library(coursekata)

# Current implementation: ~15 seconds
system.time({
  sdof <- do(1000) * f(shuffle(Thumb) ~ Gender, data = Fingers)
})
#>    user  system elapsed 
#>  14.892   0.156  15.089

# Direct computation: ~3 seconds
system.time({
  sdof <- do(1000) * {
    fit <- lm(shuffle(Thumb) ~ Gender, data = Fingers)
    summary(fit)$fstatistic[1]
  }
})
#>    user  system elapsed 
#>   2.847   0.012   2.867

extract_stat <- function(fit, type, stat, predictor = character(0)) {
  sup_out <- supernova(fit, type)  # Always builds full ANOVA table
  # ...
}

f <- function(object, data = NULL, all = FALSE, predictor = character(), type = 3) {
  # ... validation code ...
  
  # Fast path: overall F statistic without building full supernova table
  if (!all && is_empty(predictor)) {
    fstat <- summary(fit)$fstatistic
    if (is.null(fstat)) return(NA_real_)
    return(unname(fstat[1]))
  }

  # Full path: need supernova table for predictor-specific or all statistics
  stats <- extract_stat(fit, type, "F", predictor)
  if (all || !is_empty(predictor)) stats else stats[[1]]
}

test_that("f() fast path returns same value as full supernova", {
  fit <- lm(Thumb ~ Height, data = Fingers)
  fast_result <- summary(fit)$fstatistic[1]
  slow_result <- supernova(fit)$tbl$F[1]
  expect_equal(unname(fast_result), slow_result)
})

test_that("pre() fast path returns same value as full supernova", {
  fit <- lm(Thumb ~ Height, data = Fingers)
  fast_result <- summary(fit)$r.squared
  slow_result <- supernova(fit)$tbl$PRE[1]
  expect_equal(fast_result, slow_result)
})

test_that("p() fast path returns same value as full supernova", {
  fit <- lm(Thumb ~ Height, data = Fingers)
  fstat <- summary(fit)$fstatistic
  fast_result <- pf(fstat[1], fstat[2], fstat[3], lower.tail = FALSE)
  slow_result <- supernova(fit)$tbl$p[1]
  expect_equal(unname(fast_result), slow_result)
})

test_that("f() is fast enough for bootstrapping", {
  skip_on_cran()
  time <- system.time({
    sdof <- do(1000) * f(shuffle(Thumb) ~ Gender, data = Fingers)
  })
  expect_lt(time["elapsed"], 5)  # Should complete in under 5 seconds
})

test_that("f() with predictor argument still uses supernova path", {
  fit <- lm(Thumb ~ Height + RaceEthnic, data = Fingers)
  result <- f(fit, predictor = "Height")
  expect_true(is.numeric(result))
})

test_that("f() with all=TRUE still uses supernova path", {
  fit <- lm(Thumb ~ Height, data = Fingers)
  result <- f(fit, all = TRUE)
  expect_true(is.list(result))
  expect_true("f" %in% names(result))
})