"""Parsers for the output of BSD commands. Pure functions, no I/O.

FreeBSD and OpenBSD share most tools; where their output differs (``arp``,
``kern.boottime``, how ``netstat`` abbreviates networks, ``ether`` vs
``lladdr``) one parser reads both.
"""

from __future__ import annotations

import ipaddress
import re
from typing import Any, Optional

_IFACE_HEADER = re.compile(
    r"^(?P<name>[^\s:]+): flags=[0-9a-f]+<(?P<flags>[^>]*)>(?:.*?\bmtu (?P<mtu>\d+))?"
)
_SPEED = re.compile(r"\((\d+)(G?)base", re.IGNORECASE)


def _prefix_from_netmask(mask: str) -> int:
    """``0xffffff00`` (as ifconfig prints it) or ``255.255.255.0`` -> 24."""
    value = int(mask, 16) if mask.startswith("0x") else int(ipaddress.IPv4Address(mask))
    return bin(value).count("1")


def ifconfig(text: str) -> dict[str, dict[str, Any]]:
    """``ifconfig -a`` -> per interface: flags, MTU, MAC, state, speed, addresses."""
    interfaces: dict[str, dict[str, Any]] = {}
    current: Optional[dict[str, Any]] = None
    for line in text.splitlines():
        header = _IFACE_HEADER.match(line)
        if header:
            flags = set(filter(None, header["flags"].split(",")))
            current = {
                "flags": flags,
                "enabled": "UP" in flags,
                "up": "UP" in flags and "RUNNING" in flags,
                "loopback": "LOOPBACK" in flags,
                "mtu": int(header["mtu"] or 0),
                "mac": "",
                "description": "",
                "speed": -1.0,
                "ipv4": {},
                "ipv6": {},
            }
            interfaces[header["name"]] = current
            continue
        if current is None:
            continue
        words = line.split()
        if not words:
            continue
        key = words[0]
        if key in ("ether", "lladdr") and len(words) > 1:
            current["mac"] = words[1].lower()
        elif key == "inet" and len(words) > 3 and words[2] == "netmask":
            current["ipv4"][words[1]] = _prefix_from_netmask(words[3])
        elif key == "inet6" and len(words) > 3 and words[2] == "prefixlen":
            current["ipv6"][words[1].split("%")[0]] = int(words[3])
        elif key == "description:":
            current["description"] = line.split("description:", 1)[1].strip()
        elif key == "status:":
            if line.split("status:", 1)[1].strip() == "no carrier":
                current["up"] = False
        elif key == "media:":
            speed = _SPEED.search(line)
            if speed:
                current["speed"] = float(int(speed[1]) * (1000 if speed[2] else 1))
    return interfaces


def _network(destination: str, family: str) -> Optional[str]:
    """A netstat destination as a network: ``default``, ``10.0.2/24``, ``fe80::%em0/64``."""
    if destination == "default":
        return "0.0.0.0/0" if family == "ipv4" else "::/0"
    address, slash, prefix = destination.partition("/")
    address = address.split("%")[0]
    if family == "ipv4":
        octets = address.split(".")
        address = ".".join(octets + ["0"] * (4 - len(octets)))
    try:
        return str(ipaddress.ip_network(f"{address}/{prefix}" if slash else address, strict=False))
    except ValueError:
        return None


def routes(text: str) -> list[dict[str, str]]:
    """``netstat -rn`` -> the routes, without host, broadcast and loopback entries.

    FreeBSD prints ``Netif``, OpenBSD ``Iface``; the column is found from the
    header. A route through a gateway (``G``) has a next hop, any other is
    connected; ``S`` marks a static one.
    """
    result: list[dict[str, str]] = []
    family = ""
    iface_column: Optional[int] = None
    for line in text.splitlines():
        words = line.split()
        if not words:
            continue
        if words[0] in ("Internet:", "Internet6:"):
            family = "ipv4" if words[0] == "Internet:" else "ipv6"
            continue
        if words[0] == "Destination":
            names = [w for w in words if w in ("Netif", "Iface")]
            iface_column = words.index(names[0]) if names else None
            continue
        if not family or iface_column is None or len(words) <= iface_column:
            continue
        destination, gateway, flags, iface = words[0], words[1], words[2], words[iface_column]
        if iface.startswith("lo") or ("H" in flags and "G" not in flags) or "b" in flags:
            continue
        network = _network(destination, family)
        if network is None or ipaddress.ip_network(network).is_multicast:
            continue
        gateway_route = "G" in flags
        result.append(
            {
                "network": network,
                "next_hop": gateway if gateway_route else "",
                "interface": iface,
                "protocol": ("static" if "S" in flags else "dynamic")
                if gateway_route
                else "connected",
                "family": family,
            }
        )
    return result


