app.py

import logging
import re
import requests
from fastapi import FastAPI
from pydantic import BaseModel, Field
import uvicorn

# =======================
# Configuration Settings
# =======================
# URL of the SMTP API endpoint (hosted on Vercel)
SMTP_API_URL = "https://smtp-server-ten.vercel.app/smtp"  # <--- change this to your deployed Vercel endpoint

# =======================
# Logging Configuration
# =======================
logging.basicConfig(level=logging.DEBUG, format="%(asctime)s - %(levelname)s - %(message)s")
logger = logging.getLogger("bot_server")

# =======================
# Global Conversation State
# =======================
# Maps sender's WhatsApp number to conversation data.
conversations = {}

# =======================
# Helper Functions
# =======================
# Regex for validating email addresses
EMAIL_REGEX = re.compile(r"^[^@]+@[^@]+\.[^@]+$")

def validate_email(email: str) -> bool:
    return re.match(EMAIL_REGEX, email) is not None

def send_email_via_api(from_addr: str, to_addr: str, subject: str, body: str) -> bool:
    """
    Calls the external SMTP API endpoint to send an email.
    """
    payload = {
        "from": from_addr,
        "to": to_addr,
        "subject": subject,
        "body": body,
    }
    logger.debug("Calling SMTP API with payload: %s", payload)
    try:
        response = requests.post(SMTP_API_URL, json=payload, timeout=10)
        response.raise_for_status()
        result = response.json()
        logger.info("SMTP API response: %s", result)
        return result.get("success", False)
    except Exception as e:
        logger.error("Error calling SMTP API: %s", e)
        return False

# =======================
# Pydantic Models for Bot Requests
# =======================
class Text(BaseModel):
    body: str

class Message(BaseModel):
    text: Text

class BotRequest(BaseModel):
    from_: str = Field(..., alias="from")
    message: Message

# =======================
# FastAPI Bot Application
# =======================
app = FastAPI()

@app.post("/bot")
async def bot_endpoint(request_data: BotRequest):
    payload = request_data.dict(by_alias=True)
    logger.debug("Received request payload: %s", payload)
    
    sender_number = request_data.from_
    message_body = request_data.message.text.body.strip()
    logger.info("Processing message from %s: '%s'", sender_number, message_body)
    
    state = conversations.get(sender_number, {})
    
    if not state:
        conversations[sender_number] = {"step": "from"}
        response_msg = "Welcome to SMTP Assistant! Please provide your 'From' email address."
    else:
        step = state.get("step")
        logger.debug("Current step for %s: %s", sender_number, step)
        if step == "from":
            if validate_email(message_body):
                state["from"] = message_body
                state["step"] = "to"
                response_msg = "Thanks! Now, please provide the recipient's email address."
            else:
                response_msg = "Invalid email format. Please provide a valid 'From' email address."
        elif step == "to":
            if validate_email(message_body):
                state["to"] = message_body
                state["step"] = "subject"
                response_msg = "Great! Please provide the email subject."
            else:
                response_msg = "Invalid email format. Please provide a valid recipient email address."
        elif step == "subject":
            state["subject"] = message_body
            state["step"] = "body"
            response_msg = "Almost done! Please provide the email body."
        elif step == "body":
            state["body"] = message_body
            from_addr = state.get("from")
            to_addr = state.get("to")
            subject = state.get("subject")
            body = state.get("body")
            logger.info("Attempting to send email from %s to %s with subject '%s'", from_addr, to_addr, subject)
            if send_email_via_api(from_addr, to_addr, subject, body):
                response_msg = f"Email sent successfully from {from_addr} to {to_addr}."
            else:
                response_msg = "Failed to send email. Please try again later."
            del conversations[sender_number]
            logger.info("Cleared conversation state for %s", sender_number)
        else:
            response_msg = "Unrecognized step. Let's start over. Please provide your 'From' email address."
            conversations[sender_number] = {"step": "from"}
    
    logger.debug("Response message to %s: %s", sender_number, response_msg)
    return {"status": "success", "message": response_msg}

if __name__ == "__main__":
    uvicorn.run("bot_server:app", host="0.0.0.0", port=5000, reload=True)