simple nvim lua statusline, old version, lil broken

sl_port-v1.lua

vim.opt.laststatus = 2
vim.opt.statusline = sl_values

-- local sl_values

-- statusline functions
local function StatuslineMode()
    local mode = vim.fn.mode()
        if mode == 'n' then
            return "NORMAL"
        elseif mode == 'v' then
            return "VISUAL"
        elseif mode == 'i' then
            return "INSERT"
        elseif mode == 'R' then
            return "REPLACE"
    end
    return mode
end

local function StatuslineGitBranch()
    local gitbranch = ""
    if vim.bo.modifiable then
        local current_dir = vim.fn.expand("%:p:h")
        vim.cmd("lcd " .. current_dir)
        local gitrevparse = vim.fn.system("git rev-parse --abbrev-ref HEAD")
        vim.cmd("lcd -")
        if not string.find(gitrevparse, "fatal: not a git repository") then
            gitbranch = "(" .. string.gsub(gitrevparse, '\n', '') .. ") "
        end
    end
    vim.bo.gitbranch = gitbranch
end

local sl_values = [[
  "", -- left align
  "%2*\\", -- blank char
  "%2*\\%{StatuslineMode()}",
  "%2*\\",
  "%1*\\ <<",
  "%1*\\ %f", -- short filename
  "%1*\\ >>",
  "%=", -- right align
  "%*",
  "%3*\\%h%m%r", -- file flags (help, read-only, modified)
  "%4*\\%{vim.b.gitbranch}", -- include git branch
  "%3*\\%.25F", -- long filename (trimmed to 25 chars)
  "%3*\\::",
  "%3*\\%l/%L\\\\|", -- line count
  "%3*\\%y" -- file type
]]

-- highlights
vim.cmd[[
  hi User1 ctermbg=black ctermfg=grey guibg=black guifg=grey
  hi User2 ctermbg=green ctermfg=black guibg=green guifg=black
  hi User3 ctermbg=black ctermfg=lightgreen guibg=black guifg=lightgreen
]]


local ggb_au = vim.api.nvim_create_augroup('get_git_branch', { clear = true})

local function branch_name()
    local branch = vim.fn.system("git branch --slow-current 2> /dev/null | tr -d '\n'")
    if branch ~= "" then
        return branch
    else
        return ""
    end
end

vim.api.nvim_create_autocmd({"VimEnter","WinEnter","BufEnter"}, {
    callback = function()
        vim.b.branch_name = branch_name()
    end

})