local M = { 'hrsh7th/nvim-cmp' }

M.dependencies = {
  'hrsh7th/cmp-nvim-lsp',
  'hrsh7th/cmp-nvim-lua',
  'hrsh7th/cmp-path',
  'hrsh7th/cmp-buffer',
  'hrsh7th/cmp-cmdline',
  'onsails/lspkind-nvim',

  'L3MON4D3/LuaSnip',
  'saadparwaiz1/cmp_luasnip',
}

M.event = {
  'CmdlineEnter',
  'InsertEnter',
}

local make_keymap = function(cmp)
  local select = { behavior = cmp.SelectBehavior.Select }

  local either = function(yes, no)
    return function(fallback)
      if cmp.visible() then yes(fallback) else no(fallback) end
    end
  end

  -- Mappings that should work in both command line and Insert mode.
  local common = {
    ['<c-n>']    = either(cmp.mapping.select_next_item(select), cmp.mapping.complete()),
    ['<c-p>']    = either(cmp.mapping.select_prev_item(select), cmp.mapping.complete()),

    ['<down>']   = cmp.mapping.select_next_item(select),
    ['<up>']     = cmp.mapping.select_prev_item(select),

    ['<c-f>']    = cmp.mapping.scroll_docs( 3),
    ['<s-down>'] = cmp.mapping.scroll_docs( 3),
    ['<c-b>']    = cmp.mapping.scroll_docs(-3),
    ['<s-up>']   = cmp.mapping.scroll_docs(-3),

    ['<c-e>']    = cmp.mapping.abort(),
    ['<c-y>']    = cmp.mapping.confirm { select = true },
  }

  -- I want <tab> to start completion on the command line, but not in Insert.
  local keymap = {
    ['<tab>'] = {
      i = either(cmp.mapping.confirm { select = true }, function(fallback) fallback() end),
      c = either(cmp.mapping.confirm { select = true }, cmp.mapping.complete()),
    }
  }

  -- Turn { lhs = rhs } into { lhs = { i = rhs, c = rhs } }.
  for lhs, rhs in pairs(common) do
    keymap[lhs] = { i = rhs, c = rhs }
  end

  return cmp.mapping.preset.insert(keymap)
end

M.config = function(--[[plugin]]_, --[[opts]]_)
  local cmp = require 'cmp'
  local keymap = make_keymap(cmp)

  cmp.setup {
    mapping = keymap,

    enabled = function()
      local c = require 'cmp.config.context'
      return  not c.in_treesitter_capture('comment') and
              not c.in_syntax_group('Comment')
    end,

    snippet = {
      expand = function(args)
        require('luasnip').lsp_expand(args.body)
      end,
    },

    formatting = {
      format = require('lspkind').cmp_format {
        mode = 'symbol_text',

        menu = {
          buffer   = 'buf',
          nvim_lsp = 'LSP',
          nvim_lua = 'lua',
          path     = '',
        },

        symbol_map = require('fschauen.icons').kind,
      },
    },

    sources = cmp.config.sources({
      { name = 'nvim_lua' },
      { name = 'nvim_lsp' },
      { name = 'luasnip' },
    }, {
      { name = 'path' },
      { name = 'buffer', keyword_length = 5 },
    }),

    window = {
        completion = cmp.config.window.bordered(),
        documentation = cmp.config.window.bordered(),
    },

    experimental = {
      ghost_text = true,
    },
  }

  cmp.setup.cmdline(':', {
    mapping = keymap,

    completion = {
      autocomplete = false,
    },

    sources = cmp.config.sources({
      { name = 'path' }
    }, {
      { name = 'cmdline' }
    }),
  })

  cmp.setup.filetype('TelescopePrompt', { enabled = false })
end

return M