skip_if_no_torch = function() {
    skip_if_not_installed("torch")
    skip_if_not(torch::torch_is_installed(), "Torch backend not available")
}

test_that("Tuning mlp_kindling with grid_depth works", {
    skip_if_not_installed("parsnip")
    skip_if_not_installed("workflows")
    skip_if_not_installed("tune")
    skip_if_not_installed("rsample")
    skip_if_not_installed("recipes")
    skip_if_not_installed("dials")
    skip_if_no_torch()
    
    mlp_spec = mlp_kindling(
        mode = "classification",
        hidden_neurons = tune::tune(),
        activations = tune::tune(),
        output_activation = tune::tune(),
        epochs = 10
    )
    
    iris_recipe = recipes::recipe(Species ~ ., data = iris)
    wf = workflows::workflow() |>
        workflows::add_recipe(iris_recipe) |>
        workflows::add_model(mlp_spec)
    
    set.seed(123)
    folds = rsample::vfold_cv(iris, v = 2)
    
    grid = grid_depth(
        hidden_neurons(c(16L, 32L)),
        activations(c("relu", "elu")),
        output_activation(c("sigmoid", "linear")),
        n_hlayer = 2,
        size = 3,
        type = "random"
    )
    
    expect_s3_class(grid, "tbl_df")
    expect_equal(nrow(grid), 3)
    expect_true("hidden_neurons" %in% names(grid))
    expect_true("activations" %in% names(grid))
    expect_true("output_activation" %in% names(grid))
    expect_true(is.list(grid$hidden_neurons))
    expect_true(is.list(grid$activations))
    expect_equal(length(grid$hidden_neurons[[1]]), 2)
    expect_equal(length(grid$activations[[1]]), 2)
    
    out = tune::tune_grid(
        wf,
        resamples = folds,
        grid = grid,
        control = tune::control_grid(save_pred = FALSE)
    )
    
    expect_s3_class(out, "tune_results")
    expect_true(nrow(tune::collect_metrics(out)) > 0)
})

test_that("Tuning mlp_kindling with latin_hypercube grid works", {
    skip_if_not_installed("lhs")
    skip_if_not_installed("parsnip")
    skip_if_not_installed("workflows")
    skip_if_not_installed("tune")
    skip_if_no_torch()
    
    mlp_spec = mlp_kindling(
        mode = "regression",
        hidden_neurons = tune::tune(),
        activations = tune::tune(),
        epochs = 5
    )
    
    mtcars_recipe = recipes::recipe(mpg ~ ., data = mtcars)
    wf = workflows::workflow() |>
        workflows::add_recipe(mtcars_recipe) |>
        workflows::add_model(mlp_spec)
    
    set.seed(456)
    folds = rsample::vfold_cv(mtcars, v = 2)
    
    grid = grid_depth(
        hidden_neurons(c(8L, 32L)),
        activations(c("relu", "elu")),
        n_hlayer = 2:3,
        size = 4,
        type = "latin_hypercube"
    )
    
    expect_equal(nrow(grid), 4)
    expect_true(all(purrr::map_int(grid$hidden_neurons, length) %in% 2:3))
    
    results = tune::tune_grid(
        wf,
        resamples = folds,
        grid = grid,
        control = tune::control_grid(save_pred = FALSE)
    )
    
    expect_s3_class(results, "tune_results")
    
    # ---SELECT BEST---
    best = tune::select_best(results, metric = "rmse")
    expect_s3_class(best, "tbl_df")
    expect_true("hidden_neurons" %in% names(best))
})

test_that("Tuning rnn_kindling with grid_depth works", {
    skip_if_not_installed("parsnip")
    skip_if_not_installed("workflows")
    skip_if_not_installed("tune")
    skip_if_not_installed("rsample")
    skip_if_not_installed("recipes")
    skip_if_no_torch()
    
    rnn_spec = rnn_kindling(
        mode = "classification",
        hidden_neurons = tune::tune(),
        activations = tune::tune(),
        epochs = 5
    )
    
    iris_recipe = recipes::recipe(Species ~ ., data = iris)
    wf = workflows::workflow() |>
        workflows::add_recipe(iris_recipe) |>
        workflows::add_model(rnn_spec)
    
    set.seed(789)
    folds = rsample::vfold_cv(iris, v = 2)
    
    grid = grid_depth(
        hidden_neurons(c(16L, 32L)),
        activations(c("relu", "elu")),
        n_hlayer = 2,
        size = 3,
        type = "random"
    )
    
    expect_s3_class(grid, "tbl_df")
    expect_equal(nrow(grid), 3)
    expect_true("hidden_neurons" %in% names(grid))
    expect_true("activations" %in% names(grid))
    
