"""
Built-in Condition-Variablen + sicherer Mini-Parser fuer Watcher-Triggers.

Erlaubte Variablen + die EINE Funktion `near(lat, lon, radius_m)` kommen
aus diesem Modul. Condition-Ausdruck ist ein sicheres Subset von Python
(kein eval, kein exec): nur Vergleiche, Boolean-Operatoren, Whitelisted
Funktionen, Variablen aus describe_variables(), Konstanten (Zahl/Bool/Str).

Beispiele:
  disk_free_gb < 5
  hour_of_day == 8 and day_of_week == "mon"
  is_weekend and minute_of_hour == 0
  near(53.123, 7.456, 500)
  current_lat and location_age_sec < 120
"""

from __future__ import annotations

import ast
import json
import logging
import math
import os
import shutil
import time
from datetime import datetime
from pathlib import Path
from typing import Any

logger = logging.getLogger(__name__)

STATE_DIR = Path("/shared/state")


# ─── State-Helfer (gemeinsam mit Bridge: /shared/state/*.json) ──────

def _read_state(name: str) -> dict | None:
    f = STATE_DIR / f"{name}.json"
    if not f.exists():
        return None
    try:
        return json.loads(f.read_text(encoding="utf-8"))
    except Exception:
        return None


# ─── Variablen-Quellen ──────────────────────────────────────────────

def _disk_stats() -> tuple[float, float]:
    """Returns (free_gb, free_pct). Schaut /shared (geteiltes Volume) — sonst /."""
    target = "/shared" if os.path.exists("/shared") else "/"
    try:
        st = shutil.disk_usage(target)
        free_gb = st.free / (1024 ** 3)
        free_pct = 100.0 * st.free / st.total if st.total else 0.0
        return free_gb, free_pct
    except Exception as e:
        logger.warning("disk_usage: %s", e)
        return 0.0, 0.0


def _uptime_sec() -> int:
    try:
        with open("/proc/uptime", "r") as f:
            return int(float(f.read().split()[0]))
    except Exception:
        return 0


def _ram_free_mb() -> int:
    """Container-RAM: MemAvailable aus /proc/meminfo (kB → MB)."""
    try:
        with open("/proc/meminfo", "r") as f:
            for line in f:
                if line.startswith("MemAvailable:"):
                    return int(line.split()[1]) // 1024
    except Exception:
        pass
    return 0


def _cpu_load_1min() -> float:
    """load avg ueber 1 Minute (linux). Vorsicht: das ist die HOST-load,
    nicht container-spezifisch."""
    try:
        with open("/proc/loadavg", "r") as f:
            return float(f.read().split()[0])
    except Exception:
        return 0.0


_DAYS = ["mon", "tue", "wed", "thu", "fri", "sat", "sun"]


def _gps_state() -> dict[str, Any]:
    """Letzte bekannte Position aus /shared/state/location.json.
    Returns dict mit current_lat, current_lon (oder None), location_age_sec."""
    data = _read_state("location") or {}
    now = int(time.time())
    age = -1
    lat = data.get("lat")
    lon = data.get("lon")
    ts = data.get("ts_unix")
    if isinstance(ts, (int, float)):
        age = int(now - ts)
    return {
        "current_lat": float(lat) if isinstance(lat, (int, float)) else None,
        "current_lon": float(lon) if isinstance(lon, (int, float)) else None,
        "location_age_sec": age,
    }


def _user_activity_age() -> int:
    """Sekunden seit letzter User-Aktion (Chat oder Voice). -1 wenn nie."""
    data = _read_state("activity") or {}
    ts = data.get("last_user_ts")
    if not isinstance(ts, (int, float)):
        return -1
    return int(time.time() - ts)


def collect_variables() -> dict[str, Any]:
    """Liefert aktuellen Snapshot aller Built-in-Variablen + near()-Helper."""
    free_gb, free_pct = _disk_stats()
    now = datetime.now()
    gps = _gps_state()

