autocmd.lua

local yank_group = vim.api.nvim_create_augroup("highlight_yank", { clear = true })

-- Set cursor position before yanking
vim.api.nvim_create_autocmd("ModeChanged", {
	group = yank_group,
	pattern = "*",
	callback = function()
		vim.g.pre_yank_cursor_pos = vim.fn.getcurpos()
	end,
})

---@param reg Register
local function shift_reg(reg)
	---@class Register
	---@field val string
	---@field typ string

	for i = 8, 1, -1 do
		vim.fn.setreg(i + 1, vim.fn.getreg(i), vim.fn.getregtype(i))
	end

	vim.fn.setreg("1", reg.val, reg.typ)
end

vim.g.lat_small_reg = vim.fn.getreg("-")
vim.api.nvim_create_autocmd("TextYankPost", {
	group = yank_group,
	pattern = "*",
	callback = function()
		if vim.v.event.operator == "y" then
			-- Highlight the yanked area
			vim.highlight.on_yank({ higroup = "Visual", timeout = 200 })

			-- Come back to the set yank position
			vim.fn.setpos(".", vim.g.pre_yank_cursor_pos)

			-- Save yanks in the numbered registers
			shift_reg({ val = vim.fn.getreg("0"), typ = vim.fn.getregtype("0") })

			return
		end

		-- Ignore regular deletes
		if vim.v.event.regtype ~= "v" then
			return
		end

		-- Save small deletes in numbered registers
		local small = vim.fn.getreg("-")
		if small ~= vim.g.lat_small_reg then
			shift_reg({ val = small, typ = vim.fn.getregtype("-") })
			vim.g.lat_small_reg = small
		end
	end,
})

-- Save system clipboard in numbered registers
vim.g.lat_sys_reg = vim.fn.getreg("+")
vim.api.nvim_create_autocmd("FocusGained", {
	group = yank_group,
	pattern = "*",
	callback = function()
		local ok, sys_val = pcall(vim.fn.getreg, "+")
		if ok and sys_val ~= vim.g.lat_sys_reg and sys_val ~= vim.fn.getreg("1") then
			shift_reg({ val = sys_val, typ = vim.fn.getregtype("+") })
			vim.g.lat_sys_reg = sys_val
		end
	end,
})