#!/usr/bin/env python3

import argparse
import gzip
import logging
import os
import re
import signal
import sys
from enum import Enum, auto
from typing import List, Set, TextIO, Tuple

ZULIP_PATH = os.path.dirname(os.path.dirname(os.path.abspath(__file__)))
sys.path.append(ZULIP_PATH)

from scripts.lib.setup_path import setup_path

setup_path()

os.environ["DJANGO_SETTINGS_MODULE"] = "zproject.settings"

from django.conf import settings
from typing_extensions import Protocol

from scripts.lib.zulip_tools import BOLD, CYAN, ENDC, FAIL, GRAY, OKBLUE


def parser() -> argparse.ArgumentParser:
    parser = argparse.ArgumentParser(description="Search logfiles, ignoring commonly-fetched URLs.")
    log_selection = parser.add_argument_group("File selection")
    log_selection_options = log_selection.add_mutually_exclusive_group()
    log_selection_options.add_argument(
        "--log-files",
        "-n",
        help="Number of log files to search",
        choices=range(1, 16),
        type=int,
    )
    log_selection_options.add_argument(
        "--all-logs",
        "-A",
        help="Parse all logfiles, not just most recent",
        action="store_true",
    )
    log_selection_options.add_argument(
        "--min-hours",
        "-H",
        help="Estimated minimum number of hours; includes previous log file, if estimated less than this",
        type=int,
        choices=range(0, 24),
        default=3,
    )
    log_selection.add_argument(
        "--nginx",
        "-N",
        help="Parse from NGINX logs, not server.log",
        action="store_true",
    )

    filtering = parser.add_argument_group("Filtering")
    filtering.add_argument(
        "filter_terms",
        help="IP address, hostname, user-id, path, or status code to search for; multiple are AND'ed together",
        nargs="+",
    )
    filtering.add_argument(
        "--all-lines",
        "-L",
        help="Show all matching lines; equivalent to -suemtpr",
        action="store_true",
    )
    filtering.add_argument("--static", "-s", help="Include static file paths", action="store_true")
    filtering.add_argument("--uploads", "-u", help="Include file upload paths", action="store_true")
    filtering.add_argument("--avatars", "-a", help="Include avatar paths", action="store_true")
    filtering.add_argument("--events", "-e", help="Include event fetch paths", action="store_true")
    filtering.add_argument("--messages", "-m", help="Include message paths", action="store_true")
    filtering.add_argument(
        "--typing",
        "-t",
        help="Include typing notification path",
        action="store_true",
    )
    filtering.add_argument("--presence", "-p", help="Include presence paths", action="store_true")
    filtering.add_argument(
        "--report", "-r", help="Include timing report paths", action="store_true"
    )

    output = parser.add_argument_group("Output")
    output.add_argument("--full-line", "-F", help="Show full matching line", action="store_true")
    return parser


def maybe_gzip(logfile_name: str) -> TextIO:
    if logfile_name.endswith(".gz"):
        return gzip.open(logfile_name, "rt")
    return open(logfile_name, "r")


NGINX_LOG_LINE_RE = re.compile(
    r"""
      (?P<ip> \S+ ) \s+
      - \s+
      (?P<user> \S+ ) \s+
      \[
         (?P<date> \d+/\w+/\d+ )
         :
         (?P<time> \d+:\d+:\d+ )
         \s+ [+-]\d+
      \] \s+
      "
         (?P<method> \S+ )
         \s+
         (?P<path> [^"]+ )
         \s+
         (?P<http_version> HTTP/[^"]+ )
      " \s+
      (?P<code> \d+ ) \s+
      (?P<bytes> \d+ ) \s+
      "(?P<referer> [^"]* )" \s+
      "(?P<user_agent> [^"]* )" \s+
      (?P<hostname> \S+ ) \s+
      (?P<duration> \S+ )
    """,
    re.X,
)

