local M = {}

M.on_attach = function(event)
  -- NOTE: Remember that Lua is a real programming language, and as such it is possible
  -- to define small helper and utility functions so you don't have to repeat yourself.
  --
  -- In this case, we create a function that lets us more easily define mappings specific
  -- for LSP related items. It sets the mode, buffer and description for us each time.
  local map = function(keys, func, desc)
    vim.keymap.set('n', keys, func, { buffer = event.buf, desc = 'LSP: ' .. desc })
  end

  -- Jump to the definition of the word under your cursor.
  --  This is where a variable was first declared, or where a function is defined, etc.
  --  To jump back, press <C-t>.
  map('gd', vim.lsp.buf.definition, '[G]oto [D]efinition')

  -- Find references for the word under your cursor.
  map('gr', vim.lsp.buf.references, '[G]oto [R]eferences')

  -- Jump to the implementation of the word under your cursor.
  --  Useful when your language has ways of declaring types without an actual implementation.
  map('gI', vim.lsp.buf.implementation, '[G]oto [I]mplementation')

  -- Jump to the type of the word under your cursor.
  --  Useful when you're not sure what type a variable is and you want to see
  --  the definition of its *type*, not where it was *defined*.
  map('<leader>D', require('telescope.builtin').lsp_type_definitions, 'Type [D]efinition')

  -- Fuzzy find all the symbols in your current document.
  --  Symbols are things like variables, functions, types, etc.
  map('<leader>ds', require('telescope.builtin').lsp_document_symbols, '[D]ocument [S]ymbols')

  -- Fuzzy find all the symbols in your current workspace.
  --  Similar to document symbols, except searches over your entire project.
  map('<leader>ws', require('telescope.builtin').lsp_dynamic_workspace_symbols, '[W]orkspace [S]ymbols')

  -- Rename the variable under your cursor.
  --  Most Language Servers support renaming across files, etc.
  map('rr', vim.lsp.buf.rename, '[R]e[n]ame')

  -- Execute a code action, usually your cursor needs to be on top of an error
  -- or a suggestion from your LSP for this to activate.
  map('<leader>ca', vim.lsp.buf.code_action, '[C]ode [A]ction')

  -- Opens a popup that displays documentation about the word under your cursor
  --  See `:help K` for why this keymap.
  map('K', vim.lsp.buf.hover, 'Hover Documentation')

  -- WARN: This is not Goto Definition, this is Goto Declaration.
  --  For example, in C this would take you to the header.
  map('gD', vim.lsp.buf.declaration, '[G]oto [D]eclaration')

  -- The following two autocommands are used to highlight references of the
  -- word under your cursor when your cursor rests there for a little while.
  --    See `:help CursorHold` for information about when this is executed
  --
  -- When you move your cursor, the highlights will be cleared (the second autocommand).
  local client = vim.lsp.get_client_by_id(event.data.client_id)
  if client and client.server_capabilities.documentHighlightProvider then
    vim.api.nvim_create_autocmd({ 'CursorHold', 'CursorHoldI' }, {
      buffer = event.buf,
      callback = vim.lsp.buf.document_highlight,
    })

    vim.api.nvim_create_autocmd({ 'CursorMoved', 'CursorMovedI' }, {
      buffer = event.buf,
      callback = vim.lsp.buf.clear_references,
    })
  end

  -- The following autocommand is used to enable inlay hints in your
  -- code, if the language server you are using supports them
  --
  -- This may be unwanted, since they displace some of your code
  if client and client.server_capabilities.inlayHintProvider and vim.lsp.inlay_hint then
    map('<leader>th', function()
      vim.lsp.inlay_hint.enable(not vim.lsp.inlay_hint.is_enabled())
    end, '[T]oggle Inlay [H]ints')
  end

  if client.server_capabilities.documentSymbolProvider then
    require('nvim-navic').attach(client, event.buf)
  end
end

return M