#' DNN
#'
#' fits a custom deep neural network using the Multilayer Perceptron architecture. `dnn()` supports the formula syntax and allows to customize the neural network to a maximal degree.
#'
#' @param formula an object of class "\code{\link[stats]{formula}}": a description of the model that should be fitted
#' @param data matrix or data.frame with features/predictors and response variable
#' @param loss loss after which network should be optimized. Can also be distribution from the stats package or own function, see details
#' @param hidden hidden units in layers, length of hidden corresponds to number of layers
#' @param activation activation functions, can be of length one, or a vector of different activation functions for each layer
#' @param validation percentage of data set that should be taken as validation set (chosen randomly)
#' @param bias whether use biases in the layers, can be of length one, or a vector (number of hidden layers + 1 (last layer)) of logicals for each layer.
#' @param alpha add L1/L2 regularization to training  \eqn{(1 - \alpha) * |weights| + \alpha ||weights||^2} will get added for each layer. Can be single integer between 0 and 1 or vector of alpha values if layers should be regularized differently.
#' @param lambda strength of regularization: lambda penalty, \eqn{\lambda * (L1 + L2)} (see alpha)
#' @param dropout dropout rate, probability of a node getting left out during training (see \code{\link[torch]{nn_dropout}})
#' @param optimizer which optimizer used for training the network, for more adjustments to optimizer see \code{\link{config_optimizer}}
#' @param lr learning rate given to optimizer
#' @param batchsize number of samples that are used to calculate one learning rate step
#' @param shuffle if TRUE, data in each batch gets reshuffled every epoch
#' @param epochs epochs the training goes on for
#' @param bootstrap bootstrap neural network or not, numeric corresponds to number of bootstrap samples
#' @param bootstrap_parallel parallelize (CPU) bootstrapping
#' @param lr_scheduler learning rate scheduler created with \code{\link{config_lr_scheduler}}
#' @param plot plot training loss
#' @param verbose print training and validation loss of epochs
#' @param custom_parameters List of parameters/variables to be optimized. Can be used in a custom loss function. See Vignette for example.
#' @param device device on which network should be trained on. mps correspond to M1/M2 GPU devices.
#' @param early_stopping if set to integer, training will stop if loss has gotten higher for defined number of epochs in a row, will use validation loss is available.
#'
#' @details
#'
#' # Loss functions / Likelihoods
#'
#' We support loss functions and likelihoods for different tasks:
#'
#' | Name| Explanation| Example / Task|
#' | :--- | :--- | :--- |
#' | mse | mean squared error |Regression, predicting continuous values|
#' | mae | mean absolute error | Regression, predicting continuous values |
#' | softmax | categorical cross entropy |Multi-class, species classification|
#' | cross-entropy | categorical cross entropy |Multi-class, species classification|
#' | gaussian | Normal likelihood | Regression, residual error is also estimated (similar to `stats::lm()`)	|
#' | binomial | Binomial likelihood | Classification/Logistic regression, mortality|
#' | poisson | Poisson likelihood |Regression, count data, e.g. species abundances|
#'
#' # Training and convergence of neural networks
#'
#' Ensuring convergence can be tricky when training neural networks. Their training is sensitive to a combination of the learning rate (how much the weights are updated in each optimization step), the batch size (a random subset of the data is used in each optimization step), and the number of epochs (number of optimization steps). Typically, the learning rate should be decreased with the size of the neural networks (depth of the network and width of the hidden layers). We provide a baseline loss (intercept only model) that can give hints about an appropriate learning rate:
#'
#' ![](learningrates.jpg "Learning rates")
#'
#' If the training loss of the model doesn't fall below the baseline loss, the learning rate is either too high or too low. If this happens, try higher and lower learning rates.
#'
#' A common strategy is to try (manually) a few different learning rates to see if the learning rate is on the right scale.
#'
#' See the troubleshooting vignette (\code{vignette("B-Training_neural_networks")}) for more help on training and debugging neural networks.
#'
#' # Finding the right architecture
#'
#' As with the learning rate, there is no definitive guide to choosing the right architecture for the right task. However, there are some general rules/recommendations: In general, wider, and deeper neural networks can improve generalization - but this is a double-edged sword because it also increases the risk of overfitting. So, if you increase the width and depth of the network, you should also add regularization (e.g., by increasing the lambda parameter, which corresponds to the regularization strength). Furthermore, in [Pichler & Hartig, 2023](https://arxiv.org/abs/2306.10551), we investigated the effects of the hyperparameters on the prediction performance as a function of the data size. For example, we found that the `selu` activation function outperforms `relu` for small data sizes (<100 observations).
#'
#' We recommend starting with moderate sizes (like the defaults), and if the model doesn't generalize/converge, try larger networks along with a regularization that helps minimize the risk of overfitting (see \code{vignette("B-Training_neural_networks")} ).
#'
#' # Overfitting
#'
#' Overfitting means that the model fits the training data well, but generalizes poorly to new observations. We can use the validation argument to detect overfitting. If the validation loss starts to increase again at a certain point, it often means that the models are starting to overfit your training data:
#'
#' ![](overfitting.jpg "Overfitting")
#'
#' **Solutions**:
#'
#' \itemize{
#'   \item Re-train with epochs = point where model started to overfit
#'   \item Early stopping, stop training when model starts to overfit, can be specified using the `early_stopping=…` argument
#'   \item Use regularization (dropout or elastic-net, see next section)
#' }
#'
#' # Regularization
#'
#' Elastic Net regularization combines the strengths of L1 (Lasso) and L2 (Ridge) regularization. It introduces a penalty term that encourages sparse weight values while maintaining overall weight shrinkage. By controlling the sparsity of the learned model, Elastic Net regularization helps avoid overfitting while allowing for meaningful feature selection. We advise using elastic net (e.g. lambda = 0.001 and alpha = 0.2).
#'
#' Dropout regularization helps prevent overfitting by randomly disabling a portion of neurons during training. This technique encourages the network to learn more robust and generalized representations, as it prevents individual neurons from relying too heavily on specific input patterns. Dropout has been widely adopted as a simple yet effective regularization method in deep learning.
#'
