#include "harness.hpp"

#include <plot/math/transform.hpp>

using plot::Transform;

PLOT_TEST(linear_round_trip) {
  Transform t{2.0, 10.0, 3.0, -1.0, false, false};
  PLOT_CHECK_NEAR(t.to_screen_x(0.0), 10.0, 1e-12);
  PLOT_CHECK_NEAR(t.to_screen_x(5.0), 20.0, 1e-12);
  PLOT_CHECK_NEAR(t.to_data_x(20.0), 5.0, 1e-12);
  PLOT_CHECK_NEAR(t.to_data_y(t.to_screen_y(7.5)), 7.5, 1e-12);
}

PLOT_TEST(log_x_round_trip) {
  Transform t{100.0, 0.0, 1.0, 0.0, true, false};
  PLOT_CHECK_NEAR(t.to_screen_x(1.0), 0.0, 1e-12);
  PLOT_CHECK_NEAR(t.to_screen_x(10.0), 100.0, 1e-12);
  PLOT_CHECK_NEAR(t.to_data_x(100.0), 10.0, 1e-9);
}

PLOT_TEST(zoom_anchor_is_invariant) {
  // Anchoring a zoom at a data coordinate must leave that coordinate's screen
  // position unchanged.
  Transform t{1.0, 0.0, 1.0, 0.0, false, false};
  const double anchor_data = 3.25;
  const double before = t.to_screen_x(anchor_data);
  t.sx *= 4.0;
  t.tx = before - anchor_data * t.sx;
  PLOT_CHECK_NEAR(t.to_screen_x(anchor_data), before, 1e-12);
}