nvim/after/ftplugin/java.lua

local map, auto = core.misc.map, core.misc.auto

local ok, jdtls = pcall(require, "jdtls")
if not ok then
  vim.notify("jdtls not loaded, can't setup jdtls lsp or dap")
  return
end

local jdtls_install = core.mason.get_pkg_path("jdtls")
local java_dap_install = core.mason.get_pkg_path("java-debug-adapter")

-- make sure to check if things with 💀 need updating
local config = {
  cmd = {
    "java", -- 💀
    "-jar",
    vim.fn.glob(vim.fs.joinpath(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]),

  on_attach = function(_, bufnr)
    jdtls.setup.add_commands()

    -- 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)

    -- do some refreshes often because I don't trust jdtls
    pcall(vim.lsp.codelens.refresh)
    auto("BufWritePost", {
      buffer = bufnr,
      desc = "refresh codelens",
      callback = function()
        pcall(vim.lsp.codelens.refresh)
      end
    })

    -- setup nvim-dap
    local ok, dap = pcall(require, "dap")
    if not ok then
      vim.notify("dap not loaded can't setup dap for jdtls")
      return
    end

    dap.adapters.java = nil -- remove any old java adapters
    jdtls.setup_dap({ hotcodereplace = "auto" })
  end,
  init_options = {
    bundles = {
      vim.fs.joinpath(java_dap_install,
        vim.fn.glob("extension/server/com.microsoft.java.debug.plugin-*.jar",
          true)
      )
    }
	},
  -- don't print out status messages
  handlers = {
    ["language/status"] = function() end
  }
}

-- generate the path to the java file(s)
---@type string?
local cache_path = vim.fs.joinpath(vim.fn.stdpath("cache"),
  "/JavaVersion.class")
---@type string?
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
  if vim.fn.executable("javac") ~= 1 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

-- 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

local function version_check()
  -- check the java version
  local out = vim.system({
    config.cmd[1], -- use the same java executable that the lsp will be using
    (cache_path and "JavaVersion") or src_path
  }, { cwd = vim.fn.stdpath("cache"), text = true }):wait()

  -- parse the version information aquired
  local v = vim.version.parse(out.stdout)

  -- if there's an error, no version info, or the java version is
  -- less than 21 stop the lsp from starting
  if out.code ~= 0 then
    vim.notify(string.format(
      "java version check failed: exit code %s", out.code),
      vim.log.levels.ERROR)
    vim.notify(string.format(
      "%s", vim.inspect(out.stdout)), vim.log.levels.ERROR)
    return false
  elseif not v then
    vim.notify("no java version info found", vim.log.levels.ERROR)
    return false
  elseif v.major < 21 then
    vim.notify(string.format(
      "java version %s < 21.0.0 Cannot run jdtls, bailing out",
      v[1].."."..v[2].."."..v[3]), vim.log.levels.ERROR)
    return false
  end

  return true
end

-- start the jdtls with dap!
if not version_check() then
  return
end
jdtls.start_or_attach(config)