PYTHON_LOG_LINE_RE = re.compile(
    r"""
      (?P<date> \d+-\d+-\d+ ) \s+
      (?P<time> \d+:\d+:\d+\.\d+ ) \s+
      INFO \s+  # All access log lines are INFO
      (pid:\d+ \s+) ?
      \[ (?P<source> zr(:\d+)?) \] \s+
      (?P<ip>
        \d{1,3}(\.\d{1,3}){3}
      | ([a-f0-9:]+:+){1,7}[a-f0-9]*
      ) \s+
      (?P<method> [A-Z]+ ) \s+
      (?P<code> \d+ ) \s+
      (?P<duration> \S+ ) \s+ # This can be "217ms" or "1.7s"
      ( \( [^)]+ \) \s+ )*
      (?P<path> /\S* ) \s+
      .*   # Multiple extra things can go here
      \(
        (?P<user>
           ( (?P<user_id> \d+ ) | unauth )
           @
           (?P<hostname> \S+ )
         | zulip-server:\S+
         | scim-client:\S+
         | internal
        ) \s+ via \s+ (?P<user_agent> .* )
      \)
    """,
    re.X,
)


class FilterType(Enum):
    HOSTNAME = auto()
    CLIENT_IP = auto()
    USER_ID = auto()
    PATH = auto()
    STATUS = auto()


class FilterFunc(Protocol):
    def __call__(
        self, m: re.Match, t: str = ...  # type: ignore[type-arg]  # Requires Python 3.9
    ) -> bool:
        ...


def main() -> None:
    args = parser().parse_args()

    (filter_types, filter_funcs) = parse_filters(args)
    logfile_names = parse_logfile_names(args)

    try:
        for logfile_name in reversed(logfile_names):
            with maybe_gzip(logfile_name) as logfile:
                for logline in logfile:
                    # As a performance optimization, just do a substring
                    # check before we parse the line fully
                    lowered = logline.lower()
                    if not all(f in lowered for f in args.filter_terms):
                        continue

                    if args.nginx:
                        match = NGINX_LOG_LINE_RE.match(logline)
                    else:
                        match = PYTHON_LOG_LINE_RE.match(logline)
                    if match is None:
                        # We expect other types of loglines in the Python logfiles
                        if args.nginx:
                            print(f"! Failed to parse:\n{logline}", file=sys.stderr)
                        continue
                    if passes_filters(filter_funcs, match, args):
                        print_line(
                            match,
                            args,
                            filter_types=filter_types,
                        )
    except KeyboardInterrupt:
        sys.exit(signal.SIGINT + 128)


def parse_logfile_names(args: argparse.Namespace) -> List[str]:
    if args.nginx:
        base_path = "/var/log/nginx/access.log"
    else:
        base_path = "/var/log/zulip/server.log"

    logfile_names = [base_path]
    if args.all_logs:
        logfile_count = 15
    elif args.log_files is not None:
        logfile_count = args.log_files
    else:
        # Detect if there was a logfile rotation in the last
        # (min-hours)-ish hours, and if so include the previous
        # logfile as well.
        logfile_count = 1
        try:
            current_size = os.path.getsize(base_path)
            past_size = os.path.getsize(base_path + ".1")
            if current_size < (args.min_hours / 24.0) * past_size:
                logfile_count = 2
        except FileNotFoundError:
            pass
    for n in range(1, logfile_count):
        logname = f"{base_path}.{n}"
        if n > 1:
            logname += ".gz"
        logfile_names.append(logname)
    return logfile_names


def parse_filters(
    args: argparse.Namespace,
) -> Tuple[Set[FilterType], List[FilterFunc]]:
    # The heuristics below are not intended to be precise -- they
    # certainly count things as "IPv4" or "IPv6" addresses that are
    # invalid.  However, we expect the input here to already be
    # reasonably well-formed.

    filter_types = set()
    filter_funcs = []
    filter_terms = []

