"""The cached directory: `users` and `user_roles` rows written from what AD reports.

Packet Station grants no roles. `user_roles` is a cache of the roles AD groups give, rebuilt at every
sign-in, on the session's roles refresh and by the AD refresh.
"""

from __future__ import annotations

import logging
import uuid
from collections import Counter
from dataclasses import dataclass, field
from typing import Any

from psycopg.rows import dict_row
from psycopg.types.json import Jsonb

from .. import audit
from . import groups as groupmap
from . import sessions
from .ldap import AdUser, DirectoryProtocol

log = logging.getLogger(__name__)


def upsert_user(conn: Any, u: AdUser, *, groups: list[str], signin: bool = False) -> bool:
    """Insert or refresh the users row for an AD account. True when the row is new.

    A different, older row holding the same sAMAccountName (a deleted and re-created AD account) is renamed
    and marked inactive so the unique index holds and its history keeps its name.
    """
    with conn.transaction():
        conn.execute(
            "UPDATE users SET sam_account = sam_account || '~' || left(id::text, 8), active = false"
            " WHERE lower(sam_account) = lower(%s) AND id <> %s",
            (u.sam_account, u.guid),
        )
        flags = {"disabled": u.disabled, "emp_missing": not u.emp_no, "groups": groups}
        row = conn.execute(
            "INSERT INTO users (id, sam_account, upn, display_name, emp_no, email, active, directory_flags,"
            " ad_synced_at, last_signin_at)"
            " VALUES (%s, %s, %s, %s, %s, %s, %s, %s, now(), CASE WHEN %s THEN now() END)"
            " ON CONFLICT (id) DO UPDATE SET sam_account = EXCLUDED.sam_account, upn = EXCLUDED.upn,"
            " display_name = EXCLUDED.display_name, emp_no = EXCLUDED.emp_no, email = EXCLUDED.email,"
            " active = EXCLUDED.active, directory_flags = users.directory_flags || EXCLUDED.directory_flags,"
            " ad_synced_at = now(), last_signin_at = coalesce(EXCLUDED.last_signin_at, users.last_signin_at)"
            " RETURNING (xmax = 0) AS inserted",
            (
                u.guid,
                u.sam_account,
                u.upn,
                u.display_name,
                u.emp_no,
                u.email,
                not u.disabled,
                Jsonb(flags),
                signin,
            ),
        ).fetchone()
    return bool(row[0])


def set_roles(conn: Any, user_id: Any, roles: list[str]) -> None:
    """Rebuild a user's `user_roles` rows from role strings."""
    with conn.transaction():
        conn.execute("DELETE FROM user_roles WHERE user_id = %s", (user_id,))
        for text in roles:
            r = groupmap.parse_role(text)
            conn.execute(
                "INSERT INTO user_roles (user_id, role, dept_code) VALUES (%s, %s::role_kind, %s)",
                (user_id, r.kind, r.dept_code),
            )


def roles_of(conn: Any, user_id: Any) -> list[str]:
    rows = conn.execute("SELECT role::text, dept_code FROM user_roles WHERE user_id = %s", (user_id,)).fetchall()
    return groupmap.current().sort_roles(groupmap.role_from_row(r[0], r[1]) for r in rows)


def get_user(conn: Any, user_id: Any) -> dict[str, Any] | None:
    with conn.cursor(row_factory=dict_row) as cur:
        row: dict[str, Any] | None = cur.execute("SELECT * FROM users WHERE id = %s", (user_id,)).fetchone()
    return row


def end_sessions(conn: Any, user_id: Any, reason: str, *, by: str | None = None) -> list[uuid.UUID]:
    """End every live session of a user, one `auth.session_ended` audit row each. Returns the session ids."""
    rows = conn.execute(
        "SELECT id, roles_snapshot FROM sessions WHERE user_id = %s AND revoked_at IS NULL", (user_id,)
    ).fetchall()
    ended: list[uuid.UUID] = []
    for sid, snap in rows:
        if not sessions.revoke(conn, sid, reason):
            continue
        ended.append(sid)
        detail: dict[str, Any] = {"reason": reason}
        if by:
            detail["by"] = by
        audit.append(
            conn,
            action="auth.session_ended",
            user_id=user_id,
            session_id=sid,
            role_snapshot=",".join((snap or {}).get("roles", [])),
            detail=detail,
        )
    return ended


def mark_inactive(conn: Any, user_id: Any, *, reason: str, gone: bool, audit_by: str | None = None) -> list[uuid.UUID]:
    """Mark a user inactive (disabled or gone in AD), drop the roles and end the sessions.

