"""Dnsmasq daemon handler."""

import logging
from copy import deepcopy
from datetime import UTC, datetime
from pathlib import Path
from typing import Any

from jinja2 import Environment, FileSystemLoader

from daemon.iface import (
    DELETE_DNSMASQ_DNS_RECORD_REMOVE,
    DELETE_DNSMASQ_RANGES_REMOVE,
    DELETE_DNSMASQ_STATIC_LEASE_REMOVE,
    GET_DNSMASQ_CONFIG,
    GET_DNSMASQ_LEASES,
    GET_DNSMASQ_STATUS,
    PATCH_DNSMASQ_CONFIG,
    POST_DNSMASQ_APPLY,
    POST_DNSMASQ_CONFIG,
    POST_DNSMASQ_DNS_RECORD_ADD,
    POST_DNSMASQ_DOMAIN,
    POST_DNSMASQ_RANGES_ADD,
    POST_DNSMASQ_STATIC_LEASE_ADD,
    POST_DNSMASQ_UPSTREAMS,
)
from daemon.server import NotFoundError, refresh_state, registry
from lib.common import (
    _APPLY_HASH_KEY,
    config_hash,
    deep_merge,
    ensure_dirs,
    get_interface_ip,
    load_json,
    run,
    save_json,
)
from lib.sync import SyncEvent, bus

logger = logging.getLogger(__name__)

PROJECT_DIR = Path(__file__).resolve().parent.parent.parent
CONFIG_DIR = PROJECT_DIR / "config" / "dnsmasq"
DATA_DIR = PROJECT_DIR / "data" / "dnsmasq"
CONFIG_PATH = CONFIG_DIR / "config.json"
FRAGMENTS_DIR = DATA_DIR / "fragments"
DNSMASQ_CONF = "/etc/dnsmasq.d/vacuum-wall.conf"
LEASE_FILE = "/var/lib/misc/dnsmasq.leases"

ENV = Environment(
    loader=FileSystemLoader(str(PROJECT_DIR / "system")),
    autoescape=False,
    lstrip_blocks=True,
    trim_blocks=True,
)

DEFAULT_CFG: dict[str, Any] = {
    "dhcp": {"ranges": [], "static_leases": []},
    "dns": {"upstreams": ["8.8.8.8", "1.1.1.1"], "domain": None, "custom_records": []},
}


def _get_state() -> dict[str, Any] | None:
    """Retrieve cached dnsmasq state from the state store."""
    from lib.state import state as state_store

    return state_store.get("dnsmasq")


def _get_config() -> dict[str, Any]:
    """Load dnsmasq config from JSON, merging with defaults."""
    ensure_dirs(CONFIG_DIR, DATA_DIR, FRAGMENTS_DIR)
    raw = load_json(CONFIG_PATH)
    if not raw:
        return deepcopy(DEFAULT_CFG)
    return deep_merge(deepcopy(DEFAULT_CFG), raw)


def _save_config(cfg: dict[str, Any]) -> None:
    """Persist dnsmasq config to JSON after merging with defaults."""
    ensure_dirs(CONFIG_DIR, DATA_DIR, FRAGMENTS_DIR)
    merged = deep_merge(deepcopy(DEFAULT_CFG), cfg)
    save_json(CONFIG_PATH, merged)


def _generate_conf(cfg: dict[str, Any]) -> str:
    """Render dnsmasq.conf from Jinja template and config dict."""
    dhcp_cfg = cfg.get("dhcp", {})
    dns_cfg = cfg.get("dns", {})
    interfaces = [
        r["interface"] for r in dhcp_cfg.get("ranges", []) if "interface" in r
    ]

    # Fallback: use network-managed interface addresses for listen-address
    listen_addresses = []
    try:
        from lib.network import get_config as _get_net_config

        net_cfg = _get_net_config()
        for _iface, info in net_cfg.get("interfaces", {}).items():
            for addr_str in info.get("addresses", []):
                if "/" in addr_str:
                    addr_str = addr_str.split("/")[0]
                listen_addresses.append(addr_str)
    except Exception:
        pass

    tmpl = ENV.get_template("dnsmasq.conf")
    return tmpl.render(
        timestamp=datetime.now(UTC).strftime("%Y-%m-%dT%H:%M:%SZ"),
        interfaces=interfaces or None,
        listen_addresses=listen_addresses if listen_addresses else None,
        dhcp=dhcp_cfg,
        dns=dns_cfg,
        fragments_dir=str(FRAGMENTS_DIR) if FRAGMENTS_DIR.exists() else None,
    )


def _get_dnsmasq_state() -> dict[str, Any]:
    """Return cached dnsmasq state, or empty dict if unset."""
    dm = _get_state()
    if dm is None:
        return {}
    return dm


