from __future__ import annotations

import re
from typing import Any


_CHANNEL_PREFIXES = ("googlechat:", "gchat:", "google-chat:")


def normalize_googlechat_target(target: str) -> dict[str, Any]:
    if not target:
        return {"raw": target, "type": "unknown"}

    target = _strip_channel_prefix(target)

    if "@" in target and not target.startswith(("spaces/", "users/")):
        target = _convert_email_to_user(target)

    if target.startswith("spaces/"):
        parts = target.removeprefix("spaces/").split("/")
        space_id = parts[0]
        thread_key = parts[2] if len(parts) > 2 and parts[1] == "threads" else None
        return {
            "raw": target,
            "type": "thread" if thread_key else "space",
            "space_id": space_id,
            "space_name": f"spaces/{space_id}",
            "thread_key": thread_key,
            "full_target": target,
        }

    if target.startswith("users/"):
        user_id = target.removeprefix("users/")
        cleaned = user_id.removeprefix("user:")
        return {
            "raw": target,
            "type": "user",
            "user_id": cleaned,
            "user_name": f"users/{cleaned}",
            "full_target": target,
        }

    if target.startswith("user:"):
        user_id = target.removeprefix("user:")
        return {
            "raw": target,
            "type": "user",
            "user_id": user_id,
            "user_name": f"users/{user_id}",
            "full_target": f"users/{user_id}",
        }

    return {"raw": target, "type": "unknown"}


def is_googlechat_user_target(target: str) -> bool:
    target = _strip_channel_prefix(target)
    return target.startswith("users/") or target.startswith("user:")


def is_googlechat_space_target(target: str) -> bool:
    target = _strip_channel_prefix(target)
    return target.startswith("spaces/")


def resolve_targets(inputs: list[str], kind: str | None = None) -> list[dict[str, Any]]:
    results: list[dict[str, Any]] = []

    for target in inputs:
        normalized = normalize_googlechat_target(target)
        target_type = normalized.get("type", "unknown")

        if kind and target_type != kind:
            continue

        results.append(normalized)

    return results


def _strip_channel_prefix(target: str) -> str:
    for prefix in _CHANNEL_PREFIXES:
        if target.lower().startswith(prefix):
            return target[len(prefix) :]
    return target


def _convert_email_to_user(email: str) -> str:
    email_match = re.match(r"^[\w.+-]+@[\w-]+\.[\w.-]+$", email)
    if email_match:
        return f"users/{email}"
    return f"users/{email}"