"""Password and PIN sign-in, and setting a PIN. Rate limits run before any LDAP bind or PIN hash check.

Failures are written to `signin_attempts` at once (the API connection is in autocommit mode), so they count
even though the request then fails. LDAP calls never run inside a database transaction.
"""

from __future__ import annotations

import logging
from dataclasses import dataclass
from typing import Any, NoReturn

from psycopg.rows import dict_row

from .. import audit
from ..api.errors import ApiError
from ..domain import security_alerts
from ..settings import Settings
from . import devices, ratelimit, sessions
from . import directory as userdir
from . import groups as groupmap
from . import pin as pins
from .ldap import AdUser, DirectoryProtocol, LdapUnavailable

log = logging.getLogger(__name__)

PASSWORD_FAILED = "Sign-in failed. Check the account name and password."  # noqa: S105 (a message)
PIN_FAILED = "Sign-in failed."
NO_ROLE = "No role in Packet Station. Ask IT to add you to a group."
LDAP_DOWN = "The directory cannot be reached. Try again in a few minutes."


@dataclass
class SigninResult:
    token: str
    session: dict[str, Any]
    user_id: Any
    roles: list[str]
    groups: list[str]
    device: dict[str, Any] | None


def ldap_down(e: Exception) -> ApiError:
    log.warning("AD unavailable: %s", e)
    return ApiError(503, "ldap_unavailable", LDAP_DOWN)


def rate_gate(
    conn: Any,
    settings: Settings,
    *,
    accounts: list[str],
    ip: str | None,
    kind: str,
    record_account: str,
    user_id: Any = None,
    session_id: Any = None,
) -> None:
    """Raise 429 when the accounts or the address are over their limit; the refusal is recorded and audited."""
    wait = ratelimit.check(conn, settings, accounts=accounts, ip=ip)
    if wait is None:
        return
    with conn.transaction():
        ratelimit.record(
            conn,
            account=record_account,
            ip=ip,
            kind=kind,
            ok=False,
            reason=ratelimit.RATE_LIMITED,
            user_id=user_id,
            session_id=session_id,
        )
        audit.append(
            conn,
            action="auth.signin_failed",
            user_id=user_id,
            session_id=session_id,
            detail={"reason": "rate_limited", "account": record_account, "kind": kind},
            ip=ip,
        )
    minutes = max(1, (wait + 59) // 60)
    raise ApiError(
        429,
        "rate_limited",
        f"Too many failed attempts. Try again in {minutes} minute{'s' if minutes != 1 else ''}.",
        headers={"Retry-After": str(wait)},
        extra={"retry_after": wait},
    )


def _fail(
    conn: Any,
    *,
    settings: Settings,
    account: str,
    ip: str | None,
    kind: str,
    reason: str,
    status: int,
    code: str,
    detail: str,
    user_id: Any = None,
    audited: bool = False,
) -> NoReturn:
    with conn.transaction():
        ratelimit.record(conn, account=account, ip=ip, kind=kind, ok=False, reason=reason, user_id=user_id)
        if audited:
            audit.append(
                conn,
                action="auth.signin_failed",
                user_id=user_id,
                detail={"reason": reason, "account": account, "kind": kind},
                ip=ip,
            )
    security_alerts.after_failure(conn, settings, account=account, ip=ip, kind=kind, user_id=user_id)
    raise ApiError(status, code, detail)


def _start(
    conn: Any,
    settings: Settings,
    key: bytes,
    u: AdUser,
    *,
    kind: str,
    account: str,
    groups: list[str],
    roles: list[str],
    device: dict[str, Any] | None,
    ip: str | None,
    user_agent: str | None,
) -> SigninResult:
    with conn.transaction():
        userdir.upsert_user(conn, u, groups=groups, signin=True)
        userdir.set_roles(conn, u.guid, roles)
        if kind == "pin":
            pins.reset_failures(conn, u.guid)
        token, row = sessions.create(
            conn,
            settings,
            key,
            user_id=u.guid,
            kind=kind,
            roles=roles,
            groups=groups,
            device_id=device["id"] if device else None,
            ip=ip,
            user_agent=user_agent,
        )
        ratelimit.record(conn, account=account, ip=ip, kind=kind, ok=True, user_id=u.guid, session_id=row["id"])
        audit.append(
            conn,
            action="auth.signin",
            user_id=u.guid,
            session_id=row["id"],
            role_snapshot=",".join(roles),
            detail={
                "kind": kind,
                "device_id": str(device["id"]) if device else None,
                "device_name": device["name"] if device else None,
            },
            ip=ip,
        )
        if device:
            devices.touch(conn, device["id"])
    return SigninResult(token, row, u.guid, roles, groups, device)


