if not table.unpack then
    table.unpack = unpack
end

local has_words_before = function()
    local line, col = table.unpack(vim.api.nvim_win_get_cursor(0))
    return col ~= 0 and vim.api.nvim_buf_get_lines(0, line - 1, line, true)[1]:sub(col, col):match("%s") == nil
end

local luasnip = require("luasnip")
local cmp = require("cmp")
require("luasnip/loaders/from_vscode").lazy_load()
vim.o.completeopt = 'menuone,noselect'

cmp.setup {
    snippet = {
        expand = function(args)
            require('luasnip').lsp_expand(args.body)
        end,
    },
    mapping = cmp.mapping.preset.insert({
        ['<CR>'] = cmp.mapping.confirm({ select = true }),
        ['<C-n>'] = cmp.mapping.select_next_item(),
        ['<C-p>'] = cmp.mapping.select_prev_item(),
        ['<C-f>'] = cmp.mapping.scroll_docs(4),
        ['<C-d>'] = cmp.mapping.scroll_docs(-4),
        ['<C-e>'] = cmp.mapping.close(),
        ["<Tab>"] = cmp.mapping(function(fallback)
            if cmp.visible() then
                cmp.select_next_item()
            elseif luasnip.expand_or_jumpable() then
                luasnip.expand_or_jump()
            elseif has_words_before() then
                cmp.complete()
            else
                fallback()
            end
        end, { "i", "s" }),

        ["<S-Tab>"] = cmp.mapping(function(fallback)
            if cmp.visible() then
                cmp.select_prev_item()
            elseif luasnip.jumpable(-1) then
                luasnip.jump(-1)
            else
                fallback()
            end
        end, { "i", "s" }),
    }),
    sources = {
        { name = 'nvim_lsp' },
        { name = 'luasnip' },
    },
}