"""
User-level settings: AI provider configuration.
"""
from __future__ import annotations

from fastapi import APIRouter, Depends, HTTPException
from pydantic import BaseModel
from sqlalchemy import update
from sqlalchemy.ext.asyncio import AsyncSession

from app.core.security import decrypt_field, encrypt_field
from app.dependencies import get_current_user, get_db
from app.db.models.user import User

router = APIRouter(prefix="/settings", tags=["settings"])

SUPPORTED_PROVIDERS = {"anthropic", "openai"}


class AiSettingsResponse(BaseModel):
    provider: str | None
    has_api_key: bool
    base_url: str | None
    model: str | None


class AiSettingsSave(BaseModel):
    provider: str
    api_key: str = ""
    base_url: str = ""
    model: str = ""


@router.get("/ai", response_model=AiSettingsResponse)
async def get_ai_settings(user: User = Depends(get_current_user)):
    return AiSettingsResponse(
        provider=user.ai_provider,
        has_api_key=bool(user.ai_api_key_enc),
        base_url=user.ai_base_url,
        model=user.ai_model,
    )


@router.put("/ai", response_model=AiSettingsResponse)
async def save_ai_settings(
    body: AiSettingsSave,
    db: AsyncSession = Depends(get_db),
    user: User = Depends(get_current_user),
):
    if body.provider not in SUPPORTED_PROVIDERS:
        raise HTTPException(status_code=400, detail=f"Unsupported provider. Choose: {', '.join(SUPPORTED_PROVIDERS)}")

    values: dict = {
        "ai_provider": body.provider,
        "ai_base_url": body.base_url.rstrip("/") or None,
        "ai_model": body.model.strip() or None,
    }

    if body.api_key.strip():
        values["ai_api_key_enc"] = encrypt_field(body.api_key.strip())
    elif not user.ai_api_key_enc:
        raise HTTPException(status_code=400, detail="api_key is required when no key is saved yet")

    await db.execute(update(User).where(User.id == user.id).values(**values))
    await db.commit()
    return AiSettingsResponse(
        provider=body.provider,
        has_api_key=True,
        base_url=values["ai_base_url"],
        model=values["ai_model"],
    )


_STATUS_MEANINGS = {
    400: "Bad request — the model name may be invalid or the request format is unsupported.",
    401: "Unauthorised — your API key is incorrect or has been revoked.",
    403: "Forbidden — your API key doesn't have permission to use this model or endpoint.",
    404: "Not found — the API URL path is wrong. Check your custom URL doesn't include /v1 (MyMidas adds it automatically).",
    405: "Method not allowed — the API URL is pointing at the wrong place. For Open WebUI, the base URL should be just http://host:port with no path suffix.",
    422: "Unprocessable — the model name was rejected. Check it matches exactly what the provider expects.",
    429: "Rate limited — too many requests. Try again in a moment.",
    500: "Server error — the AI provider returned an internal error.",
    502: "Bad gateway — could not reach the AI provider. Check the URL is correct and the service is running.",
    503: "Service unavailable — the AI provider is down or overloaded.",
}


@router.post("/ai/test")
async def test_ai_settings(
    db: AsyncSession = Depends(get_db),
    user: User = Depends(get_current_user),
):
    """Send a minimal test prompt to verify the configured AI provider works."""
    import httpx
    from sqlalchemy import select as sa_select

    user_row = await db.get(User, user.id)
    if not user_row or not user_row.ai_provider or not user_row.ai_api_key_enc:
        return {"ok": False, "message": "No AI provider configured. Save your settings first."}

    api_key = decrypt_field(user_row.ai_api_key_enc)
    custom_base_url = (user_row.ai_base_url or "").rstrip("/")
    custom_model = (user_row.ai_model or "").strip()
    test_prompt = "Reply with the single word: OK"

    try:
        if user_row.ai_provider == "anthropic":
            base_url = custom_base_url or "https://api.anthropic.com"
            model = custom_model or "claude-haiku-4-5-20251001"
            async with httpx.AsyncClient(timeout=15) as client:
                resp = await client.post(
                    f"{base_url}/v1/messages",
                    headers={"x-api-key": api_key, "anthropic-version": "2023-06-01", "content-type": "application/json"},
                    json={"model": model, "max_tokens": 10, "messages": [{"role": "user", "content": test_prompt}]},
                )
            resp.raise_for_status()
            reply = resp.json()["content"][0]["text"].strip()

        elif user_row.ai_provider == "openai":
            base_url = custom_base_url or "https://api.openai.com"
            model = custom_model or "gpt-4o-mini"
            async with httpx.AsyncClient(timeout=15) as client:
                resp = await client.post(
                    f"{base_url}/v1/chat/completions",
                    headers={"Authorization": f"Bearer {api_key}", "content-type": "application/json"},
                    json={"model": model, "max_tokens": 10, "messages": [{"role": "user", "content": test_prompt}]},
                )
            resp.raise_for_status()
            reply = resp.json()["choices"][0]["message"]["content"].strip()

        else:
            return {"ok": False, "message": "Unknown provider."}

        return {"ok": True, "message": f'Connection successful. Model replied: "{reply}"'}

    except httpx.HTTPStatusError as e:
        code = e.response.status_code
        meaning = _STATUS_MEANINGS.get(code, f"HTTP {code} error.")
        return {"ok": False, "message": f"HTTP {code}: {meaning}"}
    except httpx.ConnectError:
        return {"ok": False, "message": "Connection refused — the URL is unreachable. Check the host and port are correct and the service is running."}
    except httpx.TimeoutException:
        return {"ok": False, "message": "Request timed out — the server didn't respond within 15 seconds."}
    except httpx.RequestError as e:
        return {"ok": False, "message": f"Network error: {e}"}


@router.delete("/ai", status_code=204)
async def clear_ai_settings(
    db: AsyncSession = Depends(get_db),
    user: User = Depends(get_current_user),
):
    await db.execute(
        update(User)
        .where(User.id == user.id)
        .values(ai_provider=None, ai_api_key_enc=None, ai_base_url=None, ai_model=None)
    )
    await db.commit()