library(gpindex)

ms_prices$rel <- with(ms_prices, price_relative(price, period, product))
ms_prices$w1 <- 1:40
ms_prices$w2 <- 40:1

epr1 <- with(
  ms_prices,
  elemental_index(rel, period, business, contrib = TRUE)
)

epr2 <- with(
  ms_prices,
  elemental_index(rel, period, business, r = -1, contrib = TRUE, na.rm = TRUE)
)

# Test a Fisher calculation
fw <- function(x, w1, w2) {
  v1 <- scale_weights(transmute_weights(1, 0)(x, w1))
  v2 <- scale_weights(transmute_weights(-1, 0)(x, w2))
  v1 + v2
}

ms_prices2 <- na.omit(ms_prices)

w <- with(ms_prices2,
          grouped(fw)(rel, w1, w2, group = interaction(period, business)))

epr3 <- with(
  ms_prices2,
  elemental_index(rel, period, business, w, contrib = TRUE)
)

test_that("results agree with an alternate implementation", {
  epr11 <- aggregate(rel ~ as.character(business) + period, ms_prices,
                     function(x) exp(weighted.mean(log(x))),
                     na.action = na.pass, drop = FALSE)
  epr22 <- aggregate(rel ~ as.character(business) + period, ms_prices,
                     function(x) 1 / weighted.mean(1 / x),
                     na.action = na.omit, drop = FALSE)
  names(epr11) <- names(epr22) <- c("level", "period", "value")

  expect_equal(as.data.frame(epr1), epr11[c(2, 1, 3)])
  expect_equal(as.data.frame(epr2), epr22[c(2, 1, 3)])
})

test_that("Fisher calculation agrees with manual calculation", {
  l <- with(ms_prices2, elemental_index(rel, period, business, w1, r = 1))
  p <- with(ms_prices2, elemental_index(rel, period, business, w2, r = -1))
  expect_equal(sqrt(as.matrix(l) * as.matrix(p)), as.matrix(epr3))

  # Should work for other kinds of superlative indexes
  fw <- function(x, w1, w2) {
    v1 <- scale_weights(transmute_weights(1.5, 0)(x))
    v2 <- scale_weights(transmute_weights(-1.5, 0)(x, w2))
    v1 + v2
  }

  w <- with(
    ms_prices2,
    grouped(fw)(rel, w1, w2, group = interaction(period, business))
  )

  sepr <- with(ms_prices2, elemental_index(rel, period, business, w))

  l <- with(ms_prices2, elemental_index(rel, period, business, r = 1.5))
  p <- with(ms_prices2, elemental_index(rel, period, business, w2, r = -1.5))
  all.equal(sqrt(as.matrix(l) * as.matrix(p)), as.matrix(sepr))
})

test_that("contributions add up", {
  sum_contrib <- \(x, ...) sum(x, ...) / (sum(!is.na(x)) > 0)
  expect_equal(epr1$index,
               lapply(epr1$contrib, \(x) sapply(x, sum_contrib) + 1))

  expect_equal(
    epr2$index,
    lapply(epr2$contrib, function(x) sapply(x, sum_contrib, na.rm = TRUE) + 1)
  )

  expect_equal(epr3$index,
               lapply(epr3$contrib, function(x) sapply(x, sum_contrib) + 1))
})

test_that("argument checking works", {
  expect_error(elemental_index(1:3, 1:2))
  expect_error(elemental_index(1:3, 1:3, 1:4))
  expect_error(elemental_index(1:3, 1:3, 1:3, w = 1:2))
  expect_error(elemental_index(1:3, factor(1:3, levels = numeric(0))))
  expect_error(elemental_index(1:3, ea = factor(1:3, levels = numeric(0))))
})