"""Departments and their stations, as the Admin edits them.

Code and slug never change (the group names derive from them; a trigger refuses it too). Stations are never deleted,
because station limits and packets point at them: `active: false` hides one. A new department is a shop department
with the three shop groups IT must create in the PacketStation OU. The support departments map to fixed roles, so a
new one would have no group and no role; it is refused.
"""

from __future__ import annotations

import re
from typing import Any

from psycopg.rows import dict_row

from .. import audit
from ..api.errors import ApiError
from ..auth import groups as groupmap

RX_CODE = re.compile(r"^[0-9A-Z]{2,4}$")
RX_SLUG = re.compile(r"^[A-Za-z][A-Za-z0-9]{1,30}$")
NAME_MAX = 80
STATION_NAME_MAX = 60
STATIONS_MAX = 60


def clean_name(value: Any, what: str, limit: int) -> str:
    text = " ".join(str(value or "").split())
    if not text:
        raise ApiError(422, "invalid_request", f"Give the {what} a name.")
    if len(text) > limit:
        raise ApiError(422, "invalid_request", f"The {what} name is longer than {limit} characters.")
    return text


def group_names_for(code: str, slug: str, kind: str, supervisor_group: bool) -> list[tuple[str, str]]:
    """(group name, role) for one department, as the group map builds them."""
    if kind == "shop":
        return [(f"PS-{code}-{slug}-{lv.capitalize()}", f"shop:{code}:{lv}") for lv in groupmap.SHOP_LEVELS]
    kinds = groupmap.OFFICE_KINDS.get(code)
    if kinds is None:
        return []
    member, sup = kinds
    out = [(f"PS-{slug}", member)]
    if supervisor_group and sup:
        out.append((f"PS-{slug}-Supervisor", sup))
    return out


def _stations(conn: Any, code: str | None = None) -> dict[str, list[dict[str, Any]]]:
    sql = "SELECT dept_code, id, name, sort, active FROM stations"
    params: tuple[Any, ...] = ()
    if code is not None:
        sql += " WHERE dept_code = %s"
        params = (code,)
    out: dict[str, list[dict[str, Any]]] = {}
    for dept, sid, name, sort, active in conn.execute(sql + " ORDER BY dept_code, sort, name, id", params):
        out.setdefault(dept, []).append({"id": int(sid), "name": name, "sort": int(sort), "active": bool(active)})
    return out


def _out(r: dict[str, Any], stations: list[dict[str, Any]], in_ou: set[str] | None) -> dict[str, Any]:
    groups = [
        {"name": name, "role": role, "in_ou": None if in_ou is None else name.lower() in in_ou}
        for name, role in group_names_for(r["code"], r["slug"], r["kind"], bool(r["supervisor_group"]))
    ]
    return {
        "code": r["code"],
        "slug": r["slug"],
        "name": r["name"],
        "kind": r["kind"],
        "sort": int(r["sort"]),
        "active": bool(r["active"]),
        "weld": bool(r["weld"]),
        "supervisor_group": bool(r["supervisor_group"]),
        "created_at": r["created_at"],
        "groups": groups,
        "stations": stations,
    }


SELECT = (
    "SELECT code, slug, name, kind::text AS kind, sort, active, weld, supervisor_group, created_at FROM departments"
)


def list_all(conn: Any, in_ou: list[str] | None) -> list[dict[str, Any]]:
    """Every department, active or not, in sort order. `in_ou` is the group names in the OU (None: unknown)."""
    lower = {n.lower() for n in in_ou} if in_ou is not None else None
    with conn.cursor(row_factory=dict_row) as cur:
        rows = cur.execute(SELECT + " ORDER BY sort, code").fetchall()
    st = _stations(conn)
    return [_out(r, st.get(r["code"], []), lower) for r in rows]


def get(conn: Any, code: str, in_ou: list[str] | None = None) -> dict[str, Any] | None:
    lower = {n.lower() for n in in_ou} if in_ou is not None else None
    with conn.cursor(row_factory=dict_row) as cur:
        r = cur.execute(SELECT + " WHERE code = %s", (code,)).fetchone()
    if r is None:
        return None
    return _out(r, _stations(conn, code).get(code, []), lower)


def _snapshot(d: dict[str, Any]) -> dict[str, Any]:
    return {k: d[k] for k in ("name", "active", "stations")}


def update(
    conn: Any,
    who: Any,
    code: str,
    *,
    name: str | None,
    active: bool | None,
    stations: list[dict[str, Any]] | None,
) -> dict[str, Any]:
    """Change the name, active and stations of one department. Audited `admin.department_updated`."""
    with conn.transaction():
        locked = conn.execute("SELECT code FROM departments WHERE code = %s FOR UPDATE", (code,)).fetchone()
        if locked is None:
            raise ApiError(404, "not_found", "No such department.")
        before = get(conn, code)
        assert before is not None
        if name is not None:
            conn.execute(
                "UPDATE departments SET name = %s WHERE code = %s", (clean_name(name, "department", NAME_MAX), code)
            )
        if active is not None:
            conn.execute("UPDATE departments SET active = %s WHERE code = %s", (bool(active), code))
        if stations is not None:
            _apply_stations(conn, code, before["stations"], stations)
        after = get(conn, code)
        assert after is not None
        if _snapshot(before) != _snapshot(after):
            audit.append(
                conn,
                action="admin.department_updated",
                user_id=who.user_id,
                session_id=who.session_id,
                role_snapshot=who.role_snapshot,
                subject_type="department",
                subject_id=code,
                detail={"before": _snapshot(before), "after": _snapshot(after)},
                ip=who.ip,
            )
    return after