#' By utilizing these regularization methods in your neural network training with the cito package, you can improve generalization performance and enhance the network's ability to handle unseen data. These techniques act as valuable tools in mitigating overfitting and promoting more robust and reliable model performance.
#'
#' # Uncertainty
#'
#' We can use bootstrapping to generate uncertainties for all outputs. Bootstrapping can be enabled by setting `bootstrap = ...` to the number of bootstrap samples to be used. Note, however, that the computational cost can be excessive.
#'
#' In some cases it may be worthwhile to parallelize bootstrapping, for example if you have a GPU and the neural network is small. Parallelization for bootstrapping can be enabled by setting the `bootstrap_parallel = ...` argument to the desired number of calls to run in parallel.
#'
#' # Custom Optimizer and Learning Rate Schedulers
#'
#' When training a network, you have the flexibility to customize the optimizer settings and learning rate scheduler to optimize the learning process. In the cito package, you can initialize these configurations using the \code{\link{config_lr_scheduler}} and \code{\link{config_optimizer}} functions.
#'
#' \code{\link{config_lr_scheduler}} allows you to define a specific learning rate scheduler that controls how the learning rate changes over time during training. This is beneficial in scenarios where you want to adaptively adjust the learning rate to improve convergence or avoid getting stuck in local optima.
#'
#' Similarly, the \code{\link{config_optimizer}} function enables you to specify the optimizer for your network. Different optimizers, such as stochastic gradient descent (SGD), Adam, or RMSprop, offer various strategies for updating the network's weights and biases during training. Choosing the right optimizer can significantly impact the training process and the final performance of your neural network.
#'
#'# How neural networks work
#' In Multilayer Perceptron (MLP) networks, each neuron is connected to every neuron in the previous layer and every neuron in the subsequent layer. The value of each neuron is computed using a weighted sum of the outputs from the previous layer, followed by the application of an activation function. Specifically, the value of a neuron is calculated as the weighted sum of the outputs of the neurons in the previous layer, combined with a bias term. This sum is then passed through an activation function, which introduces non-linearity into the network. The calculated value of each neuron becomes the input for the neurons in the next layer, and the process continues until the output layer is reached. The choice of activation function and the specific weight values determine the network's ability to learn and approximate complex relationships between inputs and outputs.
#'
#' Therefore the value of each neuron can be calculated using: \eqn{ a (\sum_j{ w_j * a_j})}. Where \eqn{w_j} is the weight and \eqn{a_j} is the value from neuron j to the current one. a() is the activation function, e.g. \eqn{ relu(x) = max(0,x)}
#'
#'
#' # Training on graphic cards
#'
#' If you have an NVIDIA CUDA-enabled device and have installed the CUDA toolkit version 11.3 and cuDNN 8.4, you can take advantage of GPU acceleration for training your neural networks. It is crucial to have these specific versions installed, as other versions may not be compatible.
#' For detailed installation instructions and more information on utilizing GPUs for training, please refer to the [mlverse: 'torch' documentation](https://torch.mlverse.org/docs/articles/installation.html).
#'
#' Note: GPU training is optional, and the package can still be used for training on CPU even without CUDA and cuDNN installations.
#'
#' @return an S3 object of class \code{"cito.dnn"} is returned. It is a list containing everything there is to know about the model and its training process.
#' The list consists of the following attributes:
#' \item{net}{An object of class "nn_sequential" "nn_module", originates from the torch package and represents the core object of this workflow.}
#' \item{call}{The original function call}
#' \item{loss}{A list which contains relevant information for the target variable and the used loss function}
#' \item{data}{Contains data used for training the model}
#' \item{weigths}{List of weights for each training epoch}
#' \item{use_model_epoch}{Integer, which defines which model from which training epoch should be used for prediction. 1 = best model, 2 = last model}
#' \item{loaded_model_epoch}{Integer, shows which model from which epoch is loaded currently into model$net.}
#' \item{model_properties}{A list of properties of the neural network, contains number of input nodes, number of output nodes, size of hidden layers, activation functions, whether bias is included and if dropout layers are included.}
#' \item{training_properties}{A list of all training parameters that were used the last time the model was trained. It consists of learning rate, information about an learning rate scheduler, information about the optimizer, number of epochs, whether early stopping was used, if plot was active, lambda and alpha for L1/L2 regularization, batchsize, shuffle, was the data set split into validation and training, which formula was used for training and at which epoch did the training stop.}
#' \item{losses}{A data.frame containing training and validation losses of each epoch}
#' @import checkmate
#' @example /inst/examples/dnn-example.R
#' @author Christian Amesoeder, Maximilian Pichler
#' @seealso \code{\link{predict.citodnn}}, \code{\link{plot.citodnn}},  \code{\link{coef.citodnn}},\code{\link{print.citodnn}}, \code{\link{summary.citodnn}}, \code{\link{continue_training}}, \code{\link{analyze_training}}, \code{\link{PDP}}, \code{\link{ALE}},
#' @export
dnn <- function(formula,
                data = NULL,
                loss = c("mse", "mae", "softmax", "cross-entropy", "gaussian", "binomial", "poisson"),
                hidden = c(50L, 50L),
                activation = c("relu", "leaky_relu", "tanh", "elu", "rrelu", "prelu", "softplus",
                               "celu", "selu", "gelu", "relu6", "sigmoid", "softsign", "hardtanh",
                               "tanhshrink", "softshrink", "hardshrink", "log_sigmoid"),
                validation = 0,
                bias = TRUE,
                lambda = 0.0,
                alpha = 0.5,
                dropout = 0.0,
                optimizer = c("sgd","adam","adadelta", "adagrad", "rmsprop", "rprop"),
                lr = 0.01,
                batchsize = 32L,
                shuffle = TRUE,
                epochs = 100,
                bootstrap = NULL,
                bootstrap_parallel = FALSE,
                plot = TRUE,
                verbose = TRUE,
                lr_scheduler = NULL,
                custom_parameters = NULL,
                device = c("cpu","cuda", "mps"),
                early_stopping = FALSE) {
  checkmate::assert(checkmate::checkMatrix(data), checkmate::checkDataFrame(data))
  checkmate::qassert(activation, "S+[1,)")
  checkmate::qassert(bias, "B+")
  checkmate::qassert(lambda, "R1[0,)")
  checkmate::qassert(validation, "R1[0,1)")
  checkmate::qassert(dropout, "R+[0,1)")
  checkmate::qassert(lr, "R+[0,)")
  checkmate::qassert(plot,"B1")
  checkmate::qassert(verbose,"B1")
  checkmate::qassert(early_stopping,c("R1[1,)","B1"))
  checkmate::qassert(device, "S+[3,)")