    With `audit_by` every ended session gets an `auth.session_ended` row naming who ended it. Returns the ids.
    """
    conn.execute(
        "UPDATE users SET active = false, directory_flags = directory_flags || %s, ad_synced_at = now() WHERE id = %s",
        (Jsonb({"disabled": not gone, "gone": gone}), user_id),
    )
    conn.execute("DELETE FROM user_roles WHERE user_id = %s", (user_id,))
    if audit_by:
        return end_sessions(conn, user_id, reason, by=audit_by)
    return sessions.revoke_user(conn, user_id, reason)


def public_user(row: dict[str, Any]) -> dict[str, Any]:
    return {
        "id": str(row["id"]),
        "sam_account": row["sam_account"],
        "upn": row.get("upn"),
        "display_name": row["display_name"],
        "emp_no": row.get("emp_no"),
        "email": row.get("email"),
    }


def ad_user_public(u: AdUser) -> dict[str, Any]:
    return {
        "id": str(u.guid),
        "dn": u.dn,
        "sam_account": u.sam_account,
        "upn": u.upn,
        "display_name": u.display_name,
        "emp_no": u.emp_no,
        "email": u.email,
    }


# ---------------------------------------------------------------- AD reconcile

RECONCILE_BY = "ad-reconcile"
LIST_CAP = 200  # names kept in a report list; the count is always whole


class ReconcileRefused(Exception):
    """AD answered, but with something that would deactivate people by mistake. Nothing was changed."""


@dataclass
class RefreshResult:
    groups_checked: int = 0
    groups_missing: list[str] = field(default_factory=list)
    groups_extra: list[str] = field(default_factory=list)
    users_seen: int = 0
    created: int = 0
    updated: int = 0
    deactivated: int = 0
    sessions_ended: int = 0
    emp_missing: list[str] = field(default_factory=list)
    emp_duplicate: list[str] = field(default_factory=list)
    created_names: list[str] = field(default_factory=list)
    deactivated_names: list[str] = field(default_factory=list)

    def as_dict(self) -> dict[str, Any]:
        """The report: lists of names (missing and extra groups, accounts without an employee ID, duplicated
        employee IDs) and counts. The same shape is the ad-reconcile run's counts."""
        return {
            "groups_checked": self.groups_checked,
            "groups_missing": self.groups_missing[:LIST_CAP],
            "groups_extra": self.groups_extra[:LIST_CAP],
            "users_seen": self.users_seen,
            "created": self.created,
            "updated": self.updated,
            "deactivated": self.deactivated,
            "sessions_ended": self.sessions_ended,
            "emp_missing": self.emp_missing[:LIST_CAP],
            "emp_duplicate": self.emp_duplicate[:LIST_CAP],
        }

    def summary(self) -> dict[str, int]:
        """Counts only, for the audit row and the log."""
        return {
            "groups_checked": self.groups_checked,
            "groups_missing": len(self.groups_missing),
            "groups_extra": len(self.groups_extra),
            "users_seen": self.users_seen,
            "created": self.created,
            "updated": self.updated,
            "deactivated": self.deactivated,
            "sessions_ended": self.sessions_ended,
            "emp_missing": len(self.emp_missing),
            "emp_duplicate": len(self.emp_duplicate),
        }


@dataclass
class _AdRead:
    """Everything the reconcile reads from AD, before any database write."""

    present: list[tuple[str, str]]  # mapped groups found in the OU: (name as mapped, dn)
    missing: list[str]
    extra: list[str]
    seen: dict[uuid.UUID, AdUser]
    member_groups: dict[uuid.UUID, set[str]]
    unseen: dict[uuid.UUID, AdUser | None]


def _read_ad(conn: Any, directory: DirectoryProtocol) -> _AdRead:
    names = groupmap.group_names()
    in_ou = {cn.lower(): (cn, dn) for cn, dn in directory.list_groups_detail()}
    mapped = {n.lower() for n in names}
    present = [(n, in_ou[n.lower()][1]) for n in names if n.lower() in in_ou]
    missing = [n for n in names if n.lower() not in in_ou]
    extra = sorted((cn for key, (cn, _) in in_ou.items() if key not in mapped), key=str.lower)
    if not present:
        raise ReconcileRefused("no mapped group was found in the OU; check LDAP_GROUP_BASE_DN")
    seen: dict[uuid.UUID, AdUser] = {}
    member_groups: dict[uuid.UUID, set[str]] = {}
    for name, dn in present:
        for u in directory.members_of_dn(dn):
            seen.setdefault(u.guid, u)
            member_groups.setdefault(u.guid, set()).add(name)
    known = [r[0] for r in conn.execute("SELECT id FROM users WHERE active ORDER BY id").fetchall()]
    unseen_ids = [uid for uid in known if uid not in seen]
    if not seen and unseen_ids:
        raise ReconcileRefused("AD listed no member in any mapped group; nobody was changed")
    unseen = directory.users_by_guid(unseen_ids) if unseen_ids else {}
    return _AdRead(present, missing, extra, seen, member_groups, unseen)


