main.py

import os
import tempfile
from fastapi import FastAPI, UploadFile, File, Header, HTTPException, Body
from fastapi.middleware.cors import CORSMiddleware
from pydantic import BaseModel
from spitch import Spitch
from langchain.prompts import PromptTemplate
from langchain_huggingface import HuggingFaceEndpoint
from langdetect import detect, DetectorFactory
from huggingface_hub.utils import HfHubHTTPError
from smebuilder_vector import retriever  # your retriever

# ----------------- CONFIG -----------------
DetectorFactory.seed = 0

SPITCH_API_KEY = os.getenv("SPITCH_API_KEY")
HF_MODEL = os.getenv("HF_MODEL", "deepseek-ai/deepseek-coder-1.3b-instruct")
FRONTEND_ORIGIN = os.getenv("ALLOWED_ORIGIN", "*")
PROJECT_API_KEY = os.getenv("PROJECT_API_KEY", "")

if not SPITCH_API_KEY:
    raise RuntimeError("Set SPITCH_API_KEY in environment before starting.")

# Init Spitch
os.environ["SPITCH_API_KEY"] = SPITCH_API_KEY
spitch_client = Spitch()

# HuggingFace LLM
llm = HuggingFaceEndpoint(
    repo_id=HF_MODEL,
    temperature=0.7,
    top_p=0.9,
    do_sample=True,
    repetition_penalty=1.1,
    max_new_tokens=2048
)

# FastAPI app
app = FastAPI(title="DevAssist AI Backend (FastAPI + LangChain)")

# CORS
app.add_middleware(
    CORSMiddleware,
    allow_origins=[FRONTEND_ORIGIN] if FRONTEND_ORIGIN != "*" else ["*"],
    allow_credentials=True,
    allow_methods=["GET", "POST", "OPTIONS"],
    allow_headers=["Authorization", "Content-Type"],
)

# ----------------- PROMPT TEMPLATES -----------------
chat_template = """You are DevAssist, an AI coding assistant.

Guidelines:
- Always format responses in Markdown.
- Do NOT use inline formatting like bold (**), italics (*), or underlines.
- Use plain text section headers (e.g., Explanation:, Steps to Fix:, Fixed Code:).
- Use bullet points (-, 1.) for steps.
- Use fenced code blocks (```python ... ```) for code.
- Be friendly yet professional; explain step by step.

Question: {question}

Answer:
"""

stt_chat_template = """You are DevAssist, an AI coding assistant.
- The input is transcribed speech. Interpret it as a dev question.
- Provide clear answers with code examples (use markdown triple backticks).
- If input is unclear, ask a clarifying question.

Spoken Question: {speech}
Answer:
"""

autodoc_template = """You are DevAssist DocBot.
- Read the code and produce professional documentation in markdown.

Code: {code}
Documentation:
"""

sme_template = """
You are a senior full-stack engineer specializing in modern front-end development.
Your job is to generate **production-ready code** for websites and apps.

Guidelines:
- Always return three separate files: index.html, styles.css, and script.js
- HTML must be semantic, responsive, and mobile-first (use <meta viewport>)
- CSS should use Flexbox/Grid and include hover/transition effects
- JavaScript must add interactivity (e.g. button actions, animations, toggles)
- Include a hero section, feature grid, testimonials, and footer
- Fill with realistic content (no lorem ipsum, no placeholders)
- Return **only valid JSON** with keys: "files" → { "index.html": "...", "styles.css": "...", "script.js": "..." }

Prompt: {user_prompt}
Context: {context}

Output:
"""

# ----------------- CHAINS -----------------
chat_chain = PromptTemplate(input_variables=["question"], template=chat_template) | llm
stt_chain = PromptTemplate(input_variables=["speech"], template=stt_chat_template) | llm
autodoc_chain = PromptTemplate(input_variables=["code"], template=autodoc_template) | llm
sme_chain = PromptTemplate(input_variables=["user_prompt", "context"], template=sme_template) | llm

# ----------------- REQUEST MODELS -----------------
class ChatRequest(BaseModel):
    question: str

class AutoDocRequest(BaseModel):
    code: str

# ----------------- AUTH -----------------
def check_auth(authorization: str | None):
    if not PROJECT_API_KEY:
        return
    if not authorization or not authorization.startswith("Bearer "):
        raise HTTPException(status_code=401, detail="Missing bearer token")
    token = authorization.split(" ", 1)[1]
    if token != PROJECT_API_KEY:
        raise HTTPException(status_code=403, detail="Invalid token")

# ----------------- ENDPOINTS -----------------
@app.get("/")
def root():
    return {"status": "DevAssist AI Backend running"}

