from __future__ import annotations

from fnmatch import fnmatchcase


def build_allowlist_candidates(
    sender_nick: str,
    sender_user: str | None = None,
    sender_host: str | None = None,
) -> list[str]:
    candidates = [sender_nick]

    if sender_user:
        candidates.append(f"{sender_nick}!{sender_user}")
    if sender_host:
        candidates.append(f"{sender_nick}@{sender_host}")
    if sender_user and sender_host:
        candidates.append(f"{sender_nick}!{sender_user}@{sender_host}")

    return candidates


def resolve_allowlist_match(
    candidates: list[str],
    allowlist: list[str],
) -> str | None:
    for candidate in candidates:
        if candidate in allowlist:
            return candidate
    for candidate in candidates:
        for entry in allowlist:
            if fnmatchcase(candidate, entry):
                return entry
    if "*" in allowlist:
        return "*"
    return None


def normalize_allow_entry(entry: str) -> str:
    for prefix in ("irc:", "irc:user:", "user:"):
        if entry.startswith(prefix):
            entry = entry[len(prefix) :]
    return entry


def looks_like_irc_target_id(target: str) -> bool:
    if target.startswith("irc:channel:") or target.startswith("irc:user:"):
        return True
    if "!" in target and "@" in target:
        return True
    return False


def normalize_irc_messaging_target(target: str) -> tuple[str, str]:
    if target.startswith("irc:channel:"):
        return "group", target.removeprefix("irc:channel:")
    if target.startswith("irc:user:"):
        return "direct", target.removeprefix("irc:user:")
    if target.startswith("#") or target.startswith("&"):
        return "group", target
    return "direct", normalize_allow_entry(target)


def resolve_targets(target: str) -> dict:
    kind, resolved = normalize_irc_messaging_target(target)
    return {"kind": kind, "id": resolved, "display_name": resolved}


def format_irc_sender_id(nick: str, user: str | None = None, host: str | None = None) -> str:
    if user and host:
        return f"{nick}!{user}@{host}"
    if user:
        return f"{nick}!{user}"
    if host:
        return f"{nick}@{host}"
    return nick