interface, Kitchenlight

    charwidth = { # Width of characters.
        'a' : 5, 'A' : 5, 'b' : 4, 'B' : 5, 'c' : 3, 'C' : 5,
        'd' : 4, 'D' : 5, 'e' : 4, 'E' : 5, 'f' : 3, 'F' : 5,
        'g' : 3, 'G' : 5, 'h' : 3, 'H' : 5, 'i' : 1, 'I' : 5,
        'j' : 2, 'J' : 5, 'k' : 3, 'K' : 5, 'l' : 3, 'L' : 5,
        'm' : 5, 'M' : 5, 'n' : 4, 'N' : 5, 'o' : 3, 'O' : 5,
        'p' : 3, 'P' : 5, 'q' : 3, 'Q' : 5, 'r' : 3, 'R' : 5,
        's' : 4, 'S' : 5, 't' : 3, 'T' : 5, 'u' : 3, 'U' : 5,
        'v' : 3, 'V' : 5, 'w' : 5, 'W' : 5, 'x' : 3, 'X' : 5,
        'y' : 3, 'Y' : 5, 'z' : 3, 'Z' : 5, '0' : 5, '1' : 4,
        '2' : 5, '3' : 5, '4' : 5, '5' : 5, '6' : 5, '7' : 5,
        '8' : 5, '9' : 5, '@' : 5, '=' : 3, '!' : 1, '"' : 3,
        '_' : 5, '-' : 3, '.' : 2, ',' : 2, '*' : 5, ':' : 2,
        '\'' : 1, '/' : 5, '(' : 2, ')' : 2, '{' : 3, '}' : 3,
        '[' : 2, ']' : 2, '<' : 3, '>' : 4, '+' : 5, '#' : 5,
        '$' : 5, '%' : 5, '$' : 5, '~' : 5, '?' : 3, ';' : 2,
        '\\' : 5, '^' : 3, '|' : 1, '`' : 2, ' ' : 3, '\t' : 5
    }

    C4Interface.debug = debug
    kl = Kitchenlight(autopower=poweron)

    # Enforce wait=True if restore=True
    wait = wait or restore

    # Store previous state.
    if restore or skip_if_off:
        c4 = C4Interface()
        saved_state = c4.pull([kl.topic, kl.powertopic])

        if skip_if_off:
            # Stop here if kitchenlight is turned off.
            if saved_state[1].payload == b'\x00':
                verbose and print("Found Kitchenlight turned off and '-i' flag given. Exiting.")
                return

    # We want to be able to restore the saved Kitchenlight if we receive a
    # SIGERM signal. We do this by creating an registering a custom exception
    # class.
    class KitchenSignalError(Exception):
        def __init__(self, signal, frame):
            self.signal = signal
            self.frame = frame

    def signal_handler(signal, frame):
        raise KitchenSignalError(signal, frame)

    try: signal.signal(signal.SIGTERM, signal_handler)
    except: pass

    try:
        while True:

            try:
                text = sys.stdin.readline()
            except KeyboardInterrupt: # Exit a bit more graceful on CTRL-C.
                verbose and print("\nInterrupted by user.", file=sys.stderr)
                sys.exit(1)

            if text == "\n": # Empty line.
                verbose and print("Info: skipping empty line")
                continue
            elif text == "": # EOF.
                break

            # Strip chars Kitchenlight can not display.
            text = text.rstrip('\n').encode("ascii", "ignore").decode("ascii")

            try: # We might well get interrupted while waiting.
                kl.text(text, delay)

                if wait:
                    from time import sleep
                    # How long shall we wait? Kitchenlight has 30 columns, each
                    # char uses 2-5 columns followed by an empty one. The
                    # traversal of one column takes 30 * <delay> ms.
                    text_width = 0
                    for c in text:
                        try:
                            text_width += (charwidth[c] + 1)
                        except KeyError:
                            # No width specified for this charachter. Let's use
                            # 4 as default.
                            text_width += 4

                    waiting_time = ((30 * delay) + (text_width * delay)) / 1000
                    verbose and print("Waiting for {} seconds ...".format(waiting_time))
                    sleep(waiting_time)

            except KeyboardInterrupt:
                verbose and print("\nInterrupted by user.", file=sys.stderr)
                sys.exit(1)

            except KitchenSignalError as error:
                verbose and print("\nInterrupted by signal {}".format(error.signal),
                                  file=sys.stderr)
                sys.exit(1)

    finally:
        # Always restore privious state if "restore" is set.
        if restore:
            re = []
            for top in saved_state: re.append((top.topic, top.payload))
            c4.push(re)


if __name__ == "__main__":
    import argparse

    parser = argparse.ArgumentParser(
        description="Read multiple lines of text from stdin and put them on \
                     the Kitchenlight.")
    parser.add_argument(
        "--debug", action="store_true",
        help="display what would be send to the MQTT broker, but do not \
              actually connect")
    parser.add_argument(
        "-d", "--delay", type=int, default=200,
        help="delay in ms (speed of the text, default is 200)")
    parser.add_argument(
        "-f", "--fork", action="store_true",
        help="fork to background")
    parser.add_argument(
        "-F", action="store_true",
        help="like '-f', but print PID of forked process to stdout")
    parser.add_argument(
        "-i", "--skip-if-off", action="store_true", default=False,
        help="do nothing if the kitchenlight is turned off")
    parser.add_argument(
        "-p", "--power-on", action="store_true", default=False,
        help="turn on Kitchenlight if it is powered off")
    parser.add_argument(
        "-r", "--restore", action="store_true", default=False,
        help="restore the Kitchenlight to its prior state after the text has \
              been displayed (implies --wait)")
    parser.add_argument(
        "-v", "--verbose", action="store_true",
        help="be more verbose")
    parser.add_argument(
        "-w", "--wait", action="store_true", default=False,
        help="wait until the text has been displayed")
    args = parser.parse_args()

    if args.fork or args.F:
        import sys
        from os import fork

        if sys.stdin.isatty():
            print("Error: cannot fork when stdin is connected to a terminal!",
                  file=sys.stderr)
            sys.exit(1)

        child_pid = fork()
        if child_pid != 0:
            if args.F:
                print(child_pid)
            elif args.verbose:
                print("Forked to PID", child_pid)

            sys.exit()

    kitchentext(delay=args.delay,
                skip_if_off=args.skip_if_off,
                poweron=args.power_on,
                restore=args.restore,
                wait=args.wait,
                verbose=args.verbose,
                debug=args.debug)