test_that("gui_parse_ids works on a data frame column", {
  df <- data.frame(sample = c("SBC300-15", "SBC450-30"))
  out <- gui_parse_ids(df, "sample")
  expect_equal(out$temperature_C, c(300, 450))
})

test_that("gui_adsorption computes qe and removal, with optional id column", {
  df <- data.frame(id = c("s1", "s2"), C0 = c(50, 50), Ce = c(12.5, 25),
                    V = c(0.05, 0.05), m = c(0.1, 0.1))
  out <- gui_adsorption(df, "C0", "Ce", "V", "m", id_col = "id")
  expect_equal(out$qe_mgg, c(18.75, 12.5))
  expect_equal(out$removal_pct, c(75, 50))
  expect_true("id" %in% names(out))
})

test_that("gui_adsorption errors on missing columns", {
  df <- data.frame(C0 = 50, Ce = 10)
  expect_error(gui_adsorption(df, "C0", "Ce", "V", "m"), "not found")
})

test_that("gui_isotherm fits langmuir and returns params/plot inputs", {
  set.seed(1)
  Ce <- c(2, 5, 10, 20, 35, 50, 70)
  qe <- (5 * 0.15 * Ce) / (1 + 0.15 * Ce) + stats::rnorm(length(Ce), 0, 0.02)
  df <- data.frame(Ce = Ce, qe = qe)
  res <- gui_isotherm(df, "Ce", "qe", "langmuir")
  expect_equal(res$model, "langmuir")
  expect_true(res$fit$R2 > 0.9)
  expect_equal(nrow(res$params), 1)
})

test_that("gui_kinetics fits pso", {
  set.seed(4)
  t <- c(5, 15, 30, 60, 120, 240)
  qt <- 4.2 * (1 - exp(-0.05 * t)) + stats::rnorm(length(t), 0, 0.02)
  df <- data.frame(t = t, qt = qt)
  res <- gui_kinetics(df, "t", "qt", "pfo")
  expect_equal(res$model, "pfo")
  expect_true(res$fit$R2 > 0.9)
})

test_that("gui_ftir_density and gui_ftir_peaks work", {
  spec <- data.frame(wn = seq(4000, 500, by = -10), i = stats::runif(351))
  out <- gui_ftir_density(spec, "wn", "i")
  expect_equal(nrow(out$table), nrow(biocharkit::ftir_band_reference()))

  peaks <- data.frame(p = c(3420, 2920, 1710))
  out2 <- gui_ftir_peaks(peaks, "p")
  expect_equal(out2$group[1], "O-H stretch")
})

test_that("gui_xrd_ci computes crystallinity index", {
  df <- data.frame(cryst = 1200, amorph = 800)
  out <- gui_xrd_ci(df, "cryst", "amorph")
  expect_equal(out$crystallinity_index, 0.6)
})

test_that("gui_correlation returns long-format results with p-values", {
  df <- data.frame(temp = c(300, 450, 600, 300, 450, 600),
                    EC = c(1.1, 1.8, 2.6, 1.0, 1.9, 2.5))
  out <- gui_correlation(df, c("temp", "EC"), "spearman")
  expect_equal(nrow(out$long), 1)
  expect_true(out$long$rho > 0.8)
})

test_that("gui_correlation errors with fewer than two columns", {
  df <- data.frame(temp = c(300, 450, 600))
  expect_error(gui_correlation(df, "temp"), "at least two")
})