"""ACME certificate daemon handler."""

import asyncio
import logging
import os
import socket
import subprocess
from contextlib import suppress
from dataclasses import dataclass, field
from datetime import UTC, datetime
from pathlib import Path
from typing import Any
from uuid import uuid4

from daemon.server import NotFoundError, refresh_state, registry

logger = logging.getLogger(__name__)

PROJECT_DIR = Path(__file__).resolve().parent.parent.parent
_ACME_HOME = PROJECT_DIR / "data" / "acme"
_DEPLOY_HOOK = str(PROJECT_DIR / "system" / "acme-deploy.sh")

_ACME_ENVIRON = {
    "HOME": str(PROJECT_DIR),
    "PATH": os.environ.get(
        "PATH", "/usr/local/sbin:/usr/local/bin:/usr/sbin:/usr/bin:/sbin:/bin"
    ),
}

_WEBROOT = PROJECT_DIR / "data" / "acme" / "www"

# In-memory store for active issuance requests.
_ISSUANCES: dict[str, "IssueRequest"] = {}
_ISSUANCE_TTL = 300  # seconds to keep completed requests


@dataclass
class IssueStep:
    """Single step in a certificate issuance workflow.

    Attributes:
        name: Machine-readable step identifier (e.g. "issue").
        label: Human-readable description shown to the user.
        status: Current state: "pending", "running", "done", or "error".
        message: Optional detail or error message for the step.
    """

    name: str
    label: str
    status: str = "pending"
    message: str | None = None


@dataclass
class IssueRequest:
    """Tracked certificate issuance request.

    Attributes:
        request_id: Unique hex identifier for polling.
        domain: Target domain for the certificate.
        email: Optional ACME contact email.
        webroot: Optional custom webroot path.
        steps: Ordered list of issuance steps.
        status: Overall status: "running", "completed", or "failed".
        created_at: Unix timestamp when request was created.
        expires_at: Unix timestamp when entry expires from store.
    """

    request_id: str
    domain: str
    email: str | None = None
    webroot: str | None = None
    steps: list[IssueStep] = field(default_factory=list)
    status: str = "running"
    created_at: float = field(default_factory=lambda: datetime.now(UTC).timestamp())
    expires_at: float | None = None

    def to_dict(self) -> dict[str, Any]:
        """Serialize request to a JSON-compatible dictionary."""
        return {
            "request_id": self.request_id,
            "domain": self.domain,
            "status": self.status,
            "steps": [
                {
                    "name": s.name,
                    "label": s.label,
                    "status": s.status,
                    "message": s.message,
                }
                for s in self.steps
            ],
            "created_at": self.created_at,
            "expires_at": self.expires_at,
        }


# ---------------------------------------------------------------------------
# Internal helpers


def _run_acme(args: list[str]) -> str:
    """Execute an acme.sh command and return combined output.

    Returns:
        Standard output (plus stderr).

    Raises:
        RuntimeError: On timeout or non-zero exit.
    """
    from lib.state import _find_acme

    acme_bin = _find_acme()
    acme_home_env = os.environ.get("ACME_HOME", str(_ACME_HOME))
    cmd = [acme_bin, "--home", acme_home_env, "--config-home", acme_home_env, *args]
    try:
        result = subprocess.run(
            cmd,
            capture_output=True,
            text=True,
            timeout=120,
            env={**os.environ, **_ACME_ENVIRON},
        )
    except subprocess.TimeoutExpired as exc:
        raise RuntimeError(f"acme.sh timed out: {' '.join(cmd)}") from exc
    output = result.stdout
    if result.stderr:
        output = output + result.stderr if output else result.stderr
    if result.returncode != 0:
        raise RuntimeError(f"acme.sh failed (rc={result.returncode}): {output.strip()}")
    return output


def _find_acme_bin() -> str:
    """Return the path to the acme.sh binary."""
    from lib.state import _find_acme

    return _find_acme()


def _get_acme_email() -> str:
    """Read registered contact email from ACME account config."""
    from lib.acme import _read_acme_email

    return _read_acme_email()


def _get_state() -> dict[str, Any] | None:
    """Return the raw ACME entry from the shared state store."""
    from lib.state import state as state_store

    return state_store.get("acme")


def _get_acme_state() -> dict[str, Any]:
    """Return the ACME state or empty dict when missing."""
    ac = _get_state()
    if ac is None:
        return {}
    return ac


def _clean_expired_issuances() -> None:
    """Remove completed requests older than TTL."""
    now = datetime.now(UTC).timestamp()
    expired = [
        rid
        for rid, req in _ISSUANCES.items()
        if req.expires_at and now > req.expires_at
    ]
    for rid in expired:
        del _ISSUANCES[rid]