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


@registry.register(GET_DNSMASQ_CONFIG)
def get_config(_request: Any, _body: Any) -> dict[str, Any]:
    """\
    Endpoint: GET /dnsmasq/config

    Returns cached config if available, otherwise loads from disk.
    """
    dm = _get_dnsmasq_state()
    if dm:
        return dm.get("config", {})
    cfg = _get_config()
    return {k: v for k, v in cfg.items() if k != _APPLY_HASH_KEY}


@registry.register(POST_DNSMASQ_CONFIG)
def save_config_handler(_request: Any, body: dict[str, Any] | None) -> dict[str, Any]:
    """\
    Endpoint: POST /dnsmasq/config

    Save full config. Raises ValueError on missing body.
    """
    if not body:
        raise ValueError("Request body required")
    _save_config(body)
    sync_result = bus.emit(
        SyncEvent("dnsmasq", "config_saved", {"action": "config_saved"})
    )
    refresh_state(["dnsmasq", *sync_result.affected_subsystems])
    return {"config_saved": True}


@registry.register(PATCH_DNSMASQ_CONFIG)
def patch_config(_request: Any, body: dict[str, Any] | None) -> dict[str, Any]:
    """\
    Endpoint: PATCH /dnsmasq/config

    Merge partial update into existing config. Raises ValueError on missing body.
    """
    if not body:
        raise ValueError("Request body required")
    current = _get_config()
    merged = deep_merge(current, body)
    _save_config(merged)
    sync_result = bus.emit(
        SyncEvent("dnsmasq", "config_saved", {"action": "config_patched"})
    )
    refresh_state(["dnsmasq", *sync_result.affected_subsystems])
    return {"config_saved": True}


@registry.register(POST_DNSMASQ_APPLY)
def apply_config(_request: Any, _body: Any) -> dict[str, Any]:
    """\
    Endpoint: POST /dnsmasq/apply

    Render config to dnsmasq.conf, write to disk, and reload dnsmasq service via sudo.
    """
    cfg = _get_config()
    conf_text = _generate_conf(cfg)
    ensure_dirs(CONFIG_DIR, DATA_DIR, FRAGMENTS_DIR)
    run(["mkdir", "-p", "/etc/dnsmasq.d"], sudo=True)
    tmp = Path("/run/vacuum-wall/dnsmasq.tmp")
    tmp.parent.mkdir(exist_ok=True)
    tmp.write_text(conf_text)
    run(["cp", "--", str(tmp), str(DNSMASQ_CONF)], sudo=True)
    tmp.unlink(missing_ok=True)
    run(["systemctl", "restart", "dnsmasq"], sudo=True)
    logger.info("dnsmasq config written and restarted")
    # Store the config hash so state collector can detect pending changes
    cfg_after = _get_config()
    cfg_after[_APPLY_HASH_KEY] = config_hash(cfg_after)
    _save_config(cfg_after)
    sync_result = bus.emit(
        SyncEvent("dnsmasq", "config_saved", {"action": "config_applied"})
    )
    refresh_state(["dnsmasq", *sync_result.affected_subsystems])
    return {"applied": True, "synced": sync_result.affected_subsystems}


@registry.register(GET_DNSMASQ_STATUS)
def get_status(_request: Any, _body: Any) -> dict[str, Any]:
    """\
    Endpoint: GET /dnsmasq/status

    Returns cached dnsmasq status object, or empty dict if unavailable.
    """
    dm = _get_dnsmasq_state()
    if dm and "status" in dm:
        return dm["status"]
    return {}


@registry.register(POST_DNSMASQ_RANGES_ADD)
def set_dhcp_range(_request: Any, body: dict[str, Any] | None) -> dict[str, Any]:
    """\
    Endpoint: POST /dnsmasq/ranges/add

    Add or update a DHCP pool range by interface. Raises ValueError on invalid input.
    Auto-populates ``gateway`` from the interface's IPv4 address when not provided.
    """
    if not body:
        raise ValueError("Request body required")
    iface = (body.get("interface") or "").strip()
    start = body.get("start", "").strip()
    end = body.get("end", "").strip()
    lease_time = body.get("lease_time", "12h")
    if not start or not end:
        raise ValueError("'start' and 'end' are required")

