"""Provider routing with failover - 基于适配器注册表的智能路由。"""

import time
from enum import Enum
from typing import TYPE_CHECKING, Literal, TypeVar

from sqlalchemy.ext.asyncio import AsyncSession

from app.core.config import settings
from app.core.logging import get_logger
from app.services.adapters import AdapterConfig, AdapterRegistry
from app.services.adapters.text.models import StoryOutput
from app.services.cost_tracker import cost_tracker
from app.services.provider_cache import get_providers
from app.services.provider_metrics import health_checker, metrics_collector

if TYPE_CHECKING:
    from app.db.admin_models import Provider

logger = get_logger(__name__)

T = TypeVar("T")

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


class RoutingStrategy(str, Enum):
    """路由策略枚举。"""

    PRIORITY = "priority"  # 按优先级排序（默认）
    COST = "cost"  # 按成本排序
    LATENCY = "latency"  # 按延迟排序
    ROUND_ROBIN = "round_robin"  # 轮询


# 默认配置映射（当 DB 无配置时使用）
# 默认配置映射（当 DB 无配置时使用）
# 这是“代码级”的默认策略，对应 .env 为空的情况
DEFAULT_PROVIDERS: dict[ProviderType, list[str]] = {
    "text": ["gemini", "openai"],
    "image": ["cqtai"],
    "tts": ["minimax", "elevenlabs", "edge_tts"],
    "storybook": ["gemini"],
}

# API Key 映射：adapter_name -> settings 属性名
API_KEY_MAP: dict[str, str] = {
    # Text
    "gemini": "text_api_key",       # Gemini 还是复用 text_api_key 字段
    "text_primary": "text_api_key", # 兼容旧别名
    "openai": "openai_api_key",

    # Image
    "cqtai": "cqtai_api_key",
    "image_primary": "image_api_key", # 兼容旧别名

    # TTS
    "minimax": "minimax_api_key",
    "elevenlabs": "elevenlabs_api_key",
    "edge_tts": "tts_api_key",      # EdgeTTS 复用 tts_api_key (通常为空)
    "tts_primary": "tts_api_key",   # 兼容旧别名
}

# 轮询计数器
_round_robin_counters: dict[ProviderType, int] = {
    "text": 0,
    "image": 0,
    "tts": 0,
}

# 延迟缓存（内存中，简化实现）
_latency_cache: dict[str, float] = {}


def _get_api_key(config_ref: str | None, adapter_name: str) -> str:
    """根据 config_ref 或适配器名称获取 API Key。"""
    # 优先使用 config_ref
    key_attr = API_KEY_MAP.get(config_ref or adapter_name, None)
    if key_attr:
        return getattr(settings, key_attr, "")
    # 回退到适配器名称
    key_attr = API_KEY_MAP.get(adapter_name, None)
    if key_attr:
        return getattr(settings, key_attr, "")
    return ""


def _get_default_config(adapter_name: str) -> AdapterConfig | None:
    """获取适配器的默认配置（无 DB 记录时使用）。返回 None 表示未知适配器。"""

    # --- Text Defaults ---
    if adapter_name in ("gemini", "text_primary"):
        return AdapterConfig(
            api_key=settings.text_api_key,
            model=settings.text_model or "gemini-2.0-flash",
            timeout_ms=60000,
        )
    if adapter_name == "openai":
        return AdapterConfig(
            api_key=getattr(settings, "openai_api_key", ""),
            model="gpt-4o-mini", # 这里可以从 settings 读取，看需求
            timeout_ms=60000,
        )

    # --- Image Defaults ---
    if adapter_name in ("cqtai"):
        return AdapterConfig(
            api_key=getattr(settings, "cqtai_api_key", ""),
            model="nano-banana-pro", # 默认使用 Pro
            timeout_ms=120000,
        )
    if adapter_name == "image_primary":
        # 如果还有地方在用 image_primary，暂时映射到快或者其他
        # 但既然我们全面整改，最好也删了。这里暂时保留一个空的 fallback 以防报错
        return AdapterConfig(
             api_key=settings.image_api_key,
             timeout_ms=120000
        )

