import warnings
from collections.abc import Sequence

from pydantic_ai.exceptions import UserError

from .settings import ImageGenerationSettings

# Shared with the `ImageGeneration` capability, which can decide the same conflict at construction.
DIMENSIONS_ASPECT_RATIO_CONFLICT = 'Image generation `dimensions` and `aspect_ratio` are mutually exclusive'


def validate_image_generation_settings(settings: ImageGenerationSettings) -> None:
    """Validate provider-independent image generation setting invariants."""
    dimensions = settings.get('dimensions')
    if dimensions is None:
        return

    if settings.get('aspect_ratio') is not None:
        raise UserError(DIMENSIONS_ASPECT_RATIO_CONFLICT)

    if (
        not isinstance(dimensions, tuple)
        or len(dimensions) != 2
        or any(not isinstance(value, int) or isinstance(value, bool) or value <= 0 for value in dimensions)
    ):
        raise UserError('Image generation `dimensions` must be a `(width, height)` tuple of positive integers')


def validate_image_count(provider: str, n: int | None) -> None:
    """Reject a count the request cannot carry at all; the provider owns its own upper bound."""
    if n is not None and (not isinstance(n, int) or isinstance(n, bool) or n <= 0):
        raise UserError(f'{provider} image generation count must be a positive integer')


def warn_image_generation_settings(
    provider: str,
    *,
    ignored: Sequence[str] = (),
    conflicts: Sequence[str] = (),
    stacklevel: int = 2,
) -> None:
    """Emit one warning for settings ignored or overridden by a provider adapter.

    `stacklevel` selects the frame the warning points at. The default `2` is the adapter's own
    `generate()` call (adapter → `warn`), deliberately chosen over the user's call site: the
    distance from `generate()` to user code is unbounded, because `ImageGenerator` and any number
    of [`WrapperImageGenerationModel`][pydantic_ai.images.WrapperImageGenerationModel] layers can
    sit in between, so the adapter that resolved the settings is the only frame always worth naming.
    """
    warning_parts: list[str] = []
    if ignored:
        names = ', '.join(f'`{name}`' for name in dict.fromkeys(ignored))
        warning_parts.append(f'ignored unsupported settings: {names}')
    if conflicts:
        names = ', '.join(f'`{name}`' for name in dict.fromkeys(conflicts))
        warning_parts.append(f'used provider-specific settings instead of: {names}')
    if warning_parts:
        warnings.warn(f'{provider} image generation {"; ".join(warning_parts)}', UserWarning, stacklevel=stacklevel)