_DURATION = re.compile(r"(?:(\d+)h)?(?:(\d+)m)?(?:(\d+)s)?$")


def duration(text: str) -> float:
    """OpenBSD's ``1h2m3s`` in seconds; -1.0 for anything else (``permanent``)."""
    match = _DURATION.match(text)
    if not text or not match or not any(match.groups()):
        return -1.0
    hours, minutes, seconds = (int(g or 0) for g in match.groups())
    return float(hours * 3600 + minutes * 60 + seconds)


_FREEBSD_ARP = re.compile(
    r"^\S+ \((?P<ip>[\d.]+)\) at (?P<mac>[0-9a-f:]{17}) on (?P<iface>\S+)"
    r"(?: expires in (?P<expires>\d+) seconds)?"
)


def arp(text: str) -> list[dict[str, Any]]:
    """``arp -an`` -> ARP entries; FreeBSD prints sentences, OpenBSD a table."""
    entries: list[dict[str, Any]] = []
    for line in text.splitlines():
        sentence = _FREEBSD_ARP.match(line)
        if sentence:
            expires = sentence["expires"]
            entries.append(
                {
                    "interface": sentence["iface"],
                    "mac": sentence["mac"],
                    "ip": sentence["ip"],
                    "age": float(expires) if expires else -1.0,
                }
            )
            continue
        words = line.split()
        if len(words) >= 4 and re.fullmatch(r"[0-9a-f:]{17}", words[1]):
            entries.append(
                {"interface": words[2], "mac": words[1], "ip": words[0], "age": duration(words[3])}
            )
    return entries


def users(passwd: str, group: str) -> list[dict[str, Any]]:
    """``/etc/passwd`` plus the supplementary groups ``/etc/group`` lists."""
    memberships: dict[str, list[str]] = {}
    for line in group.splitlines():
        parts = line.split(":")
        if len(parts) < 4 or line.startswith("#"):
            continue
        for member in filter(None, (m.strip() for m in parts[3].split(","))):
            memberships.setdefault(member, []).append(parts[0])
    result: list[dict[str, Any]] = []
    for line in passwd.splitlines():
        parts = line.split(":")
        if len(parts) < 7 or line.startswith("#"):
            continue
        name, _, uid, gid, _, home, shell = parts[:7]
        if not (uid.isdigit() and gid.isdigit()):
            continue
        result.append(
            {
                "username": name,
                "uid": int(uid),
                "gid": int(gid),
                "home": home,
                "shell": shell,
                "groups": memberships.get(name, []),
            }
        )
    return result


_PROCESS = re.compile(
    r"^(?P<user>\S+)\s+(?P<pid>\d+)\s+(?P<ppid>\d+)\s+(?P<cpu>[\d.]+)\s+(?P<mem>[\d.]+)\s+"
    r"(?P<vsz>\d+)\s+(?P<rss>\d+)\s+(?P<stat>\S+)\s+"
    r"(?P<started>\w{3}\s+\w{3}\s+\d+\s+\d\d:\d\d:\d\d\s+\d{4})\s+(?P<command>.*)$"
)


def processes(text: str) -> list[dict[str, Any]]:
    """``ps -axww -o user,pid,ppid,%cpu,%mem,vsz,rss,stat,lstart,command``.

    ``lstart`` is five words; it is matched as one field.
    """
    result: list[dict[str, Any]] = []
    for line in text.splitlines():
        match = _PROCESS.match(line)
        if not match:
            continue
        result.append(
            {
                "pid": int(match["pid"]),
                "ppid": int(match["ppid"]),
                "user": match["user"],
                "cpu": float(match["cpu"]),
                "memory": float(match["mem"]),
                "vsz": int(match["vsz"]),
                "rss": int(match["rss"]),
                "tty": "",
                "state": match["stat"][0],
                "started": match["started"],
                "command": match["command"].strip(),
            }
        )
    return result


