package commons.command;
import basics.unexpected.Failure;
import basics.unexpected.Problem;
import basics.utl.Empty;
import basics.utl.OsUtl;
import commons.application.GLOBAL;
import commons.engine.AdjustingLoopController;
import commons.engine.Command;
/**
 * This service allows for registering and using an adjustment function for a value in the context.
 * The function is registered for a key (pointing to a caontext value). For registering two keys are
 * needed. During registration the function class has to be reset. For adjusting a value call adjust
 * <key>. Since the adjustment function is stateful it knows about it's calls.
 * @author ks
 */
public class metaadjust extends Command
{

private static final String MUSTHAVE = "";
private static final String ARGS     = "name:<name-of-function>;adj-fun:<name-of-adjustment-function-bean>;adj-reset:<key>;default:<default-value>";

public void process () throws Problem
{
   String functionName = ctx.env().consume(GLOBAL.CTX_ENVKEY_ARGS, "");
   String functionImpl = ctx.consume("impl", "");
   boolean reset = ctx.getr("reset", false);
   // register key and function?
   if (!Empty.is(functionImpl))
   {
      AdjustingLoopController function = getInstance(functionImpl);
      ctx.put(functionName, function);
      OsUtl.trace(functionName + " points to adjusting loop controller " + functionImpl);
   }
   // reset?
   else if (!Empty.is(functionName))
   {
      AdjustingLoopController function = (AdjustingLoopController) ctx.getr(functionName, (AdjustingLoopController) null);
      if (function == null)
      {
         OsUtl.trace("No such Adjusting Controller (" + functionName + ")!");
         throw new Problem("No such Adjusting Controller (" + functionName + ")!");
      }
      if (reset) function.reset();
      ctx = function.adjust(ctx);
   }
}

@SuppressWarnings("unchecked")
private AdjustingLoopController getInstance (String className) throws Problem
{
   Class c = null;
   try
   {
      c = Class.forName(className);
   }
   catch (Exception e)
   {
      throw new Problem(description() + "Can't find class: " + className, e);
   }
   if (c == null) throw new Problem(description() + "Can't bind class: " + className);
   Object object = null;
   try
   {
      object = c.newInstance();
   }
   catch (InstantiationException e)
   {
      e.printStackTrace();
      throw new Failure(e);
   }
   catch (IllegalAccessException e)
   {
      e.printStackTrace();
      throw new Failure(e);
   }
   return (AdjustingLoopController) object;
}

// ---service----
public void signContract ()
{
   demand(MUSTHAVE, null);
}

public String description ()
{
   return implName() + " controls the value adjustment module. " + ARGS;
}
}