feat(ui): connect to remote ui (only debug messages for now)

co-authored-by: hlpr98 <hlpr98@gmail.com>

src/nvim/ui_client.c

@@ -0,0 +1,70 @@
+// This is an open source non-commercial project. Dear PVS-Studio, please check
+// it. PVS-Studio Static Code Analyzer for C, C++ and C#: http://www.viva64.com
+
+#include <stdbool.h>
+#include <stdint.h>
+#include <assert.h>
+
+#include "nvim/vim.h"
+#include "nvim/ui_client.h"
+#include "nvim/api/private/helpers.h"
+#include "nvim/msgpack_rpc/channel.h"
+#include "nvim/api/private/dispatch.h"
+#include "nvim/ui.h"
+
+void ui_client_init(uint64_t chan)
+{
+  Array args = ARRAY_DICT_INIT;
+  int width = 80;
+  int height = 25;
+  Dictionary opts = ARRAY_DICT_INIT;
+
+  PUT(opts, "rgb", BOOLEAN_OBJ(true));
+  PUT(opts, "ext_linegrid", BOOLEAN_OBJ(true));
+  PUT(opts, "ext_termcolors", BOOLEAN_OBJ(true));
+
+  // TODO(bfredl): use the size of the client UI
+  ADD(args, INTEGER_OBJ((int)width));
+  ADD(args, INTEGER_OBJ((int)height));
+  ADD(args, DICTIONARY_OBJ(opts));
+
+  rpc_send_event(chan, "nvim_ui_attach", args);
+  msgpack_rpc_add_redraw();  // GAME!
+  ui_client_channel_id = chan;
+}
+
+/// Handler for "redraw" events sent by the NVIM server
+///
+/// This is just a stub. The mentioned functionality will be implemented.
+///
+/// This function will be called by handle_request (in msgpack_rpc/channle.c)
+/// The individual ui_events sent by the server are individually handled
+/// by their respective handlers defined in ui_events_redraw.generated.h
+///
+/// @note The "flush" event is called only once and only after handling all
+///       the other events
+/// @param channel_id: The id of the rpc channel
+/// @param uidata: The dense array containing the ui_events sent by the server
+/// @param[out] err Error details, if any
+Object ui_client_handle_redraw(uint64_t channel_id, Array args, Error *error)
+{
+  for (size_t i = 0; i < args.size; i++) {
+    Array call = args.items[i].data.array;
+    char *method_name = call.items[0].data.string.data;
+
+    fprintf(stderr, "%s: %zu\n", method_name, call.size-1);
+  }
+  return NIL;
+}
+
+/// run the main thread in ui client mode
+///
+/// This is just a stub. the full version will handle input, resizing, etc
+void ui_client_execute(uint64_t chan)
+{
+  while (true) {
+    loop_poll_events(&main_loop, -1);
+  }
+
+  getout(0);
+}