import gradio as gr 
import os 
import torch 


from model import create_effnet_b2
from timeit import default_timer as timer 
from typing import Tuple, Dict

#setup class names 
with open('class_names.txt', 'r') as f:
  class_names = [food.strip() for food in f.readlines()]
 

#Create effnetb2 model 

#create model and transforms preparation 
effnetb2, effnetb2_transforms = create_effnetb2(num_classes = 101)

effnetb2.load_state_dict(
    torch.load(
        f='pretrained_effnetb2_feature_extractor_food101_20_percent.pth',
        map_location = torch.device('cpu')))


#Predict function
def predict(img) -> Tuple[Dict, float]:
    """Transforms and performs a prediction on img and returns prediction and time taken.
    """
    # Start the timer
    start_time = timer()
    
    # Transform the target image and add a batch dimension
    img = effnetb2_transforms(img).unsqueeze(0)
    
    # Put model into evaluation mode and turn on inference mode
    effnetb2.eval()
    with torch.inference_mode():
        # Pass the transformed image through the model and turn the prediction logits into prediction probabilities
        pred_probs = torch.softmax(effnetb2(img), dim=1)
    
    # Create a prediction label and prediction probability dictionary for each prediction class (this is the required format for Gradio's output parameter)
    pred_labels_and_probs = {class_names[i]: float(pred_probs[0][i]) for i in range(len(class_names))}
    
    # Calculate the prediction time
    pred_time = round(timer() - start_time, 5)
    
    # Return the prediction dictionary and prediction time 
    return pred_labels_and_probs, pred_time

### 4. Gradio app ###

# Create title, description and article strings
title = "FoodVision BIG 🍕🥩🍣"
description = "An EfficientNetB2 feature extractor computer vision model to classify 101 classes of food from the food 101 dataset"

# Create examples list from "examples/" directory
example_list = [["examples/" + example] for example in os.listdir("examples")]

# Create the Gradio demo
demo = gr.Interface(fn=predict, # mapping function from input to output
                    inputs=gr.Image(type="pil"), # what are the inputs?
                    outputs=[gr.Label(num_top_classes=5, label="Predictions"), # what are the outputs?
                             gr.Number(label="Prediction time (s)")], # our fn has two outputs, therefore we have two outputs
                    # Create examples list from "examples/" directory
                    examples=example_list, 
                    title=title,
                    description=description
                    )

# Launch the demo!
demo.launch()