    # --RNN type shouldn't be tunable, thus it won't exist
    expect_false("rnn_type" %in% names(grid))
    
    OUT = tune::tune_grid(
        wf,
        resamples = folds,
        grid = grid,
        control = tune::control_grid(save_pred = FALSE)
    )
    
    expect_s3_class(OUT, "tune_results")
    expect_true(nrow(tune::collect_metrics(OUT)) > 0)
})

test_that("grid_depth handles different n_hlayer specifications", {
    skip_if_no_torch()
    
    grid1 = grid_depth(
        hidden_neurons(c(16L, 32L)),
        activations(c("relu", "elu")),
        n_hlayer = 2,
        size = 5,
        type = "random"
    )
    
    expect_true(any(purrr::map_int(grid1$hidden_neurons, length) == 2))
    expect_true(any(purrr::map_int(grid1$activations, length) == 2))
    
    # ---Multiple depths---
    grid2 = grid_depth(
        hidden_neurons(c(16L, 32L)),
        activations(c("relu", "elu")),
        n_hlayer = 1:3,
        size = 9,
        type = "random"
    )
    
    depths = purrr::map_int(grid2$hidden_neurons, length)
    expect_true(all(depths %in% 1:3))
})

test_that("grid_depth works with workflow method", {
    skip_if_not_installed("parsnip")
    skip_if_not_installed("workflows")
    skip_if_no_torch()
    
    mlp_spec = mlp_kindling(
        mode = "classification",
        hidden_neurons = tune::tune(),
        activations = tune::tune(),
        epochs = tune::tune()
    )
    
    wf = workflows::workflow() |>
        workflows::add_recipe(recipes::recipe(Species ~ ., data = iris)) |>
        workflows::add_model(mlp_spec)
    
    grid = grid_depth(
        wf,
        n_hlayer = 2,
        size = 5,
        type = "random"
    )
    
    expect_s3_class(grid, "tbl_df")
    expect_true("hidden_neurons" %in% names(grid))
    expect_true("activations" %in% names(grid))
    expect_true("epochs" %in% names(grid))
})

test_that("grid_depth handles scalar parameters correctly", {
    skip_if_no_torch()
    
    grid = grid_depth(
        hidden_neurons(c(16L, 32L)),
        activations(c("relu", "elu")),
        
        # `epochs` belong to `{dials}`, not in `{kindling}`
        dials::epochs(c(10L, 50L)),
        
        # `learn_rate` belong to `{dials}`, not in `{kindling}`
        dials::learn_rate(c(0.001, 0.1)),
        
        n_hlayer = 2,
        size = 5,
        type = "random"
    )
    
    expect_equal(nrow(grid), 5)
    expect_true("epochs" %in% names(grid))
    expect_true("learn_rate" %in% names(grid))
})

test_that("finalize_workflow works with grid_depth results", {
    skip_if_not_installed("parsnip")
    skip_if_not_installed("workflows")
    skip_if_not_installed("tune")
    skip_if_not_installed("rsample")
    skip_if_no_torch()
    
    mlp_spec = mlp_kindling(
        mode = "classification",
        hidden_neurons = tune::tune(),
        activations = tune::tune(),
        epochs = 10
    )
    
    wf = workflows::workflow() |>
        workflows::add_recipe(recipes::recipe(Species ~ ., data = iris)) |>
        workflows::add_model(mlp_spec)
    
    set.seed(321)
    folds = rsample::vfold_cv(iris, v = 2)
    
    grid = grid_depth(
        hidden_neurons(c(16L, 32L)),
        activations(c("relu", "elu")),
        n_hlayer = 2,
        size = 3,
        type = "random"
    )
    
    results = tune::tune_grid(wf, folds, grid = grid)
    best = tune::select_best(results, metric = "accuracy")
    
    final_wf = tune::finalize_workflow(wf, best)
    
    expect_s3_class(final_wf, "workflow")
    
