Detect colorscheme from dbus

templates/nvim/lua/colorscheme.lua.j2

@@ -0,0 +1,91 @@
+-- {{ ansible_managed }}
+
+-- set the colorscheme whenever the background setting changes
+vim.api.nvim_create_autocmd({'OptionSet'}, {
+    pattern = {'background'},
+    callback = function()
+        if vim.o.background == 'dark' then
+            vim.cmd('colorscheme xcodedark')
+        else
+            vim.cmd('colorscheme catppuccin-latte')
+        end
+
+        -- force a full redraw:
+        vim.cmd('mode')
+    end
+})
+
+--[[
+Use `busctl --user tree` to show a tree of available services.
+Use the `Introspect` option to inspect available options:
+
+dbus-send \
+--session \
+--print-reply ]
+--reply-timeout=2000 \
+--type=method_call \
+--dest=org.freedesktop.portal.Desktop \
+/org/freedesktop/portal/desktop \
+org.freedesktop.DBus.Introspectable.Introspect
+
+--]]
+local oneshot = {
+  'dbus-send',
+  '--session',
+  '--print-reply',
+  '--reply-timeout=2000',
+  '--type=method_call',
+  '--dest=org.freedesktop.portal.Desktop',
+  '/org/freedesktop/portal/desktop',
+  'org.freedesktop.portal.Settings.ReadOne',
+  'string:org.freedesktop.appearance',
+  'string:color-scheme'
+}
+
+local set_background = vim.schedule_wrap(
+  function(object)
+    local default_background = 'light'
+
+    if object.code ~= 0 then
+      print(string.format('An error occured: \n %s', object.stderr))
+      vim.api.nvim_command(string.format('set background=%s', default_background))
+    end
+
+    local colorscheme_output = tonumber(string.match(object.stdout, 'uint32 (%d)'))
+
+    if colorscheme_output == 1 then
+      vim.api.nvim_command('set background=dark')
+    elseif colorscheme_output == 2 then
+      vim.api.nvim_command('set background=light')
+    end
+  end
+)
+
+vim.schedule(
+  function() vim.system(oneshot, { text = true }, set_background) end
+)
+
+-- Note that the last argument is a match rule,
+-- see https://dbus.freedesktop.org/doc/dbus-specification.html#message-bus-routing-match-rules.
+local monitor_command = {
+  'dbus-monitor',
+  '--session',
+  'path=/org/freedesktop/portal/desktop,' ..
+  'interface=org.freedesktop.portal.Settings,' ..
+  'member=SettingChanged,' ..
+  'arg0=org.freedesktop.appearance,'..
+  'arg1=color-scheme'
+}
+
+local detect_scheme_change = function(channel_id, data, name)
+  local line = table.concat(data)
+  local match_output = tonumber(string.match(line, "uint32 (%d)"))
+
+  if match_output == 1 then
+    vim.api.nvim_command('set background=dark')
+  elseif match_output == 2 then
+    vim.api.nvim_command('set background=light')
+  end
+end
+
+vim.fn.jobstart(monitor_command, { on_stdout = detect_scheme_change } )