# ---------------------------------------------------------------------------
# Validation helpers


def _check_domain_format(domain: str) -> tuple[bool, str]:
    """Validate basic domain name format."""
    import re as _re

    pattern = r"^[a-zA-Z0-9]([a-zA-Z0-9\-]{0,61}[a-zA-Z0-9])?(\.[a-zA-Z0-9]([a-zA-Z0-9\-]{0,61}[a-zA-Z0-9])?)*$"
    if not _re.match(pattern, domain):
        return False, "Invalid domain name format"
    return True, ""


def _check_dns_resolves(domain: str) -> tuple[bool, str]:
    """Check that domain resolves to this machine's IP via A record."""
    try:
        results = socket.getaddrinfo(domain, 80, socket.AF_UNSPEC, socket.SOCK_STREAM)
        if not results:
            return False, "Domain does not resolve to any address"

        local_ips = set()
        hostname = socket.gethostname()
        with suppress(OSError):
            local_ips.add(socket.gethostbyname(hostname))
        # Also collect all interface IPs
        try:
            import ipaddress
            from fcntl import ioctl

            def get_interfaces():
                import struct

                s = socket.socket(socket.AF_INET, socket.SOCK_STREAM)
                names = b"\x00" * 4096
                raw = ioctl(s.fileno(), 0x8912, names)
                s.close()
                ifaces = []
                for i in range(0, 4096, 32):
                    name = raw[i : i + 16].split(b"\x00")[0].decode()
                    if name == "lo":
                        continue
                    addr = struct.unpack("<I", raw[i + 16 : i + 20])[0]
                    ifaces.append(str(ipaddress.IPv4Address(addr)))
                return ifaces

            local_ips.update(get_interfaces())
        except Exception:
            pass

        resolved = False
        for _, _, _, _, addr in results:
            if addr in local_ips:
                resolved = True
                break

        if resolved:
            return True, "DNS resolves correctly"
        return (
            False,
            f"Domain resolves to {results[0][4][0]}, not this server",
        )
    except socket.gaierror:
        return False, "Domain does not resolve (NXDOMAIN or timeout)"


def _check_acme_installed() -> tuple[bool, str]:
    """Verify acme.sh binary is installed and executable."""
    try:
        _find_acme_bin()
        return True, "acme.sh found"
    except FileNotFoundError:
        return False, "acme.sh not installed"


def _check_email_configured() -> tuple[bool, str]:
    """Check whether an ACME contact email has been configured."""
    email = _get_acme_email() or ""
    if email:
        return True, f"Contact email configured: {email}"
    return False, "No ACME contact email configured"


def _check_webroot() -> tuple[bool, str]:
    """Verify the ACME webroot directory exists and is writable."""
    if _WEBROOT.is_dir() and os.access(str(_WEBROOT), os.W_OK):
        return True, "ACME webroot ready"
    return False, "ACME webroot not ready or not writable"


def _check_challenge_config() -> tuple[bool, str]:
    """Check for the ACME HTTP-01 challenge nginx config file."""
    from lib.nginx import SITES_DIR

    site_conf = SITES_DIR / "_acme-challenge.conf" if SITES_DIR else None
    if site_conf and site_conf.is_file():
        return True, "ACME challenge nginx config present"
    return False, "ACME challenge nginx config missing"


def _check_existing_cert(domain: str) -> tuple[bool, str]:
    """Warn if a valid cert already exists (not blocking)."""
    try:
        from lib.acme import days_until_expiry

        days = days_until_expiry(domain)
        if days is not None and days > 0:
            return True, f"Valid certificate exists ({days} days remaining)"
    except (ValueError, RuntimeError, FileNotFoundError):
        pass
    return True, ""


def _validate(domain: str) -> dict[str, Any]:
    """Run all pre-checks for a domain. Returns structured results."""
    checks: list[dict[str, Any]] = []
    ready = True

    check_fns = [
        ("acme_installed", _check_acme_installed, True),
        ("email_configured", _check_email_configured, True),
        ("webroot_ready", _check_webroot, True),
        ("challenge_configured", _check_challenge_config, True),
        ("domain_format", lambda: _check_domain_format(domain), True),
        ("dns_resolves", lambda: _check_dns_resolves(domain), True),
        ("existing_cert", lambda: _check_existing_cert(domain), False),
    ]

    for name, fn, blocking in check_fns:
        try:
            passed, msg = fn()
            checks.append(
                {"name": name, "passed": passed, "message": msg, "blocking": blocking}
            )
            if not passed and blocking:
                ready = False
        except Exception as exc:
            checks.append(
                {
                    "name": name,
                    "passed": False,
                    "message": str(exc),
                    "blocking": blocking,
                }
            )
            ready = False

    return {"domain": domain, "checks": checks, "ready": ready}


# ---------------------------------------------------------------------------
# Routes — status reads from state, mutations call refresh_state


@registry.register("GET", "/acme/list")
def list_certs(_request: Any, _body: Any) -> list[dict]:
    """GET /acme/list — return managed certificates."""
    ac = _get_acme_state()
    return ac.get("certs", [])


@registry.register("GET", "/acme/info")
def get_cert_info(_request: Any, body: dict[str, Any] | None) -> dict:
    """GET /acme/info — return details for a single domain certificate.

