"""
System capability checks for Bluetooth scanning.

Checks for DBus, BlueZ, adapters, permissions, and fallback tools.
"""

from __future__ import annotations

import os
import re
import shutil
import subprocess

from .constants import (
    BLUEZ_PATH,
    BLUEZ_SERVICE,
    SUBPROCESS_TIMEOUT_SHORT,
)
from .models import SystemCapabilities

# Import timeout from parent constants if available
try:
    from ..constants import SUBPROCESS_TIMEOUT_SHORT as PARENT_TIMEOUT

    SUBPROCESS_TIMEOUT_SHORT = PARENT_TIMEOUT
except ImportError:
    SUBPROCESS_TIMEOUT_SHORT = 5


def check_capabilities() -> SystemCapabilities:
    """
    Check all Bluetooth-related system capabilities.

    Returns:
        SystemCapabilities object with all checks performed.
    """
    caps = SystemCapabilities()

    # Check permissions
    caps.is_root = os.geteuid() == 0

    # Check DBus
    _check_dbus(caps)

    # Check BlueZ
    _check_bluez(caps)

    # Check adapters
    _check_adapters(caps)

    # Check rfkill status
    _check_rfkill(caps)

    # Check fallback tools
    _check_fallback_tools(caps)

    # Determine recommended backend
    _determine_recommended_backend(caps)

    return caps


def _check_dbus(caps: SystemCapabilities) -> None:
    """Check if DBus is available."""
    try:
        # Try to import dbus module
        import dbus

        caps.has_dbus = True
    except ImportError:
        caps.has_dbus = False
        caps.issues.append("Python dbus module not installed (pip install dbus-python)")


def _check_bluez(caps: SystemCapabilities) -> None:
    """Check if BlueZ service is available via DBus."""
    if not caps.has_dbus:
        return

    try:
        import dbus

        bus = dbus.SystemBus()

        # Check if BlueZ service exists
        try:
            bus.get_object(BLUEZ_SERVICE, BLUEZ_PATH)
            caps.has_bluez = True

            # Try to get BlueZ version from bluetoothd
            try:
                result = subprocess.run(
                    ["bluetoothd", "--version"], capture_output=True, text=True, timeout=SUBPROCESS_TIMEOUT_SHORT
                )
                if result.returncode == 0:
                    caps.bluez_version = result.stdout.strip()
            except (subprocess.TimeoutExpired, FileNotFoundError, OSError):
                pass

        except dbus.exceptions.DBusException as e:
            caps.has_bluez = False
            if "org.freedesktop.DBus.Error.ServiceUnknown" in str(e):
                caps.issues.append("BlueZ service not running (systemctl start bluetooth)")
            else:
                caps.issues.append(f"BlueZ DBus error: {e}")

    except Exception as e:
        caps.has_bluez = False
        caps.issues.append(f"DBus connection error: {e}")


def _check_adapters(caps: SystemCapabilities) -> None:
    """Check available Bluetooth adapters."""
    if not caps.has_dbus or not caps.has_bluez:
        # Fall back to hciconfig if available
        _check_adapters_hciconfig(caps)
        return

    try:
        import dbus

        bus = dbus.SystemBus()
        manager = dbus.Interface(bus.get_object(BLUEZ_SERVICE, "/"), "org.freedesktop.DBus.ObjectManager")

        objects = manager.GetManagedObjects()
        for path, interfaces in objects.items():
            if "org.bluez.Adapter1" in interfaces:
                adapter_props = interfaces["org.bluez.Adapter1"]
                adapter_info = {
                    "id": str(path),  # Alias for frontend
                    "path": str(path),
                    "name": str(adapter_props.get("Name", "Unknown")),
                    "address": str(adapter_props.get("Address", "Unknown")),
                    "powered": bool(adapter_props.get("Powered", False)),
                    "discovering": bool(adapter_props.get("Discovering", False)),
                    "alias": str(adapter_props.get("Alias", "")),
                }
                caps.adapters.append(adapter_info)

                # Set default adapter if not set
                if caps.default_adapter is None:
                    caps.default_adapter = str(path)

        if not caps.adapters:
            caps.issues.append("No Bluetooth adapters found")

    except Exception as e:
        caps.issues.append(f"Failed to enumerate adapters: {e}")
        # Fall back to hciconfig
        _check_adapters_hciconfig(caps)


def _check_adapters_hciconfig(caps: SystemCapabilities) -> None:
    """Check adapters using hciconfig (fallback)."""
    try:
        result = subprocess.run(["hciconfig", "-a"], capture_output=True, text=True, timeout=SUBPROCESS_TIMEOUT_SHORT)
        if result.returncode == 0:
            # Parse hciconfig output
            current_adapter = None
            for line in result.stdout.split("\n"):
                # Match adapter line (e.g., "hci0:	Type: Primary  Bus: USB")
                adapter_match = re.match(r"^(hci\d+):", line)
                if adapter_match:
                    adapter_name = adapter_match.group(1)
                    current_adapter = {
                        "id": adapter_name,  # Alias for frontend
                        "path": f"/org/bluez/{adapter_name}",
                        "name": adapter_name,
                        "address": "Unknown",
                        "powered": False,
                        "discovering": False,
                    }
                    caps.adapters.append(current_adapter)

