-- Zephyr RTOS support.
--
-- This extra is driven entirely by Zephyr's own environment variables and is
-- inert unless one of them is set, so it costs nothing on a machine that does
-- no Zephyr work and needs no per-host editing.
--
--   ZEPHYR_BASE               the zephyr repo -- presence of this enables the extra
--   ZEPHYR_SDK_INSTALL_DIR    Zephyr SDK root (toolchain variant "zephyr")
--   GNUARMEMB_TOOLCHAIN_PATH  toolchain root  (variant "gnuarmemb")
--   ZEPHYR_TOOLCHAIN_VARIANT  which of the above is in use
--
-- Zephyr is otherwise "C + CMake + Kconfig + devicetree", so clangd and cmake
-- do the heavy lifting. What clangd cannot work out unaided is the built-in
-- include paths of a cross compiler, hence --query-driver.
-- (Zephyr's build/compile_commands.json is found by clangd on its own: it
-- searches ./ and ./build of each parent directory.)

local zephyr_base = os.getenv("ZEPHYR_BASE")
local sdk_dir     = os.getenv("ZEPHYR_SDK_INSTALL_DIR")
local gnuarmemb   = os.getenv("GNUARMEMB_TOOLCHAIN_PATH")

-- Not a Zephyr environment -> contribute nothing.
if not (zephyr_base or sdk_dir or gnuarmemb) then
  return {}
end

--- Toolchain globs for clangd's --query-driver, taken from the Zephyr vars.
--- Falls back to whatever cross gcc the environment puts on $PATH when the
--- toolchain variables are not set (as with a distro-packaged toolchain).
---@return string[]
local function query_driver_globs()
  local globs, seen = {}, {}
  local function add(p)
    if p and p ~= "" and not seen[p] then
      seen[p] = true
      globs[#globs + 1] = p
    end
  end

  -- Zephyr SDK: <sdk>/<target>-zephyr-elf/bin/<target>-zephyr-elf-gcc
  if sdk_dir then
    add(sdk_dir .. "/*/bin/*-gcc")
  end

  -- gnuarmemb variant: <root>/bin/arm-none-eabi-gcc
  if gnuarmemb then
    add(gnuarmemb .. "/bin/*-gcc")
  end

  -- No toolchain var set: resolve the cross compiler through $PATH instead of
  -- assuming a prefix, and glob its real directory.
  if #globs == 0 then
    for _, cc in ipairs({
      "arm-zephyr-eabi-gcc",
      "arm-none-eabi-gcc",
      "riscv64-zephyr-elf-gcc",
      "xtensa-espressif_esp32-elf-gcc",
    }) do
      local exe = vim.fn.exepath(cc)
      if exe ~= "" then
        add(vim.fs.dirname(vim.uv.fs_realpath(exe) or exe) .. "/*-gcc")
      end
    end
  end

  return globs
end

return {
  -- Syntax for the two Zephyr-specific languages
  {
    "nvim-treesitter/nvim-treesitter",
    opts = { ensure_installed = { "devicetree", "kconfig" } },
  },

  {
    "neovim/nvim-lspconfig",
    -- Filetype detection Neovim does not ship with
    init = function()
      vim.filetype.add({
        extension = {
          overlay = "dts", -- board/shield overlays are devicetree
        },
        filename = {
          ["prj.conf"] = "kconfig",
          ["west.yml"] = "yaml",
        },
        pattern = {
          ["Kconfig.*"] = "kconfig", -- Kconfig.foo, Kconfig.defconfig, ...
          [".*/boards/.*%.conf"] = "kconfig",
          [".*/prj_.*%.conf"] = "kconfig",
          [".*_defconfig"] = "kconfig",
        },
      })
    end,

    opts = function(_, opts)
      opts.servers = opts.servers or {}
      local clangd = opts.servers.clangd or {}

      local drivers = query_driver_globs()
      if #drivers > 0 then
        clangd.cmd = clangd.cmd or { "clangd" }
        table.insert(clangd.cmd, "--query-driver=" .. table.concat(drivers, ","))
      end

      -- Treat a west workspace / Zephyr app as a project root.
      clangd.root_markers = clangd.root_markers or {}
      vim.list_extend(clangd.root_markers, { "west.yml", ".west", "prj.conf", "CMakeLists.txt" })

      opts.servers.clangd = clangd
      return opts
    end,
  },
}