// SPDX-License-Identifier: LGPL-3.0-or-later
#include <algorithm>
#include <catch2/catch_test_macros.hpp>
#include <catch2/generators/catch_generators.hpp>
#include <catch2/generators/catch_generators_adapters.hpp>
#include <catch2/generators/catch_generators_random.hpp>

#include "bresenham_line_tool.h"
#include "canvas_buffer.h"
#include "dda_line_tool.h"
#include "util.h"

TEST_CASE("Transform Mirror") {
  // elementary operations
  REQUIRE(transform(TRANSFORM_MIRROR_X, 10, 20) == std::make_pair(10, -20));
  REQUIRE(transform(TRANSFORM_MIRROR_Y, 10, 20) == std::make_pair(-10, 20));

  // composite operations
  REQUIRE(transform(TRANSFORM_MIRROR_X | TRANSFORM_MIRROR_Y, 10, 20) ==
          std::make_pair(-10, -20));
}

TEST_CASE("Transform Rotate") {
  REQUIRE(transform(TRANSFORM_ROTATE_CW, 10, 20) ==
          std::make_pair(-20, 10)); // 4th quadrant
  REQUIRE(transform(TRANSFORM_ROTATE_CW, -20, 10) ==
          std::make_pair(-10, -20)); // 3rd quadrant
  REQUIRE(transform(TRANSFORM_ROTATE_CW, -10, -20) ==
          std::make_pair(20, -10)); // 2nd quadrant
  REQUIRE(transform(TRANSFORM_ROTATE_CW, 20, -10) ==
          std::make_pair(10, 20)); // 1st quadrant

  REQUIRE(transform(TRANSFORM_ROTATE_CCW, 20, -10) ==
          std::make_pair(-10, -20)); // 1nd quadrant
  REQUIRE(transform(TRANSFORM_ROTATE_CCW, -10, -20) ==
          std::make_pair(-20, 10)); // 2rd quadrant
  REQUIRE(transform(TRANSFORM_ROTATE_CCW, -20, 10) ==
          std::make_pair(10, 20)); // 3th quadrant
  REQUIRE(transform(TRANSFORM_ROTATE_CCW, 10, 20) ==
          std::make_pair(20, -10)); // 4st quadrant
}

TEST_CASE("Transform Rotate + Mirror") {
  REQUIRE(transform(TRANSFORM_ROTATE_CW | TRANSFORM_MIRROR_X, 10, 20) ==
          std::make_pair(-20, -10));
  REQUIRE(transform(TRANSFORM_ROTATE_CW | TRANSFORM_MIRROR_Y, 10, 20) ==
          std::make_pair(20, 10));
  REQUIRE(
      transform(TRANSFORM_ROTATE_CW | TRANSFORM_MIRROR_X | TRANSFORM_MIRROR_Y,
                10, 20) == std::make_pair(20, -10));

  REQUIRE(transform(TRANSFORM_ROTATE_CCW | TRANSFORM_MIRROR_X, 10, 20) ==
          std::make_pair(20, 10));
  REQUIRE(transform(TRANSFORM_ROTATE_CCW | TRANSFORM_MIRROR_Y, 10, 20) ==
          std::make_pair(-20, -10));
  REQUIRE(
      transform(TRANSFORM_ROTATE_CCW | TRANSFORM_MIRROR_X | TRANSFORM_MIRROR_Y,
                10, 20) == std::make_pair(-20, 10));
}

TEST_CASE("Transform = Inverse Transform ○ Transform") {
  int x = GENERATE(take(10, random(-100, 100)));
  int y = GENERATE(take(10, random(-100, 100)));
  // this iterates over all possible transformations,
  // even bogus ones (like rotating cw and ccw)
  for (Transformation transformation = 0; transformation < 0b10000;
       transformation++) {
    int xt, yt;
    std::tie(xt, yt) = transform(transformation, x, y);
    int xti, yti;
    std::tie(xti, yti) = transform_inv(transformation, xt, yt);
    REQUIRE(x == xti);
    REQUIRE(y == yti);
  }
}