  device <- match.arg(device)
  if(identical (activation, c("relu", "leaky_relu", "tanh", "elu", "rrelu", "prelu", "softplus",
                              "celu", "selu", "gelu", "relu6", "sigmoid", "softsign", "hardtanh",
                              "tanhshrink", "softshrink", "hardshrink", "log_sigmoid"))) activation<- "relu"
  if(!is.function(loss) & !inherits(loss,"family")){
    loss <- match.arg(loss)
  }
  device_old = device
  device = check_device(device)

  ### Generate X & Y data ###
  if(!is.data.frame(data)) data <- data.frame(data)
  old_formula = formula
  if(!is.null(formula)){
    fct_call <- match.call()
    m <- match("formula", names(fct_call))
    if(inherits(fct_call[3]$formula, "name")) fct_call[3]$formula <- eval(fct_call[3]$formula, envir = parent.env(environment()))
    formula <- stats::as.formula(fct_call[m]$formula)
  } else {
    formula <- stats::as.formula("~.")
  }
  X <- stats::model.matrix(formula, data)
  Y <- stats::model.response(stats::model.frame(formula, data))
  ylvls <- NULL
  if(is.factor(Y)) ylvls <- levels(Y)
  if(!inherits(Y, "matrix")) Y = as.matrix(Y)



