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package com.github.egatlovs.variablemanager.exceptions;

import java.lang.reflect.Field;
import java.lang.reflect.InvocationTargetException;

/**
 * ExceptionHandler

 * 

 * This class helps creating exceptions inside of the processing classes
 * {@code ResultObject} and {@code ProcessingUnit}. Because both of them use
 * Reflection inside many situations where exceptions could be thrown are
 * present. This class uses the thrown exceptions and maps them to more readable
 * messages which help to understand what went wrong.

 *
 * @author egatlovs
 */
@SuppressWarnings("JavaDoc")
public class ExceptionHandler {

    /**
     * Maps given Exception to a Result Object Exception.
     *
     * @param e - thrown Exception
     * @param clazz - Class which caused the exception
     * @param  - The type of the Class causing the exception
     * @throws ResultObjectException is thrown at any time
     */
    public static  void createResultObjectException(Exception e, Class clazz) {
        if (e instanceof InstantiationException) {
            throw new ResultObjectException(
                    "Error received while trying to instantiate object of class " + clazz.getName(), e);
        } else if (e instanceof IllegalAccessException) {
            throw new ResultObjectException(
                    "Tried to instantiate object of class " + clazz.getName() + " but was not accessible", e);
        } else if (e instanceof IllegalArgumentException) {
            throw new ResultObjectException("Tried to instantiate object of class " + clazz.getName()
                    + " it seems no default constructor is present", e);
        } else if (e instanceof InvocationTargetException) {
            throw new ResultObjectException(
                    "Instantiation of object of class " + clazz.getName() + " has thrown an exception ", e);
        } else if (e instanceof NoSuchMethodException) {
            throw new ResultObjectException("Tried to instantiate object of class " + clazz.getName()
                    + " it seems no default constructor is present", e);
        } else if (e instanceof SecurityException) {
            throw new ResultObjectException(
                    "Tried to instantiate object of class " + clazz.getName() + " but was not accessible", e);
        } else {
            throw new ResultObjectException("Unknown Exception occured", e);
        }
    }

    /**
     * Maps given Exception to a ResultObjectException.
     *
     * @param e     - thrown Exception
     * @param field - Field which caused the Exception
     * @param obj   - Object which caused the Exception
     * @throws ResultObjectException is thrown at any time
     */
    public static void createResultObjectException(Exception e, Field field, Object obj) {
        if (e instanceof IllegalAccessException) {
            throw new ResultObjectException("Tried to access field " + field.getName() + " but was not accessible.", e);
        } else if (e instanceof IllegalArgumentException) {
            throw new ResultObjectException(
                    "Tried to access field " + field.getName() + " on wrong object " + obj.toString(), e);
        } else {
            throw new ResultObjectException("Unknown Exception occured", e);
        }
    }

    /**
     * Maps given Exception to a VariableProcessingException.
     *
     * @param e     - thrown Exception
     * @param field - Field which caused the Exception
     * @param obj   - Object which caused the Exception
     * @throws VariableProcessingException is thrown at any time
     */
    public static void createVariableProcessingException(Exception e, Field field, Object obj) {
        if (e instanceof IllegalAccessException) {
            throw new VariableProcessingException(
                    "Tried to access field " + field.getName() + " but was not accessible.", e);
        } else if (e instanceof IllegalArgumentException) {
            throw new VariableProcessingException(
                    "Tried to access field " + field.getName() + " on wrong object " + obj.toString(), e);
        } else {
            throw new VariableProcessingException("Unknown Exception occured", e);
        }
    }

}