TEST_CASE("Transformation to standard case") {
  REQUIRE(transformation_to_standard_case(5, 20, 20, 10) == 0);
  REQUIRE(transformation_to_standard_case(5, 5, 20, 15) == TRANSFORM_MIRROR_X);
  REQUIRE(transformation_to_standard_case(20, 15, 5, 5) == TRANSFORM_MIRROR_Y);
  REQUIRE(transformation_to_standard_case(20, 10, 5, 20) ==
          (TRANSFORM_MIRROR_X | TRANSFORM_MIRROR_Y));

  REQUIRE(transformation_to_standard_case(5, 20, 15, 5) ==
          (TRANSFORM_ROTATE_CW | TRANSFORM_MIRROR_X));
  REQUIRE(transformation_to_standard_case(5, 5, 15, 20) ==
          TRANSFORM_ROTATE_CCW);
  REQUIRE(transformation_to_standard_case(15, 5, 5, 20) ==
          (TRANSFORM_ROTATE_CCW | TRANSFORM_MIRROR_X));
  REQUIRE(transformation_to_standard_case(15, 20, 5, 5) == TRANSFORM_ROTATE_CW);
}

TEST_CASE("Transformation to standard case (prop)") {
  int x0 = GENERATE(take(10, random(-100, 100)));
  int y0 = GENERATE(take(10, random(-100, 100)));
  int x1 = GENERATE(take(10, random(-100, 100)));
  int y1 = GENERATE(take(10, random(-100, 100)));

  Transformation transformation =
      transformation_to_standard_case(x0, y0, x1, y1);

  transform_mut(transformation, x0, y0);
  transform_mut(transformation, x1, y1);

  REQUIRE(x0 <= x1);
  REQUIRE(y0 >= y1);
}

TEST_CASE("Bresenham/DDA line tool (prop: for every row/column, only one pixel "
          "is set)") {
  const int size = 100;
  canvas_buffer *canvas = new canvas_buffer(size, size);

  bresenham_line_tool *tool_bresenham = new bresenham_line_tool(*canvas);
  dda_line_tool *tool_dda = new dda_line_tool(*canvas);

  tool_base *tool;
  int tool_idx = GENERATE(0, 1);
  switch (tool_idx) {
  case 0:
    tool = tool_bresenham;
    break;
  case 1:
    tool = tool_dda;
    break;
  }

  int x0 = GENERATE(take(10, random(0, size - 1)));
  int y0 = GENERATE(take(10, random(0, size - 1)));
  int x1 = GENERATE(take(10, random(0, size - 1)));
  int y1 = GENERATE(take(10, random(0, size - 1)));

  tool->draw(x0, y0, x1, y1);

  int x_min = std::min(x0, x1);
  int x_max = std::max(x0, x1);
  int y_min = std::min(y0, y1);
  int y_max = std::max(y0, y1);

  // Depending on what the direction of the line (rounded to the next 90°) is,
  // either every row or column has only one pixel set.
  bool vertical = false;
  int draw_direction_min;
  int draw_direction_max;
  int unique_direction_min;
  int unique_direction_max;
  if (abs(y1 - y0) > abs(x1 - x0)) {
    vertical = true;
    draw_direction_min = y_min;
    draw_direction_max = y_max;
    unique_direction_min = x_min;
    unique_direction_max = x_max;
  } else {
    draw_direction_min = x_min;
    draw_direction_max = x_max;
    unique_direction_min = y_min;
    unique_direction_max = y_max;
  }

  bool all_sums_are_one = true;
  int sum;
  for (int dd = draw_direction_min; dd <= draw_direction_max; dd++) {
    sum = 0;
    for (int ud = unique_direction_min; ud <= unique_direction_max; ud++) {
      int x, y;
      if (vertical) {
        x = ud;
        y = dd;
      } else {
        x = dd;
        y = ud;
      }
      if (canvas->get_pixel(x, y))
        sum++;
    }
    if (sum != 1)
      all_sums_are_one = false;
  }

  REQUIRE(all_sums_are_one);
}