def _apply_stations(conn: Any, code: str, current: list[dict[str, Any]], wanted: list[dict[str, Any]]) -> None:
    by_id = {s["id"]: s for s in current}
    final: dict[int, dict[str, Any]] = {s["id"]: dict(s) for s in current}
    new: list[dict[str, Any]] = []
    seen_ids: set[int] = set()
    for w in wanted:
        sid = w.get("id")
        entry = {
            "name": clean_name(w.get("name"), "station", STATION_NAME_MAX),
            "sort": int(w.get("sort") or 0),
            "active": bool(w.get("active", True)),
        }
        if sid is None:
            new.append(entry)
            continue
        if sid not in by_id:
            raise ApiError(422, "invalid_request", f"Station {sid} is not in department {code}.")
        if sid in seen_ids:
            raise ApiError(422, "invalid_request", f"Station {sid} is listed twice.")
        seen_ids.add(sid)
        final[sid].update(entry)
    names = [s["name"].lower() for s in final.values()] + [s["name"].lower() for s in new]
    dupes = sorted({n for n in names if names.count(n) > 1})
    if dupes:
        raise ApiError(422, "duplicate_station", f"Two stations in {code} have the same name: {', '.join(dupes)}.")
    if len(final) + len(new) > STATIONS_MAX:
        raise ApiError(422, "invalid_request", f"A department has at most {STATIONS_MAX} stations.")
    renamed = [sid for sid, s in final.items() if s["name"] != by_id[sid]["name"]]
    # Names are unique per department: park the renamed ones first so two stations can swap names.
    for sid in renamed:
        conn.execute("UPDATE stations SET name = %s WHERE id = %s", (f"~{sid}~renaming", sid))
    for sid, s in final.items():
        if s != by_id[sid]:
            conn.execute(
                "UPDATE stations SET name = %s, sort = %s, active = %s WHERE id = %s",
                (s["name"], s["sort"], s["active"], sid),
            )
    for s in new:
        conn.execute(
            "INSERT INTO stations (dept_code, name, sort, active) VALUES (%s, %s, %s, %s)",
            (code, s["name"], s["sort"], s["active"]),
        )


def add(
    conn: Any,
    who: Any,
    *,
    code: str,
    slug: str,
    name: str,
    kind: str,
    weld: bool,
    supervisor_group: bool,
    stations: list[str],
) -> tuple[dict[str, Any], list[str]]:
    """Add a shop department. Returns (department, group names IT must create). Audited `admin.department_added`."""
    code, slug = code.strip(), slug.strip()
    if not RX_CODE.match(code):
        raise ApiError(422, "invalid_request", "The code is 2 to 4 capital letters or digits, like 15.")
    if not RX_SLUG.match(slug):
        raise ApiError(422, "invalid_request", "The short name is a letter, then letters or digits, no spaces.")
    if kind != "shop":
        raise ApiError(
            422,
            "support_fixed",
            "Only a shop department can be added. The support departments map to fixed roles.",
        )
    title = clean_name(name, "department", NAME_MAX)
    names: list[str] = []
    for s in stations:
        n = clean_name(s, "station", STATION_NAME_MAX)
        if n.lower() in (x.lower() for x in names):
            raise ApiError(422, "duplicate_station", f"Two stations have the same name: {n}.")
        names.append(n)
    if len(names) > STATIONS_MAX:
        raise ApiError(422, "invalid_request", f"A department has at most {STATIONS_MAX} stations.")
    with conn.transaction():
        conn.execute("LOCK TABLE departments IN SHARE ROW EXCLUSIVE MODE")
        if conn.execute("SELECT 1 FROM departments WHERE upper(code) = upper(%s)", (code,)).fetchone():
            raise ApiError(409, "code_taken", f"Department code {code} is taken.")
        if conn.execute("SELECT 1 FROM departments WHERE lower(slug) = lower(%s)", (slug,)).fetchone():
            raise ApiError(409, "slug_taken", f"The short name {slug} is taken.")
        sort = int(conn.execute("SELECT coalesce(max(sort), 0) + 10 FROM departments").fetchone()[0])
        conn.execute(
            "INSERT INTO departments (code, slug, name, kind, sort, active, supervisor_group, weld, created_at,"
            " created_by) VALUES (%s, %s, %s, %s::dept_kind, %s, true, %s, %s, now(), %s)",
            (code, slug, title, kind, sort, bool(supervisor_group), bool(weld), who.user_id),
        )
        for i, n in enumerate(names, start=1):
            conn.execute("INSERT INTO stations (dept_code, name, sort) VALUES (%s, %s, %s)", (code, n, i))
        dept = get(conn, code)
        assert dept is not None
        groups = [g["name"] for g in dept["groups"]]
        audit.append(
            conn,
            action="admin.department_added",
            user_id=who.user_id,
            session_id=who.session_id,
            role_snapshot=who.role_snapshot,
            subject_type="department",
            subject_id=code,
            detail={
                "after": {
                    "code": code,
                    "slug": slug,
                    "name": title,
                    "kind": kind,
                    "weld": bool(weld),
                    "supervisor_group": bool(supervisor_group),
                    "stations": names,
                },
                "groups_to_create": groups,
            },
            ip=who.ip,
        )
    return dept, groups