import os, json
from fastapi import FastAPI, Request, HTTPException, Query
from fastapi.responses import PlainTextResponse, JSONResponse
import httpx
import base64

app = FastAPI()

VERIFY_TOKEN = os.getenv("VERIFY_TOKEN", "")  # set in HF Secrets
PHONE_NUMBER_ID = os.getenv("PHONE_NUMBER_ID", "")
WHATSAPP_API_TOKEN = os.getenv("WHATSAPP_API_TOKEN", "")

@app.get("/webhook")  # verification
def verify(
    hub_mode: str = Query(None, alias="hub.mode"),
    hub_token: str = Query(None, alias="hub.verify_token"),
    hub_challenge: str = Query(None, alias="hub.challenge")
):
    if hub_mode == "subscribe" and hub_token == VERIFY_TOKEN:
        return PlainTextResponse(hub_challenge)
    raise HTTPException(status_code=403, detail="Invalid token")

def send_whatsapp_message(wa_id, reply):
    url = f"https://graph.facebook.com/v23.0/{PHONE_NUMBER_ID}/messages"
    headers = {
        "Authorization": f"Bearer {WHATSAPP_API_TOKEN}",
        "Content-Type": "application/json"
    }
    payload = {
        "messaging_product": "whatsapp",
        "to": wa_id,
        "type": "text",
        "text": {"body": reply}
    }
    httpx.post(url, headers=headers, json=payload)

@app.post("/webhook")  # incoming WhatsApp updates
async def receive_update(req: Request):
    data = await req.json()
    try:
        change   = data["entry"][0]["changes"][0]["value"]
        contacts = change.get("contacts")
        messages = change.get("messages")
        if not contacts or not messages:
            # Missing expected payload—ignore
            print("Ignoring update, no contacts or messages field")
            return JSONResponse({"status": "ignored", "reason": "no contacts/messages"})

        wa_id = contacts[0]["wa_id"]
        msg   = messages[0]
    except (KeyError, IndexError, TypeError) as e:
        print("Malformed webhook payload:", e)
        return JSONResponse({"status": "ignored", "reason": "malformed payload"})

    # IMAGE: if user sent an image, convert to Base64 preview
    if msg["type"] == "image":
        media_id = msg["image"]["id"]
        # 1) get media URL
        media_resp = httpx.get(
            f"https://graph.facebook.com/v23.0/{media_id}",
            headers={"Authorization": f"Bearer {WHATSAPP_API_TOKEN}"}
        )
        media_resp.raise_for_status()
        media_url = media_resp.json()["url"]
        # 2) download bytes with auth
        media_bytes = httpx.get(
            media_url,
            headers={"Authorization": f"Bearer {WHATSAPP_API_TOKEN}"}
        ).content
        # 3) encode & preview
        preview = base64.b64encode(media_bytes).decode("utf-8")[:10]
        # send back preview
        send_whatsapp_message(wa_id, f"Base64: {preview}")
        return JSONResponse({"status": "image_preview_sent", "preview": preview})

    # TEXT: simple echo
    if msg["type"] == "text":
        incoming = msg["text"]["body"]
        reply    = f"You said: {incoming}"
        send_whatsapp_message(wa_id, reply)
        return JSONResponse({"status": "replied"})

    # OTHER: ignore
    return JSONResponse({"status": "ignored", "type": msg["type"]})

# health-check endpoint for token
@app.post("/send")
async def check_token():
    token = os.getenv("WHATSAPP_API_TOKEN", "")
    if token:
        return {"token_loaded": True}
    raise HTTPException(status_code=400, detail="Token not found")

@app.get("/ping")      # health check
def ping():
    return {"pong": True}