"""Admin: users and their AD view (read-only), PIN clearing, devices, the group map, AD refresh, attempts.

Every route needs the admin role and a password session. Roles cannot be changed here: they come from AD.
"""

from __future__ import annotations

import time
import uuid
from datetime import UTC, datetime
from typing import Any

from fastapi import APIRouter, Depends, Query, Request, Response
from psycopg.rows import dict_row
from pydantic import BaseModel, Field

from .. import audit
from ..auth import devices, sessions
from ..auth import directory as userdir
from ..auth import groups as groupmap
from ..auth import pin as pins
from ..auth.ldap import LdapUnavailable
from ..auth.signin import ldap_down
from .account import active_sessions
from .deps import Db, Principal, admin_principal, directory_of, get_db
from .errors import ApiError

router = APIRouter(prefix="/api/admin", tags=["admin"])

GROUPS_CACHE_SECONDS = 300
ROLES_NOTE = "Roles come from AD groups. Ask IT to change them."


class ReasonBody(BaseModel):
    reason: str = Field(max_length=500)


def _like(q: str) -> str:
    return "%" + q.replace("\\", "\\\\").replace("%", "\\%").replace("_", "\\_") + "%"


def _roles_by_user(conn: Any, ids: list[Any]) -> dict[Any, list[str]]:
    out: dict[Any, list[str]] = {}
    if not ids:
        return out
    rows = conn.execute(
        "SELECT user_id, role::text, dept_code FROM user_roles WHERE user_id = ANY(%s)", (ids,)
    ).fetchall()
    for uid, kind, dept in rows:
        out.setdefault(uid, []).append(groupmap.role_from_row(kind, dept))
    gm = groupmap.current()
    return {k: gm.sort_roles(v) for k, v in out.items()}


USER_SELECT = (
    "SELECT u.*, p.user_id IS NOT NULL AS pin_set, p.disabled_at IS NOT NULL AS pin_disabled,"
    " (SELECT count(*) FROM users x WHERE x.emp_no = u.emp_no) AS emp_count"
    " FROM users u LEFT JOIN user_pins p ON p.user_id = u.id"
)


def _user_row(r: dict[str, Any], roles: list[str]) -> dict[str, Any]:
    flags = r.get("directory_flags") or {}
    return {
        "id": str(r["id"]),
        "sam_account": r["sam_account"],
        "display_name": r["display_name"],
        "emp_no": r["emp_no"],
        "email": r["email"],
        "active": r["active"],
        "roles": roles,
        "pin": {"set": bool(r["pin_set"]), "disabled": bool(r["pin_disabled"])},
        "flags": {
            "emp_missing": not r["emp_no"],
            "emp_duplicate": bool(r["emp_no"]) and int(r["emp_count"] or 0) > 1,
            "disabled": bool(flags.get("disabled")) or bool(flags.get("gone")),
        },
        "last_signin_at": r["last_signin_at"],
        "ad_synced_at": r["ad_synced_at"],
    }


@router.get("/users")
def users(
    p: Principal = Depends(admin_principal),  # noqa: B008
    d: Db = Depends(get_db),  # noqa: B008
    q: str = Query("", max_length=100),
) -> list[dict[str, Any]]:
    conn = d.conn
    q = q.strip()
    with conn.cursor(row_factory=dict_row) as cur:
        if q:
            pat = _like(q)
            rows = cur.execute(
                USER_SELECT + " WHERE u.sam_account ILIKE %s OR u.display_name ILIKE %s OR u.email ILIKE %s"
                " OR u.emp_no = %s ORDER BY lower(u.display_name) LIMIT 500",
                (pat, pat, pat, q),
            ).fetchall()
        else:
            rows = cur.execute(USER_SELECT + " ORDER BY lower(u.display_name) LIMIT 500").fetchall()
    roles = _roles_by_user(conn, [r["id"] for r in rows])
    return [_user_row(r, roles.get(r["id"], [])) for r in rows]


