import torch 
import torch.nn as nn
import torch.optim as optim
import torchvision
from torch.utils.data import DataLoader
import pandas as pd



def train_epoch(model, train_loader, val_loader, criterion, optimizer):
    model.train()
    train_loss = 0
    val_loss = 0
    for i, (data, target) in enumerate(train_loader):
        optimizer.zero_grad()
        
        output = model(data)
        loss = criterion(output, target)
        loss.backward()
        optimizer.step()
        
        train_loss += loss.item()
        
    train_loss /= len(train_loader)
    
    model.eval()
    with torch.no_grad():
        for i, (data, target) in enumerate(val_loader):
            output = model(data)
            loss = criterion(output, target)
            val_loss += loss.item()
        val_loss /= len(val_loader)
        
    return train_loss, val_loss

def evaluate_accuracy(model, loader):
    model.eval()
    correct = 0
    total = 0
    predictions = []
    actual = []
    
    with torch.no_grad():
        for data, target in loader:
            output = model(data)
            _, predicted = torch.max(output.data, 1)
            total += target.size(0)
            correct += (predicted == target).sum().item()
            
            out = output[:, 1].tolist()
            predictions.extend(out)
            
            act = target[:, 1].tolist()
            actual.extend(act)
            
    return correct / total, predictions, actual

def train_model(model, train_loader, val_loader, criterion, optimizer, config):
    
    history = pd.DataFrame(columns = ["Epoch", "Train Loss", "Val Loss", "Train Acc","Val Acc"]).set_index("Epoch")
    
    
    for epoch in range(config["training"]["max_epochs"]):
        train_loss, val_loss = train_epoch(model, train_loader, val_loader, criterion, optimizer)
        if config["operation"]["silent"] is False: print(f"Epoch {epoch + 1} - Train Loss: {train_loss} - Val Loss: {val_loss}")
        
        train_acc, _, _ = evaluate_accuracy(model, train_loader)
        val_acc, _, _ = evaluate_accuracy(model, val_loader)
        
        history.loc[epoch] = [train_loss, val_loss, train_acc, val_acc]
        
    return history