"""
FastAPI server for Local RAG with chat GUI.
Run with: uvicorn server:app --reload
"""
from pathlib import Path

from fastapi import FastAPI, HTTPException
from fastapi.responses import HTMLResponse
from pydantic import BaseModel

from local_rag import LocalRAG

# Initialize RAG once at startup
VECTORSTORE_PATH = "./vectorstore"
OLLAMA_MODEL = "mistral:7b"
rag = LocalRAG(vectorstore_path=VECTORSTORE_PATH, ollama_model=OLLAMA_MODEL)

app = FastAPI(title="Local RAG Chat", version="1.0.0")


class ChatRequest(BaseModel):
    message: str


class ChatResponse(BaseModel):
    answer: str
    error: str | None = None


@app.get("/", response_class=HTMLResponse)
def chat_view():
    """Serve the chat GUI."""
    html_path = Path(__file__).parent / "templates" / "chat.html"
    if not html_path.exists():
        raise HTTPException(status_code=500, detail="Chat template not found")
    return HTMLResponse(content=html_path.read_text(encoding="utf-8"))


@app.post("/api/chat", response_model=ChatResponse)
def chat(request: ChatRequest):
    """Handle a chat message and return the RAG answer."""
    if not request.message or not request.message.strip():
        return ChatResponse(answer="", error="Message cannot be empty")
    try:
        answer = rag.query(request.message.strip())
        return ChatResponse(answer=answer)
    except Exception as e:
        return ChatResponse(answer="", error=str(e))


@app.get("/api/health")
def health():
    """Health check and vector store status."""
    has_docs = rag.vectorstore is not None
    return {"status": "ok", "vectorstore_loaded": has_docs}


if __name__ == "__main__":
    import uvicorn
    uvicorn.run(app, host="0.0.0.0", port=8000)