initial commit

backend/main.py

@@ -0,0 +1,137 @@
+from fastapi import FastAPI, Depends, HTTPException
+from fastapi.middleware.cors import CORSMiddleware
+from sqlalchemy.orm import Session
+from typing import List
+from . import models, schemas
+from .database import Base, engine, SessionLocal
+from .ollama_client import list_models as ollama_list, chat as ollama_chat
+
+# Create tables
+Base.metadata.create_all(bind=engine)
+
+app = FastAPI(title="LLM Desktop Backend", version="0.1.0" )
+
+# CORS (dev-friendly; tighten later)
+app.add_middleware(
+    CORSMiddleware,
+    allow_origins=["*"],
+    allow_credentials=True,
+    allow_methods=["*"],
+    allow_headers=["*"],
+)
+
+def get_db():
+    db = SessionLocal()
+    try:
+        yield db
+    finally:
+        db.close()
+
+@app.get("/health")
+def health():
+    return {"ok": True}
+
+@app.get("/models")
+async def get_models():
+    try:
+        data = await ollama_list()
+        return {"models": [{"name": n} for n in data.get("models", [])]}
+    except Exception as e:
+        raise HTTPException(status_code=502, detail=f"Ollama not available: {e}")
+
+@app.get("/sessions", response_model=schemas.SessionsResponse)
+def get_sessions(db: Session = Depends(get_db)):
+    sessions = db.query(models.ChatSession).order_by(models.ChatSession.created_at.desc()).all()
+    return {"sessions": sessions}
+
+@app.post("/sessions", response_model=schemas.ChatSession)
+def create_session(req: schemas.CreateSessionRequest, db: Session = Depends(get_db)):
+    new_session = models.ChatSession(session_id=req.session_id)
+    db.add(new_session)
+    db.commit()
+    db.refresh(new_session)
+    return new_session
+
+@app.get("/history", response_model=schemas.HistoryResponse)
+def history(session_id: str, db: Session = Depends(get_db)):
+    session = db.query(models.ChatSession).filter(models.ChatSession.session_id == session_id).first()
+    if not session:
+        return {"messages": []}
+    rows = db.query(models.ChatMessage)             .filter(models.ChatMessage.session_pk == session.id)             .order_by(models.ChatMessage.created_at.asc())             .all()
+    msgs = [{"role": r.role, "content": r.content} for r in rows]
+    return {"messages": msgs}
+
+@app.post("/chat", response_model=schemas.ChatResponse)
+async def chat(req: schemas.ChatRequest, db: Session = Depends(get_db)):
+    # Find or create session
+    session = db.query(models.ChatSession).filter(models.ChatSession.session_id == req.session_id).first()
+    if not session:
+        session = models.ChatSession(session_id=req.session_id)
+        db.add(session)
+        db.commit()
+        db.refresh(session)
+
+    # Save user message
+    user_row = models.ChatMessage(session_pk=session.id, role='user', content=req.message)
+    db.add(user_row)
+    db.commit()
+
+    # Build minimal conversation context (last 20 messages)
+    last_msgs = db.query(models.ChatMessage)        .filter(models.ChatMessage.session_pk == session.id)        .order_by(models.ChatMessage.created_at.asc())        .all()[-20:]
+
+    messages = [{"role": m.role, "content": m.content} for m in last_msgs]
+
+    try:
+        reply = await ollama_chat(req.model, messages)
+    except Exception as e:
+        raise HTTPException(status_code=502, detail=f"Ollama error: {e}")
+
+    # Save assistant reply
+    as_row = models.ChatMessage(session_pk=session.id, role='assistant', content=reply)
+    db.add(as_row)
+    db.commit()
+
+    return {"reply": reply}
+
+@app.post("/generate-title", response_model=schemas.GenerateTitleResponse)
+async def generate_title(req: schemas.GenerateTitleRequest, db: Session = Depends(get_db)):
+    session = db.query(models.ChatSession).filter(models.ChatSession.session_id == req.session_id).first()
+    if not session:
+        raise HTTPException(status_code=404, detail="Session not found")
+
+    prompt = f"Generate a very short, concise title (5 words or less) for a chat conversation that begins with this user message: \"{req.message}\". Do not use quotation marks in the title."
+    
+    try:
+        title = await ollama_chat("llama3", [{"role": "user", "content": prompt}])
+    except Exception as e:
+        raise HTTPException(status_code=502, detail=f"Ollama error: {e}")
+
+    session.name = title
+    db.commit()
+
+    return {"title": title}
+
+@app.delete("/sessions/{session_id}")
+def delete_session(session_id: str, db: Session = Depends(get_db)):
+    session = db.query(models.ChatSession).filter(models.ChatSession.session_id == session_id).first()
+    if not session:
+        raise HTTPException(status_code=404, detail="Session not found")
+
+    # Delete associated messages
+    db.query(models.ChatMessage).filter(models.ChatMessage.session_pk == session.id).delete()
+    
+    db.delete(session)
+    db.commit()
+    return {"ok": True}
+
+@app.put("/sessions/{session_id}/rename")
+def rename_session(session_id: str, req: schemas.GenerateTitleResponse, db: Session = Depends(get_db)):
+    session = db.query(models.ChatSession).filter(models.ChatSession.session_id == session_id).first()
+    if not session:
+        raise HTTPException(status_code=404, detail="Session not found")
+
+    session.name = req.title
+    db.commit()
+    return {"ok": True}
+
+# To run standalone: python -m uvicorn backend.main:app --host 127.0.0.1 --port 8000