    # Memory-Counts aus der Vector-DB (lazy import, sonst zirkulaer)
    memory_count = 0
    pinned_count = 0
    try:
        from main import store  # type: ignore
        s = store()
        memory_count = s.count()
        try:
            pinned_count = len(s.list_pinned())
        except Exception:
            pass
    except Exception:
        pass

    vars_: dict[str, Any] = {
        # Disk + System
        "disk_free_gb":   round(free_gb, 2),
        "disk_free_pct":  round(free_pct, 1),
        "ram_free_mb":    _ram_free_mb(),
        "cpu_load_1min":  round(_cpu_load_1min(), 2),
        "uptime_sec":     _uptime_sec(),

        # Zeit
        "hour_of_day":    now.hour,
        "minute_of_hour": now.minute,
        "day_of_month":   now.day,
        "month":          now.month,
        "year":           now.year,
        "day_of_week":    _DAYS[now.weekday()],
        "is_weekend":     now.weekday() >= 5,
        "unix_timestamp": int(time.time()),

        # GPS
        "current_lat":      gps["current_lat"],
        "current_lon":      gps["current_lon"],
        "location_age_sec": gps["location_age_sec"],

        # Activity
        "last_user_message_ago_sec": _user_activity_age(),

        # Memory
        "memory_count": memory_count,
        "pinned_count": pinned_count,

        # rvs_connected: kann Brain noch nicht zuverlaessig feststellen
        # (Bridge muesste eigenen Heartbeat-State schreiben — kommt spaeter)
        "rvs_connected": False,
    }

    # Funktion-Helper — wird vom Parser als ast.Call mit Name "near" erkannt.
    # Closure ueber die GPS-Werte, damit eval keine extra Variablen braucht.
    def _near(lat: float, lon: float, radius_m: float) -> bool:
        """Haversine-Distanz: True wenn aktuelle Position < radius_m vom Punkt."""
        cur_lat = vars_.get("current_lat")
        cur_lon = vars_.get("current_lon")
        if cur_lat is None or cur_lon is None:
            return False
        try:
            R = 6371000.0
            phi1 = math.radians(float(cur_lat))
            phi2 = math.radians(float(lat))
            dphi = math.radians(float(lat) - float(cur_lat))
            dlam = math.radians(float(lon) - float(cur_lon))
            a = math.sin(dphi / 2) ** 2 + math.cos(phi1) * math.cos(phi2) * math.sin(dlam / 2) ** 2
            distance = 2 * R * math.asin(math.sqrt(a))
            return distance < float(radius_m)
        except Exception:
            return False

    vars_["near"] = _near
    return vars_


def describe_variables() -> list[dict]:
    """Beschreibung — fuer System-Prompt + UI."""
    return [
        # Disk / System
        {"name": "disk_free_gb",   "type": "number", "desc": "freier Plattenplatz in GB (auf /shared)"},
        {"name": "disk_free_pct",  "type": "number", "desc": "freier Plattenplatz in Prozent"},
        {"name": "ram_free_mb",    "type": "number", "desc": "freier RAM im Brain-Container (MB)"},
        {"name": "cpu_load_1min",  "type": "number", "desc": "Load-Avg 1min (Host)"},
        {"name": "uptime_sec",     "type": "number", "desc": "Sekunden seit Brain-Start"},
        # Zeit
        {"name": "hour_of_day",    "type": "number", "desc": "0..23, lokale Zeit"},
        {"name": "minute_of_hour", "type": "number", "desc": "0..59"},
        {"name": "day_of_month",   "type": "number", "desc": "1..31"},
        {"name": "month",          "type": "number", "desc": "1..12"},
        {"name": "year",           "type": "number", "desc": "z.B. 2026"},
        {"name": "day_of_week",    "type": "string", "desc": "mon|tue|wed|thu|fri|sat|sun"},
        {"name": "is_weekend",     "type": "bool",   "desc": "True wenn Samstag oder Sonntag"},
        {"name": "unix_timestamp", "type": "number", "desc": "Sekunden seit Epoche (UTC)"},
        # GPS
        {"name": "current_lat",      "type": "number", "desc": "letzte bekannte Breitengrad (oder None)"},
        {"name": "current_lon",      "type": "number", "desc": "letzte bekannte Laengengrad (oder None)"},
        {"name": "location_age_sec", "type": "number", "desc": "Sekunden seit letzter Position (-1 = nie)"},
        # Activity
        {"name": "last_user_message_ago_sec", "type": "number",
         "desc": "Sekunden seit letztem User-Input (-1 = nie)"},
        # Memory
        {"name": "memory_count", "type": "number", "desc": "Anzahl Memories total"},
        {"name": "pinned_count", "type": "number", "desc": "Anzahl pinned (Hot Memory)"},
        {"name": "rvs_connected", "type": "bool", "desc": "RVS-Verbindung (z.Zt. immer False)"},
    ]


