from __future__ import annotations

from typing import Any

from app.brand.errors import BrandValidationError

_PLATFORM_FIELDS: dict[str, frozenset[str]] = {
    "facebook": frozenset({"caption_style", "hashtags", "cta"}),
    "instagram": frozenset({"caption_style", "hashtags", "cta", "first_comment"}),
    "tiktok": frozenset({"caption_style", "hashtags", "cta"}),
    "x": frozenset({"caption_style", "hashtags", "cta"}),
    "youtube": frozenset({"title_pattern", "description", "tags", "cta"}),
    "linkedin": frozenset({"post_style", "hashtags", "cta"}),
    "telegram": frozenset({"caption_style", "cta"}),
    "whatsapp": frozenset({"caption_style", "cta"}),
}


def validate_platform_settings(provider: str, settings: dict[str, Any]) -> None:
    unsupported = set(settings) - _PLATFORM_FIELDS.get(provider, frozenset())
    if unsupported:
        raise BrandValidationError(
            f"Unsupported {provider} brand defaults: {', '.join(sorted(unsupported))}."
        )
    for key, value in settings.items():
        if isinstance(value, str) and len(value) > 4000:
            raise BrandValidationError(f"{provider}.{key} exceeds the supported length.")
        if isinstance(value, list) and len(value) > 100:
            raise BrandValidationError(f"{provider}.{key} contains too many values.")