#include "wapp.h"
#include "raylib.h"
#include <stdint.h>
#include <stdbool.h>
#include <assert.h>

#define WIDTH 1280
#define HEIGHT 720
#define HALF_WIDTH (WIDTH * 0.5f)
#define HALF_HEIGHT (HEIGHT * 0.5f)
#define MAX_WANDERER_DIM 8
#define MIN_WANDERER_DIM 3
#define MIN_ZONE_DIM 30
#define BG_COLOR (Color){.r = 0xea, .g = 0xf2, .b = 0xe3, .a = 0xff}
#define FG_COLOR (Color){.r = 0x42, .g = 0x4C, .b = 0x55, .a = 0xff}
#define ZONE_COLOR (Color){.r = 0xb4, .g = 0x65, .b = 0x4a, .a = 0xff}
#define WANDERER_COUNT 50000
#define ZONE_COUNT 5
#define WANDERER_SLOWDOWN_FACTOR 0.5f
#define WANDERER_SPEEDUP_FACTOR 2.0f
#define MSG_BUF_LEN 4096
#define abs(A) (A < 0 ? A * -1 : A)
#define min(A, B) (A < B ? A : B)
#define max(A, B) (A > B ? A : B)

#define OBJECT_COMMON struct {Position position; Scale scale;}

typedef struct Position Position;
struct Position {
  f32 x;
  f32 y;
};

typedef struct Scale Scale;
struct Scale {
  f32 width;
  f32 height;
};

typedef struct Velocity Velocity;
struct Velocity {
  f32 x;
  f32 y;
};

typedef struct Wanderer Wanderer;
struct Wanderer {
  OBJECT_COMMON;
  Velocity velocity;
  bool slow;
};

typedef struct SlowZone SlowZone;
struct SlowZone {
  OBJECT_COMMON;
};

void init_wanderer(Wanderer *wanderer, XOR256State *state);
void move_wanderer(Wanderer *wanderer, const SlowZone *zones);
void render_wanderer(const Wanderer *wanderer);
void init_slow_zone(SlowZone *zone,  XOR256State *state);

#ifndef NDEBUG
void render_slow_zone(const SlowZone *zone);
#endif

bool inside_zone(const Wanderer *wanderer, const SlowZone *zone);
f32 get_random_float(XOR256State *state);

int main(void) {
  InitWindow(WIDTH, HEIGHT, "DOD test");
  SetTargetFPS(120);

  Allocator arena       = wapp_mem_arena_allocator_init(MB(10));
  XOR256State state     = wapp_prng_xorshift_init_state();
  Wanderer *wanderers   = wapp_mem_allocator_alloc(&arena, sizeof(Wanderer) * WANDERER_COUNT);
  SlowZone *zones       = wapp_mem_allocator_alloc(&arena, sizeof(SlowZone) * ZONE_COUNT);
  assert(wanderers != NULL && zones != NULL);

  for (u64 i = 0; i < WANDERER_COUNT; ++i) {
    init_wanderer(&(wanderers[i]), &state);
  }
  for (u64 i = 0; i < ZONE_COUNT; ++i) {
    init_slow_zone(&(zones[i]),&state);
  }

  while (!WindowShouldClose()) {
    for (u64 i = 0; i < WANDERER_COUNT; ++i) {
      move_wanderer(&(wanderers[i]), zones);
    }

    BeginDrawing();

    ClearBackground(BG_COLOR);

#ifndef NDEBUG
    for (u64 i = 0; i < ZONE_COUNT; ++i) {
      render_slow_zone(&(zones[i]));
    }
#endif

    for (u64 i = 0; i < WANDERER_COUNT; ++i) {
      render_wanderer(&(wanderers[i]));
    }

    EndDrawing();
  }

  wapp_mem_arena_allocator_destroy(&arena);

