From 4b03b40aeb469f5491b2d3de11358c622d8214d4 Mon Sep 17 00:00:00 2001
From: =?UTF-8?q?Tom=C3=A1=C5=A1=20Vl=C4=8Dek?= <tomas.vlcek@student.tuke.sk>
Date: Wed, 15 Apr 2026 23:11:02 +0000
Subject: [PATCH] re-add du4

---
 du4/snake.c | 144 ++++++++++++++++++++++++++++++++++++++++++++++++++++
 1 file changed, 144 insertions(+)
 create mode 100644 du4/snake.c

diff --git a/du4/snake.c b/du4/snake.c
new file mode 100644
index 0000000..881f20b
--- /dev/null
+++ b/du4/snake.c
@@ -0,0 +1,144 @@
+#include "snake.h"
+#include <stdlib.h>
+#include <stdbool.h>
+
+struct snake* add_snake(struct snake* snake,int x,int y)
+{
+    //vytvori novu prazdnu instanciu a alokujee jej pamat
+   struct snake* newSnake = (struct snake*)malloc(sizeof(struct snake));
+   //prida X,Y suradnice do polia do novej hlavicky
+   newSnake->x = x;
+   newSnake->y = y;
+
+   //nalinkuje ju na staru hlavicku
+   newSnake->next = snake;
+   
+   return newSnake;
+}
+
+struct snake* remove_snake(struct snake* snake){
+
+    struct snake* currentPtr = snake;
+    struct snake* prevPtr;
+    
+    if (snake == NULL)
+    {
+        return NULL;
+    }
+    while (1)
+    {
+        //pomocny pointer -> ulozenie predoslej casti/node-u
+        prevPtr = currentPtr;
+        //skontroluje, ze ci dalsia cast je PRAZDNA.
+        if (currentPtr->next == NULL)
+        {
+            //uprava listu -> odlinkje tuto cast (tak aby prevPtr->next NEFERENCOVAL na uz uvolnenu cast)
+            prevPtr->next = NULL;
+            //uvolni pamat pre akt. cast (uvolni pamat)
+            free(currentPtr);
+            break;
+        }
+        //iteruj ku dalsiej casti (node)
+        currentPtr = currentPtr->next;
+    }
+    return snake;
+}
+
+void free_snake(struct snake* sn)
+{
+    //pomocna smernikova premenna
+    struct snake* currentPtr = sn;
+    while (currentPtr != NULL)
+    {
+        //uloz dalsiu cast, zmaz aktualnu a posun sa na dalsiu
+        struct snake* nextPtr = currentPtr->next;
+        free(currentPtr);
+        currentPtr = nextPtr;
+    }
+}
+
+int is_snake(struct snake* snake,int x,int y){
+    
+    //helper pointer/smernikova premena
+    struct snake* currentPtr = snake;
+    
+    //iteracia cez vsetky casti az dokial sa nenajde cast/node s rovnakymi X,Y suradncami 
+    while (currentPtr != NULL)
+    {
+        if (currentPtr->x == x && currentPtr->y == y)
+        {
+            return 1;
+        }
+        //prejde/iteruje na dalsiu cast
+        currentPtr = currentPtr->next;
+    }
+    return 0;
+}
+
+/* Funguje na zaklade viacerych faz, ktore sa opakuju kazdy cyklus
+    FAZY: 1. -> Kontrola kolizie (seba + vs. stien)
+          2. -> Kontrola logiky zobratia jedla (resp. kolizie s jedlom, update statusu, pripadny narast hada)
+          3. -> Realizacia pohybu  
+          4. -> finalna kontrola poctu jedla */
+int step_state(struct state* st){
+	int nx = (st->snake->x + st->sx);
+    int ny = (st->snake->y + st->sy);
+
+    //helper lok. premena na kontrolovanie, ci uz jedlo bolo zjedene v tomto update cykle
+    bool hasEatenFoodinThisCycle = false;
+
+    //** 1. faza
+    //ak je snake (nejak) mimo hracieho pola:
+    if (nx < 0 || ny < 0)
+    {
+        return END_WALL;
+    }
+    //vrati END_WALL, ak had narazi do steny (a jeho X,Y suradnice su mimo hrac. polia)
+    if (nx >= st->height || ny >= st->width)
+    {
+        return END_WALL;
+    }
+
+    //** kontrola seba kolizie
+    if (is_snake(st->snake, nx, ny)) { return END_SNAKE;}
+
+    //** 2. faza kontroly (zobratia) jedla:
+    for (int i = 0; i < FOOD_COUNT; i++)
+    {   
+        //zoberie jedlo (AK sa X,Y suradnice rovnaju)
+        if (st->foodx[i] == nx && st->foody[i] == ny)
+        {
+            //updatne stav/state hry (-1 stav signalizuje, ze jedlo bolo uz zobrate)
+            st->foodx[i] = -1;
+            st->foody[i] = -1;
+            
+            add_snake(st->snake, nx, ny);
+
+            hasEatenFoodinThisCycle = true;
+            
+            break;
+        }
+        //hra bude pokracovat normalne dalej, ak NIE JE vsetko jedlo zobrate
+        if (st->foodx[i] != -1) 
+        {
+            return END_CONTINUE;
+        }
+    }
+
+    //normalny pohyb snake-a (ak jedlo nebolo zjedene v tomto update cykle)
+    if (!hasEatenFoodinThisCycle)
+    {
+        st->snake = add_snake(st->snake, nx, ny);
+        st->snake = remove_snake(st->snake);
+    }
+
+    //faza kontrola poctu jedla 
+    for (int i = 0; i < FOOD_COUNT; i++)
+    {
+        if (st->foodx[i] != -1)
+        {
+            return END_CONTINUE;
+        }
+    }
+    return END_FOOD;
+}
\ No newline at end of file