#!/usr/bin/env python3
import re, sys, os, calendar, time

if len(sys.argv) != 3 or sys.argv[1] == "-h" or sys.argv[1] == "--help":
    print(f"Usage: {sys.argv[0]} <logdir> <outdir>")
    print("The <logdir> is expected to contain yy.mm.dd files in clog format (tunes.org/~nef/logs).")
    print("These will be converted from US/Pacific (i.e. PST/PDT) to UTC and to ZNC log format; the")
    print("output is written to <outdir>. The <logdir> is not changed.")
    if len(sys.argv) != 2: sys.exit(1)
    else: sys.exit(0)

logdir = sys.argv[1]
outdir = sys.argv[2]
os.mkdir(outdir)

class Logger:
    def __init__(self, destdir):
        self.destdir = destdir
        self.curdate = None  # (Y, m, d)
        self.events = []  # [((H, M, S), text)]

    def addevent(self, ymd, hms, text):
        if self.curdate is not None and self.curdate != ymd:
            self.writeout()

        if self.curdate is None:
            self.curdate = ymd
            self.events = [(hms, text)]
        else:
            assert self.curdate == ymd
            self.events.append((hms, text))

    def writeout(self):
        (Y, m, d) = self.curdate
        with open(os.path.join(self.destdir, f"{Y:04}-{m:02}-{d:02}.log"), "wb") as f:
            for (H, M, S), text in self.events:
                f.write(f"[{H:02}:{M:02}:{S:02}] ".encode("ascii") + text + b"\n")
        self.curdate = None
        self.events = []

# takes line from the '---' bit, i.e. after the HMS time
# returns None if this is a meta-marker
def convert_clog_to_znc(fname, line):
    m = re.match(b"^--- log: (started|ended|stopped) haskell/[0-9.]{8}$", line)
    if m is not None: return None
    m = re.match(b"^--- topic: '.*", line)
    if m is not None: return None
    m = re.match(b"^--- topic: set by .*", line)
    if m is not None: return None
    m = re.match(b"^--- names: list \\(.*", line)
    if m is not None: return None

    m = re.match(b"^--- join: ([^ ]*) \\(([^)]*)\\) joined #haskell$", line)
    if m is not None:
        return b"*** Joins: " + m[1] + b" (" + m[2] + b")"

    m = re.match(b"^--- join: ([^ ]*) joined #haskell$", line)  # join without host
    if m is not None:
        return b"*** Joins: " + m[1] + b" ()"

    m = re.match(b"^--- quit: ([^ ]*) \\((.*)\\)$", line)
    if m is not None:
        return b"*** Quits: " + m[1] + b" () (" + m[2] + b")"

    m = re.match(b"^--- part: ([^ ]*) left #haskell$", line)
    if m is not None:
        return b"*** Parts: " + m[1] + b" () ()"

    m = re.match(b"^--- topic: set to '(.*)' by ([^ ]*)$", line)
    if m is not None:
        return b"*** " + m[2] + b" changes topic to '" + m[1] + b"'"

    m = re.match(b"^--- nick: ([^ ]*) -> ([^ ]*)$", line)
    if m is not None:
        return b"*** " + m[1] + b" is now known as " + m[2]

    m = re.match(b"^--- mode: ([^ ]*) set mode: (.*)$", line)
    if m is not None:
        return b"*** " + m[1] + b" sets mode: " + m[2]

    m = re.match(b"^--- mode: ([^ ]*) set ([+-].*)$", line)
    if m is not None:
        return b"*** " + m[1] + b" sets mode: " + m[2]

    m = re.match(b"^--- kick: ([^ ]*) was kicked by ([^ ]*) \\((.*)\\)$", line)
    if m is not None:
        return b"*** " + m[0] + b" was kicked by " + m[1] + b" (" + m[2] + b")"

    m = re.match(b"^<([^>]*)> (.*)", line)
    if m is not None:
        return line

    m = re.match(b"^-([^(]*)\\(([^)]*)\\)- (.*)", line)  # notice
    if m is not None:
        return b"-" + m[0] + b"- " + m[2]

    m = re.match(b"^\\* ([^ ]*) (.*)", line)
    if m is not None:
        return b"* " + m[1] + b" " + m[2]

    m = re.match(b"^\\* ([^ ]*)$", line)  # empty action
    if m is not None:
        return b"* " + m[1] + b" "

    print(f"Cannot parse: {line!r} ({fname})")
    return b"#parseerror " + repr(line).encode("utf-8")

# returned text is None if this is no event but a meta-marker (log started or ended)
def parse_line(fname, line):
    space = line.find(b" ")
    if space != 8:
        print(f"Unparseable time: {line!r} ({fname})")
        return ((0, 0, 0), b"#parseerror " + repr(line).encode("utf-8"))
    timestr = line[:8].decode("ascii")
    try:
        (H, M, S) = re.match(r"([0-9]{2}):([0-9]{2}):([0-9]{2})$", timestr).groups()
    except Exception as e:
        raise Exception(f"Could not parse time marker on line: {line!r}")

    text = convert_clog_to_znc(fname, line[9:])
    return ((int(H), int(M), int(S)), text)

def last_sunday_in(Y, m):
    date = calendar.monthrange(Y, m)[1]  # number of days in month, i.e. last date
    while calendar.weekday(Y, m, date) != calendar.SUNDAY:
        date -= 1
    return date

def nth_sunday_in(n, Y, m):
    if n == -1:
        return last_sunday_in(Y, m)
    else:
        assert n >= 1
        date = 1
        while calendar.weekday(Y, m, date) != calendar.SUNDAY:
            date += 1
        return date + (n - 1) * 7

