test_that("get_tetrad_dir returns TETRAD_DIR env var when set and exists", {
  old_env <- Sys.getenv("TETRAD_DIR", unset = NA)
  on.exit(Sys.setenv(TETRAD_DIR = old_env), add = TRUE)

  temp_dir <- tempdir()
  Sys.setenv(TETRAD_DIR = temp_dir)

  expect_equal(get_tetrad_dir(), temp_dir)
})

test_that("get_tetrad_dir returns package cache when env var is not set", {
  old_env <- Sys.getenv("TETRAD_DIR", unset = NA)
  on.exit(Sys.setenv(TETRAD_DIR = old_env), add = TRUE)
  Sys.unsetenv("TETRAD_DIR")

  # simulate cache option
  temp_cache <- file.path(tempdir(), "cache_test")
  dir.create(temp_cache, recursive = TRUE, showWarnings = FALSE)
  old_opt <- getOption("causalDisco.tetrad_cache")
  on.exit(options(causalDisco.tetrad_cache = old_opt), add = TRUE)
  options(causalDisco.tetrad_cache = temp_cache)

  expect_equal(get_tetrad_dir(), temp_cache)
})

test_that("get_tetrad_dir returns NULL when env var set but directory does not exist", {
  old_env <- Sys.getenv("TETRAD_DIR", unset = NA)
  on.exit(Sys.setenv(TETRAD_DIR = old_env), add = TRUE)
  Sys.setenv(TETRAD_DIR = "/path/does/not/exist")

  old_opt <- getOption("causalDisco.tetrad_cache")
  on.exit(options(causalDisco.tetrad_cache = old_opt), add = TRUE)
  options(causalDisco.tetrad_cache = NULL)

  expect_null(get_tetrad_dir())
})

test_that("get_tetrad_dir returns NULL when neither env var nor cache option is set", {
  old_env <- Sys.getenv("TETRAD_DIR", unset = NA)
  on.exit(Sys.setenv(TETRAD_DIR = old_env), add = TRUE)
  Sys.unsetenv("TETRAD_DIR")

  old_opt <- getOption("causalDisco.tetrad_cache")
  on.exit(options(causalDisco.tetrad_cache = old_opt), add = TRUE)
  options(causalDisco.tetrad_cache = NULL)

  expect_null(get_tetrad_dir())
})

test_that("get_java_version returns NA when java executable not found", {
  # Stub Sys.which to return empty
  mockery::stub(get_java_version, "Sys.which", function(cmd) "")

  # Stub file.exists to always return FALSE
  mockery::stub(get_java_version, "file.exists", function(path) FALSE)

  expect_identical(get_java_version(), NA_character_)
})


test_that("get_java_version returns NA when system2 errors", {
  # Fake java path
  mockery::stub(get_java_version, "Sys.which", function(cmd) "/usr/bin/java")

  # system2 throws an error
  mockery::stub(get_java_version, "system2", function(...) stop("boom"))

  expect_identical(get_java_version(), NA_character_)
})


test_that("get_java_version returns NA when system2 returns NA in first line", {
  mockery::stub(get_java_version, "Sys.which", function(cmd) "/usr/bin/java")

  # system2 returns NA vector
  mockery::stub(get_java_version, "system2", function(...) NA_character_)

  expect_identical(get_java_version(), NA_character_)
})


test_that("get_java_version returns NA when output has no quoted version", {
  mockery::stub(get_java_version, "Sys.which", function(cmd) "/usr/bin/java")

  mockery::stub(get_java_version, "system2", function(...) {
    c(
      "java version nonsense without quotes",
      "other info"
    )
  })

  expect_identical(get_java_version(), NA_character_)
})


test_that("get_java_version extracts version correctly when present", {
  mockery::stub(get_java_version, "Sys.which", function(cmd) "/usr/bin/java")

  # Ensure the file.exists check passes
  mockery::stub(get_java_version, "file.exists", function(path) TRUE)

  # Stub system2 to return a fake java version
  mockery::stub(get_java_version, "system2", function(...) {
    c('java version "17.0.9"', "more lines")
  })

  expect_equal(get_java_version(), "17.0.9")
})

# ---- Branch 1: Java not found ----
test_that("Returns message when Java is missing", {
  mockery::stub(verify_tetrad, "get_java_version", function() {
    NA_character_
  })

  out <- verify_tetrad("1.0")
  expect_output_list(out)

  expect_false(out$installed)
  expect_false(out$java_ok)
  expect_null(out$java_version)
  expect_match(out$message, "Java not found. Install Java >= 21.")
})


# ---- Branch 2: Java < 21 ----
test_that("Returns message when Java version is too old", {
  mockery::stub(verify_tetrad, "get_java_version", function() "17.0.9")

  out <- verify_tetrad("1.0")
  expect_output_list(out)

  expect_false(out$installed)
  expect_false(out$java_ok)
  expect_equal(out$java_version, "17.0.9")
  expect_match(out$message, "Java >= 21 required")
})


# ---- Branch 3: Java OK but TETRAD_DIR is NULL ----
test_that("Returns message when tetrad directory is missing", {
  mockery::stub(verify_tetrad, "get_java_version", function() "21.0.1")
  mockery::stub(verify_tetrad, "get_tetrad_dir", function() NULL)

  out <- verify_tetrad("1.0")
  expect_output_list(out)

  expect_false(out$installed)
  expect_true(out$java_ok)
  expect_equal(out$java_version, "21.0.1")
  expect_match(out$message, "Tetrad not installed.")
})


# ---- Branch 4: Java OK, tetrad dir exists, JAR missing ----
test_that("Returns message when Tetrad JAR does not exist", {
  mockery::stub(verify_tetrad, "get_java_version", function() "21.0.1")
  mockery::stub(verify_tetrad, "get_tetrad_dir", function() "/fake/path")

  # JAR missing
  mockery::stub(verify_tetrad, "file.exists", function(...) FALSE)

  out <- verify_tetrad("1.0")
  expect_output_list(out)

  expect_false(out$installed)
  expect_true(out$java_ok)
  expect_equal(out$java_version, "21.0.1")
  expect_match(out$message, "Tetrad not installed.")
})


# ---- Branch 5: Java OK, tetrad dir exists, JAR exists -> SUCCESS ----
test_that("Successful detection when Java and Tetrad are OK", {
  mockery::stub(verify_tetrad, "get_java_version", function() "22.1.0")
  mockery::stub(verify_tetrad, "get_tetrad_dir", function() "/fake/path")

  # JAR exists
  mockery::stub(verify_tetrad, "file.exists", function(...) TRUE)

  out <- verify_tetrad("2.0")
  expect_output_list(out)

  expect_true(out$installed)
  expect_true(out$java_ok)
  expect_equal(out$version, "2.0")
  expect_equal(out$java_version, "22.1.0")
  expect_match(
    out$message,
    "Tetrad version 2.0 is installed and ready to use."
  )
})