// Copyright (c) 2023 Dominic Masters
// 
// This software is released under the MIT License.
// https://opensource.org/licenses/MIT

#include "Box.hpp"

using namespace Dawn;

bool_t boxIsPointInside(glm::vec2 point, glm::vec2 min, glm::vec2 max) {
  return (
    point.x >= min.x && point.x <= max.x &&
    point.y >= min.y && point.y <= max.y
  );
}

bool_t Dawn::boxCheckCollision(
  glm::vec2 posA, glm::vec2 minA, glm::vec2 maxA,
  glm::vec2 posB, glm::vec2 minB, glm::vec2 maxB,
  glm::vec2 velocity,
  glm::vec2 &normal,
  float_t &entryTime,
  float_t &exitTime,
  glm::vec2 &entryPoint,
  glm::vec2 &exitPoint
) {
  // Calculate the time intervals of overlap in the x and y axes
  glm::vec2 invEntry = glm::vec2(0.0f);
  glm::vec2 invExit = glm::vec2(0.0f);

  if (velocity.x >= 0.0f) {
    invEntry.x = ((minB.x + posB.x) - (maxA.x + posA.x)) / velocity.x;
    invExit.x = ((maxB.x + posB.x) - (minA.x + posA.x)) / velocity.x;
  } else {
    invEntry.x = ((maxB.x + posB.x) - (minA.x + posA.x)) / velocity.x;
    invExit.x = ((minB.x + posB.x) - (maxA.x + posA.x)) / velocity.x;
  }


  if (velocity.y >= 0.0f) {
    invEntry.y = ((minB.y + posB.y) - (maxA.y + posA.y)) / velocity.y;
    invExit.y = ((maxB.y + posB.y) - (minA.y + posA.y)) / velocity.y;
  } else {
    invEntry.y = ((maxB.y + posB.y) - (minA.y + posA.y)) / velocity.y;
    invExit.y = ((minB.y + posB.y) - (maxA.y + posA.y)) / velocity.y;
  }

  // Calculate the time of entry and exit for each axis
  glm::vec2 entry = glm::max(invEntry, glm::vec2(0.0f));
  glm::vec2 exit = glm::min(invExit, glm::vec2(1.0f));

  // Find the time of entry and exit
  entryTime = glm::max(entry.x, entry.y);
  exitTime = glm::min(exit.x, exit.y);

  // If there is no overlap in either axis, there is no collision
  if (entryTime > exitTime || entry.x < 0.0f && entry.y < 0.0f || entry.x > 1.0f || entry.y > 1.0f) {
    return false;
  }

  // Calculate the normal of the collision
  if (entry.x > entry.y) {
    if (invEntry.x < 0.0f) {
      normal = glm::vec2(1.0f, 0.0f);
    } else {
      normal = glm::vec2(-1.0f, 0.0f);
    }
  } else {
    if (invEntry.y < 0.0f) {
      normal = glm::vec2(0.0f, 1.0f);
    } else {
      normal = glm::vec2(0.0f, -1.0f);
    }
  }

  // Calculate the entry and exit points
  entryPoint = posA + velocity * entryTime;
  exitPoint = posA + velocity * exitTime;

  return true;
}

bool_t Dawn::boxIsBoxColliding(
  glm::vec2 posA, glm::vec2 minA, glm::vec2 maxA,
  glm::vec2 posB, glm::vec2 minB, glm::vec2 maxB
) {
  // Check for no overlap in X axis
  if (posA.x + maxA.x < posB.x + minB.x || posB.x + maxB.x < posA.x + minA.x) {
    return false;
  }

  // Check for no overlap in Y axis
  if (posA.y + maxA.y < posB.y + minB.y || posB.y + maxB.y < posA.y + minA.y) {
    return false;
  }
  return true;
}