def describe_functions() -> list[dict]:
    """Whitelisted Funktionen fuer Conditions."""
    return [
        {
            "name": "near",
            "signature": "near(lat, lon, radius_m)",
            "desc": "True wenn die aktuelle GPS-Position innerhalb von radius_m Metern "
                    "vom Punkt (lat, lon) liegt. Haversine. Bei unbekannter Position: False.",
        },
    ]


_ALLOWED_FUNCTIONS = {f["name"] for f in describe_functions()}


# ─── Sicherer Condition-Parser ──────────────────────────────────────

_ALLOWED_NODES = (
    ast.Expression, ast.BoolOp, ast.UnaryOp, ast.Compare,
    ast.Name, ast.Constant, ast.Load,
    ast.And, ast.Or, ast.Not,
    ast.Eq, ast.NotEq, ast.Lt, ast.LtE, ast.Gt, ast.GtE,
    ast.Call,
)


def parse_condition(expr: str) -> ast.Expression:
    """Parst einen Condition-Ausdruck und validiert ihn gegen das Safe-Subset.
    Wirft ValueError bei verbotenen Konstrukten."""
    expr = (expr or "").strip()
    if not expr:
        raise ValueError("Leere Condition")
    if len(expr) > 500:
        raise ValueError("Condition zu lang (>500 Zeichen)")
    try:
        tree = ast.parse(expr, mode="eval")
    except SyntaxError as e:
        raise ValueError(f"Condition Syntax-Fehler: {e}")
    allowed_names = {v["name"] for v in describe_variables()}
    for node in ast.walk(tree):
        if not isinstance(node, _ALLOWED_NODES):
            raise ValueError(f"Verbotener Ausdruck: {type(node).__name__}")
        if isinstance(node, ast.Call):
            # Nur direkter Funktionsname, kein attribute-access (foo.bar())
            if not isinstance(node.func, ast.Name):
                raise ValueError("Funktionsaufruf nur ueber direkten Namen erlaubt")
            if node.func.id not in _ALLOWED_FUNCTIONS:
                raise ValueError(f"Verbotene Funktion: {node.func.id}")
            # Args muessen Constants oder einzelne Names sein
            for a in node.args:
                if not isinstance(a, (ast.Constant, ast.Name, ast.UnaryOp)):
                    raise ValueError(f"Argument-Typ in {node.func.id}() nicht erlaubt")
            if node.keywords:
                raise ValueError("Keyword-Argumente in Funktionen nicht erlaubt")
        if isinstance(node, ast.Name):
            if (node.id not in allowed_names
                and node.id not in _ALLOWED_FUNCTIONS
                and node.id not in ("True", "False")):
                raise ValueError(f"Unbekannte Variable: {node.id}")
        if isinstance(node, ast.Constant):
            if not isinstance(node.value, (int, float, str, bool)) and node.value is not None:
                raise ValueError(f"Verbotener Konstant-Typ: {type(node.value).__name__}")
    return tree


def evaluate(expr: str, variables: dict[str, Any] | None = None) -> bool:
    """Evaluiert die Condition gegen die aktuellen Variablen.
    Returns bool. Bei Fehler in Variablen → False (defensiv)."""
    tree = parse_condition(expr)
    vars_ = variables if variables is not None else collect_variables()
    code = compile(tree, "<condition>", "eval")
    # Globals leer, locals enthalten Variablen + near()-Funktion → kein Builtin-Zugriff
    try:
        result = eval(code, {"__builtins__": {}}, vars_)
    except Exception as e:
        logger.warning("Condition '%s' eval-Fehler: %s", expr, e)
        return False
    return bool(result)