                    if caps.default_adapter is None:
                        caps.default_adapter = current_adapter["path"]

                elif current_adapter:
                    # Parse BD Address
                    addr_match = re.search(r"BD Address: ([0-9A-F:]+)", line, re.I)
                    if addr_match:
                        current_adapter["address"] = addr_match.group(1)

                    # Check if UP
                    if "UP RUNNING" in line:
                        current_adapter["powered"] = True

    except (subprocess.TimeoutExpired, FileNotFoundError, OSError):
        pass


def _check_rfkill(caps: SystemCapabilities) -> None:
    """Check rfkill status for Bluetooth."""
    try:
        result = subprocess.run(
            ["rfkill", "list", "bluetooth"], capture_output=True, text=True, timeout=SUBPROCESS_TIMEOUT_SHORT
        )
        if result.returncode == 0:
            output = result.stdout.lower()
            caps.is_soft_blocked = "soft blocked: yes" in output
            caps.is_hard_blocked = "hard blocked: yes" in output

            if caps.is_soft_blocked:
                caps.issues.append("Bluetooth is soft-blocked (rfkill unblock bluetooth)")
            if caps.is_hard_blocked:
                caps.issues.append("Bluetooth is hard-blocked (check hardware switch)")

    except (subprocess.TimeoutExpired, FileNotFoundError, OSError):
        pass


def _check_fallback_tools(caps: SystemCapabilities) -> None:
    """Check for fallback scanning tools."""
    # Check bleak (Python BLE library)
    try:
        import bleak

        caps.has_bleak = True
    except ImportError:
        caps.has_bleak = False

    # Check hcitool
    caps.has_hcitool = shutil.which("hcitool") is not None

    # Check bluetoothctl
    caps.has_bluetoothctl = shutil.which("bluetoothctl") is not None

    # Check btmgmt
    caps.has_btmgmt = shutil.which("btmgmt") is not None

    # Check ubertooth tools (Ubertooth One hardware)
    caps.has_ubertooth = shutil.which("ubertooth-btle") is not None

    # Check CAP_NET_ADMIN for non-root users
    if not caps.is_root:
        _check_capabilities_permission(caps)


def _check_capabilities_permission(caps: SystemCapabilities) -> None:
    """Check if process has CAP_NET_ADMIN capability."""
    try:
        result = subprocess.run(["capsh", "--print"], capture_output=True, text=True, timeout=SUBPROCESS_TIMEOUT_SHORT)
        if result.returncode == 0:
            caps.has_bluetooth_permission = "cap_net_admin" in result.stdout.lower()
    except (subprocess.TimeoutExpired, FileNotFoundError, OSError):
        # Assume no capabilities if capsh not available
        pass

    if not caps.has_bluetooth_permission and not caps.is_root:
        # Check if user is in bluetooth group
        try:
            import grp
            import pwd

            username = pwd.getpwuid(os.getuid()).pw_name
            bluetooth_group = grp.getgrnam("bluetooth")
            if username in bluetooth_group.gr_mem:
                caps.has_bluetooth_permission = True
        except (KeyError, ImportError):
            pass


def _determine_recommended_backend(caps: SystemCapabilities) -> None:
    """Determine the recommended scanning backend."""
    # NOTE: DBus/BlueZ requires a GLib main loop which Flask doesn't have.
    # For Flask applications, we prefer bleak or subprocess-based tools.

    # Prefer bleak (cross-platform, works in Flask)
    if caps.has_bleak:
        caps.recommended_backend = "bleak"
        return

    # Fallback to hcitool (requires root on Linux)
    if caps.has_hcitool and caps.is_root:
        caps.recommended_backend = "hcitool"
        return

    # Fallback to bluetoothctl
    if caps.has_bluetoothctl:
        caps.recommended_backend = "bluetoothctl"
        return

    # DBus is last resort - won't work properly with Flask but keep as option
    # for potential future use with a separate scanning daemon
    if caps.has_dbus and caps.has_bluez and caps.adapters and not caps.is_soft_blocked and not caps.is_hard_blocked:
        caps.recommended_backend = "dbus"
        return

    caps.recommended_backend = "none"
    if not caps.issues:
        caps.issues.append("No suitable Bluetooth scanning backend available")


def quick_adapter_check() -> str | None:
    """
    Quick check to find a working adapter.

    Returns:
        Adapter path/name if found, None otherwise.
    """
    caps = check_capabilities()
    return caps.default_adapter