nixos/modules/old_configs/nvim/after/plugin/lsp.lua

local lsp_zero = require('lsp-zero')

local lsp_attach = function(client, bufnr)
    -- see :help lsp-zero-keybindings
    -- to learn the available actions
    -- lsp_zero.default_keymaps({buffer = bufnr})
    --
    local opts = {buffer = bufnr, remap = false}

    vim.keymap.set('n', 'gD', vim.lsp.buf.declaration, opts)
    vim.keymap.set("n", "gd", function() vim.lsp.buf.definition() end, opts)
    vim.keymap.set("n", "K", function() vim.lsp.buf.hover() end, opts)
    vim.keymap.set("n", "<leader>vws", function() vim.lsp.buf.workspace_symbol() end, opts)
    vim.keymap.set("n", "<leader>vd", function() vim.diagnostic.open_float() end, opts)
    vim.keymap.set("n", "[d", function() vim.diagnostic.goto_next() end, opts)
    vim.keymap.set("n", "]d", function() vim.diagnostic.goto_prev() end, opts)
    vim.keymap.set("n", "<leader>vca", function() vim.lsp.buf.code_action() end, opts)
    vim.keymap.set("n", "<leader>vrr", function() vim.lsp.buf.references() end, opts)
    vim.keymap.set("n", "<leader>vrn", function() vim.lsp.buf.rename() end, opts)
    vim.keymap.set("i", "<C-h>", function() vim.lsp.buf.signature_help() end, opts)
end

lsp_zero.extend_lspconfig({
    capabilities = require('cmp_nvim_lsp').default_capabilities(),
    lsp_attach = lsp_attach,
    float_border = 'rounded',
    sign_text = true,
})

local lspconfig = require('lspconfig')

require('mason').setup({})
require('mason-lspconfig').setup({
  ensure_installed = {
      'lua_ls',
      'jdtls',
      'clangd',
      'zls',
  },
  handlers = {
      function(server_name)
          require('lspconfig')[server_name].setup({})
      end,

      -- noop is an empty function that doesn't do anything
      clangd = function()
          lspconfig.clangd.setup({
              cmd = {
                  'clangd',
                  '--background-index',
                  '--clang-tidy',
                  '--log=verbose',
                  '--header-interpolation=false', -- clangd doesn't find the files, annoying and unnecessary noise as a result
              },
              init_options = {
                  fallbackFlags = {
                      '-std=c23',
                      '-std=c++20'
                  },
              },
          })
      end,
      jdtls  = function()
          lspconfig.jdtls.setup({
              cmd = {
                  "java",
                  "-Declipse.application=org.eclipse.jdt.ls.core.id1",
                  "-Dosgi.bundles.defaultStartLevel=4",
                  "-Declipse.product=org.eclipse.jdt.ls.core.product",
                  "-Dlog.protocol=true",
                  "-Dlog.level=ALL",
                  "-Xms1g",
                  "--add-modules=ALL-SYSTEM",
                  "--add-opens",
                  "java.base/java.util=ALL-UNNAMED",
                  "--add-opens",
                  "java.base/java.lang=ALL-UNNAMED",
                  --
              },
              single_file_support = true,
              settings = {
                  java = {
                      signatureHelp = {enabled = true},
                      import = {enabled = true},
                      rename = {enabled = true}
                  }
              },
              flags = {
                  debounce_text_changes = 150,
              },
              init_options = {
                  bundles = {},
              },
          })
      end,
      zls    = lsp_zero.noop,
      lua_ls = function()
          lspconfig.lua_ls.setup({
              on_init = function(client)
                  if client.workspace_folders then
                      local path = client.workspace_folders[1].name
                      if vim.uv.fs_stat(path..'/.luarc.json') or vim.uv.fs_stat(path..'/.luarc.jsonc') then
                          return
                      end
                  end
          
                  client.config.settings.Lua = vim.tbl_deep_extend('force', client.config.settings.Lua, {
                      runtime = {
                       -- Tell the language server which version of Lua you're using
                       -- (most likely LuaJIT in the case of Neovim)
                           
                          version = 'LuaJIT'
                      },
                      -- Make the server aware of Neovim runtime files
                      workspace = {
                          checkThirdParty = false,
                          library = {
                              vim.env.VIMRUNTIME
                          }
                      }
                  })
              end,
              settings = {
                  Lua = {
                      diagnostics = {
                          globals = { 'turtle' },
                      },
                  },
              },
          })
      end,
      ols    = function()
          lspconfig.ols.setup({
              single_file_support = true,
              on_attach = function (client, buffer)
                 print('reached ols')
              end
          })
      end,
  }
})


local cmp = require('cmp')
local cmp_select = {behaviour = cmp.SelectBehavior.Select}
cmp.setup({
    sources = {
      { name = 'nvim_lsp' },
    },
    snippet = {
        expand = function(args)
            require('luasnip').lsp_expand(args.body)
        end,
    },
    mapping = cmp.mapping.preset.insert({
        ['<C-p>'] = cmp.mapping.select_prev_item(cmp_select),
        ['<C-n>'] = cmp.mapping.select_next_item(cmp_select),
        ['<C-y>'] = cmp.mapping.confirm({ select = true }),
        ['<C-Space>'] = cmp.mapping.complete(),
    }),
    formatting = lsp_zero.cmp_format(),
})

-- lsp_zero.set_preferences({
--     sign_icons = { }
-- })
-- 
-- lsp_zero.setup_nvim_cmp({
--     mapping = cmp_mappings
-- })


-- require('lspconfig').lua_ls.setup({
--     on_init = function(client)
--         if client.workspace_folders then
--             local path = client.workspace_folders[1].name
--             if vim.uv.fs_stat(path..'/.luarc.json') or vim.uv.fs_stat(path..'/.luarc.jsonc') then
--                 return
--             end
--         end
-- 
--         client.config.settings.Lua = vim.tbl_deep_extend('force', client.config.settings.Lua, {
--             -- runtime = {
--                 -- Tell the language server which version of Lua you're using
--                 -- (most likely LuaJIT in the case of Neovim)
--             --     version = 'LuaJIT'
--             -- },
--             -- Make the server aware of Neovim runtime files
--             workspace = {
--                 checkThirdParty = false,
--                 library = {
--                     vim.env.VIMRUNTIME
--                 }
--             }
--         })
--     end,
--     settings = {
--         Lua = {
--             diagnostics = {
--                 globals = { 'turtle' },
--             },
--         },
--     },
-- })

-- lsp_zero.setup()