def resolve_groups(directory: DirectoryProtocol, u: AdUser) -> tuple[list[str], list[str]]:
    """(groups in the PacketStation OU, roles they give)."""
    found = sorted(directory.groups_of(u.dn))
    return found, groupmap.roles_from_groups(found)


def password_signin(
    conn: Any,
    directory: DirectoryProtocol,
    settings: Settings,
    key: bytes,
    *,
    login: str,
    password: str,
    ip: str | None,
    user_agent: str | None,
) -> SigninResult:
    login = (login or "").strip()
    account = login.lower()[:256]
    if not login or not password:
        # Refused before LDAP: an empty password would be an anonymous bind
        _fail(
            conn,
            settings=settings,
            account=account or "(empty)",
            ip=ip,
            kind="password",
            reason="empty",
            status=401,
            code="signin_failed",
            detail=PASSWORD_FAILED,
        )
    rate_gate(conn, settings, accounts=[account], ip=ip, kind="password", record_account=account)
    try:
        u = directory.find_user(login)
    except LdapUnavailable as e:
        raise ldap_down(e) from None
    if u is None:
        _fail(
            conn,
            settings=settings,
            account=account,
            ip=ip,
            kind="password",
            reason="no_such_user",
            status=401,
            code="signin_failed",
            detail=PASSWORD_FAILED,
        )
    # The same person may type the account name or the UPN: both keys count before the bind
    aliases = sorted({a for a in (u.sam_account.lower(), (u.upn or "").lower()) if a and a != account})
    if aliases:
        rate_gate(
            conn,
            settings,
            accounts=[account, *aliases],
            ip=None,
            kind="password",
            record_account=account,
            user_id=u.guid,
        )
    try:
        ok = directory.verify_password(u.dn, password)
    except LdapUnavailable as e:
        raise ldap_down(e) from None
    if not ok:
        _fail(
            conn,
            settings=settings,
            account=account,
            ip=ip,
            kind="password",
            reason="bad_password",
            status=401,
            code="signin_failed",
            detail=PASSWORD_FAILED,
            user_id=u.guid,
        )
    if u.disabled:
        _fail(
            conn,
            settings=settings,
            account=account,
            ip=ip,
            kind="password",
            reason="disabled",
            status=401,
            code="signin_failed",
            detail=PASSWORD_FAILED,
            user_id=u.guid,
            audited=True,
        )
    try:
        groups, roles = resolve_groups(directory, u)
    except LdapUnavailable as e:
        raise ldap_down(e) from None
    if not roles:
        _fail(
            conn,
            settings=settings,
            account=account,
            ip=ip,
            kind="password",
            reason="no_role",
            status=403,
            code="no_role",
            detail=NO_ROLE,
            user_id=u.guid,
            audited=True,
        )
    return _start(
        conn,
        settings,
        key,
        u,
        kind="password",
        account=account,
        groups=groups,
        roles=roles,
        device=None,
        ip=ip,
        user_agent=user_agent,
    )


def pin_signin(
    conn: Any,
    directory: DirectoryProtocol,
    settings: Settings,
    key: bytes,
    *,
    device: dict[str, Any],
    emp_no: str,
    pin: str,
    ip: str | None,
    user_agent: str | None,
) -> SigninResult:
    emp = (emp_no or "").strip()[:64]
    account = f"emp:{emp}"

    def fail(reason: str, user_id: Any = None, *, audited: bool = False) -> NoReturn:
        _fail(
            conn,
            settings=settings,
            account=account,
            ip=ip,
            kind="pin",
            reason=reason,
            status=401,
            code="signin_failed",
            detail=PIN_FAILED,
            user_id=user_id,
            audited=audited,
        )

