test_that("construct optimizer works", {
  expect_error(
    define_optimizer(),
    "specify argument"
  )
  expect_error(
    define_optimizer(.optimizer = stats::nlm),
    "specify argument"
  )
  expect_error(
    define_optimizer(.optimizer = stats::nlm, .objective = "f"),
    "specify argument"
  )
  expect_error(
    define_optimizer(
      .optimizer = stats::nlm, .objective = "f", .initial = "p"
    ),
    "specify argument"
  )
  expect_error(
    define_optimizer(
      .optimizer = stats::nlm, .objective = "f", .initial = "p", .value = "v"
    ),
    "specify argument"
  )
  expect_error(
    define_optimizer(
      .optimizer = stats::nlm, .objective = "f", .initial = "p",
      .parameter = "z"
    ),
    "specify argument"
  )
  expect_error(
    define_optimizer(
      .optimizer = stats::nlm, .objective = "f", .initial = "p", .value = "v",
      .parameter = "z"
    ),
    "specify argument"
  )
  optimizer <- new_optimizer(
    .optimizer = pracma::nelder_mead,
    optimizer_name = "nelder_mead",
    optimizer_arguments = list("tol" = 1e-10),
    .objective = "fn",
    .initial = "x0",
    .value = "fmin",
    .parameter = "xmin",
    .direction = "min",
    .output_ignore = "restarts"
  )
  expect_s3_class(optimizer, "optimizer")
  optimizer <- validate_optimizer(optimizer)
  expect_s3_class(optimizer, "optimizer")
  expect_named(
    optimizer,
    c(
      "optimizer", "optimizer_name", "optimizer_arguments",
      "optimizer_direction", "optimizer_labels", "output_ignore"
    )
  )
})

test_that("optimizier validation works", {
  expect_error(
    define_optimizer(
      .optimizer = function(fn, x) stop("error"),
      .objective = "fn",
      .initial = "x",
      .value = "fmin",
      .parameter = "xmin",
      .direction = "min",
      .validate = TRUE
    ),
    "Optimizer test run failed"
  )
  expect_error(
    define_optimizer(
      .optimizer = stats::nlm,
      .objective = "f",
      .initial = "p",
      .value = "estimate",
      .parameter = "value",
      .direction = "min",
      .validate = TRUE
    ),
    "The optimal value is not a single"
  )
  expect_warning(
    define_optimizer(
      .optimizer = function(f, p) Sys.sleep(10),
      .objective = "f",
      .initial = "p",
      .value = "minimum",
      .parameter = "estimate",
      .direction = "min",
      .validate = TRUE,
      .validation_settings = list(
        "check_seconds" = 1
      )
    ),
    "Optimizer test run cannot be validated."
  )
  expect_error(
    define_optimizer(
      .optimizer = function(f, p) {
        return(p)
      },
      .objective = "f",
      .initial = "p",
      .value = "minimum",
      .parameter = "estimate",
      .direction = "min",
      .validate = TRUE
    ),
    "Optimizer output is not a"
  )
  expect_error(
    define_optimizer(
      .optimizer = stats::nlm,
      .objective = "f",
      .initial = "p",
      .value = "bad_name",
      .parameter = "estimate",
      .direction = "min",
      .validate = TRUE
    ),
    "is not part of the optimizer output."
  )
  expect_error(
    define_optimizer(
      .optimizer = function(f, p) list("minimum" = "not_a_numeric"),
      .objective = "f",
      .initial = "p",
      .value = "minimum",
      .parameter = "estimate",
      .direction = "min",
      .validate = TRUE
    ),
    "The optimal value is not a single"
  )
  expect_error(
    define_optimizer(
      .optimizer = stats::nlm,
      .objective = "f",
      .initial = "p",
      .value = "minimum",
      .parameter = "bad_name",
      .direction = "min",
      .validate = TRUE
    ),
    "is not part of the optimizer output."
  )
  expect_error(
    define_optimizer(
      .optimizer = function(f, p) {
        list("minimum" = 0, "estimate" = "not_a_numeric")
      },
      .objective = "f",
      .initial = "p",
      .value = "minimum",
      .parameter = "estimate",
      .direction = "min",
      .validate = TRUE
    ),
    "The optimum is not a"
  )
})

test_that("unnamed optimizer can be specified", {
  opt <- define_optimizer(
    .optimizer = function(f, p) {
      list("minimum" = 0, "parameter" = p)
    },
    .objective = "f",
    .initial = "p",
    .value = "minimum",
    .parameter = "parameter",
    .direction = "min"
  )
  expect_equal(opt$label, "unnamed_optimizer")
})

test_that("printing optimizer object works", {
  expect_snapshot(optimizer_nlm())
  expect_snapshot(optimizer_optim())
})

test_that("pre-specified optimizers work", {
  checkmate::expect_r6(optimizer_nlm(), "Optimizer")
  checkmate::expect_r6(optimizer_optim(), "Optimizer")
})

test_that("optimization works", {
  f_ackley <- function(x) {
    stopifnot(is.numeric(x), length(x) == 2)
    -20 * exp(-0.2 * sqrt(0.5 * (x[1]^2 + x[2]^2))) -
      exp(0.5 * (cos(2 * pi * x[1]) + cos(2 * pi * x[2]))) + exp(1) + 20
  }
  out <- apply_optimizer(optimizer_nlm(), f_ackley, c(-2, 2))
  expect_type(out, "list")
  expect_type(out$value, "double")
  expect_type(out$parameter, "double")
})