    # --- TTS Defaults ---
    if adapter_name == "minimax":
        # 传递 group_id 到 Adapter
        # 目前 AdapterConfig 没有 group_id 字段，我们暂时不改 Base，
        # 而是假设 Adapter 会从 config (通过 kwargs 或其他方式) 拿。
        # 实际上我们的 MiniMaxTTSAdapter 还没有处理 group_id。
        # 最简单的方法：把 group_id 藏在 api_base 里或者让 Adapter 自己去 settings 拿。
        # 鉴于 _build_config_from_provider 里我们无法传递额外参数给 Adapter.__init__，
        # 我们这里暂时返回基础配置。
        return AdapterConfig(
            api_key=getattr(settings, "minimax_api_key", ""),
            model="speech-2.6-turbo",
            timeout_ms=60000,
        )

    if adapter_name == "elevenlabs":
        return AdapterConfig(
            api_key=getattr(settings, "elevenlabs_api_key", ""),
            timeout_ms=120000,
        )
    if adapter_name in ("edge_tts", "tts_primary"):
        return AdapterConfig(
            api_key=settings.tts_api_key,
            api_base=settings.tts_api_base,
            model=settings.tts_model or "zh-CN-XiaoxiaoNeural",
            timeout_ms=120000,
        )

    # --- Others ---
    if adapter_name in ("storybook_primary", "storybook_gemini"):
        return AdapterConfig(
            api_key=settings.text_api_key,  # 复用 Gemini key
            model=settings.text_model,
            timeout_ms=120000,
        )

    # 未知适配器返回 None
    return None


def _build_config_from_provider(provider: "Provider") -> AdapterConfig:
    """从 DB Provider 记录构建 AdapterConfig。"""
    api_key = getattr(provider, "api_key", None) or ""
    if not api_key:
        api_key = _get_api_key(provider.config_ref, provider.adapter)

    default = _get_default_config(provider.adapter)
    if default is None:
        default = AdapterConfig(api_key="", timeout_ms=60000)

    return AdapterConfig(
        api_key=api_key or default.api_key,
        api_base=provider.api_base or default.api_base,
        model=provider.model or default.model,
        timeout_ms=provider.timeout_ms or default.timeout_ms,
        max_retries=provider.max_retries or default.max_retries,
        extra_config=provider.config_json or {},
    )


async def _get_providers_with_config(
    provider_type: ProviderType,
) -> list[tuple[str, AdapterConfig, "Provider | None"]]:
    """获取供应商列表及其配置。

    Returns:
        [(adapter_name, config, provider_or_none), ...] 按优先级排序
    """
    db_providers = await get_providers(provider_type)

    if db_providers:
        return [(p.adapter, _build_config_from_provider(p), p) for p in db_providers]

    settings_map = {
        "text": settings.text_providers,
        "image": settings.image_providers,
        "tts": settings.tts_providers,
    }
    names = settings_map.get(provider_type) or DEFAULT_PROVIDERS[provider_type]
    result = []
    for name in names:
        config = _get_default_config(name)
        if config is None:
            logger.warning("unknown_adapter_skipped", adapter=name, provider_type=provider_type)
            continue
        result.append((name, config, None))
    return result


def _sort_by_strategy(
    providers: list[tuple[str, AdapterConfig, "Provider | None"]],
    strategy: RoutingStrategy,
    provider_type: ProviderType,
) -> list[tuple[str, AdapterConfig, "Provider | None"]]:
    """按策略排序供应商列表。"""
    if strategy == RoutingStrategy.PRIORITY:
        # 按 priority 降序, weight 降序
        return sorted(
            providers,
            key=lambda x: (-(x[2].priority if x[2] else 0), -(x[2].weight if x[2] else 1)),
        )

    if strategy == RoutingStrategy.COST:
        # 按预估成本升序
        def get_cost(item: tuple[str, AdapterConfig, "Provider | None"]) -> float:
            adapter_class = AdapterRegistry.get(provider_type, item[0])
            if adapter_class:
                try:
                    adapter = adapter_class(item[1])
                    return adapter.estimated_cost
                except Exception:
                    pass
            return float("inf")

        return sorted(providers, key=get_cost)

    if strategy == RoutingStrategy.LATENCY:
        # 按历史延迟升序
        def get_latency(item: tuple[str, AdapterConfig, "Provider | None"]) -> float:
            return _latency_cache.get(item[0], float("inf"))

        return sorted(providers, key=get_latency)

    if strategy == RoutingStrategy.ROUND_ROBIN:
        # 轮询：旋转列表
        counter = _round_robin_counters[provider_type]
        _round_robin_counters[provider_type] = (counter + 1) % max(len(providers), 1)
        return providers[counter:] + providers[:counter]

    return providers


async def _route_with_failover(
    provider_type: ProviderType,
    strategy: RoutingStrategy = RoutingStrategy.PRIORITY,
    db: AsyncSession | None = None,
    user_id: str | None = None,
    **kwargs,
) -> T:
    """通用 provider failover 路由。

    Args:
        provider_type: 供应商类型 (text/image/tts/storybook)
        strategy: 路由策略
        db: 数据库会话（可选，用于指标收集和熔断检查）
        user_id: 用户 ID（可选，用于成本追踪和预算检查）
        **kwargs: 传递给适配器的参数
    """
    providers = await _get_providers_with_config(provider_type)

    if not providers:
        raise ValueError(f"No {provider_type} providers configured.")