  loss_obj <- get_loss(loss)

  responses = NULL
  response_column = NULL
  responses = ylvls
  if(is.null(responses)) responses = as.character(LHSForm(formula))
  if(inherits(loss_obj$call, "character")) { if(loss_obj$call == "softmax") response_column = as.character(LHSForm(formula)) }
  if(ncol(Y) > 1) responses = colnames(Y)

  if(!is.null(loss_obj$parameter)) loss_obj$parameter <- list(scale = loss_obj$parameter)
  if(!is.null(custom_parameters)){
    if(!inherits(custom_parameters,"list")){
      warning("custom_parameters has to be list")
    }else{
      custom_parameters<- lapply(custom_parameters,function(x) torch::torch_tensor(x, requires_grad = TRUE, device = device))
      loss_obj$parameter <- append(loss_obj$parameter, unlist(custom_parameters))

      }
  }

  y_dim <- ncol(Y)
  y_dtype <- torch::torch_float32()
  if(is.character(Y)) {
    y_dim <- length(unique(as.integer(as.factor(Y[,1]))))
    Y <- matrix(as.integer(as.factor(Y[,1])), ncol = 1L)
    if(inherits(loss_obj$call, "family")){
      if(loss_obj$call$family == "binomial") {
        Y <- torch::as_array(torch::nnf_one_hot(torch::torch_tensor(Y, dtype=torch::torch_long() ))$squeeze())
        Y_base = matrix(apply(as.matrix(Y), 2, mean), nrow(Y), ncol(Y), byrow = TRUE)

      }}
  }

  Y_base = matrix(apply(as.matrix(Y), 2, mean), nrow(Y), ncol(Y), byrow = TRUE)

  if(!is.function(loss_obj$call)){
    if(all(loss_obj$call == "softmax")) {
      prop = as.vector(table(Y)/sum(table(Y)))
        Y_base = matrix(prop, nrow = dim(X)[1], ncol = length(prop), byrow = TRUE) #  *stats::model.matrix(~0+., data = data.frame(Y = as.factor(Y)))
        y_dtype = torch::torch_long()
      }
  }


  if(is.null(bootstrap)) {

    loss.fkt <- loss_obj$loss
    if(!is.null(loss_obj$parameter)) list2env(loss_obj$parameter,envir = environment(fun= loss.fkt))
    base_loss = as.numeric(loss.fkt(loss_obj$link(torch::torch_tensor(as.matrix(Y_base))), torch::torch_tensor(as.matrix(Y), dtype = y_dtype))$mean())

    ### dataloader  ###
    if(validation != 0){
      valid <- sort(sample(c(1:nrow(X)),replace=FALSE,size = round(validation*nrow(X))))
      train <- c(1:nrow(X))[-valid]
      train_dl <- get_data_loader(X[train,],Y[train,], batch_size = batchsize, shuffle = shuffle, y_dtype=y_dtype)
      valid_dl <- get_data_loader(X[valid,],Y[valid,], batch_size = batchsize, shuffle = shuffle, y_dtype=y_dtype)

    }else{
      train_dl <- get_data_loader(X,Y, batch_size = batchsize, shuffle = shuffle, y_dtype=y_dtype)
      valid_dl <- NULL
    }
    if((length(hidden)+1) != length(alpha)) alpha <- rep(alpha,length(hidden)+1)

    net <- build_model(input = ncol(X), output = y_dim,
                      hidden = hidden, activation = activation,
                      bias = bias, dropout = dropout)
    model_properties <- list(input = ncol(X),
                             output = y_dim,
                             hidden = hidden,
                             activation = activation,
                             bias = bias,
                             dropout = dropout)
    training_properties <- list(lr = lr,
                               lr_scheduler = lr_scheduler,
                               optimizer = optimizer,
                               epochs = epochs,
                               early_stopping = early_stopping,
                               plot = plot,
                               validation = validation,
                               lambda = lambda,
                               alpha = alpha,
                               batchsize = batchsize,
                               shuffle = shuffle,
                               formula = formula)
    out <- list()
    class(out) <- "citodnn"
    out$net <- net
    out$call <- match.call()
    out$call$formula <- stats::terms.formula(formula,data = data)
    out$loss <- loss_obj
    out$data <- list(X = X, Y = Y, data = data)
    out$data$xlvls <- lapply(data[,sapply(data, is.factor), drop = F], function(j) levels(j) )
    out$base_loss = base_loss
    if(!is.null(ylvls))  {
      out$data$ylvls <- ylvls
      out$data$xlvls <- out$data$xlvls[-which(as.character(formula[2]) == names(out$data$xlvls))]
    }
    if(validation != 0) out$data <- append(out$data, list(validation = valid))
    out$weights <- list()
    out$use_model_epoch <- 1
    out$loaded_model_epoch <- 0
    out$model_properties <- model_properties
    out$training_properties <- training_properties
    out$device = device_old
    out$responses = responses

