feat: first draft

lua/oil/loading.lua

@@ -0,0 +1,61 @@
+local util = require("oil.util")
+local M = {}
+
+local timers = {}
+
+local FPS = 20
+
+M.is_loading = function(bufnr)
+  return timers[bufnr] ~= nil
+end
+
+M.get_bar_iter = function(opts)
+  opts = vim.tbl_deep_extend("keep", opts or {}, {
+    bar_size = 3,
+    width = 20,
+  })
+  local i = 0
+  return function()
+    local chars = { "[" }
+    for _ = 1, opts.width - 2 do
+      table.insert(chars, " ")
+    end
+    table.insert(chars, "]")
+
+    for j = i - opts.bar_size, i do
+      if j > 1 and j < opts.width then
+        chars[j] = "="
+      end
+    end
+
+    i = (i + 1) % (opts.width + opts.bar_size)
+    return table.concat(chars, "")
+  end
+end
+
+M.set_loading = function(bufnr, is_loading)
+  if is_loading then
+    if timers[bufnr] == nil then
+      local width = 20
+      timers[bufnr] = vim.loop.new_timer()
+      local bar_iter = M.get_bar_iter({ width = width })
+      timers[bufnr]:start(
+        100, -- Delay the loading screen just a bit to avoid flicker
+        math.floor(1000 / FPS),
+        vim.schedule_wrap(function()
+          if not vim.api.nvim_buf_is_valid(bufnr) or not timers[bufnr] then
+            M.set_loading(bufnr, false)
+            return
+          end
+          local lines = { util.lpad("Loading", math.floor(width / 2) - 3), bar_iter() }
+          util.render_centered_text(bufnr, lines)
+        end)
+      )
+    end
+  elseif timers[bufnr] then
+    timers[bufnr]:close()
+    timers[bufnr] = nil
+  end
+end
+
+return M