feat(nvim): Implements theme choosing depending on system theme

TODO: Support Windows

tools/nvim/lua/config/colorscheme.lua

@@ -1,2 +1,42 @@
 -- Change the colorscheme here, use SPACE u i or :FzfLua colorscheme to change colorscheme
-vim.cmd.colorscheme("catppuccin")
+
+-- https://www.reddit.com/r/neovim/comments/1d3hk1t/automatic_dark_mode_following_system_theme_on/
+local function get_system_theme()
+  -- Default value
+  local background = 'light'
+  -- First check whether we are on MacOS
+  if vim.loop.os_uname().sysname == "Darwin" then
+    -- Check if 'defaults' is executable
+    if vim.fn.executable('defaults') ~= 0 then
+      -- Execute command to check if the macOS appearance is set to Dark
+      local appleInterfaceStyle = vim.fn.system({ "defaults", "read", "-g", "AppleInterfaceStyle" })
+      if appleInterfaceStyle:find("Dark") then
+        background = 'dark'
+      end
+    end
+    -- Check if 'busctl' is executable (part of systemd)
+  elseif vim.fn.executable('busctl') ~= 0 then
+    -- Get the current color scheme from xdg-desktop-portal using busctl
+    local result = vim.fn.system({
+      "busctl", "--user", "call", "org.freedesktop.portal.Desktop", "/org/freedesktop/portal/desktop",
+      "org.freedesktop.portal.Settings", "ReadOne", "ss", "org.freedesktop.appearance", "color-scheme"
+    })
+    -- The result is in the form of "v u 0" for light and "v u 1" for dark
+    local color_scheme = result:match("u%s+(%d+)")
+
+    if color_scheme == '1' then
+      background = 'dark'
+    end
+  else
+  end
+
+  return background
+end
+
+if get_system_theme() == 'dark' then
+  vim.o.background = 'dark'
+  vim.cmd.colorscheme("catppuccin")
+else
+  vim.o.background = 'light'
+  vim.cmd.colorscheme("rose-pine")
+end