    # Resolve gateway: explicit value > existing range value > interface IP
    gateway = body.get("gateway")
    if not gateway:
        # Check existing range for same interface
        cfg_tmp = _get_config()
        for r in cfg_tmp["dhcp"]["ranges"]:
            if r.get("interface") == iface:
                gateway = r.get("gateway")
                break
        # Fall back to interface's own IP
        if not gateway and iface:
            gateway = get_interface_ip(iface)

    cfg = _get_config()
    ranges = cfg["dhcp"]["ranges"]
    found = False
    for i, r in enumerate(ranges):
        if r.get("interface") == iface:
            ranges[i] = {
                "interface": iface,
                "start": start,
                "end": end,
                "lease_time": lease_time,
            }
            if gateway:
                ranges[i]["gateway"] = gateway
            if body.get("dns"):
                ranges[i]["dns"] = body["dns"]
            found = True
            break
    if not found:
        entry: dict[str, Any] = {
            "interface": iface,
            "start": start,
            "end": end,
            "lease_time": lease_time,
        }
        if gateway:
            entry["gateway"] = gateway
        if body.get("dns"):
            entry["dns"] = body["dns"]
        ranges.append(entry)
    _save_config(cfg)
    sync_result = bus.emit(
        SyncEvent(
            "dnsmasq", "config_saved", {"action": "range_added", "interface": iface}
        )
    )
    refresh_state(["dnsmasq", *sync_result.affected_subsystems])
    return {"interface": iface, "start": start, "end": end}


@registry.register(DELETE_DNSMASQ_RANGES_REMOVE)
def remove_dhcp_range(_request: Any, body: dict[str, Any] | None) -> dict[str, Any]:
    """\
    Endpoint: DELETE /dnsmasq/ranges/remove

    Remove DHCP range matching interface + start + end. Raises NotFoundError if missing.
    """
    if not body:
        raise ValueError("Request body required")
    iface = body.get("interface", "").strip() or ""
    start = body.get("start", "").strip()
    end = body.get("end", "").strip()
    if not start or not end:
        raise ValueError("'start' and 'end' are required")
    cfg = _get_config()
    ranges = cfg["dhcp"]["ranges"]
    before = len(ranges)
    cfg["dhcp"]["ranges"] = [
        r
        for r in ranges
        if not (
            r.get("interface") == iface
            and r.get("start") == start
            and r.get("end") == end
        )
    ]
    if len(cfg["dhcp"]["ranges"]) == before:
        raise NotFoundError(
            f"DHCP range for interface '{iface}' ({start}-{end}) not found"
        )
    _save_config(cfg)
    sync_result = bus.emit(
        SyncEvent(
            "dnsmasq", "config_saved", {"action": "range_removed", "interface": iface}
        )
    )
    refresh_state(["dnsmasq", *sync_result.affected_subsystems])
    return {"interface": iface, "start": start, "end": end}


@registry.register(GET_DNSMASQ_LEASES)
def get_leases(_request: Any, _body: Any) -> list[dict[str, Any]]:
    """\
    Endpoint: GET /dnsmasq/leases

    Returns cached DHCP lease list from state, or empty list if unavailable.
    """
    dm = _get_dnsmasq_state()
    if dm:
        return dm.get("leases", [])
    return []


@registry.register(POST_DNSMASQ_STATIC_LEASE_ADD)
def add_static_lease(_request: Any, body: dict[str, Any] | None) -> dict[str, Any]:
    """\
    Endpoint: POST /dnsmasq/static-lease/add

    Add or update a static DHCP lease by MAC address. Raises ValueError on invalid input.
    """
    if not body:
        raise ValueError("Request body required")
    mac = body.get("mac", "").strip()
    ip = body.get("ip", "").strip()
    hostname = body.get("hostname")
    if not mac or not ip:
        raise ValueError("'mac' and 'ip' are required")
    cfg = _get_config()
    leases = cfg["dhcp"]["static_leases"]
    for i, lease in enumerate(leases):
        if lease["mac"].lower() == mac.lower():
            leases[i].update({"mac": mac, "ip": ip})
            if hostname is not None:
                leases[i]["hostname"] = hostname
            _save_config(cfg)
            sync_result = bus.emit(
                SyncEvent(
                    "dnsmasq",
                    "config_saved",
                    {"action": "static_lease_added", "mac": mac},
                )
            )
            refresh_state(["dnsmasq", *sync_result.affected_subsystems])
            return {"mac": mac, "ip": ip, "hostname": hostname}
    entry: dict[str, Any] = {"mac": mac, "ip": ip}
    if hostname:
        entry["hostname"] = hostname
    leases.append(entry)
    _save_config(cfg)
    sync_result = bus.emit(
        SyncEvent(
            "dnsmasq", "config_saved", {"action": "static_lease_added", "mac": mac}
        )
    )
    refresh_state(["dnsmasq", *sync_result.affected_subsystems])
    return {"mac": mac, "ip": ip, "hostname": hostname}


@registry.register(DELETE_DNSMASQ_STATIC_LEASE_REMOVE)
def remove_static_lease(_request: Any, body: dict[str, Any] | None) -> dict[str, Any]:
    """\
    Endpoint: DELETE /dnsmasq/static-lease/remove

