import logging
import os
from collections.abc import Mapping
from dataclasses import dataclass
from typing import Any, Protocol, cast

import httpx
from sqlalchemy import select

from app.core.errors import (
    DependencyUnavailableError,
    RecoverableAgentError,
    UpstreamTimeoutError,
)
from app.infrastructure.db import SessionFactory
from app.model.configuration import ModelEndpointConfig


class ModelGateway(Protocol):
    async def generate(self, *, endpoint_code: str, prompt: str, timeout_ms: int) -> str: ...

    async def embed(self, *, endpoint_code: str, text: str, timeout_ms: int) -> list[float]: ...


class EndpointSettings(Protocol):
    endpoint_code: str
    base_url: str
    model_name: str
    secret_ref: str


logger = logging.getLogger(__name__)


class EnvironmentSecretResolver:
    def resolve(self, secret_ref: str) -> str:
        if not secret_ref.startswith("env:"):
            raise RecoverableAgentError("模型密钥必须使用 env: 引用")
        name = secret_ref.removeprefix("env:")
        value = os.getenv(name)
        if not value:
            raise RecoverableAgentError("模型密钥未配置")
        return value


#: `task_type` → 端点必须具备的能力标签。
#:
#: 取值来自全仓实际调用点与**现库端点实际声明的能力**（实测：
#: `embedding-primary` = `["embedding"]`、`chat-primary` = `["chat"]`）：
#: `embedding`（向量化：`bootstrap.get_memory_embedding_service`、`knowledge_vector_worker`）、
#: `chat`（生成/复述合并：`customer_service`）、
#: `intent_classification`（`BaseAgent.classify_intent`）、
#: `memory_extraction` / `text_generation`（结构化文本生成）。
#:
#: ⚠️ `intent_classification` 必须映射到 `chat`，**不能**映射成同名的
#: `intent_classification`：现库没有任何端点声明该能力，同名映射会筛出空集，
#: 依赖"回退到全部端点"才不至于失败——那是把配置缺陷掩盖成巧合。
#: 未列入的 `task_type` 不做过滤（无法判断该要哪种能力），但会**告警留痕**（见 `resolve`）。
REQUIRED_CAPABILITY_BY_TASK_TYPE: dict[str, str] = {
    "embedding": "embedding",
    "chat": "chat",
    "intent_classification": "chat",
    "memory_extraction": "text_generation",
    # 风控的几处 task_type：它们要的都是"能生成文本"的端点，与 memory_extraction 同理。
    # 不登记就会落到"未映射 → 返回全部端点"的分支，而能否选到文本端点就取决于
    # `model_endpoint_config` 的**行顺序**——实测风控能跑通，仅仅因为 deepseek-flash(id=3)
    # 恰好排在 qwen-embedding(id=5) 前面。这种"靠数据顺序才对"的隐式依赖必须消掉。
    "risk_agent_chat": "text_generation",
    "risk_analysis": "text_generation",
    "risk_script": "text_generation",
    "risk_summary": "text_generation",
    "daily_report_suggestion": "text_generation",
    "text_generation": "text_generation",
}


class OpenAICompatibleGateway:
    """供应商无关的 Chat Completions Adapter；密钥只从 secret_ref 解析。"""

    def __init__(
        self,
        endpoints: Mapping[str, EndpointSettings],
        *,
        secret_resolver: EnvironmentSecretResolver | None = None,
        client: httpx.AsyncClient | None = None,
    ) -> None:
        self.endpoints = endpoints
        self.secret_resolver = secret_resolver or EnvironmentSecretResolver()
        self.client = client
        self._owns_client = client is None

    async def generate(self, *, endpoint_code: str, prompt: str, timeout_ms: int) -> str:
        endpoint = self.endpoints.get(endpoint_code)
        if endpoint is None:
            raise RecoverableAgentError("模型端点未注册")
        token = self.secret_resolver.resolve(endpoint.secret_ref)
        url = endpoint.base_url.rstrip("/") + "/chat/completions"
        payload = {
            "model": endpoint.model_name,
            "messages": [{"role": "user", "content": prompt}],
            "temperature": 0,
        }
        client = self.client or httpx.AsyncClient()
        try:
            response = await client.post(
                url,
                headers={"Authorization": f"Bearer {token}", "Content-Type": "application/json"},
                json=payload,
                timeout=httpx.Timeout(timeout_ms / 1000),
            )
            response.raise_for_status()
            body: Any = response.json()
            content = body.get("choices", [{}])[0].get("message", {}).get("content")
            if not isinstance(content, str) or not content.strip():
                raise DependencyUnavailableError("模型响应缺少文本")
            return content
        except httpx.TimeoutException as exc:
            raise UpstreamTimeoutError("模型端点调用超时") from exc
        except httpx.HTTPError as exc:
            raise DependencyUnavailableError("模型端点调用失败") from exc
        finally:
            if self._owns_client:
                await client.aclose()

