"""Networkd daemon handler.

Registers routes for managing systemd-networkd interface configuration
via config/network/config.json and generated .network files.
"""

import contextlib
import logging
import re
from pathlib import Path
from typing import Any

from daemon.iface import (
    GET_NETWORK_INFER_DHCP_RANGES,
    GET_NETWORK_INFER_ZONES,
    GET_NETWORK_INTERFACE_NAME,
    GET_NETWORK_INTERFACES,
    POST_NETWORK_APPLY,
    POST_NETWORK_INTERFACE_NAME,
    POST_NETWORK_INTERFACE_RELOAD,
    POST_NETWORK_SYSCTL_SET,
)
from daemon.server import NotFoundError, registry
from lib.common import run, validate_interface_name
from lib.dnsmasq import set_upstreams
from lib.network import (
    KNOWN_INTERFACE_KEYS,
    collect_upstream_dns,
    generate_network_files,
    get_config,
    infer_dhcp_ranges,
    infer_zones,
    parse_networkctl_status,
    render_network_file,
    save_config,
)

logger = logging.getLogger(__name__)

PROJECT_DIR = Path(__file__).resolve().parent.parent.parent
CONFIG_DIR = PROJECT_DIR / "config" / "network"
DATA_DIR = PROJECT_DIR / "data" / "networkd"


def _copy_and_reload(iface_name: str) -> None:
    """Copy generated 99-<name>.network file to /etc/systemd/network/ and reload."""
    validate_interface_name(iface_name)
    src = DATA_DIR / f"99-{iface_name}.network"
    dst_dir = Path("/etc/systemd/network")
    run(["mkdir", "-p", str(dst_dir)], sudo=True)
    dst = dst_dir / f"99-{iface_name}.network"
    run(["cp", str(src), str(dst)], sudo=True)

    # Remove lower-priority .network files that match this interface
    # (they would override our config due to higher systemd priority)
    if dst_dir.exists():
        for f in dst_dir.iterdir():
            if (
                f.name.endswith(".network")
                and f.name != dst.name
                and _matches_interface(f.name, iface_name)
            ):
                with contextlib.suppress(Exception):
                    run(["rm", str(f)], sudo=True)
                    logger.info("Removed conflicting file: %s", f.name)

    run(["networkctl", "reload"], sudo=True)
    run(["networkctl", "reconfigure", iface_name], sudo=True)


def _matches_interface(filename: str, iface_name: str) -> bool:
    """Check if a .network filename would match the given interface."""
    base = filename.replace(".network", "")
    # Strip numeric priority prefix (e.g. "50-eth1" → "eth1")
    if "-" in base and base.split("-", 1)[0].isdigit():
        base = base.split("-", 1)[1]
    return base == iface_name


def _extract_iface_from_filename(filename: str) -> str | None:
    """Extract interface name from a .network filename (e.g. '50-eth1.network' → 'eth1')."""
    base = filename.replace(".network", "")
    if "-" in base and base.split("-", 1)[0].isdigit():
        return base.split("-", 1)[1]
    return base if base else None


def _full_reload() -> None:
    """Reload networkd for all interfaces."""
    run(["networkctl", "reload"], sudo=True)


# ---------------------------------------------------------------------------
# Routes
# ---------------------------------------------------------------------------


@registry.register(GET_NETWORK_INTERFACES)
def get_interfaces(_request: Any, _body: Any) -> dict[str, Any]:
    """GET /network/interfaces — return all interface config + runtime state."""
    cfg = get_config()
    ifaces_cfg = cfg.get("interfaces", {})

    runtime: dict[str, Any] = {}
    with contextlib.suppress(Exception):
        raw = run(["networkctl", "status", "--all"], sudo=True)
        runtime = parse_networkctl_status(raw)

    merged: dict[str, Any] = {}
    for name, config_entry in ifaces_cfg.items():
        merged[name] = {
            "config": config_entry,
            "runtime": runtime.get(name, {}),
        }

    from lib.state import _now_iso

    return {"interfaces": merged, "timestamp": _now_iso()}


@registry.register(GET_NETWORK_INTERFACE_NAME)
def get_interface(_request: Any, body: dict[str, Any] | None) -> dict[str, Any]:
    """GET /network/interfaces/<name> — return config for one interface."""
    if not body or "name" not in body:
        raise ValueError("Interface name is required")
    name = validate_interface_name(body["name"])
    cfg = get_config()
    ifaces = cfg.get("interfaces", {})
    if name not in ifaces:
        raise NotFoundError(f"Interface '{name}' not found in config")

    runtime: dict[str, Any] = {}
    with contextlib.suppress(Exception):
        raw = run(["networkctl", "status", "--all"], sudo=True)
        runtime = parse_networkctl_status(raw)

    return {
        "name": name,
        "config": ifaces[name],
        "runtime": runtime.get(name, {}),
    }


@registry.register(POST_NETWORK_INTERFACE_NAME)
def save_interface(_request: Any, body: dict[str, Any] | None) -> dict[str, Any]:
    """POST /network/interfaces/<name> — save config, render, apply."""
    if not body:
        raise ValueError("Request body required")
    name = validate_interface_name(body.get("name", ""))

    iface_cfg = {k: v for k, v in body.items() if k not in ("name",)}

    unknown = set(iface_cfg.keys()) - KNOWN_INTERFACE_KEYS
    if unknown:
        logger.warning(
            "Interface '%s': unexpected config keys %s — these will be "
            "saved but not rendered to .network files",
            name,
            sorted(unknown),
        )

    with contextlib.suppress(Exception):
        raw = run(["networkctl", "status", "--all"], sudo=True)
        runtime = parse_networkctl_status(raw)
        if name not in runtime:
            logger.warning(
                "Interface '%s' not found in networkctl "
                "(config saved but networkd will ignore it)",
                name,
            )

    cfg = get_config()
    cfg.setdefault("interfaces", {})
    cfg["interfaces"][name] = iface_cfg
    save_config(cfg)

    content = render_network_file(name, iface_cfg)
    DATA_DIR.mkdir(parents=True, exist_ok=True)
    (DATA_DIR / f"99-{name}.network").write_text(content)

