context("smooth_height")

data = data.frame(X = c(0,10,20), Y = c(0,0,0), Z = c(0,1,2))
las = LAS(data)

test_that("smooth_height works with average", {

  las <- smooth_height(las, 1, "average")
  expect_equal(las@data$Z, las@data$Zraw)

  las <- unsmooth_height(las)

  las <- smooth_height(las, 20, "average")
  expect_equal(las@data$Z, c(0.5, 1, 1.5))

  las <- unsmooth_height(las)

  las <- smooth_height(las, 50, "average")
  expect_equal(las@data$Z, c(1, 1, 1))

  unsmooth_height(las)
})

test_that("smooth_height works with gaussian", {

  las <- smooth_height(las, 1, "gaussian", sigma = 2)
  expect_equal(las@data$Z, las@data$Zraw)

  las <- unsmooth_height(las)

  las <- smooth_height(las, 20, "gaussian", sigma = 2)
  expect_equal(las@data$Z, las@data$Zraw, tolerance = 0.001)

  las <- unsmooth_height(las)

  las <- smooth_height(las, 20, "gaussian", sigma = 10)

  w1 = 1/(20*pi)*exp(-100/200)
  w2 = 1/(20*pi)
  z1 = (w2*data$Z[1] + w1*data$Z[2])/(w1+w2)
  z3 = (w1*data$Z[2] + w2*data$Z[3])/(w1+w2)
  expected = c(z1, 1, z3)
  lidR:::fast_quantization(expected, las@header@PHB$`Z scale factor`, las@header@PHB$`Z scale factor`)
  expect_equal(las@data$Z, expected)

  las <- unsmooth_height(las)
})