def crontab(text: str, *, system: bool = False, user: str = "") -> list[dict[str, str]]:
    """A crontab -> its jobs. A system crontab names the user in the sixth field."""
    jobs: list[dict[str, str]] = []
    for line in text.splitlines():
        line = line.strip()
        if not line or line.startswith("#") or re.match(r"^[A-Za-z_][A-Za-z0-9_]*\s*=", line):
            continue
        fields = 1 if line.startswith("@") else 5
        parts = line.split(None, fields + (1 if system else 0))
        if len(parts) < fields + (2 if system else 1):
            continue
        schedule = " ".join(parts[:fields])
        owner = parts[fields] if system else user
        command = parts[-1]
        jobs.append({"user": owner, "schedule": schedule, "command": command})
    return jobs


def boottime(text: str) -> Optional[int]:
    """``sysctl -n kern.boottime``: FreeBSD ``{ sec = N, … }``, OpenBSD ``N``."""
    match = re.search(r"sec = (\d+)", text) or re.fullmatch(r"\s*(\d+)\s*", text)
    return int(match[1]) if match else None


def _socket(
    proto: str, local: str, family: str, process: Optional[str], pid: Optional[int]
) -> Optional[dict[str, Any]]:
    """A ListeningSocketDict from a local endpoint: ``*:22``, ``[::1]:25``,
    ``127.0.0.1:25``, ``[fe80::1%lo0]:25`` (sockstat, fstat) or ``*.22``,
    ``::1.25``, ``fe80::1%lo0.25`` (netstat)."""
    if local.startswith("["):
        address, _, port = local[1:].partition("]:")
    elif local.count(":") == 1 or local.startswith("*:"):
        address, _, port = local.rpartition(":")
    else:
        address, _, port = local.rpartition(".")
    if not port.isdigit() or int(port) == 0:
        return None
    address, _, zone = address.partition("%")
    if address == "*":
        address = "0.0.0.0" if family == "4" else "::"
    return {
        "proto": proto,
        "address": address,
        "port": int(port),
        "interface": zone or None,
        "process": process,
        "pid": pid,
        "unit": None,
        "container_id": None,
    }


def _unique(sockets: list[Optional[dict[str, Any]]]) -> list[dict[str, Any]]:
    """One entry per socket, the first process holding it, as ss reports it."""
    seen: set[tuple] = set()
    result = []
    for s in sockets:
        if s is None:
            continue
        key = (s["proto"], s["address"], s["port"], s["interface"])
        if key not in seen:
            seen.add(key)
            result.append(s)
    return result


def sockstat(text: str) -> list[dict[str, Any]]:
    """FreeBSD ``sockstat -46lq -P tcp,udp``: USER COMMAND PID FD PROTO LOCAL FOREIGN."""
    sockets = []
    for line in text.splitlines():
        words = line.split()
        if len(words) < 7 or not words[2].isdigit() or words[4][:3] not in ("tcp", "udp"):
            continue
        proto, family = words[4][:3], words[4][3:]
        sockets.append(_socket(proto, words[5], family, words[1], int(words[2])))
    return _unique(sockets)


def fstat_sockets(text: str) -> list[dict[str, Any]]:
    """OpenBSD ``fstat -n``: the internet sockets nothing is connected to.

    ``USER CMD PID FD internet[6] stream|dgram tcp|udp [0xPCB] LOCAL [ARROW REMOTE]``;
    a socket with an arrow is connected, one bound to port 0 is not bound.
    """
    sockets = []
    for line in text.splitlines():
        words = line.split()
        if len(words) < 8 or words[4] not in ("internet", "internet6"):
            continue
        if any(arrow in words for arrow in ("<--", "-->", "<->")):
            continue
        family = "6" if words[4] == "internet6" else "4"
        sockets.append(_socket(words[6], words[-1], family, words[1], int(words[2])))
    return _unique(sockets)


def netstat_listening(text: str) -> list[dict[str, Any]]:
    """``netstat -an``: listening TCP and bound UDP sockets, without their process."""
    sockets = []
    for line in text.splitlines():
        words = line.split()
        if len(words) < 5 or words[0][:3] not in ("tcp", "udp"):
            continue
        proto, family = words[0][:3], "6" if words[0].endswith("6") else "4"
        local, foreign = words[3], words[4]
        if proto == "tcp" and words[-1] != "LISTEN":
            continue
        if proto == "udp" and foreign != "*.*":
            continue
        sockets.append(_socket(proto, local, family, None, None))
    return _unique(sockets)