from __future__ import annotations

import logging
from typing import Any

from .normalize import normalize_user_target, strip_nc_prefix

logger = logging.getLogger(__name__)


def resolve_approver_id(user_id: str) -> str:
    approver_id = strip_nc_prefix(user_id)
    return f"nc:{approver_id}"


def resolve_allow_from_approvers(config: dict[str, Any]) -> list[str]:
    allow_from = config.get("allow_from", config.get("allowFrom", []))
    return [normalize_user_target(strip_nc_prefix(entry)) for entry in allow_from]


def check_approval_required(
    user_id: str,
    config: dict[str, Any],
    paired_users: set[str] | None = None,
) -> dict[str, Any]:
    dm_policy = config.get("dm_policy", "pairing")

    if dm_policy == "open":
        return {"approval_required": False, "reason": "dm_policy is open"}

    if dm_policy == "disabled":
        return {"approval_required": True, "reason": "dm_policy is disabled", "action": "block"}

    if dm_policy == "allowlist":
        allow_from = config.get("allow_from", config.get("allowFrom", []))
        approved = any(
            normalize_user_target(strip_nc_prefix(e)) == normalize_user_target(strip_nc_prefix(user_id))
            for e in allow_from
        )
        if approved:
            return {"approval_required": False, "reason": "User is in allowlist"}
        return {"approval_required": True, "reason": "User not in allowlist", "action": "block"}

    if dm_policy == "pairing":
        if paired_users and user_id in paired_users:
            return {"approval_required": False, "reason": "User is already paired"}
        return {
            "approval_required": True,
            "reason": "User not paired",
            "action": "pair",
            "approver_id": resolve_approver_id(user_id),
        }

    return {"approval_required": True, "reason": f"Unknown dm_policy: {dm_policy}"}