feat(ui): init fold logic (#2)

- extract logic from nvim config

lua/better-folds/folds.lua

@@ -0,0 +1,18 @@
+local right = ""
+local l = "ℓ"
+
+--  [9ℓ]: text_from_the_first_line  󰇼󰇼󰇼󰇼󰇼󰇼󰇼󰇼󰇼󰇼󰇼󰇼󰇼󰇼󰇼󰇼󰇼󰇼󰇼󰇼󰇼󰇼󰇼󰇼󰇼󰇼󰇼󰇼󰇼󰇼󰇼󰇼󰇼󰇼󰇼󰇼󰇼󰇼󰇼󰇼󰇼󰇼󰇼󰇼󰇼󰇼󰇼󰇼󰇼󰇼󰇼󰇼󰇼󰇼󰇼󰇼󰇼󰇼󰇼󰇼󰇼󰇼󰇼󰇼󰇼󰇼󰇼󰇼󰇼󰇼󰇼󰇼󰇼󰇼󰇼󰇼󰇼󰇼󰇼󰇼󰇼󰇼
+
+local M = {}
+
+function M.foldtext()
+	local foldstart, foldend = vim.v.foldstart, vim.v.foldend
+	local fold_length = foldend - foldstart + 1
+
+	local first_line = vim.fn.getline(foldstart)
+	local sanitized_first_line = string.gsub(first_line, "^%s*(.*)[{[]$", "%1")
+
+	return string.format("%s [%i%s]: %s %s ", right, fold_length, l, sanitized_first_line, right)
+end
+
+return M

lua/better-folds/init.lua

@@ -1,7 +1,7 @@
 local M = {}
 
 function M.setup()
-	vim.notify("hello")
+	vim.opt.foldtext = 'v:lua.require("better-folds.folds").foldtext()'
 end
 
 return M