    if not emp or not pin:
        fail("empty")
    rate_gate(conn, settings, accounts=[account], ip=ip, kind="pin", record_account=account)
    with conn.cursor(row_factory=dict_row) as cur:
        rows = cur.execute(
            "SELECT u.id, u.active, p.hash, p.disabled_at FROM users u"
            " LEFT JOIN user_pins p ON p.user_id = u.id WHERE u.emp_no = %s",
            (emp,),
        ).fetchall()
    if not rows:
        fail("no_such_user")
    if len(rows) > 1:
        fail("emp_duplicate")
    row = rows[0]
    uid = row["id"]
    if not row["active"]:
        fail("inactive", uid)
    if row["hash"] is None:
        fail("no_pin", uid)
    if row["disabled_at"] is not None:
        fail("pin_disabled", uid)
    if not pins.verify_hash(row["hash"], pin):
        with conn.transaction():
            ratelimit.record(conn, account=account, ip=ip, kind="pin", ok=False, reason="bad_pin", user_id=uid)
            pins.register_failure(conn, settings, uid, ip=ip, where="signin")
        security_alerts.after_failure(conn, settings, account=account, ip=ip, kind="pin", user_id=uid)
        raise ApiError(401, "signin_failed", PIN_FAILED)
    try:
        u = directory.get_user_by_guid(uid)
    except LdapUnavailable as e:
        raise ldap_down(e) from None
    if u is None or u.disabled:
        with conn.transaction():
            userdir.mark_inactive(conn, uid, reason="ad_gone" if u is None else "ad_disabled", gone=u is None)
        fail("disabled", uid, audited=True)
    try:
        groups, roles = resolve_groups(directory, u)
    except LdapUnavailable as e:
        raise ldap_down(e) from None
    if not roles:
        _fail(
            conn,
            settings=settings,
            account=account,
            ip=ip,
            kind="pin",
            reason="no_role",
            status=403,
            code="no_role",
            detail=NO_ROLE,
            user_id=uid,
            audited=True,
        )
    return _start(
        conn,
        settings,
        key,
        u,
        kind="pin",
        account=account,
        groups=groups,
        roles=roles,
        device=device,
        ip=ip,
        user_agent=user_agent,
    )


def set_pin(
    conn: Any,
    directory: DirectoryProtocol,
    settings: Settings,
    actor: sessions.Actor,
    *,
    password: str,
    new_pin: str,
    ip: str | None,
) -> None:
    """Set or change the actor's PIN. Needs the domain password in the same request (password session only)."""
    if not pins.valid_format(new_pin or "", settings):
        raise ApiError(
            400,
            "invalid_pin",
            f"The PIN must be {settings.pin_min_digits} to {settings.pin_max_digits} digits.",
        )
    account = f"user:{actor.user_id}"
    rate_gate(
        conn,
        settings,
        accounts=[account, actor.sam_account.lower()],
        ip=ip,
        kind="pin_set",
        record_account=account,
        user_id=actor.user_id,
        session_id=actor.session_id,
    )
    try:
        u = directory.get_user_by_guid(actor.user_id)
        ok = bool(u and not u.disabled and password and directory.verify_password(u.dn, password))
    except LdapUnavailable as e:
        raise ldap_down(e) from None
    if not ok:
        ratelimit.record(
            conn,
            account=account,
            ip=ip,
            kind="pin_set",
            ok=False,
            reason="bad_password",
            user_id=actor.user_id,
            session_id=actor.session_id,
        )
        security_alerts.after_failure(conn, settings, account=account, ip=ip, kind="pin_set", user_id=actor.user_id)
        raise ApiError(403, "bad_password", "The password is wrong.")
    with conn.transaction():
        pins.set_pin(conn, actor.user_id, new_pin)
        ratelimit.record(
            conn, account=account, ip=ip, kind="pin_set", ok=True, user_id=actor.user_id, session_id=actor.session_id
        )
        audit.append(
            conn,
            action="pin.set",
            user_id=actor.user_id,
            session_id=actor.session_id,
            role_snapshot=actor.role_snapshot,
            subject_type="user",
            subject_id=actor.user_id,
            ip=ip,
        )