from __future__ import annotations

import enum
from typing import Any

ALLOW_ENTRY_PREFIXES = ("zoa:", "zalo_oa:")


class DMPolicy(enum.StrEnum):
    OPEN = "open"
    PAIRING = "pairing"
    ALLOWLIST = "allowlist"
    DISABLED = "disabled"


def normalize_allow_entry(entry: str) -> str:
    for prefix in ALLOW_ENTRY_PREFIXES:
        if entry.lower().startswith(prefix):
            return entry[len(prefix) :]
    return entry


def resolve_dm_policy(config: dict[str, Any]) -> DMPolicy:
    policy_str = config.get("dm_policy", config.get("dmPolicy", ""))
    if policy_str == "open":
        return DMPolicy.OPEN
    if policy_str == "pairing":
        return DMPolicy.PAIRING
    if policy_str == "allowlist":
        return DMPolicy.ALLOWLIST
    if policy_str == "disabled":
        return DMPolicy.DISABLED
    return DMPolicy.OPEN


def load_allowlist(config: dict[str, Any]) -> set[str]:
    raw = config.get("allowFrom", [])
    if not isinstance(raw, list):
        raw = []
    if "*" in raw:
        return {"*"}
    return {normalize_allow_entry(str(entry)) for entry in raw}


def check_dm_allowed(user_id: str, policy: DMPolicy, allowlist: set[str]) -> bool:
    if policy == DMPolicy.OPEN:
        return True
    if policy == DMPolicy.DISABLED:
        return False
    if policy == DMPolicy.ALLOWLIST:
        if "*" in allowlist:
            return True
        return user_id in allowlist
    if policy == DMPolicy.PAIRING:
        if "*" in allowlist:
            return True
        return user_id in allowlist
    return False


def collect_security_warnings(config: dict[str, Any]) -> list[dict[str, Any]]:
    warnings: list[dict[str, Any]] = []
    policy = resolve_dm_policy(config)
    allowlist = load_allowlist(config)
    webhook = config.get("webhook", {})

    if policy == DMPolicy.OPEN:
        warnings.append(
            {
                "severity": "warning",
                "type": "dm_policy_open",
                "message": "DM policy is 'open' — any follower can send messages without restriction",
                "recommendation": "Consider switching to 'allowlist' or 'pairing' for production",
            }
        )

    if policy == DMPolicy.ALLOWLIST and not allowlist:
        warnings.append(
            {
                "severity": "error",
                "type": "empty_allowlist",
                "message": "DM policy is 'allowlist' but allowFrom is empty — no users can message the OA",
                "recommendation": "Add user IDs to allowFrom or change policy to 'open'",
            }
        )

    if policy == DMPolicy.PAIRING and not allowlist and "*" not in allowlist:
        warnings.append(
            {
                "severity": "info",
                "type": "pairing_no_preset",
                "message": "DM policy is 'pairing' with empty allowFrom — all pairing requests will be processed",
                "recommendation": "Add pre-approved user IDs to allowFrom for faster onboarding",
            }
        )

    if policy == DMPolicy.ALLOWLIST and "*" in allowlist:
        warnings.append(
            {
                "severity": "info",
                "type": "allowlist_wildcard",
                "message": "allowFrom contains '*' wildcard — effectively same as 'open' policy",
                "recommendation": "Use '*' only in development or use 'open' policy explicitly",
            }
        )

    if not webhook.get("url"):
        warnings.append(
            {
                "severity": "info",
                "type": "webhook_not_configured",
                "message": "Webhook URL not configured — messages will only be received via polling",
                "recommendation": "Configure a webhook URL for real-time message delivery",
            }
        )

    if not webhook.get("mac_key"):
        warnings.append(
            {
                "severity": "warning",
                "type": "webhook_mac_key_missing",
                "message": "Webhook MAC key not configured — webhook signature verification is disabled",
                "recommendation": "Set ZALO_WEBHOOK_MAC_KEY or webhook.mac_key to enable signature verification",
            }
        )

    return warnings