backend/chat_textgen.py

import os, requests, json, time
from utils.constants import ROUTER_TEXTGEN_URL, REQUEST_TIMEOUT_SECONDS_DEFAULT, RETRIES_DEFAULT, BACKOFF_SECONDS_DEFAULT
from utils.persona import AI_GYNO_PERSONA_V4

def _headers():
    tok = os.getenv("HF_API_TOKEN") or os.getenv("HF_TOKEN")
    return {"Authorization": f"Bearer {tok}", "Content-Type": "application/json"} if tok else {}

def chat(user_message: str, mode: str = "patient") -> str:
    url = os.getenv("HF_CHAT_ENDPOINT") or ROUTER_TEXTGEN_URL
    headers = _headers()
    if not headers:
        return "⚠ Set HF_API_TOKEN (or HF_TOKEN) in Secrets."

    style = "Explain simply and reassure." if mode=="patient" else "Use clinical phrasing, list differentials and next steps."
    prompt = f"""{AI_GYNO_PERSONA_V4}

Patient message:
{user_message}

Mode: {mode}
Instructions:
- {style}
- Provide likely causes, initial tests, red-flags (2-5), and 2-3 next steps.
- If missing key info, ask 2 follow-up questions.
- Keep response concise (<= 250 words).
"""

    payload = {
        "inputs": prompt,
        "parameters": {"max_new_tokens": 400, "temperature": 0.2, "return_full_text": False}
    }

    for attempt in range(1, RETRIES_DEFAULT+1):
        try:
            r = requests.post(url, headers=headers, json=payload, timeout=REQUEST_TIMEOUT_SECONDS_DEFAULT)
            txt = r.text
            # detect HTML / loading
            if "<html" in txt.lower():
                if "loading" in txt.lower():
                    time.sleep(BACKOFF_SECONDS_DEFAULT * attempt); continue
                return f"⚠ Non-JSON HTML response: {txt[:500]}"
            try:
                data = r.json()
            except Exception:
                return txt[:2000]
            # Text generation style
            if isinstance(data, list) and data and "generated_text" in data[0]:
                return data[0]["generated_text"]
            if isinstance(data, dict) and "generated_text" in data:
                return data["generated_text"]
            # Some routers return {'text': '...'} or similar
            if isinstance(data, dict) and "text" in data:
                return data["text"]
            return "⚠ Unexpected response: " + json.dumps(data)[:1200]
        except Exception as e:
            time.sleep(BACKOFF_SECONDS_DEFAULT * attempt)
    return "❌ Endpoint unreachable after retries."