def refresh_from_ad(
    conn: Any,
    directory: DirectoryProtocol,
    *,
    actor: sessions.Actor | None = None,
    ip: str | None = None,
    run_id: int | None = None,
) -> RefreshResult:
    """The AD reconcile. List the OU (missing and extra groups), enumerate the members of every mapped group
    (IN_CHAIN, paged), upsert them on objectGUID and rebuild their roles. An active user AD no longer lists in
    any group is looked up by GUID: gone or disabled means inactive with the sessions ended (`ad_gone`,
    `ad_disabled`); still there means no roles and the sessions ended (`roles_lost`). directory_flags gets
    emp_missing, emp_duplicate, gone and disabled.

    Every AD read happens first, then the writes in one transaction, so no lock is held while AD answers.
    Raises LdapUnavailable when AD cannot be read and ReconcileRefused when what it read looks wrong.
    """
    res = RefreshResult()
    ad = _read_ad(conn, directory)
    res.groups_missing = ad.missing
    res.groups_extra = ad.extra
    res.groups_checked = len(ad.present)
    res.users_seen = len(ad.seen)

    enabled = [u for u in ad.seen.values() if not u.disabled]
    enabled += [u for u in ad.unseen.values() if u is not None and not u.disabled]
    res.emp_missing = sorted(u.sam_account for u in enabled if not u.emp_no)
    counts = Counter(u.emp_no for u in enabled if u.emp_no)
    res.emp_duplicate = sorted(e for e, n in counts.items() if n > 1)
    dup = set(res.emp_duplicate)
    who: dict[str, Any] = {
        "user_id": actor.user_id if actor else None,
        "session_id": actor.session_id if actor else None,
        "role_snapshot": actor.role_snapshot if actor else None,
    }

    def deactivated(uid: uuid.UUID, reason: str, sam: str) -> None:
        res.deactivated += 1
        res.deactivated_names.append(sam)
        audit.append(
            conn,
            action="ad.user_deactivated",
            subject_type="user",
            subject_id=uid,
            detail={"reason": reason, "sam_account": sam},
            ip=ip,
            **who,
        )

    def flags(uid: uuid.UUID, u: AdUser | None) -> None:
        conn.execute(
            "UPDATE users SET directory_flags = directory_flags || %s WHERE id = %s",
            (Jsonb({"emp_duplicate": bool(u and u.emp_no and u.emp_no in dup), "gone": u is None}), uid),
        )

    with conn.transaction():
        for guid, u in ad.seen.items():
            grp = groupmap.mapped_groups(ad.member_groups[guid])
            was = conn.execute("SELECT active FROM users WHERE id = %s", (guid,)).fetchone()
            if upsert_user(conn, u, groups=grp):
                res.created += 1
                res.created_names.append(u.sam_account)
            else:
                res.updated += 1
            flags(guid, u)
            roles = [] if u.disabled else groupmap.roles_from_groups(grp)
            set_roles(conn, guid, roles)
            if u.disabled:
                res.sessions_ended += len(end_sessions(conn, guid, "ad_disabled", by=RECONCILE_BY))
                if was is not None and was[0]:
                    deactivated(guid, "disabled", u.sam_account)
            elif not roles:
                res.sessions_ended += len(end_sessions(conn, guid, "roles_lost", by=RECONCILE_BY))
        for uid, found in ad.unseen.items():
            if found is None or found.disabled:
                row = conn.execute("SELECT sam_account FROM users WHERE id = %s", (uid,)).fetchone()
                ended = mark_inactive(
                    conn,
                    uid,
                    reason="ad_gone" if found is None else "ad_disabled",
                    gone=found is None,
                    audit_by=RECONCILE_BY,
                )
                res.sessions_ended += len(ended)
                flags(uid, found)
                deactivated(uid, "gone" if found is None else "disabled", row[0] if row else str(uid))
            else:
                upsert_user(conn, found, groups=[])
                flags(uid, found)
                set_roles(conn, uid, [])
                res.sessions_ended += len(end_sessions(conn, uid, "roles_lost", by=RECONCILE_BY))
        detail: dict[str, Any] = dict(res.summary())
        if run_id is not None:
            detail["run_id"] = run_id
        audit.append(conn, action="ad.refresh", detail=detail, ip=ip, **who)
    log.info("AD reconcile: %s", res.summary())
    return res


reconcile = refresh_from_ad