# Public input validation only: these test calls must fail before any trial is simulated.
# Save as tests/testthat/test-find-n-req-validation.R

test_that("find_n_req validates inputs before running simulations", {
  never_called <- function(...) stop("generator must not be called")
  args <- list(
    F_followup = 12, tau = 36,
    thresholds = list(p_risk_min = 0.10, n_risk_min = 10,
                      p_support_min = 0.95),
    trial_generator = never_called,
    trial_args = list(A = 48),
    N_lower = 100, N_upper = 200,
    coarse_step = 20, fine_step = 10,
    n_coarse = 2, n_fine = 3, n_validate = 4,
    power_target = 0.80,
    search_seed = 202614, validation_seed = 202615,
    alpha = 0.05
  )
  invalid <- function(...) do.call(find_n_req, utils::modifyList(args, list(...)))

  expect_error(invalid(F_followup = -1), "F_followup")
  expect_error(invalid(tau = 0), "tau")
  expect_error(invalid(N_lower = 200), "N_lower")
  expect_error(invalid(N_upper = 100), "N_lower")
  expect_error(invalid(coarse_step = 0), "coarse_step")
  expect_error(invalid(fine_step = 0), "fine_step")
  expect_error(invalid(coarse_step = 15), "coarse_step")
  expect_error(invalid(N_upper = 205), "N_upper - N_lower")
  expect_error(invalid(n_coarse = 0), "n_coarse")
  expect_error(invalid(n_fine = 1.5), "n_fine")
  expect_error(invalid(n_validate = -1), "n_validate")
  expect_error(invalid(power_target = 1), "power_target")
  expect_error(invalid(alpha = 0), "alpha")
  expect_error(invalid(trial_generator = "not a function"), "trial_generator")
  expect_error(invalid(trial_args = list(N = 160)), "trial_args")
  expect_error(invalid(search_seed = -1), "search_seed")
  expect_error(invalid(validation_seed = 202614),
               "search_seed and validation_seed must differ")
  expect_error(invalid(thresholds = list(p_risk_min = 2,
                                        n_risk_min = 10,
                                        p_support_min = 0.95)), "thresholds")

  missing_threshold <- args
  missing_threshold$thresholds <- list(p_risk_min = 0.10, n_risk_min = 10)
  expect_error(do.call(find_n_req, missing_threshold), "thresholds")

  missing_sim_count <- args
  missing_sim_count$n_validate <- NULL
  expect_error(do.call(find_n_req, missing_sim_count), "n_validate")
})

test_that("invalid find_n_req inputs do not consume caller RNG", {
  set.seed(20261015)
  before <- .Random.seed
  expect_error(find_n_req(
    F_followup = 12, tau = 36,
    thresholds = list(p_risk_min = 0.10, n_risk_min = 10,
                      p_support_min = 0.95),
    trial_generator = function(...) stop("must not run"),
    N_lower = 100, N_upper = 200,
    n_coarse = 2, n_fine = 3, n_validate = 4,
    search_seed = 202614, validation_seed = 202614
  ), "must differ")
  expect_identical(.Random.seed, before)
})