app.py

import gradio as gr
import torch
import torch.nn as nn
import librosa
import numpy as np
import whisper
import pandas as pd
from datasets import load_dataset
from sklearn.feature_extraction.text import TfidfVectorizer
from sklearn.linear_model import LogisticRegression
from sklearn.utils import resample

device = torch.device("cpu")

# ================= LOAD DATASET =================
data1 = pd.read_csv("spam_dataset.csv")
data2 = load_dataset("ucirvine/sms_spam")
data2 = data2["train"].to_pandas()
data2 = data2.rename(columns={"sms": "text", "label": "label"})

data = pd.concat([data1, data2], ignore_index=True)

# ================= FIX LABELS =================
# Ensure labels are 0 (ham) and 1 (spam)
data["label"] = data["label"].astype(int)

# ================= BALANCE DATASET =================
ham = data[data.label == 0]
spam = data[data.label == 1]

min_size = min(len(ham), len(spam))

ham_bal = resample(ham, replace=False, n_samples=min_size, random_state=42)
spam_bal = resample(spam, replace=False, n_samples=min_size, random_state=42)

data = pd.concat([ham_bal, spam_bal])

texts = data["text"]
labels = data["label"]

# ================= ML TRAINING =================
vectorizer = TfidfVectorizer(stop_words="english")
X = vectorizer.fit_transform(texts)

ml_model = LogisticRegression(max_iter=200)
ml_model.fit(X, labels)

# ================= CNN MODEL =================
class ScamAudioCNN(nn.Module):
    def __init__(self):
        super(ScamAudioCNN, self).__init__()
        self.conv1 = nn.Conv2d(1, 16, 3, padding=1)
        self.pool = nn.MaxPool2d(2, 2)
        self.conv2 = nn.Conv2d(16, 32, 3, padding=1)
        self.fc1 = nn.Linear(32 * 10 * 25, 128)
        self.fc2 = nn.Linear(128, 2)

    def forward(self, x):
        x = self.pool(torch.relu(self.conv1(x)))
        x = self.pool(torch.relu(self.conv2(x)))
        x = x.view(x.size(0), -1)
        x = torch.relu(self.fc1(x))
        x = self.fc2(x)
        return x

cnn_model = ScamAudioCNN().to(device)

# ================= LOAD CNN =================
try:
    cnn_model.load_state_dict(torch.load("scam_audio_model.pth", map_location=device))
    cnn_model.eval()
    cnn_loaded = True
except:
    cnn_loaded = False
    print("⚠️ CNN model not found, skipping CNN contribution")

# ================= WHISPER =================
whisper_model = whisper.load_model("tiny", device="cpu")

# ================= MFCC =================
def extract_features(file_path, max_len=100):
    y, sr = librosa.load(file_path, sr=16000)
    mfcc = librosa.feature.mfcc(y=y, sr=sr, n_mfcc=40)

    if mfcc.shape[1] < max_len:
        mfcc = np.pad(mfcc, ((0,0),(0,max_len-mfcc.shape[1])))
    else:
        mfcc = mfcc[:, :max_len]

    mfcc = mfcc[np.newaxis, np.newaxis, :, :]
    return torch.tensor(mfcc, dtype=torch.float32)

# ================= TRANSCRIPTION =================
def transcribe_audio(file_path):
    result = whisper_model.transcribe(file_path)
    return result["text"].lower()

# ================= KEYWORDS =================
scam_keywords = [
    "otp","bank","account","verify","urgent","blocked","suspend",
    "credit card","loan","refund","investment","crypto","kyc",
    "password","security","congratulations","won","winner","prize",
    "claim","fee","pay","offer","lottery","jackpot","gift","free"
]

def keyword_score(text):
    found = [w for w in scam_keywords if w in text]
    score = 0 if len(found) == 0 else min(len(found)/3, 1.0)
    return score, found

# ================= ML PREDICTION =================
def ml_predict(text):
    X_test = vectorizer.transform([text])
    prob = ml_model.predict_proba(X_test)[0][1]
    return prob

# ================= MAIN =================
def analyze_audio(audio):

    if audio is None:
        return "No audio detected."

    try:
        # TRANSCRIBE
        transcript = transcribe_audio(audio)

        # KEYWORD
        k_score, words = keyword_score(transcript)

        # ML
        ml_score = ml_predict(transcript)

        # CNN (optional)
        cnn_score = 0
        if cnn_loaded:
            features = extract_features(audio).to(device)
            with torch.no_grad():
                out = cnn_model(features)
                probs = torch.softmax(out, dim=1)
                cnn_score = probs[0][1].item()

        # DEBUG PRINTS
        print("Transcript:", transcript)
        print("Keyword Score:", k_score)
        print("ML Score:", ml_score)
        print("CNN Score:", cnn_score)

        # FINAL SCORE (balanced weights)
        final_score = (0.2 * k_score) + (0.5 * ml_score) + (0.3 * cnn_score)

        # THRESHOLD FIXED
        if final_score < 0.40:
            risk = "Low Risk"
            result = "NOT SPAM"
        elif final_score < 0.65:
            risk = "Medium Risk"
            result = "SPAM"
        else:
            risk = "High Scam Risk"
            result = "SPAM"

        return f"""
Transcript: {transcript}

Spam Words Found: {', '.join(words) if words else 'None'}

Scores:
Keyword: {k_score:.2f}
ML: {ml_score:.2f}
CNN: {cnn_score:.2f}

Final Probability: {final_score*100:.2f}%
Risk Level: {risk}
Final Result: {result}
"""

    except Exception as e:
        return f"Error: {str(e)}"

# ================= UI =================
with gr.Blocks() as demo:
    gr.Markdown("# 🎙️ Hybrid Voice Scam Detection System")
    gr.Markdown("Speech + AI + Keyword Detection")

    audio_input = gr.Audio(sources=["microphone", "upload"], type="filepath")
    output = gr.Textbox(lines=12)

    gr.Button("Analyze").click(
        analyze_audio,
        inputs=audio_input,
        outputs=output
    )

demo.launch()