delete made for two cases out of 6, not tested yet tho

bp_tree.c

@@ -56,6 +56,14 @@ void bp_node_shift(node *nd, int index) {
     }
 }
 
+void bp_node_shit_del(node *nd, int index) {
+    for (int i = index; i < M - 1; i++) {
+        nd->user[i] = nd->user[i + 1];
+        nd->data[i] = nd->data[i + 1];
+    }
+    nd->data[M - 1] = 0;
+}
+
 node *bp_split(node *nd) {
     node *new = bp_create_node();
     /*
@@ -289,6 +297,66 @@ node *bp_insert_val(node *tree, entry person) {
     return tree;
 }
 
+// DELETE ----------------------------------------------------------
+
+control bp_delete_from(node *nd, uint64_t key) {
+    control c = {.value = 0};
+    for (int i = 0; i < M; i++) {
+        if (nd->data[i] == key) {
+            nd->data[i] = 0;
+            nd->count--;
+            if (i != M - 1 && nd->data[i + 1] != 0) {
+                bp_node_shit_del(nd, i);
+            }
+            if (i == 0) {
+                c.value = nd->data[0];
+            }
+        }
+    }
+    return c;
+}
+
+control bp_delete(node *nd, uint64_t key, int depth) {
+    control c;
+    if (bp_is_leaf(nd)) {
+        c = bp_delete_from(nd, key);
+    } else {
+        for (int i = 0; i < M; i++) {
+            if (nd->data[i] > key || nd->data[i] == 0) {
+                c = bp_delete(nd->childs[i], key, depth + 1);
+                break;
+            }
+
+            // if a current key was deleted, we must replace it with the new key
+            if (c.value != 0 && depth != 0) {
+                for (int i = 0; i < M; i++)
+                    if (nd->data[i] == key)
+                        nd->data[i] = c.value;
+
+                return c;
+            }
+        }
+    }
+
+    if (c.value != 0) {
+        return c;
+    }
+    return CONST_CONTR;
+}
+
+node *bp_delete_val(node *tree, char phone[11]) {
+    uint64_t hash_i = generate_key(phone);
+
+    control c = bp_delete(tree, hash_i, 0);
+
+    if (c.value != 0) {
+        for (int i = 0; i < M; i++)
+            if (tree->data[i] == hash_i)
+                tree->data[i] = c.value;
+    }
+    return tree;
+}
+
 // SEARCH ----------------------------------------------------------
 
 entry bp_search_node(node *tree, uint64_t hash) {