#!/usr/bin/env python3
# SPDX-License-Identifier: GPL-2.0-or-later
# Author: Oliver Smith
# Copyright 2021 sysmocom - s.f.m.c. GmbH <info@sysmocom.de>
import argparse
import sys
import datetime


def parse_args():
    parser = argparse.ArgumentParser(prog="parse_strace")
    parser.add_argument("strace_file",
                        help="an strace file generated by dump.sh")
    args = parser.parse_args()
    return args

def parse_iov_str(iov):
    """
    :param iov: strace iov string, looks like this:
                '[{iov_base="AT\0", iov_len=3}, {iov_base="[0] AT< +EXLCE:...'
    :returns: list of iov strings, e.g.:
                ["AT", "[0] AT< +EXLCE:...", ...]
    """
    ret = []

    assert iov.startswith("[{")
    rest = iov[2:]
    while rest:
        if rest.startswith("iov_base=\""):
            key_value, rest = rest.split(', iov_len', 1)
            value = key_value.split('"', 1)[1]
            ret += [value]
        elif rest.startswith("="):
            iov_len, rest = rest.split("}", 1)
        elif rest.startswith(", {"):
            _, rest = rest.split("{", 1)
        elif rest.startswith("]"):
            # parts at the end of writev are not interesting: iov count and
            # bytes written
            break
        else:
            assert False, f"failed to parse rest of iov:" \
                          f"\n\niov: {iov}" \
                          f"\n\nrest: {rest}"
    return ret


def parse_at(cmd):
    is_at = False
    i = 0
    for i in range(len(cmd["iov"])):
        iov_base = cmd["iov"][i]
        if iov_base.startswith("[0] AT"):
            is_at = True
            break
    if not is_at:
        return

    desc = "\n   ".join(cmd["iov"][i:])

    # Cut '[0 AT< '
    desc = desc[8:]

    # Cut suffixes like ' (RIL_URC_READER, tid:502968382704)'
    desc = desc.split(" (RIL_URC_", 1)[0]
    desc = desc.split(" (RIL_CMD_", 1)[0]
    desc = desc.split(" (RIL_ATCI_", 1)[0]

    if desc.endswith("\\n\\0"):
        desc=desc[:-4]



    cmd["type"] = "at"
    cmd["desc"] = desc
    cmd["towards_modem"] = "AT>" in iov_base


def parse_writev(strace_file):
    """
    :param strace_file: path to strace file generated by dump.sh
    :returns: a list of writev calls found in the strace file, looks like this:
              [{"desc": "AT+EXCLE",  # human readable short version
                "fd": "74<socket:[8970]>"
                "iov": ["AT", "[0 AT< +EXLCE:...", ...],
                "pid": 985,
                "time": 1632220184.069225,
                "time_rel": 0.000077,
                "towards_modem": True,
                "type": "at"}, ...]
              type is one of:
                * "at"
                * "unknown"
    """
    ret = []
    failed = 0
    with open(strace_file) as handle:
        for line in handle:
            if "writev(" not in line:
                continue
            cmd = {}
            rest = line.rstrip()

            # Cut pid, time, time_rel
            # rest = '985   1632220184.068694 (+     0.000148) writev(...'
            # => ['985', '1632220184.068694', '(+', '0.000148)', 'writev(...'
            pid, time, _, time_rel, rest = rest.split(None, 4)
            cmd["pid"] = int(pid)
            cmd["time"] = float(time)
            cmd["time_rel"] = time_rel.split(")")[0]

            # Cut writev
            # rest = 'writev(74<socket:[8970]>, [{iov_base="...'
            writev, rest = rest.split("(", 1)
            assert writev == "writev"

            # Cut fd
            # rest = '74<socket:[8970]>, [{iov_base="...'
            cmd["fd"], rest = rest.split(", ", 1)

            cmd["iov"] = parse_iov_str(rest)

            cmd["type"] = "unknown"
            cmd["desc"] = cmd["iov"]
            cmd["towards_modem"] = True

            parse_at(cmd)

            ret += [cmd]

    return ret


def print_cmds(cmds):
    """ :param cmds: return of parse_at_cmds() """
    for cmd in cmds:
        if cmd["type"] == "unknown":
            continue

        direction = " ->" if cmd["towards_modem"] else "<- "
        time = datetime.datetime.fromtimestamp(cmd["time"]).strftime('%H:%M:%S')

        print(f"{time} (ril {direction} modem) {cmd['desc']}")


def main():
    args = parse_args()
    cmds = parse_writev(args.strace_file)
    print_cmds(cmds)


if __name__ == "__main__":
    sys.exit(main())