    ### training loop ###
    out <- train_model(model = out,epochs = epochs, device = device, train_dl = train_dl, valid_dl = valid_dl, verbose = verbose)


  } else {
    out <- list()
    class(out) <- "citodnnBootstrap"


    if(bootstrap_parallel == FALSE) {
      pb = progress::progress_bar$new(total = bootstrap, format = "[:bar] :percent :eta", width = round(getOption("width")/2))
      models = list()

      for(b in 1:bootstrap) {
        indices <- sample(nrow(data),replace = TRUE)
        m = do.call(dnn, args = list(
          formula = formula, data = data[indices,], loss = loss, hidden = hidden, activation = activation,
          bias = bias, validation = validation,lambda = lambda, alpha = alpha,lr = lr, dropout = dropout,
          optimizer = optimizer,batchsize = batchsize,shuffle = shuffle, epochs = epochs, plot = FALSE, verbose = FALSE,
          bootstrap = NULL, device = device_old, custom_parameters = custom_parameters, lr_scheduler = lr_scheduler, early_stopping = early_stopping,
          bootstrap_parallel = FALSE
        ))
        pb$tick()
        models[[b]] = m
      }

    } else {
      if(is.logical(bootstrap_parallel)) {
        if(bootstrap_parallel) {
          bootstrap_parallel = parallel::detectCores() -1
        }
      }
      if(is.numeric(bootstrap_parallel)) {
        backend = parabar::start_backend(bootstrap_parallel)
        parabar::export(backend, ls(environment()), environment())
      }
      parabar::configure_bar(type = "modern", format = "[:bar] :percent :eta", width = round(getOption("width")/2))
      models <- parabar::par_lapply(backend, 1:bootstrap, function(i) {
        indices <- sample(nrow(data),replace = TRUE)
        m = do.call(dnn, args = list(
          formula = formula, data = data[indices,], loss = loss, hidden = hidden, activation = activation,
          bias = bias, validation = validation,lambda = lambda, alpha = alpha,lr = lr, dropout = dropout,
          optimizer = optimizer,batchsize = batchsize,shuffle = shuffle, epochs = epochs, plot = FALSE, verbose = FALSE,
          bootstrap = NULL, device = device_old, custom_parameters = custom_parameters, lr_scheduler = lr_scheduler, early_stopping = early_stopping,
          bootstrap_parallel = FALSE
        ))
        m
      })
      if(!is.null(backend)) parabar::stop_backend(backend)

    }

    out$models <- models
    out$data <- list(X = X, Y = Y, data = data)
    out$device = device_old
    out$responses = responses
    out$loss = loss_obj$call
    out$response_column = response_column
  }
  return(out)
}

#' Print class citodnn
#'
#' @param x a model created by \code{\link{dnn}}
#' @param ... additional arguments
#' @return prediction matrix
#' @example /inst/examples/print.citodnn-example.R
#' @return original object x gets returned
#' @export
print.citodnn <- function(x,...){
  x <- check_model(x)
  print(x$call)
  print(x$net)
  return(invisible(x))
}

#' @rdname print.citodnn
#' @export
print.citodnnBootstrap <- function(x,...){
  x$models <- lapply(x$models, check_model)
  print(x$models[[1]]$net)
  return(invisible(x))
}

#' Extract Model Residuals
#'
#' Returns residuals of training set.
#'
#' @param object a model created by \code{\link{dnn}}
#' @param ... no additional arguments implemented
#' @return residuals of training set
#' @export
residuals.citodnn <- function(object,...){
  object <- check_model(object)
  out <- data.frame(
    true = object$data$Y,
    pred = stats::predict(object, object$data$data)
  )
  return(out)
}





