local opts = {
    -- this might not be needed anymore
    termguicolors = true,

    -- copy indent on a new line
    autoindent = true,

    -- :h tabstop, 2. point
    -- use appropriate number of spaces to insert a <Tab>
    expandtab = true,
    shiftwidth = 4,
    softtabstop = 4,
    tabstop = 8,

    -- use english for spellchecking
    spelllang = "en_gb",

    -- tab completion, zsh style
    wildmode = "longest:full,full",

    -- put one space for join (not two)
    joinspaces = false,

    -- keep n lines above/below cursor while scrolling
    scrolloff = 4,

    -- line numbers
    number = true,

    -- manual folding
    foldcolumn = "0",
    foldlevel = 99,
    foldlevelstart = 99,
    foldenable = true,

    -- set the terminal title
    title = true,

    -- wrap using 'breakat' character
    linebreak = true,

    -- new split panes will split to below and right
    splitbelow = true,
    splitright = true,

    -- use relative line numbers
    relativenumber = true,

    -- we are already using a cursorline, don't clobber linter messages
    showmode = false,

    -- jump to the matching bracket briefly
    showmatch = true,

    -- persistent undo
    undofile = true,

    -- lower case searches ignore case, upper case searches do not
    ignorecase = true,
    smartcase = true,

    -- https://stackoverflow.com/a/3445040/
    -- switch case labels
    cinoptions = "l1",

}

for opt, val in pairs(opts) do
    vim.o[opt] = val
end

-- interact with system clipboard
vim.opt.clipboard:append('unnamedplus')

vim.opt.wildignore = {
    '*.o', '*.obj', '*.class', '*.aux', '*.lof', '*.log', '*.lot', '*.fls',
    '*.toc', '*.fmt', '*.fot', '*.cb', '*.cb2', '.*.lb', '.dvi', '*.xdv',
    '*.bbl', '*.bcf', '*.blg', '*-blx.aux', '*-blx.bib', '*.run.xml',
    '*.fdb_latexmk', '*.synctex', '*.synctex(busy)', '*.synctex.gz',
    '*.synctex.gz(busy)', '*.pdfsync'
}

-- iwhite: ignore changes in amount of white space.
-- vertical: start diff mode with vertical splits
-- filler: show filler lines,
vim.opt.diffopt = {
    "iwhite", "vertical", "filler", "algorithm:patience", "indent-heuristic"
}

-- menu: use a popup menu to show the possible completions
-- preview: show extra information
vim.opt.completeopt = { "menu", "menuone", "noselect" }

if vim.fn.executable("rg") then
    vim.o.grepprg = "rg --vimgrep --no-heading --smart-case"
    vim.o.grepformat = "%f:%l:%c:%m,%f:%l:%m"
end