package org.test4j.json.decoder.base;

import java.lang.reflect.ParameterizedType;
import java.lang.reflect.Type;

import org.test4j.json.decoder.IDecoder;
import org.test4j.tools.commons.ClazzHelper;

/**
 * json串解码器基类<br>
 * 解码：从json字符串反序列为java对象<br>
 * 加码：将java对象序列化为json字符串<br>
 * 
 * @author darui.wudr
 */
@SuppressWarnings({ "rawtypes", "unchecked" })
public abstract class BaseDecoder implements IDecoder {

    protected DecoderException getError(String value, String to) {
        String msg = String.format("couldn't convert \"%s\" to %s", value, to);
        return new DecoderException(msg);
    }

    protected DecoderException getError(String value, String to, Throwable e) {
        String msg = String.format("couldn't convert \"%s\" to %s", value, to);
        return new DecoderException(msg, e);
    }

    /**
     * 获取第n个泛型变量，n从0开始
     * 
     * @param type
     * @param index
     * @return
     */
    protected Type getArgType(ParameterizedType type, int index) {
        if (type == null || index < 0) {
            return null;
        }
        Type[] types = type.getActualTypeArguments();
        if (types == null || index >= types.length) {
            return null;
        }
        return types[index];
    }

    protected Class getRawType(Type type, Class _default) {
        if (type instanceof Class) {
            return (Class) type;
        } else if (type instanceof ParameterizedType) {
            Type raw = ((ParameterizedType) type).getRawType();
            return this.getRawType(raw, _default);
        } else {
            return _default == null ? Object.class : _default;
        }
    }

    protected boolean isInterfaceOrAbstract(Type type) {
        Class raw = this.getRawType(type, null);
        return ClazzHelper.isInterfaceOrAbstract(raw);
    }

    protected <T> T newInstance(Type type) {
        Class claz = this.getRawType(type, null);
        Object o = ClazzHelper.newInstance(claz);
        return (T) o;
    }
}