    Raises:
        ValueError: When domain is missing.
        NotFoundError: When no certificate exists for domain.
    """
    if not body or "domain" not in body:
        raise ValueError("'domain' is required")
    domain = body["domain"]
    certs = list_certs(None, None)
    for c in certs:
        if c["domain"] == domain or domain in c.get("san_domains", []):
            return c
    raise NotFoundError(f"No certificate found for domain: {domain}")


@registry.register("POST", "/acme/validate")
def validate_cert(_request: Any, body: dict[str, Any] | None) -> dict[str, Any]:
    """POST /acme/validate — run pre-flight checks for a domain.

    Raises:
        ValueError: When domain is missing.
    """
    if not body:
        raise ValueError("Request body required")
    domain = body.get("domain", "").strip()
    if not domain:
        raise ValueError("'domain' is required")
    return _validate(domain)


@registry.register("POST", "/acme/issue")
async def issue_cert(_request: Any, body: dict[str, Any] | None) -> dict[str, Any]:
    """POST /acme/issue — create a new certificate issuance request.

    Deduplicates in-progress requests. Spawns background task for actual issuance.

    Raises:
        ValueError: When domain is missing.
        RuntimeError: When pre-flight checks fail.
    """
    if not body:
        raise ValueError("Request body required")
    domain = body.get("domain", "").strip()
    if not domain:
        raise ValueError("'domain' is required")
    email = body.get("email", "").strip() or None
    webroot = body.get("webroot")

    _clean_expired_issuances()

    # Dedup: if domain already has an active request, return existing ID
    for existing in _ISSUANCES.values():
        if existing.domain == domain and existing.status == "running":
            return {
                "request_id": existing.request_id,
                "status": "existing",
                "domain": domain,
                "message": "Issuance already in progress for this domain",
            }

    # Run pre-flight checks
    _validate_checks = _validate(domain)
    if not _validate_checks["ready"]:
        failed = [
            c["name"]
            for c in _validate_checks["checks"]
            if not c["passed"] and c["blocking"]
        ]
        raise RuntimeError(f"Pre-flight checks failed: {', '.join(failed)}")

    # Create tracked request
    request_id = uuid4().hex[:12]
    steps = [
        IssueStep(name="issue", label="Issuing certificate"),
        IssueStep(name="deploy", label="Registering deploy hook"),
        IssueStep(name="refresh", label="Refreshing certificate state"),
    ]

    req = IssueRequest(
        request_id=request_id,
        domain=domain,
        email=email,
        webroot=webroot,
        steps=steps,
    )
    _ISSUANCES[request_id] = req

    # Spawn background task
    _task = asyncio.create_task(_run_issue(req))  # noqa: RUF006 — task runs to completion on its own

    return {"request_id": request_id, "domain": domain}


@registry.register("GET", "/acme/issue/status")
def get_issuance_status(_request: Any, body: dict[str, Any] | None) -> dict[str, Any]:
    """GET /acme/issue/status — poll status of an issuance request.

    Raises:
        ValueError: When id is missing.
        NotFoundError: When request_id is unknown.
    """
    request_id = (body or {}).get("id", "").strip()
    if not request_id:
        raise ValueError("'id' is required")

    req = _ISSUANCES.get(request_id)
    if not req:
        raise NotFoundError(f"Issuance request {request_id} not found")

    return req.to_dict()


async def _run_issue(req: IssueRequest) -> None:
    """Background task: run acme.sh steps, update step status."""
    try:
        # Step 1: issue
        req.steps[0].status = "running"
        args: list[str] = ["--issue", "-d", req.domain]
        args.extend(["--webroot", req.webroot or str(_WEBROOT)])
        contact = req.email
        if not contact:
            contact = _get_acme_email()
        if contact:
            args.extend(["-m", contact])
        args.append("--force")
        output = _run_acme(args)
        req.steps[0].status = "done"
        req.steps[0].message = output.strip()[:200]

