#!/usr/bin/python3
"""Output Starlink user terminal data info in text format.

This script pulls the current status info and/or metrics computed from the
history data and prints them to a file or stdout either once or in a periodic
loop. By default, it will print the results in CSV format.

Note that using this script to record the alert_detail group mode as CSV
data is not recommended, because the number of alerts and their relative
order in the output can change with the dish software. Instead of using
the alert_detail mode, you can use the alerts bitmask in the status group.
"""

from datetime import datetime
import logging
import os
import signal
import sys
import time

import dish_common
import starlink_grpc

COUNTER_FIELD = "end_counter"
VERBOSE_FIELD_MAP = {
    # status fields (the remainder are either self-explanatory or I don't
    # know with confidence what they mean)
    "alerts": "Alerts bit field",

    # ping_drop fields
    "samples": "Parsed samples",
    "end_counter": "Sample counter",
    "total_ping_drop": "Total ping drop",
    "count_full_ping_drop": "Count of drop == 1",
    "count_obstructed": "Obstructed",
    "total_obstructed_ping_drop": "Obstructed ping drop",
    "count_full_obstructed_ping_drop": "Obstructed drop == 1",
    "count_unscheduled": "Unscheduled",
    "total_unscheduled_ping_drop": "Unscheduled ping drop",
    "count_full_unscheduled_ping_drop": "Unscheduled drop == 1",

    # ping_run_length fields
    "init_run_fragment": "Initial drop run fragment",
    "final_run_fragment": "Final drop run fragment",
    "run_seconds": "Per-second drop runs",
    "run_minutes": "Per-minute drop runs",

    # ping_latency fields
    "mean_all_ping_latency": "Mean RTT, drop < 1",
    "deciles_all_ping_latency": "RTT deciles, drop < 1",
    "mean_full_ping_latency": "Mean RTT, drop == 0",
    "deciles_full_ping_latency": "RTT deciles, drop == 0",
    "stdev_full_ping_latency": "RTT standard deviation, drop == 0",

    # ping_loaded_latency is still experimental, so leave those unexplained

    # usage fields
    "download_usage": "Bytes downloaded",
    "upload_usage": "Bytes uploaded",
}


class Terminated(Exception):
    pass


def handle_sigterm(signum, frame):
    # Turn SIGTERM into an exception so main loop can clean up
    raise Terminated


def parse_args():
    parser = dish_common.create_arg_parser(
        output_description="print it in text format; by default, will print in CSV format")

    group = parser.add_argument_group(title="CSV output options")
    group.add_argument("-H",
                       "--print-header",
                       action="store_true",
                       help="Print CSV header instead of parsing data")
    group.add_argument("-O",
                       "--out-file",
                       default="-",
                       help="Output file path; if set, can also be used to resume from prior "
                       "history sample counter, default: write to standard output")
    group.add_argument("-k",
                       "--skip-query",
                       action="store_true",
                       help="Skip querying for prior sample write point in history modes")

    opts = dish_common.run_arg_parser(parser)

    if (opts.history_stats_mode or opts.status_mode) and opts.bulk_mode and not opts.verbose:
        parser.error("bulk_history cannot be combined with other modes for CSV output")

    # Technically possible, but a pain to implement, so just disallow it. User
    # probably doesn't realize how weird it would be, anyway, given that stats
    # data reports at a different rate from status data in this case.
    if opts.history_stats_mode and opts.status_mode and not opts.verbose and opts.poll_loops > 1:
        parser.error("usage of --poll-loops with history stats modes cannot be mixed with status "
                     "modes for CSV output")

    opts.skip_query |= opts.no_counter | opts.verbose
    if opts.out_file == "-":
        opts.no_stdout_errors = True

    return opts


def open_out_file(opts, mode):
    if opts.out_file == "-":
        # open new file, so it can be closed later without affecting sys.stdout
        return os.fdopen(sys.stdout.fileno(), "w", buffering=1, closefd=False)
    return open(opts.out_file, mode, buffering=1)


def print_header(opts, print_file):
    header = ["datetimestamp_utc"]

    def header_add(names):
        for name in names:
            name, start, end = dish_common.BRACKETS_RE.match(name).group(1, 4, 5)
            if start:
                header.extend(name + "_" + str(x) for x in range(int(start), int(end)))
            elif end:
                header.extend(name + "_" + str(x) for x in range(int(end)))
            else:
                header.append(name)

    if opts.status_mode:
        context = starlink_grpc.ChannelContext(target=opts.target)
        try:
            name_groups = starlink_grpc.status_field_names(context=context)
        except starlink_grpc.GrpcError as e:
            dish_common.conn_error(opts, "Failure reflecting status field names: %s", str(e))
            return 1
        if "status" in opts.mode:
            header_add(name_groups[0])
        if "obstruction_detail" in opts.mode:
            header_add(name_groups[1])
        if "alert_detail" in opts.mode:
            header_add(name_groups[2])

    if opts.bulk_mode:
        general, bulk = starlink_grpc.history_bulk_field_names()
        header_add(bulk)

