from fastapi import FastAPI, HTTPException, BackgroundTasks, Depends, Header, status, Query from fastapi.middleware.cors import CORSMiddleware from fastapi.security import APIKeyHeader from pydantic import BaseModel, EmailStr, Field from typing import Optional, Tuple from enum import Enum import os import base64 import pickle import pandas as pd from dotenv import load_dotenv from langchain_openai import ChatOpenAI from langchain.schema import HumanMessage, SystemMessage from email.mime.text import MIMEText from google.auth.transport.requests import Request from google.oauth2.credentials import Credentials from google_auth_oauthlib.flow import InstalledAppFlow from googleapiclient.discovery import build from googleapiclient.errors import HttpError from datetime import datetime import json from langfuse import Langfuse from langfuse.langchain import CallbackHandler load_dotenv() langfuse = Langfuse( secret_key=os.getenv("SECRET_KEY"), public_key=os.getenv("PUBLIC_KEY"), host=os.getenv("APP_HOST") ) langfuse_handler = CallbackHandler() # Load environment variables (not needed on Hugging Face, but harmless) # ------------------------------------------ # Security Configuration # ------------------------------------------ API_PASSWORD = os.getenv("API_PASSWORD", "Synapse@2025") # Can be overridden by env var api_key_header = APIKeyHeader(name="X-API-Key", auto_error=False) def verify_api_key(api_key: Optional[str] = Depends(api_key_header)) -> str: """ Verify the API key/password provided in the request header. """ if api_key is None: raise HTTPException( status_code=status.HTTP_401_UNAUTHORIZED, detail="API Key required. Please provide X-API-Key header.", headers={"WWW-Authenticate": "ApiKey"}, ) if api_key != API_PASSWORD: raise HTTPException( status_code=status.HTTP_401_UNAUTHORIZED, detail="Invalid API Key", headers={"WWW-Authenticate": "ApiKey"}, ) return api_key # ------------------------------------------ # Helper: Write GOOGLE_CREDENTIALS_JSON to file if needed # ------------------------------------------ def ensure_credentials_file(): credentials_env = os.getenv("GOOGLE_CREDENTIALS_JSON") credentials_path = "credentials_SYNAPSE.json" if not os.path.exists(credentials_path): if not credentials_env: raise Exception("GOOGLE_CREDENTIALS_JSON not found in environment variables.") try: parsed_json = json.loads(credentials_env) except json.JSONDecodeError: raise Exception("Invalid JSON in GOOGLE_CREDENTIALS_JSON") with open(credentials_path, "w") as f: json.dump(parsed_json, f, indent=2) return credentials_path # ------------------------------------------ # FastAPI app # ------------------------------------------ app = FastAPI(title="Recruitment Message Generator API", version="1.0.0") app.add_middleware( CORSMiddleware, allow_origins=["*"], allow_credentials=True, allow_methods=["*"], allow_headers=["*"], ) SCOPES = ["https://www.googleapis.com/auth/gmail.send"] openai_api_key = os.getenv("OPENAI_API_KEY") # ------------------------------------------ # Enums and Models # ------------------------------------------ class MessageType(str, Enum): OUTREACH = "outreach" INTRODUCTORY = "introductory" FOLLOWUP = "followup" class GenerateMessageRequest(BaseModel): job_evaluation: Optional[str] = Field(None, description="(Optional) Recruiter's evaluation of candidate for the job") sender_email: EmailStr reply_to_email: Optional[EmailStr] = Field(None, description="Recruiter's email for reply-to header") recipient_email: EmailStr candidate_name: str current_role: str current_company: str company_name: str role: str recruiter_name: str organisation: str message_type: MessageType send_email: bool = False past_conversation: Optional[str] = Field(None, description="(Optional) Previous messages with candidate") job_location: Optional[str] = Field(None, description="(Optional) Job location (e.g., 'Sterling, VA')") company_blurb: Optional[str] = Field(None, description="(Optional) Brief description of company mission/industry") culture: Optional[str] = Field(None, description="(Optional) Company culture description (e.g., 'fast-moving, tight-knit team')") job_responsibilities: Optional[str] = Field(None, description="(Optional) Key responsibilities and duties for the role") candidate_experience: Optional[str] = Field(None, description="(Optional) Specific skills and experience of the candidate") class FeedbackRequest(BaseModel): message: str feedback: str class AuthenticateRequest(BaseModel): email: EmailStr class AuthenticateResponse(BaseModel): success: bool message: str error: Optional[str] = None class MessageResponse(BaseModel): success: bool message: str email_sent: bool = False email_subject: Optional[str] = None error: Optional[str] = None class SendMessageRequest(BaseModel): subject: str email_body: str sender_email: EmailStr recipient_email: EmailStr reply_to_email: Optional[EmailStr] = None # ------------------------------------------ # Gmail Helper Functions # ------------------------------------------ def get_token_file_path(email: