from __future__ import annotations

from ..ddns_models import DdnsSettings, UpdateResult

SUPPORTED_DNS_PROVIDERS = {"", "cloudflare", "rfc2136"}


class DnsProviderError(RuntimeError):
    """Raised for expected DNS provider publish/delete failures."""


class DnsConfigurationError(RuntimeError):
    """Raised when DNS provider settings are invalid at startup."""


def publish_dns(result: UpdateResult, settings: DdnsSettings) -> None:
    validate_dns_provider_settings(settings)
    provider = _normalized_provider(settings)
    if provider == "cloudflare":
        from .cloudflare import publish_cloudflare

        publish_cloudflare(result, settings)
        return
    if settings.rfc2136_server or provider == "rfc2136":
        from .rfc2136 import publish_rfc2136

        publish_rfc2136(result, settings)
        return
    if settings.require_dns_provider:
        raise DnsProviderError("DNS provider is required but not configured")


def delete_dns_records(hostname: str, settings: DdnsSettings) -> None:
    validate_dns_provider_settings(settings)
    provider = _normalized_provider(settings)
    if provider == "cloudflare":
        from .cloudflare import delete_cloudflare_records

        delete_cloudflare_records(hostname, settings)
        return
    if settings.rfc2136_server or provider == "rfc2136":
        from .rfc2136 import delete_rfc2136_records

        delete_rfc2136_records(hostname, settings)
        return
    if settings.require_dns_provider:
        raise DnsProviderError("DNS provider is required but not configured")


def dns_backend_configured(settings: DdnsSettings) -> bool:
    validate_dns_provider_settings(settings)
    provider = _normalized_provider(settings)
    return provider == "cloudflare" or provider == "rfc2136" or bool(settings.rfc2136_server)


def validate_dns_provider_settings(settings: DdnsSettings) -> None:
    provider = _normalized_provider(settings)
    if provider not in SUPPORTED_DNS_PROVIDERS:
        raise DnsConfigurationError(f"Unsupported DDNS_DNS_PROVIDER: {settings.dns_provider}")
    if not settings.require_dns_provider:
        return
    if provider == "cloudflare":
        if not settings.cloudflare_api_token or not settings.cloudflare_zone_id:
            raise DnsConfigurationError(
                "DDNS_CLOUDFLARE_API_TOKEN and DDNS_CLOUDFLARE_ZONE_ID are required when DDNS_DNS_PROVIDER=cloudflare"
            )
        return
    if provider == "rfc2136" or settings.rfc2136_server:
        if not settings.rfc2136_server or not settings.rfc2136_zone:
            raise DnsConfigurationError(
                "DDNS_RFC2136_SERVER and DDNS_RFC2136_ZONE are required when RFC2136 DNS publishing is enabled"
            )
        return
    raise DnsConfigurationError("DDNS_REQUIRE_DNS_PROVIDER is set but no DNS backend is configured")


def _normalized_provider(settings: DdnsSettings) -> str:
    return settings.dns_provider.strip().lower()