"""Provider boundary for local and future model backends."""

from __future__ import annotations

import json
import os
from collections.abc import AsyncIterator
from typing import Any, Protocol

import httpx
from fastapi import HTTPException


class ModelProvider(Protocol):
    name: str
    default_model: str
    base_url: str

    def prepare_payload(self, payload: dict[str, Any]) -> dict[str, Any]: ...

    async def complete(
        self, payload: dict[str, Any], *, timeout_seconds: float = 180.0
    ) -> dict[str, Any]: ...

    async def stream(
        self, payload: dict[str, Any]
    ) -> AsyncIterator[dict[str, Any]]: ...

    async def list_models(self) -> list[str]: ...


class OllamaProvider:
    name = "ollama"

    def __init__(self, base_url: str, default_model: str) -> None:
        self.base_url = base_url.rstrip("/")
        self.default_model = default_model

    def prepare_payload(self, payload: dict[str, Any]) -> dict[str, Any]:
        prepared = dict(payload)
        model = str(prepared.get("model", self.default_model))
        prepared.setdefault("model", model)
        # Gemma 4 via Ollama otherwise returns its reasoning in a separate field.
        if model.lower().startswith("gemma4"):
            prepared.setdefault("reasoning_effort", "none")
        return prepared

    async def complete(
        self, payload: dict[str, Any], *, timeout_seconds: float = 180.0
    ) -> dict[str, Any]:
        try:
            async with httpx.AsyncClient(timeout=timeout_seconds) as client:
                response = await client.post(
                    f"{self.base_url}/chat/completions",
                    json=self.prepare_payload(payload),
                )
                response.raise_for_status()
                return response.json()
        except httpx.HTTPStatusError as exc:
            detail = exc.response.text[:400] or "رفض خادم النموذج الطلب."
            raise HTTPException(
                status_code=502,
                detail=f"خطأ من خادم النموذج المحلي: {detail}",
            ) from exc
        except httpx.RequestError as exc:
            raise HTTPException(
                status_code=503,
                detail="تعذر الاتصال بـ Ollama المحلي على العنوان المضبوط.",
            ) from exc
        except ValueError as exc:
            raise HTTPException(
                status_code=502, detail="أعاد Ollama استجابة JSON غير صالحة."
            ) from exc

    async def stream(
        self, payload: dict[str, Any]
    ) -> AsyncIterator[dict[str, Any]]:
        try:
            timeout = httpx.Timeout(connect=15.0, read=None, write=30.0, pool=30.0)
            async with httpx.AsyncClient(timeout=timeout) as client:
                async with client.stream(
                    "POST",
                    f"{self.base_url}/chat/completions",
                    json=self.prepare_payload(payload),
                ) as response:
                    if response.status_code >= 400:
                        detail = (await response.aread()).decode("utf-8", "replace")[:400]
                        yield {"error": f"Ollama {response.status_code}: {detail}"}
                        return
                    async for line in response.aiter_lines():
                        if not line.startswith("data:"):
                            continue
                        raw = line[5:].strip()
                        if raw == "[DONE]":
                            yield {"done": True}
                            return
                        try:
                            event = json.loads(raw)
                            delta = event["choices"][0].get("delta", {}).get("content")
                        except (ValueError, KeyError, IndexError, TypeError):
                            continue
                        if delta:
                            yield {"delta": delta}
                    yield {"done": True}
        except httpx.RequestError:
            yield {"error": "تعذر الاتصال بـ Ollama المحلي."}

    async def list_models(self) -> list[str]:
        ollama_base = (
            self.base_url[:-3] if self.base_url.endswith("/v1") else self.base_url
        )
        try:
            async with httpx.AsyncClient(timeout=10.0) as client:
                response = await client.get(f"{ollama_base}/api/tags")
                response.raise_for_status()
                payload = response.json()
        except (httpx.HTTPError, ValueError) as exc:
            raise HTTPException(
                status_code=503,
                detail="تعذر جلب قائمة النماذج من Ollama المحلي.",
            ) from exc
        return [
            item["name"]
            for item in payload.get("models", [])
            if isinstance(item, dict) and item.get("name")
        ]


def get_model_provider() -> ModelProvider:
    provider_name = os.getenv("MODEL_PROVIDER", "ollama").strip().lower()
    if provider_name != "ollama":
        raise HTTPException(
            status_code=503,
            detail=f"مزوّد النموذج '{provider_name}' غير مدعوم حاليًا.",
        )
    return OllamaProvider(
        base_url=os.getenv("LOCAL_LLM_BASE_URL", "http://127.0.0.1:11434/v1"),
        default_model=os.getenv("LOCAL_MODEL", "gemma4:e2b"),
    )