@router.get("/users/{user_id}")
def user_detail(
    user_id: uuid.UUID,
    request: Request,
    p: Principal = Depends(admin_principal),  # noqa: B008
    d: Db = Depends(get_db),  # noqa: B008
) -> dict[str, Any]:
    conn = d.conn
    with conn.cursor(row_factory=dict_row) as cur:
        r = cur.execute(USER_SELECT + " WHERE u.id = %s", (user_id,)).fetchone()
    if r is None:
        raise ApiError(404, "not_found", "No such user.")
    out = _user_row(r, _roles_by_user(conn, [user_id]).get(user_id, []))
    directory = directory_of(request)
    try:
        u = directory.get_user_by_guid(user_id)
        out["groups"] = sorted(directory.groups_of(u.dn)) if u is not None else []
        out["groups_source"] = "ad"
        out["in_ad"] = u is not None
    except LdapUnavailable:
        out["groups"] = list((r.get("directory_flags") or {}).get("groups", []))
        out["groups_source"] = "cache"
        out["in_ad"] = None
    out["sessions"] = active_sessions(conn, user_id)
    out["note"] = ROLES_NOTE
    return out


@router.get("/ad/lookup")
def ad_lookup(
    request: Request,
    p: Principal = Depends(admin_principal),  # noqa: B008
    login: str = Query(..., min_length=1, max_length=256),
) -> dict[str, Any]:
    directory = directory_of(request)
    try:
        u = directory.find_user(login)
        if u is None:
            return {"found": False, "user": None, "groups": [], "roles": [], "disabled": False}
        found = sorted(directory.groups_of(u.dn))
    except LdapUnavailable as e:
        raise ldap_down(e) from None
    return {
        "found": True,
        "user": userdir.ad_user_public(u),
        "groups": found,
        "roles": groupmap.roles_from_groups(found),
        "disabled": u.disabled,
        "note": ROLES_NOTE,
    }


@router.delete("/users/{user_id}/pin", status_code=204)
def clear_pin(
    user_id: uuid.UUID,
    body: ReasonBody,
    p: Principal = Depends(admin_principal),  # noqa: B008
    d: Db = Depends(get_db),  # noqa: B008
) -> Response:
    reason = body.reason.strip()
    if not reason:
        raise ApiError(400, "reason_required", "Give a reason for clearing the PIN.")
    conn = d.conn
    with conn.transaction():
        if not pins.clear(conn, user_id):
            raise ApiError(404, "not_found", "That user has no PIN.")
        audit.append(
            conn,
            action="pin.cleared",
            user_id=p.user_id,
            session_id=p.session_id,
            role_snapshot=p.role_snapshot,
            subject_type="user",
            subject_id=user_id,
            it_reason=reason,
            ip=p.ip,
        )
    return Response(status_code=204)


@router.get("/devices")
def device_list(p: Principal = Depends(admin_principal), d: Db = Depends(get_db)) -> list[dict[str, Any]]:  # noqa: B008
    with d.conn.cursor(row_factory=dict_row) as cur:
        rows = cur.execute(
            "SELECT d.id, d.name, d.registered_by, u.display_name AS registered_by_name, d.registered_at,"
            " d.last_seen_at, d.revoked_at,"
            " (SELECT count(*) FROM sessions s WHERE s.device_id = d.id AND s.revoked_at IS NULL"
            "  AND s.expires_at > now()) AS active_sessions"
            " FROM devices d LEFT JOIN users u ON u.id = d.registered_by"
            " ORDER BY d.revoked_at IS NOT NULL, lower(d.name)"
        ).fetchall()
    return [
        {
            "id": str(r["id"]),
            "name": r["name"],
            "registered_by": (
                {"id": str(r["registered_by"]), "display_name": r["registered_by_name"]} if r["registered_by"] else None
            ),
            "registered_at": r["registered_at"],
            "last_seen_at": r["last_seen_at"],
            "revoked_at": r["revoked_at"],
            "active_sessions": int(r["active_sessions"]),
        }
        for r in rows
    ]