    # ---Final parameters stores into a list—expect no failures---
    testthat::expect_no_failure({
        final_nn_model = parsnip::fit(final_wf, data = iris)
        final_nn_model
    })
})

# ============================================================================
# NEW TESTS FOR n_hlayers PARAMETER TUNING
# ============================================================================

test_that("grid_depth accepts n_hlayers() parameter object", {
    skip_if_no_torch()
    
    grid = grid_depth(
        hidden_neurons(c(16L, 32L)),
        activations(c("relu", "elu")),
        n_hlayer = n_hlayers(range = c(2L, 4L)),
        size = 6,
        type = "random"
    )
    
    expect_s3_class(grid, "tbl_df")
    expect_equal(nrow(grid), 6)
    expect_true("hidden_neurons" %in% names(grid))
    expect_true("activations" %in% names(grid))
    
    # Check that depths vary within the specified range
    depths = purrr::map_int(grid$hidden_neurons, length)
    expect_true(all(depths >= 2 & depths <= 4))
    expect_true(all(depths %in% 2:4))
})

test_that("grid_depth with n_hlayers() parameter in regular grid", {
    skip_if_no_torch()
    
    grid = grid_depth(
        hidden_neurons(c(16L, 32L)),
        activations(c("relu", "elu")),
        n_hlayer = n_hlayers(range = c(1L, 3L)),
        type = "regular",
        levels = 2
    )
    
    expect_s3_class(grid, "tbl_df")
    expect_true(nrow(grid) > 0)
    
    # Check that depths are within range
    depths = purrr::map_int(grid$hidden_neurons, length)
    expect_true(all(depths >= 1 & depths <= 3))
})

test_that("grid_depth with n_hlayers() in latin_hypercube", {
    skip_if_not_installed("lhs")
    skip_if_no_torch()
    
    grid = grid_depth(
        hidden_neurons(c(8L, 64L)),
        activations(c("relu", "elu", "selu")),
        n_hlayer = n_hlayers(range = c(2L, 5L)),
        size = 10,
        type = "latin_hypercube"
    )
    
    expect_equal(nrow(grid), 10)
    depths = purrr::map_int(grid$hidden_neurons, length)
    expect_true(all(depths >= 2 & depths <= 5))
    
    # Check activations match neuron depths
    activation_depths = purrr::map_int(grid$activations, length)
    expect_equal(depths, activation_depths)
})

test_that("Tuning mlp_kindling with n_hlayers parameter works end-to-end", {
    skip_if_not_installed("parsnip")
    skip_if_not_installed("workflows")
    skip_if_not_installed("tune")
    skip_if_not_installed("rsample")
    skip_if_not_installed("recipes")
    skip_if_no_torch()
    
    mlp_spec = mlp_kindling(
        mode = "classification",
        hidden_neurons = tune::tune(),
        activations = tune::tune(),
        epochs = 10
    )
    
    iris_recipe = recipes::recipe(Species ~ ., data = iris)
    wf = workflows::workflow() |>
        workflows::add_recipe(iris_recipe) |>
        workflows::add_model(mlp_spec)
    
    set.seed(999)
    folds = rsample::vfold_cv(iris, v = 2)
    
    # Use n_hlayers() parameter to tune depth
    grid = grid_depth(
        hidden_neurons(c(16L, 32L)),
        activations(c("relu", "elu")),
        n_hlayer = n_hlayers(range = c(1L, 3L)),
        size = 6,
        type = "random"
    )
    
    expect_equal(nrow(grid), 6)
    
    depths = purrr::map_int(grid$hidden_neurons, length)
    expect_true(length(unique(depths)) > 1)
    
    results = tune::tune_grid(
        wf,
        resamples = folds,
        grid = grid,
        control = tune::control_grid(save_pred = FALSE)
    )
    
    expect_s3_class(results, "tune_results")
    expect_true(nrow(tune::collect_metrics(results)) > 0)
    
    best = tune::select_best(results, metric = "accuracy")
    expect_s3_class(best, "tbl_df")
    expect_true("hidden_neurons" %in% names(best))
    expect_true(is.list(best$hidden_neurons))
    
    final_wf = tune::finalize_workflow(wf, best)
    expect_s3_class(final_wf, "workflow")
})