    # Deploy to system. In containerized environments this may fail
    # (e.g. read-only /run/sudo timestamps) — don't let that block the save.
    deployed = True
    try:
        _copy_and_reload(name)
    except Exception:
        deployed = False
        logger.warning(
            "Interface '%s' config saved but failed to deploy to "
            "systemd-networkd (sudo/system unavailable)",
            name,
            exc_info=True,
        )

    logger.info("Interface '%s' config saved (applied=%s)", name, deployed)
    return {"name": name, "applied": deployed}


@registry.register(POST_NETWORK_INTERFACE_RELOAD)
def reload_interface(_request: Any, body: dict[str, Any] | None) -> dict[str, Any]:
    """POST /network/interfaces/<name>/reload — reload networkd for interface."""
    if not body or "name" not in body:
        raise ValueError("'name' is required in request body")
    name = validate_interface_name(body["name"])

    with contextlib.suppress(Exception):
        run(["networkctl", "reconfigure", name], sudo=True)

    logger.info("Interface '%s' reloaded", name)
    return {"name": name, "reloaded": True}


@registry.register(POST_NETWORK_APPLY)
def apply_all(_request: Any, _body: Any) -> dict[str, Any]:
    """POST /network/apply — apply ALL interfaces (full sync)."""
    cfg = get_config()
    result = generate_network_files(cfg)
    generated = result.get("generated", [])
    cleaned = result.get("cleaned", [])

    # Remove stale/conflicting files from system dir
    expected_names = {f.name for f in generated}
    managed_ifaces = {
        f.name.replace("99-", "").replace(".network", "") for f in generated
    }
    sys_dir = Path("/etc/systemd/network")
    if sys_dir.exists():
        for f in sys_dir.iterdir():
            if f.name.endswith(".network") and f.name not in expected_names:
                iface_from_file = _extract_iface_from_filename(f.name)
                if iface_from_file and iface_from_file in managed_ifaces:
                    # Remove conflicting external configs for managed interfaces
                    with contextlib.suppress(Exception):
                        run(["rm", str(f)], sudo=True)
                        cleaned.append(f)

    for f in generated:
        dst = sys_dir / f.name
        run(["mkdir", "-p", str(sys_dir)], sudo=True)
        run(["cp", str(f), str(dst)], sudo=True)

    _full_reload()

    # TF-8: sync DNS upstreams to dnsmasq
    try:
        upstreams = collect_upstream_dns(cfg)
        if upstreams:
            set_upstreams(upstreams)
            logger.info("Synced %d DNS upstreams to dnsmasq", len(upstreams))
    except Exception:
        logger.warning("Failed to sync DNS upstreams to dnsmasq", exc_info=True)

    logger.info(
        "Network config applied: %d interfaces, %d stale cleaned",
        len(generated),
        len(cleaned),
    )
    return {
        "applied": len(generated),
        "files": [str(p) for p in generated],
        "cleaned": [str(p) for p in cleaned],
    }


@registry.register(GET_NETWORK_INFER_DHCP_RANGES)
def get_infer_dhcp_ranges(_request: Any, _body: Any) -> dict[str, Any]:
    """GET /network/infer-dhcp-ranges — suggest DHCP ranges from static IPs."""
    cfg = get_config()
    ranges = infer_dhcp_ranges(cfg)
    return {"ranges": ranges}


@registry.register(GET_NETWORK_INFER_ZONES)
def get_infer_zones(_request: Any, _body: Any) -> dict[str, Any]:
    """GET /network/infer-zones — suggest firewalld zones from interface config."""
    cfg = get_config()
    zones = infer_zones(cfg)
    return {"zones": zones}


@registry.register(POST_NETWORK_SYSCTL_SET)
def set_sysctl(_request: Any, body: dict[str, Any] | None) -> dict[str, Any]:
    """POST /sysctl/set — set a sysctl kernel parameter value.

    Writes the value via `sysctl -w`, then verifies by reading it back.

    Raises:
        ValueError: When name or value is missing.
    """
    if not body:
        raise ValueError("Request body required")
    name = body.get("name", "").strip()
    if not name:
        raise ValueError("'name' is required")
    if not re.match(r"^[a-zA-Z0-9_]+(\.[a-zA-Z0-9_]+)*$", name):
        raise ValueError("'name' is not a valid sysctl key")
    value = str(body.get("value", "")).strip()
    if not value:
        raise ValueError("'value' is required")

    run(["sysctl", "-w", f"{name}={value}"], sudo=True)

    # Verify by reading back via /proc/sys (no sudo needed for reads, avoid
    # triggering sudoers for read-only sysctl which is not whitelisted)
    proc_path = Path(f"/proc/sys/{name.replace('.', '/')}")
    read_value = proc_path.read_text().strip()
    if read_value != value:
        raise RuntimeError(
            f"sysctl verify failed: set {name}={value} but read back {read_value}"
        )

    logger.info("sysctl %s set to %s", name, value)
    return {"name": name, "value": value}