@router.delete("/devices/{device_id}", status_code=204)
def revoke_device(
    device_id: uuid.UUID,
    p: Principal = Depends(admin_principal),  # noqa: B008
    d: Db = Depends(get_db),  # noqa: B008
) -> Response:
    conn = d.conn
    found = devices.get(conn, device_id)
    if found is None:
        raise ApiError(404, "not_found", "No such device.")
    with conn.transaction():
        if devices.revoke(conn, device_id, p.user_id):
            ended = sessions.revoke_where(conn, "device_id = %s AND kind = 'pin'", (device_id,), "device_revoked")
            audit.append(
                conn,
                action="device.revoked",
                user_id=p.user_id,
                session_id=p.session_id,
                role_snapshot=p.role_snapshot,
                subject_type="device",
                subject_id=device_id,
                detail={"name": found["name"], "sessions_ended": len(ended)},
                ip=p.ip,
            )
    return Response(status_code=204)


def _group_map_view(request: Request) -> dict[str, Any]:
    cache: dict[str, Any] | None = getattr(request.app.state, "groups_cache", None)
    if cache is None or time.monotonic() - cache["t"] > GROUPS_CACHE_SECONDS:
        try:
            in_ad: list[str] | None = directory_of(request).list_groups()
        except LdapUnavailable:
            in_ad = None
        cache = {"t": time.monotonic(), "checked_at": datetime.now(UTC), "in_ad": in_ad}
        request.app.state.groups_cache = cache
    names: list[str] | None = cache["in_ad"]
    lower = {n.lower() for n in names} if names is not None else None
    gm = groupmap.current()
    out = []
    for name, role in gm.entries:
        out.append(
            {
                "name": name,
                "role": str(role),
                "dept_code": role.dept_code,
                "in_ad": None if lower is None else name.lower() in lower,
            }
        )
    extra = sorted(n for n in names or [] if gm.role_for(n) is None)
    return {"checked_at": cache["checked_at"], "ad_reachable": names is not None, "groups": out, "extra_in_ou": extra}


@router.get("/groups")
def group_map(request: Request, p: Principal = Depends(admin_principal)) -> dict[str, Any]:  # noqa: B008
    return _group_map_view(request)


@router.post("/ad/refresh")
def ad_refresh(
    request: Request,
    p: Principal = Depends(admin_principal),  # noqa: B008
    d: Db = Depends(get_db),  # noqa: B008
) -> dict[str, Any]:
    try:
        res = userdir.refresh_from_ad(d.conn, directory_of(request), actor=p.actor, ip=p.ip)
    except LdapUnavailable as e:
        raise ldap_down(e) from None
    request.app.state.groups_cache = None
    return res.as_dict()


@router.get("/signin-attempts")
def signin_attempts(
    p: Principal = Depends(admin_principal),  # noqa: B008
    d: Db = Depends(get_db),  # noqa: B008
    limit: int = Query(100, ge=1, le=1000),
) -> list[dict[str, Any]]:
    with d.conn.cursor(row_factory=dict_row) as cur:
        rows = cur.execute(
            "SELECT a.id, a.at, a.account, host(a.ip) AS ip, a.kind, a.reason, a.user_id, a.session_id,"
            " u.display_name FROM signin_attempts a LEFT JOIN users u ON u.id = a.user_id"
            " WHERE NOT a.ok ORDER BY a.id DESC LIMIT %s",
            (limit,),
        ).fetchall()
    return [
        {
            "id": r["id"],
            "at": r["at"],
            "account": r["account"],
            "ip": r["ip"],
            "kind": r["kind"],
            "reason": r["reason"],
            "user_id": str(r["user_id"]) if r["user_id"] else None,
            "display_name": r["display_name"],
        }
        for r in rows
    ]