local cmp = require 'cmp'
local luasnip = require 'luasnip'

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

cmp.setup({
  snippet = {
    expand = function(args)
      require('luasnip').lsp_expand(args.body)
    end
  },
  window = {
    completion = cmp.config.window.bordered(),
    documentation = cmp.config.window.bordered(),
  },
  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 = true }),
    ["<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 = cmp.config.sources({
    { name = 'nvim_lsp' },
    { name = 'luasnip' },
    { name = 'path' },
    { name = 'buffer' },
  })
})

cmp.setup.cmdline('/', {
  mapping = cmp.mapping.preset.cmdline(),
  sources = {
    { name = 'buffer' },
    { name = 'luasnip' }
  }
})

cmp.setup.cmdline(':', {
  mapping = cmp.mapping.preset.cmdline(),
  sources = cmp.config.sources({
    { name = 'path' }
  }, {
    { name = 'cmdline' }
  })
})

local capabilities = require('cmp_nvim_lsp').default_capabilities()
require('lspconfig')['gopls'].setup {
  capabilities = capabilities
}