# A unit test for Arima() function
test_that("tests for a non-ts object", {
  set.seed(123)
  abc <- rnorm(50, 5, 1)
  fit <- Arima(abc, order = c(2, 0, 1))
  expect_identical(fit$arma, c(2L, 1L, 0L, 0L, 1L, 0L, 0L))
})

test_that("tests for a ts with the seasonal component", {
  fit <- Arima(wineind, order = c(1, 1, 1), seasonal = c(0, 1, 1))
  expect_identical(fit$arma, c(1L, 1L, 0L, 1L, 12L, 1L, 1L))
})

test_that("tests for ARIMA errors", {
  fit <- Arima(wineind, order = c(1, 1, 1), seasonal = c(0, 1, 1))
  expect_identical(residuals(fit, type = "regression"), wineind)
})

test_that("tests for arimaorder", {
  for (ar in 0:2) {
    for (i in 0:1) {
      for (ma in 0:2) {
        fitarima <- Arima(
          lynx,
          order = c(ar, i, ma),
          method = "ML",
          include.constant = TRUE,
          lambda = 0.5
        )
        if (!inherits(fitarima, "try-error")) {
          arextracted <- fitarima$arma[1]
          iextracted <- fitarima$arma[6]
          maextracted <- fitarima$arma[2]
          expect_true(all(
            arimaorder(fitarima) == c(arextracted, iextracted, maextracted)
          ))
          expect_named(arimaorder(fitarima), c("p", "d", "q"))
          expect_true(arimaorder(fitarima)["p"] == ar)
          expect_true(arimaorder(fitarima)["d"] == i)
          expect_true(arimaorder(fitarima)["q"] == ma)
        }
      }
    }
  }

  # Test ar
  arMod <- ar(lynx, order.max = 2)
  expect_true(arimaorder(arMod)["p"] == 2)
  expect_true(arimaorder(arMod)["d"] == 0)
  expect_true(arimaorder(arMod)["q"] == 0)
  expect_named(arimaorder(arMod), c("p", "d", "q"))

  # Test SARIMA
  sarimaMod <- Arima(wineind, order = c(1, 1, 2), seasonal = c(0, 1, 1))
  expect_named(
    arimaorder(sarimaMod),
    c("p", "d", "q", "P", "D", "Q", "Frequency")
  )
  expect_true(arimaorder(sarimaMod)["p"] == 1)
  expect_true(arimaorder(sarimaMod)["d"] == 1)
  expect_true(arimaorder(sarimaMod)["q"] == 2)
  expect_true(arimaorder(sarimaMod)["P"] == 0)
  expect_true(arimaorder(sarimaMod)["D"] == 1)
  expect_true(arimaorder(sarimaMod)["Q"] == 1)
  expect_true(arimaorder(sarimaMod)["Frequency"] == frequency(wineind))

  # Test fracdiff
  set.seed(4)
  fracdiffMod <- fracdiff::fracdiff(lynx, nar = 2)
  expect_named(arimaorder(fracdiffMod), c("p", "d", "q"))
  expect_true(arimaorder(fracdiffMod)["p"] == 2)
  expect_true(arimaorder(fracdiffMod)["d"] >= 0)
  expect_true(arimaorder(fracdiffMod)["d"] <= 1)
  expect_true(arimaorder(fracdiffMod)["p"] == 2)
})

test_that("tests for forecast.Arima", {
  fit1 <- Arima(
    wineind,
    order = c(1, 1, 2),
    seasonal = c(0, 1, 1),
    method = "CSS"
  )
  expect_warning(forecast.Arima(fit1, xreg = 1:10), "xreg not required")
  expect_warning(forecast.Arima(fit1, include.drift = TRUE))
  expect_true(all.equal(
    forecast.Arima(fit1, bootstrap = TRUE, npaths = 100)$mean,
    forecast.Arima(fit1)$mean
  ))

  fit2 <- Arima(
    wineind,
    order = c(1, 0, 1),
    seasonal = c(0, 0, 0),
    include.drift = TRUE
  )
  expect_warning(Arima(wineind, order = c(1, 2, 1), include.drift = TRUE))
  expect_true("drift" %in% names(coef(fit2)))
  expect_length(forecast.Arima(fit2)$mean, 2 * frequency(wineind))

  fit3 <- Arima(
    wineind,
    order = c(1, 1, 2),
    seasonal = c(0, 1, 1),
    include.mean = FALSE
  )
  expect_false("intercept" %in% names(coef(fit3)))
  expect_true(frequency(forecast.Arima(fit3)$mean) == frequency(wineind))

  fit4 <- Arima(
    wineind,
    order = c(1, 1, 2),
    seasonal = c(0, 1, 1),
    xreg = rnorm(length(wineind))
  )
  expect_error(forecast.Arima(fit4))
  expect_error(forecast.Arima(fit4, xreg = matrix(rnorm(40), ncol = 2)))
  forecast.Arima(fit4, xreg = rnorm(20))$mean |>
    expect_length(20)

  fit5 <- Arima(
    wineind[1:150],
    order = c(1, 1, 2),
    seasonal = c(0, 1, 1),
    method = "ML"
  )
  expect_true(
    accuracy(fit5)[1, "MAPE"] <
      accuracy(Arima(wineind, model = fit5))[1, "MAPE"]
  )

  fit6 <- Arima(
    wineind,
    order = c(1, 1, 2),
    seasonal = c(0, 1, 1),
    method = "CSS",
    lambda = 5
  )
  expect_false(identical(fit1$coef, fit6$coef))
})

test_that("tests for search.arima", {
  set.seed(444)
  arimasim <- arima.sim(
    n = 300,
    model = list(ar = runif(8, -.1, 0.1), ma = runif(8, -0.1, 0.1), sd = 0.1)
  )
  expect_true(
    AIC(auto.arima(arimasim)) >= AIC(auto.arima(arimasim, stepwise = FALSE))
  )
})

test_that("tests for forecast.ar()", {
  fitar <- ar(taylor)
  arfc <- forecast.ar(fitar)$mean
  expect_identical(
    arfc,
    forecast.ar(fitar, bootstrap = TRUE, npaths = 100)$mean
  )
  expect_identical(arfc, forecast.ar(fitar, fan = TRUE)$mean)
  expect_error(forecast.ar(fitar, level = -10))
  expect_error(forecast.ar(fitar, level = 110))
  expect_true(all(arfc + 1 == forecast.ar(fitar, lambda = 1)$mean))
  arfcbc <- forecast.ar(fitar, lambda = 2)
  arfcabc <- forecast.ar(fitar, lambda = 2, biasadj = TRUE)
  expect_false(identical(arfcbc$mean, arfcabc$mean))
})

test_that("tests for as.character.Arima()", {
  expect_match(as.character(auto.arima(woolyrnq)), regexp = "ARIMA")
})