nvim/lua/conf/plugins/jdtls.lua

local misc = require('core.misc')
local lsp = require('core.lsp.functions')
local map, auto = misc.map, misc.auto

return { 'mfussenegger/nvim-jdtls',
  disable = not vim.fn.has("nvim-0.6.0"),
  requires = 'mfussenegger/nvim-dap',
  function()
    auto("FileType", {
      pattern = "java",
      callback = function()
        local jdtls = require('jdtls')
        local jdtls_install = require('mason-registry').get_package('jdtls'):get_install_path()

        -- make sure to check if things with 💀 need updating
        local config = {
          cmd = {
            'java', -- 💀
            '-jar', vim.fn.glob(jdtls_install..'/plugins/org.eclipse.equinox.launcher_*.jar'), -- 💀
            '-configuration', jdtls_install..'/config_linux',
            '-data', vim.fn.stdpath('cache')..'/nvim-jdtls',

            '--add-modules=ALL-SYSTEM',
            '--add-opens', 'java.base/java.lang=ALL-UNNAMED',
            '--add-opens', 'java.base/java.util=ALL-UNNAMED',
            '-Declipse.application=org.eclipse.jdt.ls.core.id1',
            '-Declipse.product=org.eclipse.jdt.ls.core.product',
            '-Dlog.level=ALL',
            '-Dlog.protocol=true',
            '-Dosgi.bundles.defaultStartLevel=4',
            '-Xmx1G',
          },
          root_dir = vim.fs.dirname(vim.fs.find({
            'gradlew',
            '.git',
            'mvnw',
            'settings.gradle', -- Gradle (multi-project)
            'settings.gradle.kts', -- Gradle (multi-project)
            'build.xml', -- Ant
            'pom.xml', -- Maven
          }, { upward = true })[1]),

          -- don't print out status messages
          handlers = {
            ['language/status'] = function() end
          },

          on_attach = function(_, bufnr)
            -- add some jdtls specific mappings
            local opts = { buffer = bufnr }
            map('n', 'cri', jdtls.organize_imports, opts)
            map('n', 'crv', jdtls.extract_variable, opts)
            map('n', 'crc', jdtls.extract_constant, opts)
            map('x', 'crv', function() jdtls.extract_variable(true) end, opts)
            map('x', 'crc', function() jdtls.extract_constant(true) end, opts)
            map('x', 'crm', function() jdtls.extract_method(true) end, opts)

            pcall(vim.lsp.codelens.refresh)
            auto('BufWritePost', {
              buffer = bufnr,
              desc = 'refresh codelens',
              callback = function()
                pcall(vim.lsp.codelens.refresh)
              end
            })
          end,
          capabilities = lsp.capabilities
        }

        -- generate the path to the java file(s)
        ---@type string|nil
        local cache_path = vim.fs.joinpath(vim.fn.stdpath("cache"), "/JavaVersion.class")
        ---@type string|nil
        local src_path = vim.fs.joinpath(vim.fn.stdpath("config"), "/extras/JavaVersion.java")

        -- if either path is invalid
        if not cache_path or not src_path then
          return
        end

        --- build a cache of the JavaVersion code
        local function build_cache()
          -- check if we have javac
          vim.system({ "javac" }, {}, function(out)
            if out.code == 127 then
              cache_path = nil
              return
            end

            -- compile our code
            vim.system({ 'javac', src_path, '-d', vim.fn.stdpath("cache") }, {}, function(out)
              if out.code ~= 0 then
                cache_path = nil
              end
            end)
          end)
        end

        -- check if we have a compiled version of JavaVersion
        local f, _ = io.open(cache_path, "r")
        if not f then -- if we don't have a cache
          build_cache()
        else
          io.close(f)
        end

        -- check the java version
        local buffer = {}
        vim.fn.jobstart({
          config.cmd[1],
          (cache_path and "JavaVersion") or src_path
        }, {
            cwd = vim.fn.stdpath("cache"),
            stdin = nil,
            on_stdout = function(_, data, _)
              table.insert(buffer, table.concat(data))
            end,
            on_exit = function(_, exit_code, _)
              local v = vim.version.parse(table.concat(buffer))

              -- if there's an error, no version info, or the java version is
              -- less than 17 stop the lsp from starting
              if exit_code ~= 0 then
                vim.notify(string.format(
                  "java version check failed: exit code %s", exit_code),
                  vim.log.levels.ERROR, { title = misc.appid })
                return
              elseif not v then
                vim.notify("no java version info found", vim.log.levels.ERROR,
                  { title = misc.appid })
                return
              elseif v.major < 17 then
                vim.notify(string.format(
                  "java version %s < 17.0.0 Cannot run jdtls, bailing out",
                  v[1].."."..v[2].."."..v[3]),
                  vim.log.levels.ERROR, { title = misc.appid })
                return
              end

              -- start lsp
              jdtls.start_or_attach(config)
            end
          })
      end
    })
  end
}