From 53d20619ec206183cf45202d5f573a9aed46ffdf Mon Sep 17 00:00:00 2001
From: mintsuki <mintsuki@protonmail.com>
Date: Fri, 7 Oct 2022 07:35:08 +0200
Subject: [PATCH] menu: Properly handly high number of entries

---
 common/menu.c | 26 +++++++++++++++++++++-----
 1 file changed, 21 insertions(+), 5 deletions(-)

diff --git a/common/menu.c b/common/menu.c
index 55958ae6..a87280fb 100644
--- a/common/menu.c
+++ b/common/menu.c
@@ -493,7 +493,7 @@ refresh:
     goto refresh;
 }
 
-static size_t print_tree(const char *shift, size_t level, size_t base_index, size_t selected_entry,
+static size_t print_tree(size_t offset, size_t window, const char *shift, size_t level, size_t base_index, size_t selected_entry,
                       struct menu_entry *current_entry,
                       struct menu_entry **selected_menu_entry) {
     size_t max_entries = 0;
@@ -506,6 +506,12 @@ static size_t print_tree(const char *shift, size_t level, size_t base_index, siz
     for (;;) {
         if (current_entry == NULL)
             break;
+        if (!no_print && base_index + max_entries < offset) {
+            goto skip_line;
+        }
+        if (!no_print && base_index + max_entries >= offset + window) {
+            goto skip_line;
+        }
         if (!no_print) print("%s", shift);
         if (level) {
             for (size_t i = level - 1; i > 0; i--) {
@@ -536,8 +542,9 @@ static size_t print_tree(const char *shift, size_t level, size_t base_index, siz
             if (!no_print) print("\e[7m");
         }
         if (!no_print) print(" %s \e[27m\n", current_entry->name);
+skip_line:
         if (current_entry->sub && current_entry->expanded) {
-            max_entries += print_tree(shift, level + 1, base_index + max_entries + 1,
+            max_entries += print_tree(offset, window, shift, level + 1, base_index + max_entries + 1,
                                       selected_entry,
                                       current_entry->sub,
                                       selected_menu_entry);
@@ -699,7 +706,7 @@ noreturn void _menu(bool first_run) {
     if (!skip_timeout && !timeout) {
         // Use print tree to load up selected_menu_entry and determine if the
         // default entry is valid.
-        print_tree(NULL, 0, 0, selected_entry, menu_tree, &selected_menu_entry);
+        print_tree(0, 0, NULL, 0, 0, selected_entry, menu_tree, &selected_menu_entry);
         if (selected_menu_entry == NULL || selected_menu_entry->sub != NULL) {
             quiet = false;
             print("Default entry is not valid or directory, booting to menu.\n");
@@ -711,7 +718,16 @@ noreturn void _menu(bool first_run) {
 
     menu_init_term();
 
+    size_t tree_offset = 0;
+
 refresh:
+    if (selected_entry >= tree_offset + term->rows - 10) {
+        tree_offset = selected_entry - (term->rows - 11);
+    }
+    if (selected_entry < tree_offset) {
+        tree_offset = selected_entry;
+    }
+
     term->autoflush = false;
 
     term->disable_cursor(term);
@@ -770,7 +786,7 @@ refresh:
         set_cursor_pos_helper(x, y + 2);
     }
 
-    size_t max_entries = print_tree(serial ? "|   " : "\xb3   ", 0, 0, selected_entry, menu_tree,
+    size_t max_entries = print_tree(tree_offset, term->rows - 10, serial ? "|   " : "\xb3   ", 0, 0, selected_entry, menu_tree,
                                  &selected_menu_entry);
 
     {
@@ -834,7 +850,7 @@ timeout_aborted:
                 int ent = (c - '0') - 1;
                 if (ent < (int)max_entries) {
                     selected_entry = ent;
-                    print_tree(NULL, 0, 0, selected_entry, menu_tree,
+                    print_tree(0, 0, NULL, 0, 0, selected_entry, menu_tree,
                                &selected_menu_entry);
                     goto autoboot;
                 }