"""Provider capability and routing policy definitions."""

from dataclasses import dataclass
from enum import Enum
from typing import Literal, Protocol, TypeAlias

ProviderType: TypeAlias = Literal["text", "image", "tts", "storybook"]


class RoutingStrategy(str, Enum):
    """How providers should be ordered before failover execution."""

    PRIORITY = "priority"
    COST = "cost"
    LATENCY = "latency"
    ROUND_ROBIN = "round_robin"


@dataclass(frozen=True)
class CapabilityPolicy:
    """Product-level capability policy for one provider family."""

    capability: ProviderType
    label: str
    description: str
    settings_attr: str
    default_providers: tuple[str, ...]
    default_strategy: RoutingStrategy = RoutingStrategy.PRIORITY
    demo_provider: str | None = None


class ProviderSettings(Protocol):
    """Settings fields required by provider policy resolution."""

    text_providers: list[str]
    image_providers: list[str]
    tts_providers: list[str]
    storybook_providers: list[str]
    enable_demo_providers: bool


CAPABILITY_POLICIES: dict[ProviderType, CapabilityPolicy] = {
    "text": CapabilityPolicy(
        capability="text",
        label="文本生成",
        description="生成或润色儿童故事文本。",
        settings_attr="text_providers",
        default_providers=("gemini", "openai"),
        demo_provider="demo",
    ),
    "image": CapabilityPolicy(
        capability="image",
        label="图片生成",
        description="生成故事封面或绘本插图。",
        settings_attr="image_providers",
        default_providers=("cqtai",),
        demo_provider="demo",
    ),
    "tts": CapabilityPolicy(
        capability="tts",
        label="语音合成",
        description="将故事文本合成为可播放音频。",
        settings_attr="tts_providers",
        default_providers=("minimax", "elevenlabs", "edge_tts"),
    ),
    "storybook": CapabilityPolicy(
        capability="storybook",
        label="绘本结构生成",
        description="生成多页绘本结构、分镜文本和插图提示词。",
        settings_attr="storybook_providers",
        default_providers=("storybook_primary",),
        demo_provider="demo",
    ),
}


DEFAULT_PROVIDERS: dict[ProviderType, list[str]] = {
    capability: list(policy.default_providers)
    for capability, policy in CAPABILITY_POLICIES.items()
}


API_KEY_MAP: dict[str, str] = {
    # Text
    "gemini": "text_api_key",
    "text_primary": "text_api_key",
    "text_api_key": "text_api_key",
    "openai": "openai_api_key",
    "openai_api_key": "openai_api_key",
    # Image
    "cqtai": "cqtai_api_key",
    "cqtai_api_key": "cqtai_api_key",
    "antigravity": "antigravity_api_key",
    "antigravity_api_key": "antigravity_api_key",
    "image_primary": "image_api_key",
    "image_api_key": "image_api_key",
    # TTS
    "minimax": "minimax_api_key",
    "minimax_api_key": "minimax_api_key",
    "elevenlabs": "elevenlabs_api_key",
    "elevenlabs_api_key": "elevenlabs_api_key",
    "edge_tts": "tts_api_key",
    "tts_primary": "tts_api_key",
    "tts_api_key": "tts_api_key",
}


def get_capability_policy(capability: ProviderType) -> CapabilityPolicy:
    """Return the product policy for a provider capability."""

    return CAPABILITY_POLICIES[capability]


def get_provider_names_from_settings(
    capability: ProviderType,
    settings: ProviderSettings,
) -> list[str]:
    """Resolve provider order from settings, falling back to capability defaults."""

    policy = get_capability_policy(capability)
    configured = getattr(settings, policy.settings_attr, None)
    names = list(configured or policy.default_providers)

    if (
        settings.enable_demo_providers
        and policy.demo_provider
        and policy.demo_provider not in names
    ):
        names = [policy.demo_provider, *names]

    return names


def list_capability_policies() -> list[dict[str, object]]:
    """Return a serializable capability policy overview for admin/docs use."""

    return [
        {
            "capability": policy.capability,
            "label": policy.label,
            "description": policy.description,
            "settings_attr": policy.settings_attr,
            "default_providers": list(policy.default_providers),
            "default_strategy": policy.default_strategy.value,
            "demo_provider": policy.demo_provider,
        }
        for policy in CAPABILITY_POLICIES.values()
    ]