local has_words_before = function()
  local line, col = 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 cmp = require("cmp")
local luasnip = require("luasnip")

cmp.setup({
  snippet = {
    expand = function(args)
      luasnip.lsp_expand(args.body)
    end
  },
  sources = cmp.config.sources({
    { name = "nvim_lsp" },
    { name = "nvim_lsp_signature_help" },
    { name = "luasnip" },
    { name = "path" },
    { name = "buffer" },
    { name = "nvim-lua" },
    { name = "calc" },
  }),
  mapping = cmp.mapping.preset.insert({
    ["<C-b>"] = cmp.mapping.scroll_docs(-4),
    ["<C-f>"] = cmp.mapping.scroll_docs(4),
    ["<C-Space>"] = cmp.mapping.complete({}),
    ["<C-e>"] = cmp.mapping.abort(),
    ["<CR>"] = cmp.mapping.confirm({ select = false }), -- Accept currently selected item. Set `select` to `false` to only confirm explicitly selected items.
    ["<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" }),
  }),
  experimental = { ghost_text = true },
  window = {
    completion = cmp.config.window.bordered(),
    documentation = cmp.config.window.bordered(),
  },
  formatting = {
    fields = { "menu", "abbr", "kind" },
    format = function(entry, item)
      local menu_icon = {
        nvim_lsp = "λ",
        luasnip = "⋗",
        buffer = "Ω",
        path = "🖿",
      }

      item.menu = menu_icon[entry.source.name]
      return item
    end,
  },
})

-- `/` cmdline setup.
cmp.setup.cmdline("/", {
  sources = cmp.config.sources(
    { name = "buffer" }
  )
})

-- `:` cmdline setup.
cmp.setup.cmdline(":", {
  sources = cmp.config.sources(
    { name = "path" },
    { name = "cmdline" }
  )
})