### 1. Imports and class names setup ###
import gradio as gr
import os
import torch

from model import create_effnetb0
from timeit import default_timer as timer
from typing import Tuple, Dict

# Setup class names
class_names = ['cup_cakes', 'donuts', 'french_fries', 'ice_cream']

### 2. Model and transforms preparation ###

# Create EffNetB0 model
effnetb0, effnetb0_transforms = create_effnetb0()

# Load saved weights
effnetb0.load_state_dict(
    torch.load(
        f="effnetb0_data20_10epoch.pth",
        map_location=torch.device("cpu"),  # load to CPU
    )
)


### 3. Predict function ###

# Create 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 = effnetb0_transforms(img).unsqueeze(0)

    # Put model into evaluation mode and turn on inference mode
    effnetb0.eval()
    with torch.inference_mode():
        # Pass the transformed image through the model and turn the prediction logits into prediction probabilities
        pred_probs = torch.softmax(effnetb0(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 = "Food Classifier"
description = "An EfficientNetB0 feature extractor computer vision model to classify images of French_fries, Cup_cakes, Ice_Cream, and Donuts."
article = "Created at google collab. Documentation at https://medium.com/me/stories/public, Code repository at https://github.com/Alyxx-The-Sniper/CNN "

# 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=4, 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,
                    article=article)

# Launch the demo!
demo.launch()