# Tests for detect_lag function

test_that("detect_lag works with basic input", {
  dat <- simulate_invasion(n_years = 30, lag_duration = 10, seed = 123)
  result <- detect_lag(dat$year, dat$count)

  expect_s3_class(result, "invalag")
  expect_true(!is.na(result$breakpoint[1]))
  expect_true(result$lag_duration > 0)
  expect_true(is.numeric(result$pre_slope))
  expect_true(is.numeric(result$post_slope))
})

test_that("detect_lag handles effort correction", {
  dat <- simulate_invasion(n_years = 30, effort = TRUE, seed = 123)

  result <- detect_lag(dat$year, dat$count, effort = dat$effort)

  expect_s3_class(result, "invalag")
  expect_true(result$effort_corrected)
})

test_that("detect_lag handles transformations", {
  dat <- simulate_invasion(seed = 123)

  result_log <- detect_lag(dat$year, dat$count, transform = "log")
  result_sqrt <- detect_lag(dat$year, dat$count, transform = "sqrt")
  result_log10 <- detect_lag(dat$year, dat$count, transform = "log10")

  expect_equal(result_log$transform, "log")
  expect_equal(result_sqrt$transform, "sqrt")
  expect_equal(result_log10$transform, "log10")
})

test_that("detect_lag validates input", {
  # Different lengths
  expect_error(detect_lag(1:10, 1:5))

  # Non-numeric
  expect_error(detect_lag(letters[1:10], 1:10))

  # Too few points
  expect_error(detect_lag(1:3, c(1, 2, 3)))

  # Negative counts
  expect_error(detect_lag(1:10, c(-1, 2, 3, 4, 5, 6, 7, 8, 9, 10)))
})

test_that("detect_lag method='all' compares methods", {
  skip_if_not_installed("changepoint")
  skip_if_not_installed("mgcv")

  dat <- simulate_invasion(seed = 123)
  result <- detect_lag(dat$year, dat$count, method = "all")

  expect_true(!is.null(result$comparison))
  expect_true(nrow(result$comparison) >= 1)
})

test_that("print and summary methods work", {
  dat <- simulate_invasion(seed = 123)
  result <- detect_lag(dat$year, dat$count)

  expect_output(print(result), "INVASION LAG PHASE")
  expect_output(summary(result), "DETAILED SUMMARY")
})