refine module support and package loading

lua/dep/modules/module.lua

@@ -0,0 +1,55 @@
+local spec_man = require("dep.spec")
+local packager = require("dep.package")
+
+---@class module
+---@field name string name of the module
+---@field path string path to the module
+---@field mod table the module
+local module = {}
+
+--- Initialize a module
+---@param self table?
+---@param modpath string path to the module
+---@param prefix string? the prefix to all modules
+---@param overrides spec? a module override
+---@return module|false module false on failure to load module
+---@nodiscard
+function module:new(modpath, prefix, overrides)
+  local ok, err
+  local o = {}
+  self = {}
+  self.__index = self
+  setmetatable(o, self)
+
+  o.name = "<unnamed module>"
+  if type(modpath) == "string" then
+    if prefix ~= nil then
+      if prefix:sub(#prefix) ~= "." and modpath:sub(1, 2) ~= "." then
+        modpath = "."..modpath
+      end
+      o.path = prefix..modpath
+    else
+      o.path = modpath
+    end
+    o.name = modpath
+    ok, o.mod = pcall(require, o.path)
+    if not ok then
+      return false
+    end
+  end
+  o.name = o.mod.name or o.name
+
+  -- allow a module to be a spec
+  if spec_man.check(o.mod, true) ~= false then
+    o.mod = { o.mod }
+  end
+
+  ok, err = pcall(packager.register_speclist, o.mod, overrides)
+  if not ok then
+    error(string.format("%s <- %s", err, o.name))
+  end
+
+  return self
+end
+
+return module