"""Custody: who holds a packet right now, and the Who predicates. A direct port of guard.js holds()."""

from __future__ import annotations

from collections.abc import Mapping
from typing import Any

from .actions import ACTIVE, SUPPORT_CODES, Who
from .principal import PacketState, Principal

WORKER, LEAD, SUPERVISOR = 1, 2, 3


def works_on(principal: Principal, state: PacketState) -> bool:
    """A member of the packet's department whose station limits allow the packet's station.

    Leads and supervisors always pass. A worker passes when they have no station limits or the limits hold
    the packet's station. This is the old worksOn(); START and SUBMIT add the assigned-welder check.
    """
    level = principal.level(state.dept)
    if level == 0:
        return False
    if level >= LEAD:
        return True
    return not principal.station_limits or (
        state.station_id is not None and state.station_id in principal.station_limits
    )


def holds(principal: Principal, state: PacketState) -> bool:
    """True when the principal holds the packet in its current status. Admin is not a holder; see the bypass."""
    st = state.status
    if st == "draft":
        return "CL" in principal.support
    if st == "warehouse":
        return "WH" in principal.support
    if st in ("ready", "review"):
        return principal.level(state.dept) >= LEAD
    if st in ACTIVE:
        return principal.level(state.dept) >= LEAD or works_on(principal, state)
    if st == "qc":
        return "QC" in principal.support
    if st == "complete":
        return "CL" in principal.support
    return False


def holder_name(state: PacketState, dept_name: str | None = None, station_name: str | None = None) -> str:
    """Who has the packet, for messages. The department name falls back to its code."""
    st = state.status
    if st == "draft":
        return "Clerical"
    if st == "warehouse":
        return "Warehouse"
    if st == "qc":
        return "Q.C."
    if st == "complete":
        return "Clerical (data book)"
    if st == "filed":
        return "the data book (filed)"
    name = dept_name or state.dept
    if st in ACTIVE and station_name:
        return f"{name} · {station_name}"
    return name


def _works_on_assigned(principal: Principal, state: PacketState) -> bool:
    """START and SUBMIT: a lead or above in the department, or the assigned welder within their station limits."""
    level = principal.level(state.dept)
    if level >= LEAD:
        return True
    return (
        level == WORKER
        and principal.user_id is not None
        and state.welder_id is not None
        and str(state.welder_id) == str(principal.user_id)
        and works_on(principal, state)
    )


def _co_verifier(principal: Principal, extra: Mapping[str, Any]) -> bool:
    """A supervisor of the department named in the request (extra["dept"])."""
    dept = extra.get("dept")
    if not isinstance(dept, str) or not dept:
        return False
    if dept in ("WH", "QC"):
        return dept in principal.support_sup
    if dept in SUPPORT_CODES:
        return False  # Clerical issues change orders; it never verifies them. PM has no supervisor.
    return principal.level(dept) >= SUPERVISOR


def allows(who: Who, principal: Principal, state: PacketState, extra: Mapping[str, Any]) -> bool:
    """Evaluate one Who predicate. Admin is never allowed here except by Who.ADMIN; the bypass is a rule."""
    if who is Who.CL:
        return "CL" in principal.support
    if who is Who.CL_SUP:
        return "CL" in principal.support_sup
    if who is Who.WH:
        return "WH" in principal.support
    if who is Who.WH_SUP:
        return "WH" in principal.support_sup
    if who is Who.QC:
        return "QC" in principal.support
    if who is Who.QC_SUP:
        return "QC" in principal.support_sup
    if who is Who.CL_OR_QC:
        return "CL" in principal.support or "QC" in principal.support
    if who is Who.HOLDER:
        return holds(principal, state)
    if who is Who.DEPT_LEAD:
        return principal.level(state.dept) >= LEAD
    if who is Who.DEPT_SUP:
        return principal.level(state.dept) >= SUPERVISOR
    if who is Who.WORKS_ON:
        return _works_on_assigned(principal, state)
    if who is Who.CO_VERIFIER:
        return _co_verifier(principal, extra)
    if who is Who.ADMIN:
        return principal.admin
    if who is Who.SYSTEM:
        return principal.system is not None
    return False