    if opts.history_stats_mode:
        groups = starlink_grpc.history_stats_field_names()
        general, ping, runlen, latency, loaded, usage = groups[0:6]
        header_add(general)
        if "ping_drop" in opts.mode:
            header_add(ping)
        if "ping_run_length" in opts.mode:
            header_add(runlen)
        if "ping_loaded_latency" in opts.mode:
            header_add(loaded)
        if "ping_latency" in opts.mode:
            header_add(latency)
        if "usage" in opts.mode:
            header_add(usage)

    print(",".join(header), file=print_file)
    return 0


def get_prior_counter(opts, gstate):
    # This implementation is terrible in that it makes a bunch of assumptions.
    # Those assumptions should be true for files generated by this script, but
    # it would be better not to make them. However, it also only works if the
    # CSV file has a header that correctly matches the last line of the file,
    # and there's really no way to verify that, so it's garbage in, garbage
    # out, anyway. It also reads the entire file line-by-line, which is not
    # great.
    try:
        with open_out_file(opts, "r") as csv_file:
            header = csv_file.readline().split(",")
            column = header.index(COUNTER_FIELD)
            last_line = None
            for last_line in csv_file:
                pass
        if last_line is not None:
            gstate.counter_stats = int(last_line.split(",")[column])
    except (IndexError, OSError, ValueError):
        pass


def loop_body(opts, gstate, print_file, shutdown=False):
    csv_data = []

    def xform(val):
        return "" if val is None else str(val)

    def cb_data_add_item(name, val, category):
        if opts.verbose:
            csv_data.append("{0:22} {1}".format(
                VERBOSE_FIELD_MAP.get(name, name) + ":", xform(val)))
        else:
            # special case for get_status failure: this will be the lone item added
            if name == "state" and val == "DISH_UNREACHABLE":
                csv_data.extend(["", "", "", val])
            else:
                csv_data.append(xform(val))

    def cb_data_add_sequence(name, val, category, start):
        if opts.verbose:
            csv_data.append("{0:22} {1}".format(
                VERBOSE_FIELD_MAP.get(name, name) + ":",
                ", ".join(xform(subval) for subval in val)))
        else:
            csv_data.extend(xform(subval) for subval in val)

    def cb_add_bulk(bulk, count, timestamp, counter):
        if opts.verbose:
            print("Time range (UTC):      {0} -> {1}".format(
                datetime.utcfromtimestamp(timestamp).isoformat(),
                datetime.utcfromtimestamp(timestamp + count).isoformat()),
                  file=print_file)
            for key, val in bulk.items():
                print("{0:22} {1}".format(key + ":", ", ".join(xform(subval) for subval in val)),
                      file=print_file)
            if opts.loop_interval > 0.0:
                print(file=print_file)
        else:
            for i in range(count):
                timestamp += 1
                fields = [datetime.utcfromtimestamp(timestamp).isoformat()]
                fields.extend([xform(val[i]) for val in bulk.values()])
                print(",".join(fields), file=print_file)

    rc, status_ts, hist_ts = dish_common.get_data(opts,
                                                  gstate,
                                                  cb_data_add_item,
                                                  cb_data_add_sequence,
                                                  add_bulk=cb_add_bulk,
                                                  flush_history=shutdown)

    if opts.verbose:
        if csv_data:
            print("\n".join(csv_data), file=print_file)
            if opts.loop_interval > 0.0:
                print(file=print_file)
    else:
        if csv_data:
            timestamp = status_ts if status_ts is not None else hist_ts
            csv_data.insert(0, datetime.utcfromtimestamp(timestamp).isoformat())
            print(",".join(csv_data), file=print_file)

    return rc


def main():
    opts = parse_args()

    logging.basicConfig(format="%(levelname)s: %(message)s")

    if opts.print_header:
        try:
            with open_out_file(opts, "a") as print_file:
                rc = print_header(opts, print_file)
        except OSError as e:
            logging.error("Failed opening output file: %s", str(e))
            rc = 1
        sys.exit(rc)

    gstate = dish_common.GlobalState(target=opts.target)
    if opts.out_file != "-" and not opts.skip_query and opts.history_stats_mode:
        get_prior_counter(opts, gstate)

    try:
        print_file = open_out_file(opts, "a")
    except OSError as e:
        logging.error("Failed opening output file: %s", str(e))
        sys.exit(1)
    signal.signal(signal.SIGTERM, handle_sigterm)

    rc = 0
    try:
        next_loop = time.monotonic()
        while True:
            rc = loop_body(opts, gstate, print_file)
            if opts.loop_interval > 0.0:
                now = time.monotonic()
                next_loop = max(next_loop + opts.loop_interval, now)
                time.sleep(next_loop - now)
            else:
                break
    except (KeyboardInterrupt, Terminated):
        pass
    finally:
        loop_body(opts, gstate, print_file, shutdown=True)
        print_file.close()
        gstate.shutdown()

    sys.exit(rc)


if __name__ == '__main__':
    main()