auto complete for modify tags

lua/go.lua

@@ -163,7 +163,7 @@ function go.setup(cfg)
   vim.cmd(
     [[command! -nargs=*  -complete=custom,v:lua.package.loaded.go.modify_tags_complete GoModifyTag lua require("go.tags").modify(<f-args>)]]
   )
-  vim.cmd([[command! -nargs=* GoAddTag lua require("go.tags").add(<f-args>)]])
+  vim.cmd([[command! -nargs=*  -complete=custom,v:lua.package.loaded.go.add_tags_complete  GoAddTag lua require("go.tags").add(<f-args>)]])
   vim.cmd([[command! -nargs=* GoRmTag lua require("go.tags").rm(<f-args>)]])
   vim.cmd(
     [[command! -nargs=* -complete=custom,v:lua.package.loaded.go.impl_complete GoImpl  lua require("go.impl").run(<f-args>)]]
@@ -297,4 +297,33 @@ go.modify_tags_complete = function(_, _, _)
   return table.concat(opts, "\n")
 end
 
+
+-- how to deal complete https://github.com/vim-scripts/marvim/blob/c159856871aa18fa4f3249c6aa312c52f586d1ef/plugin/marvim.vim#L259
+
+-- go.add_tags_complete = function(arglead, line, pos)
+go.add_tags_complete = function(arglead, line, _)
+  -- print("lead: ",arglead, "L", line, "p" )
+  local transf = { "camelcase", "snakecase", "lispcase", 'pascalcase', "titlecase", 'keep' }
+  local ret = {}
+  if #vim.split(line, '%s+') >= 2 then
+    if vim.startswith("-transform", arglead) then
+      return "-transform"
+    end
+    table.foreach(transf, function(_, tag)
+      if vim.startswith(tag, arglead) then
+        ret[#ret + 1] = tag
+      end
+    end)
+    if #ret > 0 then
+      return table.concat(ret, "\n")
+    end
+    return table.concat(transf, '\n')
+  end
+
+  local opts = {
+    "json", "json.yml", "-transform",
+  }
+  return table.concat(opts, "\n")
+end
+
 return go