From 3b8d18d5d94cb3258055b658dccdea8a71766e74 Mon Sep 17 00:00:00 2001
From: Miloslav Macko <miloslav.macko@student.tuke.sk>
Date: Wed, 10 Apr 2024 23:11:18 +0200
Subject: [PATCH] 10.4

---
 du7/snake.c | 91 +++++++++++++++++++++++++++++++++++++++++++++++++++++
 1 file changed, 91 insertions(+)
 create mode 100644 du7/snake.c

diff --git a/du7/snake.c b/du7/snake.c
new file mode 100644
index 0000000..1075d55
--- /dev/null
+++ b/du7/snake.c
@@ -0,0 +1,91 @@
+#include "snake.h"
+#include <stdlib.h>
+
+struct snake* add_snake(struct snake* snake, int x, int y) {
+    struct snake* new_head = (struct snake*)malloc(sizeof(struct snake));
+    if (!new_head) {
+        // Memory allocation failed
+        return NULL;
+    }
+    new_head->x = x;
+    new_head->y = y;
+    new_head->next = snake;
+    return new_head;
+}
+
+struct snake* remove_snake(struct snake* snake) {
+    if (!snake) {
+        // Snake is empty
+        return NULL;
+    }
+    struct snake* new_head = snake->next;
+    free(snake);
+    return new_head;
+}
+
+int is_snake(struct snake* snake, int x, int y) {
+    while (snake) {
+        if (snake->x == x && snake->y == y) {
+            return 1; // Found snake part at given coordinates
+        }
+        snake = snake->next;
+    }
+    return 0; // Snake part not found
+}
+
+void free_snake(struct snake* sn) {
+    while (sn) {
+        struct snake* temp = sn;
+        sn = sn->next;
+        free(temp);
+    }
+}
+
+int step_state(struct state* state) {
+    // Calculate new position of the snake head
+    int new_x = state->snake->x + state->sx;
+    int new_y = state->snake->y + state->sy;
+
+    // Check if snake hits a wall
+    if (new_x < 0 || new_x >= state->width || new_y < 0 || new_y >= state->height) {
+        return END_WALL;
+    }
+
+    // Check if snake hits itself
+    if (is_snake(state->snake->next, new_x, new_y)) {
+        return END_SNAKE;
+    }
+
+    // Check if snake eats food
+    int i;
+    for (i = 0; i < FOOD_COUNT; i++) {
+        if (state->foodx[i] == new_x && state->foody[i] == new_y) {
+            // Food eaten, mark it as negative
+            state->foodx[i] = -1;
+            state->foody[i] = -1;
+            // Add new snake part at the food position
+            state->snake = add_snake(state->snake, new_x, new_y);
+            if (state->snake == NULL) {
+                // Memory allocation failed
+                return END_USER;
+            }
+            // Check if no food left
+            int food_left = 0;
+            for (int j = 0; j < FOOD_COUNT; j++) {
+                if (state->foodx[j] >= 0 && state->foody[j] >= 0) {
+                    food_left = 1;
+                    break;
+                }
+            }
+            if (!food_left) {
+                return END_FOOD; // No food left
+            }
+            return END_CONTINUE; // Food eaten, continue the game
+        }
+    }
+
+    // Add new snake part on the new position and remove the last part of the snake
+    state->snake = add_snake(state->snake, new_x, new_y);
+    state->snake = remove_snake(state->snake->next);
+    return END_CONTINUE;
+}