str) -> str: tokens_dir = "gmail_tokens" if not os.path.exists(tokens_dir): os.makedirs(tokens_dir) safe_email = email.replace("@", "_at_").replace(".", "_dot_") return os.path.join(tokens_dir, f"token_{safe_email}.pickle") def check_user_token_exists(email: str) -> bool: token_file = get_token_file_path(email) return os.path.exists(token_file) def load_user_credentials(email: str): token_file = get_token_file_path(email) if os.path.exists(token_file): try: with open(token_file, 'rb') as token: creds = pickle.load(token) return creds except Exception: if os.path.exists(token_file): os.remove(token_file) return None def save_user_credentials(email: str, creds): token_file = get_token_file_path(email) with open(token_file, 'wb') as token: pickle.dump(creds, token) def create_new_credentials(email: str): credentials_path = ensure_credentials_file() flow = InstalledAppFlow.from_client_secrets_file( credentials_path, SCOPES ) creds = flow.run_local_server(port=0) save_user_credentials(email, creds) return creds def authenticate_gmail(email: str, create_if_missing: bool = False): creds = load_user_credentials(email) if creds: if creds.expired and creds.refresh_token: try: creds.refresh(Request()) save_user_credentials(email, creds) except Exception: if create_if_missing: try: creds = create_new_credentials(email) except: return None else: return None elif not creds.valid: creds = None if not creds: if create_if_missing: try: creds = create_new_credentials(email) except: return None else: return None try: service = build("gmail", "v1", credentials=creds) return service except Exception: return None from email.mime.text import MIMEText def create_email_message(sender: str, to: str, subject: str, message_text: str, reply_to: Optional[str] = None, is_html: bool = False): if is_html: message = MIMEText(message_text, "html") else: message = MIMEText(message_text, "plain") message["To"] = to message["From"] = sender message["Subject"] = subject if reply_to: message["Reply-To"] = reply_to raw_message = base64.urlsafe_b64encode(message.as_bytes()).decode() return {"raw": raw_message} def send_gmail_message(service, user_id: str, message: dict): try: result = service.users().messages().send(userId=user_id, body=message).execute() return result is not None except HttpError: return False # ------------------------------------------ # LLM (OpenAI) Message Generation Helpers # ------------------------------------------ def refine_message_with_feedback( original_message: str, feedback: str, ) -> Tuple[str, str]: api_key = os.getenv("OPENAI_API_KEY") llm = ChatOpenAI( model="gpt-4o-mini", temperature=0.7, max_tokens=600, openai_api_key=api_key ) prompt = f""" Please refine the following recruitment message based on the provided feedback: ORIGINAL MESSAGE: {original_message} FEEDBACK: {feedback} Please provide your response in the following format: SUBJECT: [Your subject line here] BODY: [Your refined email body content here] Keep the same warm, conversational tone and intent as the original message, but incorporate the feedback to improve it. Make sure the message feels personal and approachable. """ try: messages = [ SystemMessage(content="You are a friendly and approachable recruitment specialist. Refine the given message based on feedback while maintaining a warm, conversational tone and the original intent."), HumanMessage(content=prompt) ] response = llm.invoke(messages, config={"callbacks": [langfuse_handler]}) content = response.content.strip() subject_line = "" body_content = "" lines = content.split('\n') body_found = False body_lines = [] for line in lines: line_stripped = line.strip() # Handle both plain text and markdown formats if line_stripped.startswith('SUBJECT:') or line_stripped.startswith('**SUBJECT:**'): subject_line = line_stripped.replace('SUBJECT:', '').replace('**SUBJECT:**', '').replace('**', '').strip() elif line_stripped.startswith('BODY:') or line_stripped.startswith('**BODY:**'): body_found = True elif body_found and line_stripped: body_lines.append(line) body_content = '\n'.join(body_lines).strip() # Clean up any remaining markdown formatting from body if body_content: body_content = body_content.replace('**', '') if not subject_line: subject_line = "Recruitment Opportunity - Updated" if not body_content: body_content = content return subject_line, body_content except Exception as e: raise HTTPException(status_code=500, detail=f"Error refining message: {str(e)}") def generate_recruitment_message_with_subject( msg_type: str, company: str, role_title: str, recruiter: str, org: str, candidate: str, current_pos: str, evaluation: Optional[str] = None, feedback: Optional[str] = None, past_conversation: Optional[str] = None, job_location: Optional[str] = None, company_blurb: Optional[str] = None, culture: Optional[str] = None, job_responsibilities: Optional[str] = None, candidate_experience: Optional[str] = None ) -> Tuple[str, str]: api_key = os.getenv("OPENAI_API_KEY") llm = ChatOpenAI( model="gpt-4o-mini", temperature=0.7, max_tokens=600, openai_api_key=api_key ) # Outreach: Only request consent if msg_type == "outreach": prompt = f""" Generate a warm and friendly initial outreach message to a candidate. - Introduce yourself as {recruiter} from {org} in a casual, approachable way - Mention you came across their profile and were impressed by their background - Share that you're reaching out about an exciting opportunity ({role_title}) at {company} - Ask if they'd be interested in learning more about this role - Use a conversational tone - think of it as reaching out to a colleague or friend - Do NOT discuss any job evaluation or judgment. - Keep it concise but warm and engaging - No placeholders like [Candidate Name] or [Role Title] in the output. """ else: base_prompt = f""" Generate a friendly and professional recruitment {msg_type} with the following details: - Company hiring: {company} - Role: {role_title} - Recruiter: {recruiter} from {org} - Candidate: {candidate} - Candidate's current position: {current_pos} """ # Add optional additional details if provided if job_location: base_prompt += f"- Job location: {job_location}\n" if company_blurb: base_prompt += f"- Company description: {company_blurb}\n" if culture: base_prompt += f"- Company culture: {culture}\n" if job_responsibilities: base_prompt += f"- Job responsibilities: {job_responsibilities}\n" if candidate_experience: base_prompt += f"- Candidate's specific experience: {candidate_experience}\n" if evaluation: base_prompt += f"- Evaluation: {evaluation}\n" prompt = base_prompt if msg_type == "introductory": prompt += """ Create a friendly and engaging introductory message that: - Thanks the candidate warmly for their response and interest - Shares exciting details about the role and company culture - Explains why you think this opportunity would be a great fit for their background - Suggests next steps (like a casual chat or coffee meeting) in a relaxed way - Uses a conversational, approachable tone while staying professional - Shows genuine enthusiasm about the opportunity - if in the Evaluation the verdict is rejected, Send a polite rejection message instead. """ else: # followup prompt += """ Create a friendly and follow-up message that: - References your previous conversation in a warm, personal way - Shows continued enthusiasm and interest in the candidate - Addresses any concerns they might have in a supportive manner - Shares additional exciting reasons why this role would be perfect for them - Includes a relaxed but clear call to action - Uses a conversational tone that feels like catching up with someone """ # Use feedback if provided if feedback: prompt += f"\n\nPlease modify the message based on this feedback: {feedback}" # Use past conversation if provided if past_conversation: prompt += f""" Use the following past conversation as context to inform your reply: PAST CONVERSATION: {past_conversation} Write a reply message to the candidate, maintaining professionalism and continuity. """ prompt += """ Please provide your response in the following format: SUBJECT: [Your subject line here] BODY: [Your email body content here] """ try: messages = [ SystemMessage(content="You are a friendly and approachable recruitment specialist who writes warm, engaging messages. Generate both an email subject line and body content. Use a conversational tone that feels personal and genuine while maintaining professionalism. Follow the exact format requested."), HumanMessage(content=prompt) ] response = llm.invoke(messages, config={"callbacks": [langfuse_handler]}) content = response.content.strip() subject_line = "" body_content = "" lines = content.split('\n') body_found = False body_lines = [] for line in lines: line_stripped = line.strip() # Handle both plain text and markdown formats if line_stripped.startswith('SUBJECT:') or line_stripped.startswith('**SUBJECT:**'): subject_line = line_stripped.replace('SUBJECT:', '').replace('**SUBJECT:**', '').replace('**', '').strip() elif line_stripped.startswith('BODY:') or line_stripped.startswith('**BODY:**'): body_found = True elif body_found and line_stripped: body_lines.append(line) body_content = '\n'.join(body_lines).strip() # Clean up any remaining markdown formatting from body if body_content: body_content = body_content.replace('**', '') if not subject_line: subject_line = f"Opportunity at {company} - {role_title}" if not body_content: body_content = content return subject_line, body_content except Exception as e: raise HTTPException(status_code=500, detail=f"Error generating message: {str(e)}") def format_email_html(body: str, sender_name: Optional[str]=None, sender_org: Optional[str]=None): """Wrap plain text body in an HTML template for better appearance.""" import re # Smart paragraphing and formatting body = body.strip() # Convert markdown-style formatting body = re.sub(r'\*\*(.*?)\*\*', r'\1', body) # Bold text body = re.sub(r'\*(.*?)\*', r'\1', body) # Italic text # Smart paragraphing body = re.sub(r"\n\s*\n", "

