From 13245ebf76c6911dde283f0be180423c12d9b79c Mon Sep 17 00:00:00 2001
From: William Wilgus <me.theuser@yahoo.com>
Date: Sat, 14 Sep 2019 04:35:15 -0500
Subject: lua add menu callback

forum user fprockboxer asked for a way to detect long presses within the
do_menu routine this adds that functionality

result = rb.do_menu("Title",t_items, start, menu_callback)

function menu_callback(action)
    ...
    return action
end

Change-Id: I110c590095a743a57d0a7d45b24309899a4629cf
---
 apps/plugins/lua/rocklib.c | 49 ++++++++++++++++++++++++++++++++++++++++++++++
 1 file changed, 49 insertions(+)

diff --git a/apps/plugins/lua/rocklib.c b/apps/plugins/lua/rocklib.c
index 033975d7fe..77b49dc8ec 100644
--- a/apps/plugins/lua/rocklib.c
+++ b/apps/plugins/lua/rocklib.c
@@ -202,18 +202,60 @@ RB_WRAP(gui_syncyesno_run)
     return 1;
 }
 
+static lua_State* store_luastate(lua_State *L, bool bStore)
+{
+    /* it is dangerous to store the lua state byond its guaranteed lifetime
+       be sure to clear state asap (as in before you exit the calling function) */
+    static lua_State *LStored = NULL;
+    if(bStore)
+        LStored = L;
+    return LStored;
+}
+
+static int menu_callback(int action, const struct menu_item_ex *this_item)
+{
+    (void) this_item;
+    static int lua_ref = LUA_NOREF;
+    lua_State *L = store_luastate(NULL, false);
+    if(!L)
+    {
+        lua_ref = action;
+        action = ACTION_STD_CANCEL;
+    }
+    else if (lua_ref != LUA_NOREF)
+    {
+        lua_rawgeti(L, LUA_REGISTRYINDEX, lua_ref);
+        lua_pushnumber(L, action);
+        lua_pcall (L, 1, 1, 0);
+        action = luaL_optnumber (L, -1, ACTION_STD_CANCEL);
+        lua_pop(L, 1);
+    }
+
+    return action;
+}
+
 RB_WRAP(do_menu)
 {
     struct menu_callback_with_desc menu_desc = {NULL, NULL, Icon_NOICON};
     struct menu_item_ex menu = {MT_RETURN_ID | MENU_HAS_DESC, {.strings = NULL},
                                 {.callback_and_desc = &menu_desc}};
     int n, start_selected;
+    int ref_lua = LUA_NOREF;
     const char **items, *title;
 
     title = luaL_checkstring(L, 1);
 
     start_selected = lua_tointeger(L, 3);
 
+    if (lua_isfunction (L, -1))
+    {
+        /*lua callback function cb(action) return action end */
+        ref_lua = luaL_ref(L, LUA_REGISTRYINDEX);
+        menu_callback(ref_lua, NULL);
+        store_luastate(L, true);
+        menu_desc.menu_callback = &menu_callback;
+    }
+
     /* newuserdata will be pushed onto stack after args*/
     items = get_table_items(L, 2, &n);
 
@@ -223,6 +265,13 @@ RB_WRAP(do_menu)
 
     int result = rb->do_menu(&menu, &start_selected, NULL, false);
 
+    if (ref_lua != LUA_NOREF)
+    {
+            store_luastate(NULL, true);
+            luaL_unref (L, LUA_REGISTRYINDEX, ref_lua);
+            menu_callback(LUA_NOREF, NULL);
+    }
+
     lua_pushinteger(L, result);
     return 1;
 }
-- 
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