app.py

from fastapi import FastAPI, File, UploadFile, Body
from fastapi.responses import RedirectResponse
from fastapi.middleware.cors import CORSMiddleware
from PIL import Image
import io
import numpy as np
from structure import ImagePredictionResponse, TextPredictionRequest, TextPredictionResponse, PredictionEntry
from textPreprocess import predict_text
from imagePreprocess import CNNPredict, CLIPPredict
import tensorflow as tf

origins=[
    "http://localhost:5173",
    "http://localhost",
    "https://authentica-ai.vercel.app",
]

app = FastAPI(
    title="Authentica API",
    description=(
        "Simple demo API for image and text prediction. "
        "Upload an image to `/predict/image` or POST text to `/predict/text`."
    ),
    version="0.1.0",
)
app.add_middleware(
    CORSMiddleware,
    allow_origins=origins,
    allow_credentials=True,
    allow_methods=["*"],
    allow_headers=["*"],
)

@app.get("/", include_in_schema=False)
async def root():
    # Redirect to the automatic Swagger UI provided by FastAPI
    return RedirectResponse(url="/docs")

@app.post(
    "/predict/image",
    response_model=ImagePredictionResponse,
    summary="Predict image using all available models",
    description="Upload an image file (jpg/png). It is evaluated on all 3 models and class index/confidence is returned.",
)
async def predict(image: UploadFile = File(...)):
    """Accept an image upload and return a prediction using loaded model."""
    
    image_data = await image.read()
    pil_img = Image.open(io.BytesIO(image_data)).convert("RGB")
    
    predictions=[]
    cnnPred = CNNPredict(pil_img)
    if isinstance(cnnPred, str):
        # An error occurred during CNN prediction
        print("CNN preprocessing error:", cnnPred)
        predictions.append(PredictionEntry(model="CNN", error=cnnPred, predicted_class=-1, confidence=0.0))
    else:
        cnn_class = 1 if cnnPred >= 0.5 else 0
        cnn_conf = cnnPred if cnnPred >= 0.5 else 1 - cnnPred
        predictions.append(  PredictionEntry(model="CNN", predicted_class=cnn_class, confidence=round(float(cnn_conf), 4)))
    clipPred = CLIPPredict(pil_img)
    if isinstance(clipPred, str):
        # An error occurred during CLIP prediction
        print("CLIP error:", clipPred)
        predictions.append(PredictionEntry(model="CLIP", error=clipPred, predicted_class=-1, confidence=0.0))
    else:
        clip_class = 1 if clipPred > 0.5 else 0
        clip_conf = clipPred if clipPred >= 0.5 else 1 - clipPred
        predictions.append(  PredictionEntry(model="CLIP", predicted_class=clip_class, confidence=round(float(clip_conf), 4)))
    #print(f"CNN Prediction (AI prob): {cnnPred:.4f}")
    #print(f"ResNet Prediction (AI prob): {resnetPred:.4f}")
    #print(f"CLIP Prediction (AI prob): {clipPred:.4f}")
    #Predicted classes 1 is Real, 0 is AI
    return ImagePredictionResponse(predictions=predictions)

@app.post(
    "/predict/text",
    response_model=TextPredictionResponse,
    summary="Predict text",
    description="POST a JSON body with `text` to get a predicted label and confidence.",
)
async def predict_text_endpoint(payload: TextPredictionRequest = Body(...)):
    """Accept a text string and return a prediction of whether it's human or AI-generated."""
    try:
        # Use the text prediction function from textPreprocess.py
        result = predict_text(payload.text)
        
        return TextPredictionResponse(
            predicted_class=result["predicted_class"], 
            confidence_ai=result["confidence_ai"],
            confidence_human=result["confidence_human"]
        )
    except Exception as e:
        # Return a fallback response in case of error
        print(f"Error in text prediction: {e}")
        return TextPredictionResponse(predicted_class="Human", confidence_ai=-100.0, confidence_human=-100.0)