", body) # Double newlines => new paragraph body = re.sub(r"\n", "
", body) # Single newlines =>
# Optional signature with better styling signature = "" if sender_name or sender_org: signature = f"""

Best regards,

""" if sender_name: signature += f'

{sender_name}

' if sender_org: signature += f'

{sender_org}

' signature += "
" html = f""" Recruitment Message

Professional Recruitment Message

{body}

{signature}

This message was generated by Synapse Recruitment Platform

Please reply to this email for any inquiries

""" return html # ------------------------------------------ # FastAPI Endpoints # ------------------------------------------ @app.get("/") async def root(): """Root endpoint - public access""" return { "message": "Recruitment Message Generator API", "version": "1.0.0", "authentication": "Required for all endpoints except / and /health", "auth_header": "X-API-Key", "endpoints": [ "/generate-message", "/refine-message", "/authenticate", "/send-message", "/docs" ] } @app.post("/send-message", response_model=MessageResponse, dependencies=[Depends(verify_api_key)]) async def send_message( subject: str = Query(..., description="Email subject"), email_body: str = Query(..., description="Email body content"), sender_email: str = Query(..., description="Sender's email address"), recipient_email: str = Query(..., description="Recipient's email address"), reply_to_email: Optional[str] = Query(None, description="Reply-to email address") ): try: # Authenticate sender service = authenticate_gmail(sender_email) if not service: return MessageResponse( success=False, message="", error="Gmail authentication failed" ) formatted_html = format_email_html( email_body ) # Create the email email_message = create_email_message( sender=sender_email, to=recipient_email, subject=subject, message_text=formatted_html, reply_to=reply_to_email, is_html=True ) # Send the email email_sent = send_gmail_message(service, "me", email_message) if email_sent: return MessageResponse( success=True, message="Email sent successfully.", email_sent=True, email_subject=subject ) else: return MessageResponse( success=False, message="", email_sent=False, email_subject=subject, error="Failed to send via Gmail API" ) except Exception as e: return MessageResponse( success=False, message="", error=str(e) ) @app.post("/generate-message", response_model=MessageResponse, dependencies=[Depends(verify_api_key)]) async def generate_message( background_tasks: BackgroundTasks, sender_email: str = Query(..., description="Sender's email address"), recipient_email: str = Query(..., description="Recipient's email address"), candidate_name: str = Query(..., description="Candidate's name"), current_role: str = Query(..., description="Candidate's current role"), current_company: str = Query(..., description="Candidate's current company"), company_name: str = Query(..., description="Company name for the job"), role: str = Query(..., description="Job role title"), recruiter_name: str = Query(..., description="Recruiter's name"), organisation: str = Query(..., description="Recruiting organisation"), message_type: MessageType = Query(..., description="Type of message"), job_evaluation: Optional[str] = Query(None, description="Recruiter's evaluation of candidate for the job"), reply_to_email: Optional[str] = Query(None, description="Recruiter's email for reply-to header"), send_email: bool = Query(False, description="Whether to send the email"), past_conversation: Optional[str] = Query(None, description="Previous messages with candidate"), job_location: Optional[str] = Query(None, description="Job location (e.g., 'Sterling, VA')"), company_blurb: Optional[str] = Query(None, description="Brief description of company mission/industry"), culture: Optional[str] = Query(None, description="Company culture description (e.g., 'fast-moving, tight-knit team')"), job_responsibilities: Optional[str] = Query(None, description="Key responsibilities and duties for the role"), candidate_experience: Optional[str] = Query(None, description="Specific skills and experience of the candidate") ): try: current_position = f"{current_role} at {current_company}" email_subject, generated_message = generate_recruitment_message_with_subject( msg_type=message_type.value.replace('followup', 'follow-up'), company=company_name, role_title=role, recruiter=recruiter_name, org=organisation, candidate=candidate_name, current_pos=current_position, evaluation=job_evaluation, past_conversation=past_conversation, job_location=job_location, company_blurb=company_blurb, culture=culture, job_responsibilities=job_responsibilities, candidate_experience=candidate_experience ) email_sent = False if send_email: registered_users = [] if os.path.exists("registered_users.csv"): df = pd.read_csv("registered_users.csv") registered_users = df['email'].tolist() if 'email' in df.columns else [] if sender_email.lower() not in [user.lower() for user in registered_users]: return MessageResponse( success=True, message=generated_message, email_sent=False, email_subject=email_subject, error="Email not sent: Sender email is not registered" ) service = authenticate_gmail(sender_email) if service: formatted_html = format_email_html( generated_message, sender_name=recruiter_name, sender_org=organisation ) email_message = create_email_message( sender=sender_email, to=recipient_email, subject=email_subject, message_text=formatted_html, reply_to=reply_to_email, is_html=True ) email_sent = send_gmail_message(service, "me", email_message) if not email_sent: return MessageResponse( success=True, message=generated_message, email_sent=False, email_subject=email_subject, error="Email not sent: Failed to send via Gmail API" ) else: return MessageResponse( success=True, message=generated_message, email_sent=False, email_subject=email_subject, error="Email not sent: Gmail authentication failed" ) return MessageResponse( success=True, message=generated_message, email_sent=email_sent, email_subject=email_subject ) except Exception as e: return MessageResponse( success=False, message="", error=str(e) ) @app.post("/refine-message", response_model=MessageResponse, dependencies=[Depends(verify_api_key)]) async def refine_message(request: FeedbackRequest): try: email_subject, refined_message = refine_message_with_feedback( original_message=request.message, feedback=request.feedback ) return MessageResponse( success=True, message=refined_message, email_sent=False, email_subject=email_subject ) except Exception as e: return MessageResponse( success=False, message="", error=str(e) ) @app.post("/authenticate", response_model=AuthenticateResponse, dependencies=[Depends(verify_api_key)]) async def authenticate_user(request: AuthenticateRequest): try: if check_user_token_exists(request.email): service = authenticate_gmail(request.email, create_if_missing=False) if service: return AuthenticateResponse( success=True, message="User already authenticated and token is valid" ) else: service = authenticate_gmail(request.email, create_if_missing=True) if service: return AuthenticateResponse( success=True, message="Token refreshed successfully" ) else: return AuthenticateResponse( success=False, message="Failed to refresh token", error="Could not refresh existing token. Please check credentials.json" ) else: try: creds = create_new_credentials(request.email) if creds: return AuthenticateResponse( success=True, message="Authentication successful. Token created and saved." ) else: return AuthenticateResponse( success=False, message="Authentication failed", error="Failed to create credentials" ) except Exception as e: return AuthenticateResponse( success=False, message="Authentication failed", error=str(e) ) except Exception as e: return AuthenticateResponse( success=False, message="Authentication error", error=str(e) ) @app.get("/health") async def health_check(): """Health check endpoint - public access""" return {"status": "healthy", "timestamp": datetime.utcnow().isoformat()} # Protected documentation endpoint @app.get("/docs", dependencies=[Depends(verify_api_key)]) async def get_documentation(): """This will be handled by FastAPI's built-in docs""" pass if __name__ == "__main__": import uvicorn uvicorn.run(app, host="0.0.0.0", port=8000) # Additional Infor: Job Location, Company Blurb, Culture, Job Responsibilities, Candidate Experience