    # 按策略排序
    sorted_providers = _sort_by_strategy(providers, strategy, provider_type)

    # 如果有 db 会话，过滤掉熔断的供应商
    if db:
        healthy_providers = []
        for item in sorted_providers:
            name, config, db_provider = item
            provider_id = db_provider.id if db_provider else name
            if await health_checker.is_healthy(db, provider_id):
                healthy_providers.append(item)
            else:
                logger.debug("provider_circuit_open", adapter=name, provider_id=provider_id)
        # 如果所有供应商都熔断，仍然尝试第一个（允许恢复）
        if not healthy_providers:
            healthy_providers = sorted_providers[:1]
        sorted_providers = healthy_providers

    errors: list[str] = []
    for name, config, db_provider in sorted_providers:
        adapter_class = AdapterRegistry.get(provider_type, name)
        if not adapter_class:
            errors.append(f"{name}: 适配器未注册")
            continue

        provider_id = db_provider.id if db_provider else name

        try:
            logger.debug(
                "provider_attempt",
                provider_type=provider_type,
                adapter=name,
                strategy=strategy.value,
            )

            adapter = adapter_class(config)

            # 执行并计时
            start_time = time.time()
            result = await adapter.execute(**kwargs)
            latency_ms = int((time.time() - start_time) * 1000)

            # 更新延迟缓存
            _latency_cache[name] = latency_ms

            # 记录成功指标
            if db:
                await metrics_collector.record_call(
                    db,
                    provider_id=provider_id,
                    success=True,
                    latency_ms=latency_ms,
                    cost_usd=adapter.estimated_cost,
                )
                await health_checker.record_call_result(db, provider_id, success=True)

                # 记录用户成本
                if user_id:
                    await cost_tracker.record_cost(
                        db,
                        user_id=user_id,
                        provider_name=name,
                        capability=provider_type,
                        estimated_cost=adapter.estimated_cost,
                        provider_id=provider_id if db_provider else None,
                    )

            logger.info(
                "provider_success",
                provider_type=provider_type,
                adapter=name,
                latency_ms=latency_ms,
            )
            return result

        except Exception as exc:
            error_msg = str(exc)
            logger.warning(
                "provider_failed",
                provider_type=provider_type,
                adapter=name,
                error=error_msg,
            )
            errors.append(f"{name}: {exc}")

            # 记录失败指标
            if db:
                await metrics_collector.record_call(
                    db,
                    provider_id=provider_id,
                    success=False,
                    error_message=error_msg,
                )
                await health_checker.record_call_result(
                    db, provider_id, success=False, error=error_msg
                )

    raise ValueError(f"No {provider_type} provider succeeded. Errors: {' | '.join(errors)}")


async def generate_story_content(
    input_type: Literal["keywords", "full_story"],
    data: str,
    education_theme: str | None = None,
    memory_context: str | None = None,
    strategy: RoutingStrategy = RoutingStrategy.PRIORITY,
    db: AsyncSession | None = None,
) -> StoryOutput:
    """生成或润色故事，支持 failover。"""
    return await _route_with_failover(
        "text",
        strategy=strategy,
        db=db,
        input_type=input_type,
        data=data,
        education_theme=education_theme,
        memory_context=memory_context,
    )


async def generate_image(
    prompt: str,
    strategy: RoutingStrategy = RoutingStrategy.PRIORITY,
    db: AsyncSession | None = None,
    **kwargs,
) -> str:
    """生成图片，返回 URL，支持 failover。"""
    return await _route_with_failover("image", strategy=strategy, db=db, prompt=prompt, **kwargs)


async def text_to_speech(
    text: str,
    strategy: RoutingStrategy = RoutingStrategy.PRIORITY,
    db: AsyncSession | None = None,
) -> bytes:
    """文本转语音，返回 MP3 bytes，支持 failover。"""
    return await _route_with_failover("tts", strategy=strategy, db=db, text=text)


async def generate_storybook(
    keywords: str,
    page_count: int = 6,
    education_theme: str | None = None,
    memory_context: str | None = None,
    strategy: RoutingStrategy = RoutingStrategy.PRIORITY,
    db: AsyncSession | None = None,
):
    """生成分页故事书，支持 failover。"""
    from app.services.adapters.storybook.primary import Storybook

    result: Storybook = await _route_with_failover(
        "storybook",
        strategy=strategy,
        db=db,
        keywords=keywords,
        page_count=page_count,
        education_theme=education_theme,
        memory_context=memory_context,
    )
    return result