package tb;

import drjava.util.Tree;

import net.luaos.tb.common.Solution;

import org.luaj.vm2.Globals;

import org.luaj.vm2.LuaTable;

import org.luaj.vm2.LuaValue;

import org.luaj.vm2.compiler.LuaC;

import org.luaj.vm2.lib.jse.JsePlatform;

import java.io.ByteArrayInputStream;

import java.io.IOException;

import java.io.InputStream;

public class sol_lua extends Solution {

  String code;

  public sol_lua() {}

  public sol_lua(String code) {

    this.code = code;

  }

  public void fromTree(Tree tree) {

    code = tree.getString(0);

  }

  public Tree toTree() {

    return new Tree(this).add(code);

  }

  public String compute(String input) {

    return callLuaSolution(createLuaEnvironment(), code, input);

  }

  public static String callLuaSolution(LuaTable _G, String code, String input) {

    if (input != null)

      _G.set("input", input);

    // compile into a chunk, or load as a class

    InputStream is =  new ByteArrayInputStream(code.getBytes());

    LuaValue chunk = null;

    try {

      chunk = LuaC.instance.load(is, "script", _G);

    } catch (IOException e) {  // not gonna happen anyway

      throw new RuntimeException(e);

    }

    // Check correct type (probably optional)

    chunk.checkclosure();

    // The chunk can be called with arguments as desired.

    LuaValue result = chunk.call();

    return luaResultToString(result);

  }

  public static String luaResultToString(LuaValue result) {

    return result.isnil() ? null : result.toString();

  }

  /** If this is changed, make sure the environment is extendable (not a singleton!)

   *  Or change the caller site to make a clone first. */

  public static LuaTable createLuaEnvironment() {

    // create an environment to run in

    LuaTable _G = new LuaTable(); //JsePlatform.standardGlobals();

    Globals standardGlobals = JsePlatform.standardGlobals();

    _G.set("_G", _G);

    _G.set("print", standardGlobals.get("print"));

    _G.set("pairs", standardGlobals.get("pairs"));

    return _G;

  }

}