    Remove static lease by MAC. Raises NotFoundError if no match.
    """
    if not body:
        raise ValueError("Request body required")
    mac = body.get("mac", "").strip()
    if not mac:
        raise ValueError("'mac' is required")
    cfg = _get_config()
    leases = cfg["dhcp"]["static_leases"]
    before = len(leases)
    cfg["dhcp"]["static_leases"] = [
        lease for lease in leases if lease["mac"].lower() != mac.lower()
    ]
    if len(cfg["dhcp"]["static_leases"]) == before:
        raise NotFoundError(f"Static lease for MAC '{mac}' not found")
    _save_config(cfg)
    sync_result = bus.emit(
        SyncEvent(
            "dnsmasq", "config_saved", {"action": "static_lease_removed", "mac": mac}
        )
    )
    refresh_state(["dnsmasq", *sync_result.affected_subsystems])
    return {"mac": mac}


@registry.register(POST_DNSMASQ_DNS_RECORD_ADD)
def add_dns_record(_request: Any, body: dict[str, Any] | None) -> dict[str, Any]:
    """\
    Endpoint: POST /dnsmasq/dns-record/add

    Add or update a custom DNS record by name. Raises ValueError on invalid input.
    """
    if not body:
        raise ValueError("Request body required")
    name = body.get("name", "").strip()
    address = body.get("address", "").strip()
    hostname = body.get("hostname")
    if not name or not address:
        raise ValueError("'name' and 'address' are required")
    cfg = _get_config()
    records = cfg["dns"]["custom_records"]
    for i, r in enumerate(records):
        if r["name"] == name:
            records[i].update({"name": name, "address": address})
            if hostname is not None:
                records[i]["hostname"] = hostname
            _save_config(cfg)
            sync_result = bus.emit(
                SyncEvent(
                    "dnsmasq",
                    "config_saved",
                    {"action": "dns_record_added", "name": name},
                )
            )
            refresh_state(["dnsmasq", *sync_result.affected_subsystems])
            return {"name": name, "address": address, "hostname": hostname}
    entry: dict[str, Any] = {"name": name, "address": address}
    if hostname:
        entry["hostname"] = hostname
    records.append(entry)
    _save_config(cfg)
    sync_result = bus.emit(
        SyncEvent(
            "dnsmasq", "config_saved", {"action": "dns_record_added", "name": name}
        )
    )
    refresh_state(["dnsmasq", *sync_result.affected_subsystems])
    return {"name": name, "address": address, "hostname": hostname}


@registry.register(DELETE_DNSMASQ_DNS_RECORD_REMOVE)
def remove_dns_record(_request: Any, body: dict[str, Any] | None) -> dict[str, Any]:
    """\
    Endpoint: DELETE /dnsmasq/dns-record/remove

    Remove custom DNS record by name. Raises NotFoundError if no match.
    """
    if not body:
        raise ValueError("Request body required")
    name = body.get("name", "").strip()
    if not name:
        raise ValueError("'name' is required")
    cfg = _get_config()
    records = cfg["dns"]["custom_records"]
    before = len(records)
    cfg["dns"]["custom_records"] = [r for r in records if r["name"] != name]
    if len(cfg["dns"]["custom_records"]) == before:
        raise NotFoundError(f"DNS record '{name}' not found")
    _save_config(cfg)
    sync_result = bus.emit(
        SyncEvent(
            "dnsmasq", "config_saved", {"action": "dns_record_removed", "name": name}
        )
    )
    refresh_state(["dnsmasq", *sync_result.affected_subsystems])
    return {"name": name}


@registry.register(POST_DNSMASQ_UPSTREAMS)
def set_upstreams(_request: Any, body: dict[str, Any] | None) -> dict[str, Any]:
    """\
    Endpoint: POST /dnsmasq/upstreams

    Replace DNS upstream servers list. Raises ValueError if servers field missing.
    """
    if not body or "servers" not in body:
        raise ValueError("'servers' is required")
    cfg = _get_config()
    cfg["dns"]["upstreams"] = list(body["servers"])
    _save_config(cfg)
    sync_result = bus.emit(
        SyncEvent("dnsmasq", "config_saved", {"action": "upstreams_set"})
    )
    refresh_state(["dnsmasq", *sync_result.affected_subsystems])
    return {"upstreams": cfg["dns"]["upstreams"]}


@registry.register(POST_DNSMASQ_DOMAIN)
def set_domain(_request: Any, body: dict[str, Any] | None) -> dict[str, Any]:
    """\
    Endpoint: POST /dnsmasq/domain

    Set or clear the local DNS domain. Raises ValueError on missing body.
    """
    if not body:
        raise ValueError("Request body required")
    domain = body.get("domain")
    cfg = _get_config()
    cfg["dns"]["domain"] = domain if domain else None
    _save_config(cfg)
    sync_result = bus.emit(
        SyncEvent("dnsmasq", "config_saved", {"action": "domain_set"})
    )
    refresh_state(["dnsmasq", *sync_result.affected_subsystems])
    return {"domain": cfg["dns"]["domain"]}