test_that("grid_depth with n_hlayers() in parameters object", {
    skip_if_no_torch()
    
    params = dials::parameters(
        hidden_neurons(c(16L, 64L)),
        activations(c("relu", "elu")),
        n_hlayers(range = c(2L, 4L))
    )
    
    grid = grid_depth(
        params,
        size = 8,
        type = "random"
    )
    
    expect_equal(nrow(grid), 8)
    expect_true("hidden_neurons" %in% names(grid))
    expect_true("activations" %in% names(grid))
    
    depths = purrr::map_int(grid$hidden_neurons, length)
    expect_true(all(depths >= 2 & depths <= 4))
})

test_that("grid_depth with n_hlayers() and scalar parameters", {
    skip_if_no_torch()
    
    grid = grid_depth(
        hidden_neurons(c(16L, 32L)),
        activations(c("relu", "elu")),
        dials::epochs(c(10L, 50L)),
        dials::learn_rate(c(0.001, 0.1)),
        n_hlayer = n_hlayers(range = c(1L, 3L)),
        size = 10,
        type = "random"
    )
    
    expect_equal(nrow(grid), 10)
    expect_true(all(c("hidden_neurons", "activations", "epochs", "learn_rate") %in% names(grid)))
    
    depths = purrr::map_int(grid$hidden_neurons, length)
    expect_true(all(depths >= 1 & depths <= 3))
})

test_that("n_hlayers parameter respects custom ranges", {
    skip_if_no_torch()
    
    grid1 = grid_depth(
        hidden_neurons(c(16L, 32L)),
        activations(c("relu")),
        n_hlayer = n_hlayers(range = c(1L, 2L)),
        size = 10,
        type = "random"
    )
    
    depths1 = purrr::map_int(grid1$hidden_neurons, length)
    expect_true(all(depths1 %in% 1:2))
    
    grid2 = grid_depth(
        hidden_neurons(c(16L, 32L)),
        activations(c("relu")),
        n_hlayer = n_hlayers(range = c(3L, 6L)),
        size = 10,
        type = "random"
    )
    
    depths2 = purrr::map_int(grid2$hidden_neurons, length)
    expect_true(all(depths2 >= 3 & depths2 <= 6))
})

test_that("grid_depth backward compatibility with integer vector n_hlayer", {
    skip_if_no_torch()
    
    grid1 = grid_depth(
        hidden_neurons(c(16L, 32L)),
        activations(c("relu", "elu")),
        n_hlayer = 2,
        size = 5,
        type = "random"
    )
    
    depths1 = purrr::map_int(grid1$hidden_neurons, length)
    expect_true(all(depths1 == 2))
    
    grid2 = grid_depth(
        hidden_neurons(c(16L, 32L)),
        activations(c("relu", "elu")),
        n_hlayer = 2:4,
        size = 9,
        type = "random"
    )
    
    depths2 = purrr::map_int(grid2$hidden_neurons, length)
    expect_true(all(depths2 %in% 2:4))
})

test_that("Tuning rnn_kindling with n_hlayers parameter", {
    skip_if_not_installed("parsnip")
    skip_if_not_installed("workflows")
    skip_if_not_installed("tune")
    skip_if_not_installed("rsample")
    skip_if_no_torch()
    
    rnn_spec = rnn_kindling(
        mode = "classification",
        hidden_neurons = tune::tune(),
        activations = tune::tune(),
        epochs = 5
    )
    
    wf = workflows::workflow() |>
        workflows::add_recipe(recipes::recipe(Species ~ ., data = iris)) |>
        workflows::add_model(rnn_spec)
    
    set.seed(777)
    folds = rsample::vfold_cv(iris, v = 2)
    
    grid = grid_depth(
        hidden_neurons(c(16L, 32L)),
        activations(c("relu", "hardtanh")),
        n_hlayer = n_hlayers(range = c(1L, 3L)),
        size = 5,
        type = "random"
    )
    
    depths = purrr::map_int(grid$hidden_neurons, length)
    expect_true(all(depths >= 1 & depths <= 3))
    
    results = tune::tune_grid(
        wf,
        resamples = folds,
        grid = grid,
        control = tune::control_grid(save_pred = FALSE)
    )
    
    expect_s3_class(results, "tune_results")
    expect_true(nrow(tune::collect_metrics(results)) > 0)
})