/**
 * Logback: the reliable, generic, fast and flexible logging framework.
 * Copyright (C) 1999-2013, QOS.ch. All rights reserved.
 *
 * This program and the accompanying materials are dual-licensed under
 * either the terms of the Eclipse Public License v1.0 as published by
 * the Eclipse Foundation
 *
 *   or (per the licensee's choosing)
 *
 * under the terms of the GNU Lesser General Public License version 2.1
 * as published by the Free Software Foundation.
 */
package ch.qos.logback.core.joran.util;

import java.lang.reflect.Method;
import java.lang.reflect.Modifier;
import java.nio.charset.Charset;
import java.nio.charset.UnsupportedCharsetException;

import ch.qos.logback.core.CoreConstants;
import ch.qos.logback.core.spi.ContextAware;

/**
 * Utility class which can convert string into objects.
 * @author Ceki G&uuml;lc&uuml;
 *
 */
public class StringToObjectConverter {

  private static final Class<?>[] STING_CLASS_PARAMETER = new Class[] { String.class };

  static public boolean canBeBuiltFromSimpleString(Class<?> parameterClass) {
    Package p = parameterClass.getPackage();
    if (parameterClass.isPrimitive()) {
      return true;
    } else if (p != null && "java.lang".equals(p.getName())) {
      return true;
    } else if (followsTheValueOfConvention(parameterClass)) {
      return true;
    } else if (parameterClass.isEnum()) {
      return true;
    } else if (isOfTypeCharset(parameterClass)) {
      return true;
    }
    return false;
  }

  /**
   * Convert <code>val</code> a String parameter to an object of a given type.
   */
  @SuppressWarnings("unchecked")
  public static Object convertArg(ContextAware ca, String val, Class<?> type) {
    if (val == null) {
      return null;
    }
    String v = val.trim();
    if (String.class.isAssignableFrom(type)) {
      return v;
    } else if (Integer.TYPE.isAssignableFrom(type)) {
      return new Integer(v);
    } else if (Long.TYPE.isAssignableFrom(type)) {
      return new Long(v);
    } else if (Float.TYPE.isAssignableFrom(type)) {
      return new Float(v);
    } else if (Double.TYPE.isAssignableFrom(type)) {
      return new Double(v);
    } else if (Boolean.TYPE.isAssignableFrom(type)) {
      if ("true".equalsIgnoreCase(v)) {
        return Boolean.TRUE;
      } else if ("false".equalsIgnoreCase(v)) {
        return Boolean.FALSE;
      }
    } else if (type.isEnum()) {
      return convertToEnum(ca, v, (Class<? extends Enum>) type);
    } else if (StringToObjectConverter.followsTheValueOfConvention(type)) {
      return convertByValueOfMethod(ca, type, v);
    } else if (isOfTypeCharset(type)) {
      return convertToCharset(ca, val);
    }

    return null;
  }

  static private boolean isOfTypeCharset(Class<?> type) {
    return Charset.class.isAssignableFrom(type);
  }

  static private Charset convertToCharset(ContextAware ca, String val) {
    try {
      return Charset.forName(val);
    } catch (UnsupportedCharsetException e) {
      ca.addError("Failed to get charset [" + val + "]", e);
      return null;
    }
  }

  static private boolean followsTheValueOfConvention(Class<?> parameterClass) {
    try {
      Method valueOfMethod = parameterClass.getMethod(CoreConstants.VALUE_OF,
          STING_CLASS_PARAMETER);
      int mod = valueOfMethod.getModifiers();
      if (Modifier.isStatic(mod)) {
        return true;
      }
    } catch (SecurityException e) {
      // nop
    } catch (NoSuchMethodException e) {
      // nop
    }
    return false;
  }

  private static Object convertByValueOfMethod(ContextAware ca, Class<?> type,
      String val) {
    try {
      Method valueOfMethod = type.getMethod(CoreConstants.VALUE_OF,
          STING_CLASS_PARAMETER);
      return valueOfMethod.invoke(null, val);
    } catch (Exception e) {
      ca.addError("Failed to invoke " + CoreConstants.VALUE_OF
          + "{} method in class [" + type.getName() + "] with value [" + val
          + "]");
      return null;
    }
  }

  @SuppressWarnings("unchecked")
  private static Object convertToEnum(ContextAware ca, String val,
      Class<? extends Enum> enumType) {
    return Enum.valueOf(enumType, val);
  }

  boolean isBuildableFromSimpleString() {
    return false;
  }
}