    for filter_term in args.filter_terms:
        if re.match(r"[1-5][0-9][0-9]$", filter_term):
            filter_func = lambda m, t=filter_term: m["code"] == t
            filter_type = FilterType.STATUS
            if not args.nginx and filter_term == "502":
                logging.warning("Adding --nginx -- 502's do not appear in Django logs.")
                args.nginx = True
        elif re.match(r"[1-5]xx$", filter_term):
            filter_term = filter_term[0]
            filter_func = lambda m, t=filter_term: m["code"].startswith(t)
            filter_type = FilterType.STATUS
        elif re.match(r"\d+$", filter_term):
            if args.nginx:
                raise parser().error("Cannot parse user-ids with nginx logs; try without --nginx")
            filter_func = lambda m, t=filter_term: m["user_id"] == t
            filter_type = FilterType.USER_ID
        elif re.match(r"\d{1,3}(\.\d{1,3}){3}$", filter_term):
            filter_func = lambda m, t=filter_term: m["ip"] == t
            filter_type = FilterType.CLIENT_IP
        elif re.match(r"([a-f0-9:]+:+){1,7}[a-f0-9]+$", filter_term):
            filter_func = lambda m, t=filter_term: m["ip"] == t
            filter_type = FilterType.CLIENT_IP
        elif re.match(r"[a-z0-9]([a-z0-9-]*[a-z0-9])?$", filter_term.lower()):
            filter_term = filter_term.lower()
            if args.nginx:
                filter_func = lambda m, t=filter_term: m["hostname"].startswith(t + ".")
            else:
                filter_func = lambda m, t=filter_term: m["hostname"] == t
            filter_type = FilterType.HOSTNAME
        elif re.match(r"[a-z0-9-]+(\.[a-z0-9-]+)+$", filter_term.lower()) and re.search(
            r"[a-z-]", filter_term.lower()
        ):
            if not args.nginx:
                raise parser().error("Cannot parse full domains with Python logs; try --nginx")
            filter_term = filter_term.lower()
            filter_func = lambda m, t=filter_term: m["hostname"] == t
            filter_type = FilterType.HOSTNAME
        elif re.match(r"/\S*$", filter_term):
            filter_func = lambda m, t=filter_term: m["path"] == t
            filter_type = FilterType.PATH
            args.all_lines = True
        else:
            raise RuntimeError(
                f"Can't parse {filter_term} as an IP, hostname, user-id, path, or status code."
            )
        if filter_type in filter_types:
            parser().error("Supplied the same time of value more than once, which cannot match!")
        filter_types.add(filter_type)
        filter_funcs.append(filter_func)
        filter_terms.append(filter_term)

    # Push back the modified raw strings, so we can use them for fast substring searches
    args.filter_terms = filter_terms

    return (filter_types, filter_funcs)


def passes_filters(
    string_filters: List[FilterFunc],
    match: re.Match,  # type: ignore[type-arg]  # Requires Python 3.9
    args: argparse.Namespace,
) -> bool:
    if not all(f(match) for f in string_filters):
        return False

    if args.all_lines:
        return True

    path = match["path"]
    if path.startswith("/static/") and not args.static:
        return False
    if path.startswith("/user_uploads/") and not args.uploads:
        return False
    if path.startswith(("/user_avatars/", "/avatar/")) and not args.avatars:
        return False
    if re.match(r"/(json|api/v1)/events($|\?|/)", path) and not args.events:
        return False
    if path in ("/api/v1/typing", "/json/typing") and not args.typing:
        return False
    if re.match(r"/(json|api/v1)/messages($|\?|/)", path) and not args.messages:
        return False
    if path in ("/api/v1/users/me/presence", "/json/users/me/presence") and not args.messages:
        return False
    if path.startswith(("/api/v1/report/", "/json/report/")) and not args.report:
        return False

    return True


def print_line(
    match: re.Match,  # type: ignore[type-arg]  # Requires Python 3.9
    args: argparse.Namespace,
    filter_types: Set[FilterType],
) -> None:
    if args.full_line:
        print(match.group(0))
        return

    if args.all_logs or args.log_files is not None and args.log_files > 1:
        ts = match["date"] + ":" + match["time"]
    else:
        ts = match["time"]

    if match["duration"].endswith("ms"):
        duration = match["duration"][:-2]
    else:
        duration = str(int(float(match["duration"][:-1]) * 1000))

    code = int(match["code"])
    indicator = " "
    color = ""
    if code == 401:
        indicator = ":"
        color = CYAN
    elif code == 499:
        indicator = "-"
        color = GRAY
    elif code >= 400 and code < 499:
        indicator = ">"
        color = OKBLUE
    elif code >= 500 and code <= 599:
        indicator = "!"
        color = FAIL
    url = f"{BOLD}{match['path']}"
    if FilterType.HOSTNAME not in filter_types:
        hostname = match["hostname"]
        if hostname is None:
            hostname = "???." + settings.EXTERNAL_HOST
        elif not args.nginx:
            if hostname != "root":
                hostname += "." + settings.EXTERNAL_HOST
            elif settings.EXTERNAL_HOST == "zulipchat.com":
                hostname = "zulip.com"
            else:
                hostname = settings.EXTERNAL_HOST
        url = "https://" + hostname + url

    user_id = ""
    if not args.nginx and match["user_id"] is not None:
        user_id = match["user_id"] + "@"

    parts = [
        ts,
        f"{duration:>5}ms",
        f"{user_id:7}" if not args.nginx and FilterType.USER_ID not in filter_types else None,
        f"{match['ip']:39}" if FilterType.CLIENT_IP not in filter_types else None,
        indicator + match["code"],
        f"{match['method']:6}",
        url,
    ]

    print(color + " ".join([p for p in parts if p is not None]) + ENDC)


if __name__ == "__main__":
    main()