        # Step 2: deploy
        req.steps[1].status = "running"
        _run_acme(["--deploy", "-d", req.domain, "--deploy-hook", _DEPLOY_HOOK])
        req.steps[1].status = "done"
        req.steps[1].message = "Deploy hook registered"

        # Step 3: refresh state
        req.steps[2].status = "running"
        refresh_state(["acme"])
        req.steps[2].status = "done"
        req.steps[2].message = "State refreshed"

        req.status = "completed"
        req.expires_at = datetime.now(UTC).timestamp() + _ISSUANCE_TTL
        logger.info(
            "Certificate for %s issued (request %s)", req.domain, req.request_id
        )
    except Exception as exc:
        # Mark current running step as error, overall as failed
        for step in req.steps:
            if step.status == "running":
                step.status = "error"
                step.message = str(exc)
                break
        else:
            req.steps.append(
                IssueStep(name="error", label="Error", status="error", message=str(exc))
            )
        req.status = "failed"
        req.expires_at = datetime.now(UTC).timestamp() + _ISSUANCE_TTL
        logger.error("Cert issuance for %s failed: %s", req.domain, exc)


@registry.register("POST", "/acme/renew")
def renew_cert(_request: Any, body: dict[str, Any] | None) -> dict[str, Any]:
    """POST /acme/renew — renew a certificate for the given domain.

    Args:
        force: Force renewal regardless of expiry.

    Raises:
        ValueError: When domain is missing.
    """
    if not body:
        raise ValueError("Request body required")
    domain = body.get("domain", "").strip()
    if not domain:
        raise ValueError("'domain' is required")
    force = body.get("force", False)
    args: list[str] = ["--renew", "-d", domain]
    if force:
        args.append("--force")
    output = _run_acme(args)
    _run_acme(["--deploy", "-d", domain, "--deploy-hook", _DEPLOY_HOOK])
    logger.info("Certificate for %s renewed", domain)
    refresh_state(["acme"])
    return {"domain": domain, "output": output.strip()}


@registry.register("DELETE", "/acme/remove")
def remove_cert(_request: Any, body: dict[str, Any] | None) -> dict[str, Any]:
    """DELETE /acme/remove — remove a certificate from ACME management.

    Raises:
        ValueError: When domain is missing.
    """
    if not body:
        raise ValueError("Request body required")
    domain = body.get("domain", "").strip()
    if not domain:
        raise ValueError("'domain' is required")
    _run_acme(["--remove", "-d", domain])
    logger.info("Certificate for %s removed", domain)
    refresh_state(["acme"])
    return {"domain": domain}


@registry.register("POST", "/acme/email")
def set_email(_request: Any, body: dict[str, Any] | None) -> dict[str, Any]:
    """POST /acme/email — set the ACME contact email via account registration.

    Raises:
        ValueError: When email is missing.
    """
    if not body:
        raise ValueError("Request body required")
    email = body.get("email", "").strip()
    if not email:
        raise ValueError("'email' is required")
    _run_acme(["--register-account", "-m", email])
    # Persist to declarative ACME config
    acme_cfg = PROJECT_DIR / "config" / "acme" / "config.json"
    acme_cfg.parent.mkdir(parents=True, exist_ok=True)
    import json as _json

    _acme_data: dict[str, str] = {}
    if acme_cfg.is_file():
        _acme_data = _json.loads(acme_cfg.read_text())
    _acme_data["email"] = email
    acme_cfg.write_text(_json.dumps(_acme_data, indent=4) + "\n")
    logger.info("ACME email set to %s", email)
    refresh_state(["acme"])
    return {"email": email}


@registry.register("GET", "/acme/email")
def get_email(_request: Any, _body: Any) -> dict[str, Any]:
    """GET /acme/email — return the currently configured ACME contact email."""
    ac = _get_acme_state()
    email = ""
    if ac:
        email = ac.get("email", "")
    if not email:
        email = _get_acme_email()
    return {"email": email}


@registry.register("GET", "/acme/paths")
def get_cert_paths(_request: Any, body: dict[str, Any] | None) -> dict[str, str]:
    """GET /acme/paths — return filesystem paths for a domain's certificate files.

    Raises:
        ValueError: When domain is missing.
    """
    if not body or "domain" not in body:
        raise ValueError("'domain' is required")
    domain = body["domain"]
    acme_home_env = os.environ.get("ACME_HOME", str(_ACME_HOME))
    acme_home = str(Path(acme_home_env) / domain)
    return {
        "cert": f"{acme_home}/{domain}.cert",
        "key": f"{acme_home}/{domain}.key",
        "ca": f"{acme_home}/ca.cer",
        "fullchain": f"{acme_home}/fullchain.cer",
    }