#' Summarize Neural Network of class citodnn
#'
#' Performs a Feature Importance calculation based on Permutations
#'
#' @details
#'
#' Performs the feature importance calculation as suggested by  Fisher, Rudin, and Dominici (2018), and the mean and standard deviation of the average conditional Effects as suggested by Pichler & Hartig (2023).
#'
#' Feature importances are in their interpretation similar to a ANOVA. Main and interaction effects are absorbed into the features. Also, feature importances are prone to collinearity between features, i.e. if two features are collinear, the importances might be overestimated.
#'
#' Average conditional effects (ACE) are similar to marginal effects and approximate linear effects, i.e. their interpretation is similar to effects in a linear regression model.
#'
#' The standard deviation of the ACE informs about the non-linearity of the feature effects. Higher values correlate with stronger non-linearities.
#'
#' For each feature n permutation get done and original and permuted predictive mean squared error (\eqn{e_{perm}} & \eqn{e_{orig}}) get evaluated with \eqn{ FI_j= e_{perm}/e_{orig}}. Based on Mean Squared Error.
#'
#' @param object a model of class citodnn created by \code{\link{dnn}}
#' @param n_permute number of permutations performed. Default is \eqn{3 * \sqrt{n}}, where n euqals then number of samples in the training set
#' @param device for calculating variable importance and conditional effects
#' @param ... additional arguments
#' @return summary.citodnn returns an object of class "summary.citodnn", a list with components
#' @export
summary.citodnn <- function(object, n_permute = NULL, device = NULL, ...){
  object <- check_model(object)
  out <- list()
  class(out) <- "summary.citodnn"
  if(is.null(device)) device = object$device
  out$importance <- get_importance(object, n_permute, device)
  out$conditionalEffects = conditionalEffects(object, device = device)
  out$ACE = sapply(out$conditionalEffects, function(R) diag(R$mean))
  colnames(out$ACE) = paste0("Response_", 1:ncol(out$ACE))
  out$ASCE = sapply(out$conditionalEffects, function(R) diag(R$sd))
  colnames(out$ASCE) = paste0("Response_", 1:ncol(out$ASCE))
  rownames(out$ASCE) = rownames(out$ACE)
  return(out)
}



#' Print method for class summary.citodnn
#'
#' @param x a summary object created by \code{\link{summary.citodnn}}
#' @param ... additional arguments
#' @return List with Matrices for importance, average CE, absolute sum of CE, and standard deviation of the CE
#' @export
print.summary.citodnn <- function(x, ... ){
  out = list()
  cat("Summary of Deep Neural Network Model\n")
  cat("\nFeature Importance:\n")
  print(x$importance)
  cat("\nAverage Conditional Effects:\n")
  print(x$ACE)
  cat("\nStandard Deviation of Conditional Effects:\n")
  print(x$ASCE)
  out$importance = x$importance
  out$ACE = x$ACE
  out$ASCE = x$ASCE
  return(invisible(out))
}



#' @rdname summary.citodnn
#' @export
summary.citodnnBootstrap <- function(object, n_permute = NULL, device = NULL, ...){
  object$models <- lapply(object$models, check_model)
  out <- list()
  class(out) <- "summary.citodnnBootstrap"
  if(is.null(device)) device = object$device
  out$importance <- lapply(object$models, function(m) get_importance(m, n_permute, device = device))
  out$conditionalEffects <- lapply(object$models, function(m) conditionalEffects(m, device = device))

  if(!is.null(out$importance[[1]])){
    res_imps = list()
    for(i in 2:ncol(out$importance[[1]])) {
      tmp = sapply(out$importance, function(X) X[,i])
      imps = apply(tmp, 1, mean) - 1
      imps_se = apply(tmp, 1, stats::sd)

      coefmat = cbind(
        as.vector(as.matrix(imps)),
        as.vector(as.matrix(imps_se)),
        as.vector(as.matrix(imps/imps_se)),
        as.vector(as.matrix(stats::pnorm(abs(imps/imps_se), lower.tail = FALSE)*2))
      )
      colnames(coefmat) = c("Importance", "Std.Err", "Z value", "Pr(>|z|)")
      resp = object$responses[i-1]
      if(inherits(object$loss, "character")) { if(object$loss == "softmax") resp = object$response_column }
      rownames(coefmat) = paste0(out$importance[[1]]$variable, " \U2192 ", resp)
      if(ncol(out$importance[[1]]) > 2) coefmat = rbind(coefmat, c(NA))
      res_imps[[i-1]] = coefmat
    }
    out$importance_coefmat = do.call(rbind, res_imps)
  } else {
    out$importance_coefmat = NULL
  }


  res_ACE = list()

  for(i in 1:length(out$conditionalEffects[[1]])) {
    tmp = sapply(1:length(out$conditionalEffects), function(j) diag(out$conditionalEffects[[j]][[i]]$mean))
    eff = apply(tmp, 1, mean)
    eff_se = apply(tmp, 1, stats::sd)