  CloseWindow();

  return 0;
}

void init_wanderer(Wanderer *wanderer, XOR256State *state) {
  wanderer->position = (Position){
    .x = wapp_prng_xorshift_256(state) % WIDTH,
    .y = wapp_prng_xorshift_256(state) % HEIGHT,
  };

  f32 scale = (f32)((wapp_prng_xorshift_256(state) % (MAX_WANDERER_DIM + 1 - MIN_WANDERER_DIM)) + MIN_WANDERER_DIM);
  wanderer->scale = (Scale){
    .width  = scale,
    .height = scale,
  };

  wanderer->velocity = (Velocity){
    .x = get_random_float(state),
    .y = get_random_float(state),
  };
}

void move_wanderer(Wanderer *wanderer, const SlowZone *zones) {
  wanderer->position.x += wanderer->velocity.x;
  wanderer->position.y += wanderer->velocity.y;

  f32 max_x = WIDTH - wanderer->scale.width;
  f32 max_y = HEIGHT - wanderer->scale.height;

  if (wanderer->position.x < 0 || wanderer->position.x >= max_x) {
    wanderer->position.x = min(max(wanderer->position.x, 0), max_x);
    wanderer->velocity.x *= -1;
  }

  if (wanderer->position.y < 0 || wanderer->position.y >= max_y) {
    wanderer->position.y = min(max(wanderer->position.y, 0), max_y);
    wanderer->velocity.y *= -1;
  }

  bool was_slow  = wanderer->slow;
  wanderer->slow = false;
  for (u64 i = 0; i < ZONE_COUNT; ++i) {
    if (inside_zone(wanderer, &(zones[i]))) {
      wanderer->slow = true;
      break;
    }
  }

  if (!was_slow && wanderer->slow) {
    wanderer->velocity.x *= WANDERER_SLOWDOWN_FACTOR;
    wanderer->velocity.y *= WANDERER_SLOWDOWN_FACTOR;
  } else if (was_slow && !(wanderer->slow)) {
    wanderer->velocity.x *= WANDERER_SPEEDUP_FACTOR;
    wanderer->velocity.y *= WANDERER_SPEEDUP_FACTOR;
  }
}

void render_wanderer(const Wanderer *wanderer) {
  Color color = wanderer->slow ? ZONE_COLOR : FG_COLOR;
  DrawRectangle(
    (i32)wanderer->position.x,
    (i32)wanderer->position.y,
    (i32)wanderer->scale.width,
    (i32)wanderer->scale.height,
    color
  );
}

void init_slow_zone(SlowZone *zone,  XOR256State *state) {
  zone->position = (Position){
    .x = wapp_prng_xorshift_256(state) % WIDTH,
    .y = wapp_prng_xorshift_256(state) % HEIGHT,
  };

  zone->scale = (Scale){
    .width = wapp_prng_xorshift_256(state) % ((u64)HALF_WIDTH - MIN_ZONE_DIM) + MIN_ZONE_DIM,
    .height = wapp_prng_xorshift_256(state) % ((u64)HALF_HEIGHT - MIN_ZONE_DIM) + MIN_ZONE_DIM,
  };
}

#ifndef NDEBUG
void render_slow_zone(const SlowZone *zone) {
  DrawRectangleLines(
    zone->position.x,
    zone->position.y,
    zone->scale.width,
    zone->scale.height,
    ZONE_COLOR
  );
}
#endif

bool inside_zone(const Wanderer *wanderer, const SlowZone *zone) {
  f32 wanderer_min_x = wanderer->position.x + wanderer->scale.width;
  f32 wanderer_min_y = wanderer->position.y + wanderer->scale.height;
  f32 wanderer_max_x = wanderer->position.x;
  f32 wanderer_max_y = wanderer->position.y;

  f32 zone_x0 = zone->position.x;
  f32 zone_y0 = zone->position.y;
  f32 zone_x1 = zone->position.x + zone->scale.width;
  f32 zone_y1 = zone->position.y + zone->scale.height;

  return (wanderer_min_x > zone_x0 && wanderer_min_y > zone_y0 &&
          wanderer_max_x < zone_x1 && wanderer_max_y < zone_y1);
}

f32 get_random_float(XOR256State *state) {
  i64 random = (i64)wapp_prng_xorshift_256(state) - INT64_MAX;
  return (f32)(random) / (f32)(INT64_MAX);
}