assert last_sunday_in(2026, 3) == 29
assert last_sunday_in(2026, 10) == 25

assert nth_sunday_in(2, 2026, 3) == 8
assert nth_sunday_in(1, 2026, 10) == 4

def convert_logfile(filename, logger):
    try:
        (Y, m, d) = re.match(r".*/([0-9]{2}).([0-9]{2}).([0-9]{2})$", filename).groups()
        Y = 2000 + int(Y)
        m = int(m)
        d = int(d)
    except Exception as e:
        raise Exception(f"Could not parse log file name {filename!r}")

    if Y <= 2006:
        # DST starts on the first Sunday in April at 02:00 PST
        enterdst = (4, nth_sunday_in(1, Y, 4))
        # DST ends on the last Sunday in October at 02:00 PDT, which isn't reached
        # and instead we continue from 01:00 PST
        leavedst = (10, last_sunday_in(Y, 10))
    else:
        # DST starts on the second Sunday in March at 02:00 PST
        enterdst = (3, nth_sunday_in(2, Y, 3))
        # DST ends on the first Sunday in October at 02:00 PDT, which isn't reached
        # and instead we continue from 01:00 PST
        leavedst = (11, nth_sunday_in(1, Y, 11))

    with open(filename, "rb") as f:
        prevHMS = None  # logged time
        prevYmdHMS2 = None  # UTC time
        switchedToWinter = None  # only ever used on 'leavedst' day

        for line in f:
            if line[-1] == b"\n"[0]: line = line[:-1]
            if line[-1] == b"\r"[0]: line = line[:-1]
            (H, M, S), text = parse_line(filename, line)
            if text is None: continue  # meta-marker

            if (m, d) < enterdst or \
                    ((m, d) == enterdst and (H, M, S) < (2, 0, 0)) or \
                    ((m, d) == leavedst and (H, M, S) >= (2, 0, 0)) or \
                    (m, d) > leavedst:
                # PST = UTC-8; add because interpreting a PST time as UTC
                # leaves you 8 hours in the past of what it should be
                timestamp = calendar.timegm((Y, m, d, H, M, S)) + 8*3600

            elif ((m, d) == enterdst and (H, M, S) >= (3, 0, 0)) or \
                    ((m, d) > enterdst and (m, d) < leavedst) or \
                    ((m, d) == leavedst and (H, M, S) < (1, 0, 0)):
                # PDT = UTC-7
                timestamp = calendar.timegm((Y, m, d, H, M, S)) + 7*3600

            elif (m, d) == enterdst and (2, 0, 0) <= (H, M, S) < (3, 0, 0):
                raise Exception(f"Invalid time in limbo between PST and PDT: {filename!r}: {line!r}")

            elif (m, d) == leavedst and (1, 0, 0) <= (H, M, S) < (2, 0, 0):
                # ambiguous interval: either before or after the PDT->PST switch
                if switchedToWinter is None: switchedToWinter = False  # mark that we entered here
                if prevHMS is not None and (H, M, S) < prevHMS:  # time warp means that's the switch
                    switchedToWinter = True
                if not switchedToWinter:
                    timestamp = calendar.timegm((Y, m, d, H, M, S)) + 7*3600  # PDT
                else:
                    timestamp = calendar.timegm((Y, m, d, H, M, S)) + 8*3600  # PST

            Y2, m2, d2, H2, M2, S2, *_ = time.gmtime(timestamp)
            if prevYmdHMS2 is not None and ((Y2, m2, d2), (H2, M2, S2)) < prevYmdHMS2:
                print(f"Time reversal: {line!r} ({filename})")
                logger.addevent(*prevYmdHMS2, b"#non-monotonic-time " + line)
            else:
                logger.addevent((Y2, m2, d2), (H2, M2, S2), text)
                prevYmdHMS2 = ((Y2, m2, d2), (H2, M2, S2))

            prevHMS = (H, M, S)

        if switchedToWinter == False:
            print(f"{filename!r}: ambiguous PDT->PST switch")

print("Converting")
logger = Logger(outdir)
for filename in sorted(os.listdir(logdir)):
    convert_logfile(os.path.join(logdir, filename), logger)
logger.writeout()

#  print("Checking")
#  def enumerate_channel(chandir):
#      events = []
#      for filename in sorted(os.listdir(chandir)):
#          with open(os.path.join(chandir, filename), "rb") as f:
#              lines = f.read().split(b"\n")
#          if lines[-1] == b"": lines = lines[:-1]

#          def compute_stamp(line):
#              timepart = line[:10].decode("ascii")
#              Y, m, d, H, M, S, *_ = re.match(r"^(....)-(..)-(..)\.log\|\[(..):(..):(..)\]$", filename + "|" + timepart).groups()
#              return calendar.timegm((int(Y), int(m), int(d), int(H), int(M), int(S)))

#          events += [(compute_stamp(line), line[line.index(b" "[0])+1:])
#                     for line in lines]
#      return events

#  for network in os.listdir(logdir):
#      for channel in os.listdir(os.path.join(logdir, network)):
#          src_events = enumerate_channel(os.path.join(logdir, network, channel))
#          out_events = enumerate_channel(os.path.join(outdir, network, channel))

#          assert len(src_events) == len(out_events)
#          assert [ev[1] for ev in src_events] == [ev[1] for ev in out_events]
#          out_prev_stamp = 0
#          for i in range(len(src_events)):
#              assert abs(src_events[i][0] - out_events[i][0]) in [3600, 7200]
#              if out_events[i][0] < out_prev_stamp:
#                  print(src_events[i])
#                  print(out_events[i])
#                  sys.exit(1)
#              out_prev_stamp = out_events[i][0]

#  print("OK")