"""Pydantic models for bulkgen YAML configuration."""

from __future__ import annotations

import enum
from pathlib import Path
from typing import Self

import yaml
from pydantic import BaseModel, model_validator

from bulkgen.providers.models import Capability

IMAGE_EXTENSIONS: frozenset[str] = frozenset({".png", ".jpg", ".jpeg", ".webp"})
TEXT_EXTENSIONS: frozenset[str] = frozenset({".md", ".txt"})


class TargetType(enum.Enum):
    """The kind of artifact a target produces."""

    IMAGE = "image"
    TEXT = "text"


class Defaults(BaseModel):
    """Default model names, applied when a target does not specify its own."""

    text_model: str = "pixtral-large-latest"
    image_model: str = "flux-2-pro"


class TargetConfig(BaseModel):
    """Configuration for a single build target."""

    prompt: str
    model: str | None = None
    inputs: list[str] = []
    reference_images: list[str] = []
    control_images: list[str] = []
    width: int | None = None
    height: int | None = None


class ProjectConfig(BaseModel):
    """Top-level configuration parsed from ``<name>.bulkgen.yaml``."""

    defaults: Defaults = Defaults()
    targets: dict[str, TargetConfig]

    @model_validator(mode="after")
    def _validate_non_empty_targets(self) -> Self:
        if not self.targets:
            msg = "At least one target must be defined"
            raise ValueError(msg)
        return self


def target_type_from_capabilities(capabilities: frozenset[Capability]) -> TargetType:
    """Derive the target type from a set of required capabilities."""
    from bulkgen.providers.models import Capability

    if Capability.TEXT_TO_IMAGE in capabilities:
        return TargetType.IMAGE
    return TargetType.TEXT


def load_config(config_path: Path) -> ProjectConfig:
    """Load and validate a ``.bulkgen.yaml`` file."""
    with config_path.open() as f:
        raw = yaml.safe_load(f)  # pyright: ignore[reportAny]
    return ProjectConfig.model_validate(raw)