# Set number of data.table threads to 1
data.table::setDTthreads(threads = 2L)
# Set number of collapse threads to 1
collapse::set_collapse(nthreads = 1L)

testthat::test_that("Time elapsed", {

  # Documentation examples
  testthat::expect_equal(time_elapsed(c(3, 4, 6, NA, NA, 9),
                                      rolling = TRUE,
                                      fill = NA,
                                      time_by = 1,
                                      na_skip = TRUE),
                         c(NA, 1, 2, NA, NA, 3))
  testthat::expect_equal(time_elapsed(c(NA, NA, 3, 4, 6, NA, 8),
                                      rolling = FALSE,
                                      fill = NA,
                                      time_by = 1,
                                      na_skip = TRUE),
                         c(NA, NA, 0, 1, 3, NA, 5))
  set.seed(123876123)
  df <- dplyr::tibble(g = sample.int(100, 10^4, replace = TRUE),
                      x = round(rnorm(10^4), 1))
  df$x2 <- df$x
  df$x2[sample.int(10^4, 2 * (10^3), replace = FALSE)] <- NA

  testthat::expect_equal(
    time_elapsed(df$x, time_by = 1, rolling = TRUE,
                 fill = 0),
    c(0, diff(df$x))
  )
  testthat::expect_equal(
    time_elapsed(df$x, time_by = 1, rolling = TRUE,
                 fill = NA),
    c(NA, diff(df$x))
  )
  testthat::expect_equal(
    time_elapsed(df$x, time_by = 1, rolling = FALSE),
    c(0, cumsum(diff(df$x)))
  )

  testthat::expect_equal(
    time_elapsed(df$x2, time_by = 1, rolling = FALSE,
                 na_skip = TRUE),
    df$x2 - df$x2[1]
  )
  testthat::expect_equal(
    time_elapsed(df$x2, time_by = 0.1, rolling = FALSE,
                 na_skip = FALSE),
    (df$x2 - df$x2[1]) / 0.1
  )

# Grouped -----------------------------------------------------------------

  testthat::expect_equal(
    time_elapsed(df$x, time_by = 1,
                 g = df$g,
                 rolling = TRUE, fill = 0),
    df %>%
      dplyr::mutate(t = c(0, diff(x)),
                    .by = g) %>%
      dplyr::pull(t)
  )
  testthat::expect_equal(
    time_elapsed(df$x2, time_by = 1,
                 g = df$g,
                 rolling = TRUE, fill = 0,
                 na_skip = TRUE),
    df %>%
      dplyr::mutate(t = time_elapsed(x2, time_by = 1, na_skip = TRUE,
                                     fill = 0),
                    .by = g) %>%
      dplyr::pull(t)
  )
  testthat::expect_equal(
    time_elapsed(df$x2, time_by = 1,
                 g = df$g,
                 rolling = TRUE, fill = 0,
                 na_skip = FALSE),
    df %>%
      dplyr::mutate(t = time_elapsed(x2, time_by = 1, na_skip = FALSE,
                                     fill = 0),
                    .by = g) %>%
      dplyr::pull(t)
  )
  testthat::expect_equal(
    time_elapsed(df$x, time_by = 1,
                 g = df$g,
                 rolling = TRUE, fill = 0,
                 na_skip = FALSE),
    df %>%
      dplyr::mutate(t = time_elapsed(x, time_by = 1, na_skip = FALSE,
                                     fill = 0),
                    .by = g) %>%
      dplyr::pull(t)
  )

  testthat::expect_equal(
    time_elapsed(df$x2, time_by = 1,
                 g = df$g,
                 rolling = FALSE,
                 na_skip = FALSE),
    df %>%
      dplyr::mutate(t = x2 - dplyr::first(x2),
                    # t = dplyr::if_else(dplyr::row_number() == 1L, 0, t),
                    .by = g) %>%
      dplyr::pull(t)
  )

  testthat::expect_equal(
    time_elapsed(df$x2, time_by = 1,
                 g = df$g,
                 rolling = FALSE,
                 na_skip = TRUE),
    df %>%
      dplyr::mutate(t = x2 - dplyr::first(x2, na_rm = TRUE),
                    # t = dplyr::if_else(dplyr::row_number() == 1L, 0, t),
                    .by = g) %>%
      dplyr::pull(t)
  )
})