    coefmat = cbind(
      as.vector(as.matrix(eff)),
      as.vector(as.matrix(eff_se)),
      as.vector(as.matrix(eff/eff_se)),
      as.vector(as.matrix(stats::pnorm(abs(eff/eff_se), lower.tail = FALSE)*2))
    )
    colnames(coefmat) = c("ACE", "Std.Err", "Z value", "Pr(>|z|)")
    rownames(coefmat) = paste0( rownames(out$conditionalEffects[[1]][[1]]$mean), " \U2192 ", object$responses[i])
    if(i != length(out$conditionalEffects[[1]])) coefmat = rbind(coefmat, c(NA))
    res_ACE[[i]] = coefmat
  }
  out$ACE_coefmat = do.call(rbind, res_ACE)


  res_ASCE = list()

  for(i in 1:length(out$conditionalEffects[[1]])) {
    tmp = sapply(1:length(out$conditionalEffects), function(j) diag(out$conditionalEffects[[j]][[i]]$sd))
    eff = apply(tmp, 1, mean)
    eff_se = apply(tmp, 1, stats::sd)

    coefmat = cbind(
      as.vector(as.matrix(eff)),
      as.vector(as.matrix(eff_se)),
      as.vector(as.matrix(eff/eff_se)),
      as.vector(as.matrix(stats::pnorm(abs(eff/eff_se), lower.tail = FALSE)*2))
    )
    colnames(coefmat) = c("ACE", "Std.Err", "Z value", "Pr(>|z|)")
    rownames(coefmat) = paste0(rownames(out$conditionalEffects[[1]][[1]]$mean), " \U2192 ", object$responses[i])
    if(i != length(out$conditionalEffects[[1]])) coefmat = rbind(coefmat, c(NA))
    res_ASCE[[i]] = coefmat
  }
  out$ASCE_coefmat = do.call(rbind, res_ASCE)

  return(out)
}


#' @rdname print.summary.citodnn
#' @export
print.summary.citodnnBootstrap <- function(x, ... ){
  out = list()
  cat("Summary of Deep Neural Network Model\n\n")
  #cat("\t##########################################################\n")
  cli::cli_h3(cli::style_bold("Feature Importance \n"))
  #cat("\t##########################################################\n")
  #cat("\nFeature Importance:\n")

  if(!is.null(x$importance_coefmat)) stats::printCoefmat(x$importance_coefmat, signif.stars = getOption("show.signif.stars"), digits = 3, na.print = "")


  #cat("\n\n\t##########################################################\n")
  cat("\n\n")
  cli::cli_h3(cli::style_bold("Average Conditional Effects"))
  #cat("\t##########################################################\n")

  #cat("\nAverage Conditional Effects:\n")
  stats::printCoefmat(x$ACE_coefmat, signif.stars = getOption("show.signif.stars"), digits = 3, na.print = "")

  #cat("\n\n\t##########################################################\n")
  cat("\n\n")
  cli::cli_h3(cli::style_bold("Standard Deviation of Conditional Effects \n"))
  #cat("\t##########################################################\n")
  #cat("\nAbsolute sum of Conditional Effects:\n")

  res_ASCE = list()

  stats::printCoefmat(x$ASCE_coefmat, signif.stars = getOption("show.signif.stars"), digits = 3, na.print = "")


  out$importance = x$res_imps
  out$ACE = x$res_ACE
  out$AbsCE = x$res_ASCE
  return(invisible(out))
}


#' Returns list of parameters the neural network model currently has in use
#'
#' @param object a model created by \code{\link{dnn}}
#' @param ... nothing implemented yet
#' @return list of weights of neural network
#'
#' @example /inst/examples/coef.citodnn-example.R
#' @export
coef.citodnn <- function(object,...){
  return(object$weights[object$use_model_epoch])
}

#' @rdname coef.citodnn
#' @export
coef.citodnnBootstrap <- function(object, ...) {
  return(lapply(object$models, stats::coef))
}


#' Predict from a fitted dnn model
#'
#' @param object a model created by \code{\link{dnn}}
#' @param newdata new data for predictions
#' @param type which value should be calculated, either raw response, output of link function or predicted class (in case of classification)
#' @param device device on which network should be trained on.
#' @param ... additional arguments
#' @return prediction matrix
#'
#' @example /inst/examples/predict.citodnn-example.R
#' @export
predict.citodnn <- function(object, newdata = NULL, type=c("link", "response", "class"), device = c("cpu","cuda", "mps"),...) {

  checkmate::assert( checkmate::checkNull(newdata),
                     checkmate::checkMatrix(newdata),
                     checkmate::checkDataFrame(newdata),
                     checkmate::checkScalarNA(newdata))
  object <- check_model(object)

  type <- match.arg(type)

  device <- match.arg(device)

  if(type %in% c("link","class")) {
    link <- object$loss$invlink
  }else{
    link = function(a) a
  }

  device <- check_device(device)

  object$net$to(device = device)