@app.post("/chat")
def chat(req: ChatRequest, authorization: str | None = Header(None)):
    check_auth(authorization)
    try:
        answer = chat_chain.invoke({"question": req.question})
        return {"reply": answer.strip() if isinstance(answer, str) else str(answer)}
    except HfHubHTTPError as e:
        if "exceeded" in str(e).lower() or "quota" in str(e).lower():
            return {"reply": "⚠️ Daily token limit reached. Try again in 24 hours."}
        raise e

@app.post("/stt")
async def stt_audio(file: UploadFile = File(...), lang_hint: str | None = None, authorization: str | None = Header(None)):
    check_auth(authorization)

    suffix = os.path.splitext(file.filename)[1] or ".wav"
    with tempfile.NamedTemporaryFile(delete=False, suffix=suffix) as tf:
        tf.write(await file.read())
        tmp_path = tf.name

    try:
        if lang_hint:
            resp = spitch_client.speech.transcribe(language=lang_hint, content=open(tmp_path, "rb").read())
        else:
            resp = spitch_client.speech.transcribe(content=open(tmp_path, "rb").read())
    except Exception:
        resp = spitch_client.speech.transcribe(language="en", content=open(tmp_path, "rb").read())

    transcription = getattr(resp, "text", "") or (resp.get("text", "") if isinstance(resp, dict) else "")
    try:
        detected_lang = detect(transcription) if transcription.strip() else "en"
    except Exception:
        detected_lang = "en"

    translation = transcription
    if detected_lang != "en":
        try:
            translation_resp = spitch_client.text.translate(text=transcription, source=detected_lang, target="en")
            translation = getattr(translation_resp, "text", "") or translation_resp.get("text", "")
        except Exception:
            translation = transcription

    reply = stt_chain.invoke({"speech": translation})
    return {
        "transcription": transcription,
        "detected_language": detected_lang,
        "translation": translation,
        "reply": reply.strip() if isinstance(reply, str) else str(reply)
    }

@app.post("/autodoc")
def autodoc(req: AutoDocRequest, authorization: str | None = Header(None)):
    check_auth(authorization)
    docs = autodoc_chain.invoke({"code": req.code})
    return {"documentation": docs.strip() if isinstance(docs, str) else str(docs)}

@app.post("/sme/generate")
async def sme_generate(payload: dict = Body(...)):
    try:
        user_prompt = payload.get("user_prompt", "")
        context_docs = retriever.get_relevant_documents(user_prompt)
        context = "\n".join([doc.page_content for doc in context_docs]) if context_docs else "No extra context"
        response = sme_chain.invoke({"user_prompt": user_prompt, "context": context})
        return {"success": True, "data": response}
    except HfHubHTTPError as e:
        if "exceeded" in str(e).lower() or "quota" in str(e).lower():
            return {"success": False, "error": "⚠️ Token quota for today has been used. Please come back in 24 hours."}
        raise e

@app.post("/sme/speech-generate")
async def sme_speech_generate(file: UploadFile = File(...), lang_hint: str | None = None, authorization: str | None = Header(None)):
    check_auth(authorization)

    suffix = os.path.splitext(file.filename)[1] or ".wav"
    with tempfile.NamedTemporaryFile(delete=False, suffix=suffix) as tf:
        tf.write(await file.read())
        tmp_path = tf.name

    try:
        if lang_hint:
            resp = spitch_client.speech.transcribe(language=lang_hint, content=open(tmp_path, "rb").read())
        else:
            resp = spitch_client.speech.transcribe(content=open(tmp_path, "rb").read())
    except Exception:
        resp = spitch_client.speech.transcribe(language="en", content=open(tmp_path, "rb").read())

    transcription = getattr(resp, "text", "") or (resp.get("text", "") if isinstance(resp, dict) else "")
    try:
        detected_lang = detect(transcription) if transcription.strip() else "en"
    except Exception:
        detected_lang = "en"

    translation = transcription
    if detected_lang != "en":
        try:
            translation_resp = spitch_client.text.translate(text=transcription, source=detected_lang, target="en")
            translation = getattr(translation_resp, "text", "") or translation_resp.get("text", "")
        except Exception:
            translation = transcription

    try:
        context_docs = retriever.get_relevant_documents(translation)
        context = "\n".join([doc.page_content for doc in context_docs]) if context_docs else "No extra context"
        sme_response = sme_chain.invoke({"user_prompt": translation, "context": context})
        return {
            "success": True,
            "transcription": transcription,
            "detected_language": detected_lang,
            "translation": translation,
            "sme_site": sme_response
        }
    except HfHubHTTPError as e:
        if "exceeded" in str(e).lower() or "quota" in str(e).lower():
            return {"success": False, "error": "⚠️ Token quota for today has been used. Please come back in 24 hours."}
        raise e

# ----------------- MAIN -----------------
if __name__ == "__main__":
    import uvicorn
    uvicorn.run("main:app", host="0.0.0.0", port=7860, reload=False)