from fastapi import FastAPI
from pydantic import BaseModel
from typing import List, Dict, Any
from transformers import AutoTokenizer, AutoModelForSequenceClassification, pipeline, AutoModelForTokenClassification
import torch
import re

# --- Load your fine-tuned model from Hugging Face Hub ---
MODEL_REPO = "sathish2352/email-classifier-model"
PII_MODEL = "Davlan/xlm-roberta-base-ner-hrl"

tokenizer = AutoTokenizer.from_pretrained(MODEL_REPO)
model = AutoModelForSequenceClassification.from_pretrained(MODEL_REPO)
ner_tokenizer = AutoTokenizer.from_pretrained(PII_MODEL)
ner_model = AutoModelForTokenClassification.from_pretrained(PII_MODEL)
ner_pipe = pipeline("token-classification", model=ner_model, tokenizer=ner_tokenizer, aggregation_strategy="simple")
model.eval()

app = FastAPI()

class EmailInput(BaseModel):
    input_email_body: str

# --- PII Masking Function ---
import re
from transformers import pipeline, AutoModelForTokenClassification, AutoTokenizer
def mask_pii_multilingual(text: str):

    # Load model only once globally if needed
    model_name = "Davlan/xlm-roberta-base-ner-hrl"
    tokenizer = AutoTokenizer.from_pretrained(model_name)
    model = AutoModelForTokenClassification.from_pretrained(model_name)
    ner_pipe = pipeline("token-classification", model=model, tokenizer=tokenizer, aggregation_strategy="simple")

    regex_patterns = {
        "email": r"\b[A-Za-z0-9._%+-]+@[A-Za-z0-9.-]+\.[A-Za-z]{2,}\b",
        "phone_number": r"(?:\+?\d{1,3})?[-.\s]?\(?\d{1,4}\)?[-.\s]?\d{2,4}[-.\s]?\d{2,4}[-.\s]?\d{2,4}",
        "dob": r"\b(0?[1-9]|[12][0-9]|3[01])[-/](0?[1-9]|1[012])[-/](19[5-9]\d|20[0-3]\d)\b",
        "aadhar_num": r"\b\d{4}[\s-]?\d{4}[\s-]?\d{4}\b",
        "credit_debit_no": r"\b(?:\d{4}[\s-]?){3}\d{4}\b",
        "cvv_no": r"\b\d{3,4}\b",
        "expiry_no": r"\b(0[1-9]|1[0-2])[/-]?(?:\d{2}|\d{4})\b"
    }

    entities = []
    masked_text = text
    offsets = []

    # Step 1: Apply regex PII masking first
    for entity_type, pattern in regex_patterns.items():
        for match in re.finditer(pattern, text):
            start, end = match.start(), match.end()
            if any(start < e[1] and end > e[0] for e in offsets):
                continue
            token = f"[{entity_type}]"
            entity_val = text[start:end]
            masked_text = masked_text[:start] + token + masked_text[end:]
            offsets.append((start, end))
            entities.append({
                "position": [start, end],
                "classification": entity_type,
                "entity": entity_val
            })

    # Step 2: Run NER on updated masked_text to avoid overlap
    ner_results = ner_pipe(masked_text)
    for ent in ner_results:
        start, end = ent["start"], ent["end"]
        if ent["entity_group"] != "PER":
            continue
        if any(start < e[1] and end > e[0] for e in offsets):
            continue
        token = "[full_name]"
        entity_val = text[start:end]
        masked_text = masked_text[:start] + token + masked_text[end:]
        entities.append({
            "position": [start, end],
            "classification": "full_name",
            "entity": entity_val
        })
        offsets.append((start, end))

    # Sort final result
    entities.sort(key=lambda x: x["position"][0])
    return masked_text, entities


# --- API Endpoint ---
@app.post("/classify")
def classify_email(input: EmailInput):
    original_text = input.input_email_body

    # Step 1: Mask PII
    masked_text, masked_entities = mask_pii_multilingual(original_text)

    # Step 2: Classification
    inputs = tokenizer(masked_text, return_tensors="pt", truncation=True, padding=True)
    with torch.no_grad():
        logits = model(**inputs).logits
        pred = torch.argmax(logits, dim=1).item()

    label_map = {0: "Incident", 1: "Request", 2: "Change", 3: "Problem"}

    return {
        "input_email_body": original_text,
        "list_of_masked_entities": masked_entities,
        "masked_email": masked_text,
        "category_of_the_email": label_map[pred]
    }
if __name__ == "__main__":
    import uvicorn
    uvicorn.run("app:app", host="0.0.0.0", port=7860)