  ### TO DO: use dataloaders via get_data_loader function
  if(is.null(newdata)){
    newdata = torch::torch_tensor(object$data$X, device = device)
  } else {
    if(is.data.frame(newdata)) {
      newdata <- stats::model.matrix(stats::as.formula(stats::delete.response(object$call$formula)), newdata,xlev = object$data$xlvls)
    } else {
      newdata <- stats::model.matrix(stats::as.formula(stats::delete.response(object$call$formula)), data.frame(newdata),xlev = object$data$xlvls)
    }
    newdata <- torch::torch_tensor(newdata, device = device)
  }

  pred <- torch::as_array(link(object$net(newdata))$to(device="cpu"))

  if(!is.null(object$data$ylvls)) colnames(pred) <- object$data$ylvls
  if(type == "class") pred <- as.factor(apply(pred,1, function(x) object$data$ylvls[which.max(x)]))

  rownames(pred) <- rownames(newdata)


  return(pred)
}




#' @rdname predict.citodnn
#' @export
predict.citodnnBootstrap <- function(object, newdata = NULL, type=c("link", "response", "class"), device = c("cpu","cuda", "mps"),...) {

  checkmate::assert( checkmate::checkNull(newdata),
                     checkmate::checkMatrix(newdata),
                     checkmate::checkDataFrame(newdata),
                     checkmate::checkScalarNA(newdata))

  if(is.null(newdata)) newdata = object$data$X

  predictions = lapply(object$models, function(m) stats::predict(m, newdata = newdata, type = type, device = device))
  return(abind::abind(predictions, along = 0L))
}




#' Creates graph plot which gives an overview of the network architecture.
#'
#' @param x a model created by \code{\link{dnn}}
#' @param node_size size of node in plot
#' @param scale_edges edge weight gets scaled according to other weights (layer specific)
#' @param ... no further functionality implemented yet
#' @return A plot made with 'ggraph' + 'igraph' that represents the neural network
#' @example /inst/examples/plot.citodnn-example.R
#' @export
plot.citodnn<- function(x, node_size = 1, scale_edges = FALSE,...){

  sapply(c("igraph","ggraph","ggplot2"),function(x)
    if (!requireNamespace(x, quietly = TRUE)) {
      stop(
        paste0("Package \"",x,"\" must be installed to use this function."),
        call. = FALSE
      )
    })
  checkmate::qassert(node_size, "R+[0,)")
  checkmate::qassert(scale_edges, "B1")

  weights <- coef.citodnn(x)
  input <- ncol(weights[[1]][1][[1]])-1
  structure <- data.frame(expand.grid(from=paste0("1;",c(1:input)),
                                      to = paste0("2;",c(1:(nrow(weights[[1]][1][[1]]))))),
                          value = scale(c(t(weights[[1]][1][[1]][1:input])), center=scale_edges,scale= scale_edges))
  x_pos<- c(rep(1,input))
  y_pos<- c(0,rep(1:input,each=2) *c(1,-1))[1:input]
  num_layer <-  2

  if(length(weights[[1]])>1){
    for (i in 2:length(weights[[1]])){
      if (grepl("weight",names(weights[[1]][i]))){
        structure <- rbind(structure, data.frame(expand.grid(from=paste0(num_layer,";",c(1:(ncol(weights[[1]][i][[1]])))),
                                                             to = paste0(num_layer + 1,";",c(1:(nrow(weights[[1]][i][[1]]))))),
                                                 value= scale(c(t(weights[[1]][i][[1]])), center=scale_edges,scale= scale_edges)))
        x_pos <- c(x_pos, rep(num_layer, x$model_properties$hidden[num_layer-1]))
        y_pos <- c(y_pos, c(0,rep(1:x$model_properties$hidden[num_layer-1],each=2) *c(1,-1))[1:x$model_properties$hidden[num_layer-1]])
        num_layer <- num_layer + 1

      }
    }
  }
  x_pos <- c(x_pos, rep(num_layer,x$model_properties$output))
  y_pos <- c(y_pos, c(0,rep(1:input,each=2) *c(1,-1))[1:x$model_properties$output])


  graph<- igraph::graph_from_data_frame(structure)
  layout <- ggraph::create_layout(graph, layout= "manual", x = x_pos, y = y_pos)

  p<- ggraph::ggraph(layout)+
    ggraph::geom_edge_link( ggplot2::aes(width = abs(structure$value))) +
    ggraph::geom_node_point(size = node_size)
  print(p)
}


#' @rdname plot.citodnn
#' @param which_model which model from the ensemble should be plotted
#' @export
plot.citodnnBootstrap <- function(x, node_size = 1, scale_edges = FALSE,which_model = 1,...){
 plot(x$models[[which_model]], node_size = node_size, scale_edges = scale_edges)
}