module.exports = grammar({
  name: 'nixshell',

  rules: {
    source_file: $ => seq($.first_line, repeat($.non_first_line)),

    first_line: $ => seq($.shebang_open, $.opt_ws, optional(seq($.env, $.ws)), $.nix_shell),
    non_first_line: $ => seq($.newline, $.annotation_line),
    annotation_line: $ => seq($.shebang_open, $.opt_ws, $.nix_shell, $.nix_shell_args),
    embedded_script_line: $ => /.*/,

    shebang_open: $ => /#!/,
    // TODO: allow `usr/bin/env`, `env`
    env: $ => '/usr/bin/env',
    nix_shell: $ => 'nix-shell',
    nix_shell_args: $ => ' -i bash',
    ws: $ => / +/,
    opt_ws: $ => / */,
    newline: $ => '\n',
  }
});