    async def embed(self, *, endpoint_code: str, text: str, timeout_ms: int) -> list[float]:
        """OpenAI-compatible Embeddings Adapter；密钥同样只从 secret_ref 解析。"""
        endpoint = self.endpoints.get(endpoint_code)
        if endpoint is None:
            raise RecoverableAgentError("模型端点未注册")
        token = self.secret_resolver.resolve(endpoint.secret_ref)
        url = endpoint.base_url.rstrip("/") + "/embeddings"
        payload = {"model": endpoint.model_name, "input": text}
        client = self.client or httpx.AsyncClient()
        try:
            response = await client.post(
                url,
                headers={"Authorization": f"Bearer {token}", "Content-Type": "application/json"},
                json=payload,
                timeout=httpx.Timeout(timeout_ms / 1000),
            )
            response.raise_for_status()
            body: Any = response.json()
            vector = _first_embedding(body)
            if vector is None:
                raise DependencyUnavailableError("向量响应缺少 embedding")
            return vector
        except httpx.TimeoutException as exc:
            raise UpstreamTimeoutError("向量端点调用超时") from exc
        except httpx.HTTPError as exc:
            raise DependencyUnavailableError("向量端点调用失败") from exc
        finally:
            if self._owns_client:
                await client.aclose()


def _first_embedding(body: Any) -> list[float] | None:
    """取 OpenAI-compatible 响应的首条向量；结构不符时返回 None，由调用方失败关闭。"""
    data = body.get("data") if isinstance(body, dict) else None
    if not isinstance(data, list) or not data:
        return None
    entry = data[0]
    raw = entry.get("embedding") if isinstance(entry, dict) else None
    if not isinstance(raw, list) or not raw:
        return None
    try:
        return [float(value) for value in raw]
    except (TypeError, ValueError):
        return None


class DatabaseModelGateway:
    """从当前数据库端点配置动态构造已批准的 OpenAI-compatible Adapter。"""

    async def _endpoint(self, endpoint_code: str) -> ModelEndpointConfig:
        async with SessionFactory() as session:
            endpoint = await session.scalar(select(ModelEndpointConfig).where(
                ModelEndpointConfig.endpoint_code == endpoint_code,
                ModelEndpointConfig.status == "active",
            ))
        if endpoint is None:
            raise RecoverableAgentError("模型端点未注册或未激活")
        return endpoint

    async def generate(self, *, endpoint_code: str, prompt: str, timeout_ms: int) -> str:
        endpoint = await self._endpoint(endpoint_code)
        adapter = OpenAICompatibleGateway(
            {endpoint.endpoint_code: cast(EndpointSettings, endpoint)}
        )
        return await adapter.generate(
            endpoint_code=endpoint.endpoint_code, prompt=prompt, timeout_ms=timeout_ms
        )

    async def embed(self, *, endpoint_code: str, text: str, timeout_ms: int) -> list[float]:
        endpoint = await self._endpoint(endpoint_code)
        adapter = OpenAICompatibleGateway(
            {endpoint.endpoint_code: cast(EndpointSettings, endpoint)}
        )
        return await adapter.embed(
            endpoint_code=endpoint.endpoint_code, text=text, timeout_ms=timeout_ms
        )


#: 历史别名，指向上面的唯一映射表。保留名字是为了不破坏既有引用；
#: **两个名字不要各存一份内容**——那正是"修复被后续合并悄悄回退"的成因。
TASK_CAPABILITY = REQUIRED_CAPABILITY_BY_TASK_TYPE


class DatabaseModelEndpointResolver:
    """按 `task_type` 筛选当前已激活的模型端点。

    修复的缺陷：原实现 `del agent_type, task_type` 后返回**全部** active 端点，而
    `ModelDispatchService` 的 `generate`/`embed` 走的是**不同上游路径**
    （`/chat/completions` 与 `/embeddings`），且只按顺序尝试前 `max(1, max_attempts)`
    （默认 2）个。两者叠加的后果是「能不能选到支持该任务的端点」取决于端点在表里的顺序——
    实测表现为每次 embedding 都先拿文本生成端点失败一次再落到真正的向量端点，
    端点一多就会**耗尽尝试次数**直接失败。

    筛选策略保持保守：只在确实筛到端点时收窄；未映射的 task_type、以及「一个都没声明
    该能力」的配置缺口，都退回全部端点，让故障表现为**调用失败**而不是解析为空。
    """

