feat: refactor Portal.Content as a class

lua/portal/content.lua

@@ -0,0 +1,31 @@
+---@class Portal.Content
+---@field type string
+---@field buffer integer
+---@field cursor { row: integer, col: integer }
+---@field callback fun(c: Portal.Content)
+---@field extra table
+local Content = {}
+Content.__index = Content
+
+function Content:new(content)
+    assert(content.buffer, ("Portal: invalid content.buffer %s"):format(vim.inspect(content.buffer)))
+    assert(
+        content.cursor and content.cursor.row and content.cursor.col,
+        ("Portal: invalid content.cursor %s"):format(vim.inspect(content.cursor))
+    )
+    assert(
+        type(content.callback) == "function",
+        ("Portal: invalid content.callback %s"):format(vim.inspect(content.callback))
+    )
+
+    content.extra = content.extra or {}
+    setmetatable(content, self)
+
+    return content
+end
+
+function Content:select()
+    return self.callback(self)
+end
+
+return Content