#include "raylib.h"
#include <math.h>

#define STAR_COUNT 200

typedef struct
{
   int x;
   int y;
   float brightness;
   float phase;
} Star;

typedef enum
{
   PAUSE_NONE,
   PAUSE_RESUME,
   PAUSE_QUIT
} PauseAction;

/* --- INIT --- */

static void InitStars(Star *stars, int count, int width, int height)
{
   for (int i = 0; i < count; i++)
   {
      stars[i].x = GetRandomValue(0, width);
      stars[i].y = GetRandomValue(0, height * 2 / 3); /* Upper sky. */
      stars[i].brightness = (float)GetRandomValue(30, 100) / 100.0f;
      stars[i].phase = (float)GetRandomValue(0, 628) / 100.0f; /* ~0..2pi */
   }
}

/* --- DRAW: 2D BACKGROUND --- */

static void DrawSky(int width, int height)
{
   /* Two vertical gradients: white->blue (top), blue->black (bottom).
      Replaces 480 DrawLine calls — fixes the tearing. */
   Color white = { 255, 255, 255, 255 };
   Color blue  = { 40, 80, 160, 255 };
   Color black = { 0, 0, 0, 255 };
   DrawRectangleGradientV(0, 0, width, height / 2, white, blue);
   DrawRectangleGradientV(0, height / 2, width, height - height / 2, blue, black);
}

static void DrawStars(const Star *stars, int count, float time)
{
   for (int i = 0; i < count; i++)
   {
      float twinkle = 0.5f + 0.5f * sinf(time * 2.0f + stars[i].phase);
      unsigned char a = (unsigned char)(255.0f * stars[i].brightness * twinkle);
      DrawCircle(stars[i].x, stars[i].y, 2.0f * twinkle,
            (Color){ 255, 255, 255, (unsigned char)(a / 3) });
      DrawPixel(stars[i].x, stars[i].y, (Color){ 255, 255, 255, a });
   }
}

static void DrawCrosshair(int width, int height)
{
   int cx = width / 2;
   int cy = height / 2;
   Color c = { 255, 255, 255, 120 };
   DrawLine(cx - 8, cy, cx - 3, cy, c);
   DrawLine(cx + 3, cy, cx + 8, cy, c);
   DrawLine(cx, cy - 8, cx, cy - 3, c);
   DrawLine(cx, cy + 3, cx, cy + 8, c);
}

/* --- DRAW: PAUSE MENU --- */

static PauseAction DrawPauseMenu(int width, int height)
{
   /* Dim overlay. */
   DrawRectangle(0, 0, width, height, (Color){ 0, 0, 0, 160 });
   /* Title. */
   const char *title = "PAUSED";
   int title_size = 60;
   int title_w = MeasureText(title, title_size);
   DrawText(title, (width - title_w) / 2, height / 2 - 130, title_size, RAYWHITE);
   /* Resume button. */
   Rectangle resume_btn = { width / 2 - 100, height / 2 - 20, 200, 50 };
   bool resume_hover = CheckCollisionPointRec(GetMousePosition(), resume_btn);
   DrawRectangleRec(resume_btn,
         resume_hover ? (Color){ 80, 80, 130, 255 } : (Color){ 50, 50, 90, 255 });
   DrawRectangleLinesEx(resume_btn, 2, RAYWHITE);
   DrawText("RESUME", resume_btn.x + 53, resume_btn.y + 12, 30, RAYWHITE);
   /* Quit button. */
   Rectangle quit_btn = { width / 2 - 100, height / 2 + 50, 200, 50 };
   bool quit_hover = CheckCollisionPointRec(GetMousePosition(), quit_btn);
   DrawRectangleRec(quit_btn,
         quit_hover ? (Color){ 130, 50, 50, 255 } : (Color){ 90, 30, 30, 255 });
   DrawRectangleLinesEx(quit_btn, 2, RAYWHITE);
   DrawText("QUIT", quit_btn.x + 68, quit_btn.y + 12, 30, RAYWHITE);
   /* Handle clicks. */
   if (resume_hover && IsMouseButtonPressed(MOUSE_BUTTON_LEFT))
      return PAUSE_RESUME;
   if (quit_hover && IsMouseButtonPressed(MOUSE_BUTTON_LEFT))
      return PAUSE_QUIT;
   return PAUSE_NONE;
}

/* --- MAIN --- */

int main(int argc, char *argv[])
{
   (void)argc;
   (void)argv;
   const int screen_width = 720;
   const int screen_height = 480;
   InitWindow(screen_width, screen_height, "prj tiny");
   SetTargetFPS(60);
   SetExitKey(KEY_NULL); /* Take over ESC ourselves. */
   /* 3D Camera. */
   Camera3D camera = { 0 };
   camera.position   = (Vector3){ 0.0f, 2.0f, 8.0f };
   camera.target     = (Vector3){ 0.0f, 1.0f, 0.0f };
   camera.up         = (Vector3){ 0.0f, 1.0f, 0.0f };
   camera.fovy       = 60.0f;
   camera.projection = CAMERA_PERSPECTIVE;
   Star stars[STAR_COUNT];
   InitStars(stars, STAR_COUNT, screen_width, screen_height);
   bool paused = false;
   DisableCursor(); /* Capture mouse for camera look. */
   while (!WindowShouldClose())
   {
      /* --- INPUT --- */
      if (IsKeyPressed(KEY_ESCAPE))
      {
         paused = !paused;
         if (paused)
            EnableCursor();
         else
            DisableCursor();
      }
      if (!paused)
         UpdateCamera(&camera, CAMERA_FIRST_PERSON);
      /* --- DRAW --- */
      float time = (float)GetTime();
      BeginDrawing();
         ClearBackground(BLACK);
         DrawSky(screen_width, screen_height);
         DrawStars(stars, STAR_COUNT, time);
         BeginMode3D(camera);
            DrawPlane((Vector3){ 0, 0, 0 }, (Vector2){ 256, 256 }, BEIGE);
            DrawCube((Vector3){ 0, 1.05f, 0 }, 2, 2, 2, RED);
         EndMode3D();
         if (!paused)
         {
            DrawCrosshair(screen_width, screen_height);
            DrawText("prj tiny - ESC to pause", 10, 10, 20, DARKGRAY);
         }
         else
         {
            PauseAction action = DrawPauseMenu(screen_width, screen_height);
            if (action == PAUSE_RESUME)
            {
               paused = false;
               DisableCursor();
            }
            else if (action == PAUSE_QUIT)
               break;
         }
      EndDrawing();
   }
   CloseWindow();
   return 0;
}