    async def resolve(self, *, agent_type: str, task_type: str) -> list[ModelEndpointConfig]:
        del agent_type  # 按 agent_type 分配端点的路由仍由发布配置与 ModelRouterService 扩展。
        required = REQUIRED_CAPABILITY_BY_TASK_TYPE.get(task_type)
        async with SessionFactory() as session:
            endpoints = list(await session.scalars(select(ModelEndpointConfig).where(
                ModelEndpointConfig.status == "active"
            )))
        if required is None:
            # 未登记的 task_type 仍退回全部端点（保守策略：让故障表现为调用失败、
            # 而不是解析为空），但必须留下痕迹。静默退回会让"选端点靠表行顺序"这类问题
            # 在下游以"偶发调用失败"的形式冒出来，极难定位。
            logger.warning(
                "模型端点筛选：task_type=%r 未登记能力映射，退回全部 active 端点；"
                "请在 REQUIRED_CAPABILITY_BY_TASK_TYPE 中补上它对应的能力",
                task_type,
            )
            return endpoints
        matched = [
            endpoint for endpoint in endpoints
            if isinstance(endpoint.capabilities, list) and required in endpoint.capabilities
        ]
        # `capabilities` 为 NULL/空 的端点绝不会被 `matched` 选中（不能裸奔到错误的网关方法上）；
        # 但整批都没声明该能力时退回全部端点，避免把这个配置缺口伪装成"没有可用端点"。
        if required == "embedding" and len(matched) > 1:
            # 配置守卫：声明朝 `embedding` 能力的 active 端点应**恰好 1 个**。
            # 后端会按顺序只试前 `max(1, max_attempts)`（默认 2）个端点，端点一多就会被截断；
            # 更隐蔽的是模型混用——Milvus 集合里向量维度固定 1024，若两个端点背后的模型不同，
            # 写入向量与查询向量就不在同一个空间，`COSINE` 相似度会整体失真：
            # **不报错，只是越答越差**（这类故障最难定位）。这里只告警、不改行为。
            logger.warning(
                "模型端点筛选：active 端点中有 %d 个声明 embedding 能力（%s）；"
                "向量化端点应恰好 1 个——多端点会让索引向量与查询向量可能来自不同模型，"
                "相似度整体失真且不报错。请停用多余端点或去掉其 embedding 能力声明",
                len(matched),
                ", ".join(str(getattr(e, "endpoint_code", "?")) for e in matched),
            )
        return matched or endpoints


@dataclass(frozen=True)
class ModelExecution:
    endpoint_code: str
    text: str
    attempts: int
    degraded: bool = False


@dataclass(frozen=True)
class ModelEmbedding:
    endpoint_code: str
    vector: list[float]
    attempts: int
    degraded: bool = False


class ModelDispatchService:
    """Executes only router-approved endpoints and falls back in declared order."""

    def __init__(self, gateway: ModelGateway) -> None:
        self.gateway = gateway

    async def generate(
        self,
        endpoints: list[Any],
        prompt: str,
        *,
        max_attempts: int = 2,
    ) -> ModelExecution:
        last_error: Exception | None = None
        attempts = 0
        for endpoint in endpoints[: max(1, max_attempts)]:
            attempts += 1
            try:
                text = await self.gateway.generate(
                    endpoint_code=endpoint.endpoint_code,
                    prompt=prompt,
                    timeout_ms=endpoint.timeout_ms,
                )
                return ModelExecution(endpoint.endpoint_code, text, attempts, attempts > 1)
            except Exception as exc:
                last_error = exc
        raise RecoverableAgentError("所有已批准模型端点调用失败") from last_error

    async def embed(
        self, endpoints: list[Any], text: str, *, max_attempts: int = 2
    ) -> ModelEmbedding:
        """与文本生成同族的受控降级：按声明顺序尝试，成功即返回并标记是否降级。"""
        last_error: Exception | None = None
        attempts = 0
        for endpoint in endpoints[: max(1, max_attempts)]:
            attempts += 1
            try:
                vector = await self.gateway.embed(
                    endpoint_code=endpoint.endpoint_code,
                    text=text,
                    timeout_ms=endpoint.timeout_ms,
                )
                return ModelEmbedding(endpoint.endpoint_code, vector, attempts, attempts > 1)
            except Exception as exc:
                last_error = exc
        raise RecoverableAgentError("所有已批准向量端点调用失败") from last_error


class ModelGenerationService:
    """业务 Agent 的唯一模型生成入口。路由结果必须先由 ModelRouterService 给出。"""

    def __init__(self, dispatch: ModelDispatchService) -> None:
        self.dispatch = dispatch

    async def generate(
        self, endpoints: list[Any], prompt: str, *, max_attempts: int = 2
    ) -> ModelExecution:
        if not endpoints:
            raise RecoverableAgentError("没有可用的已批准模型端点")
        return await self.dispatch.generate(endpoints, prompt, max_attempts=max_attempts)


class ModelEmbeddingService:
    """文本向量化入口（记忆语义召回等只读用途），与生成同样必须先经过端点解析。"""

    def __init__(self, dispatch: ModelDispatchService) -> None:
        self.dispatch = dispatch

    async def embed(
        self, endpoints: list[Any], text: str, *, max_attempts: int = 2
    ) -> ModelEmbedding:
        if not endpoints:
            raise RecoverableAgentError("没有可用的已批准向量端点")
        return await self.dispatch.embed(endpoints, text, max_attempts=max_attempts)