package com.fasterxml.jackson.databind.jsontype.impl;

import java.util.Collections;
import java.util.HashSet;
import java.util.Set;

import com.fasterxml.jackson.databind.DeserializationContext;
import com.fasterxml.jackson.databind.JavaType;
import com.fasterxml.jackson.databind.JsonMappingException;

/**
 * Helper class used to encapsulate rules that determine subtypes that
 * are invalid to use, even with default typing, mostly due to security
 * concerns.
 * Used by <code>BeanDeserializerFacotry</code>
 *
 * @since 2.8.11
 */
public class SubTypeValidator
{
    protected final static String PREFIX_STRING = "org.springframework.";
    /**
     * Set of well-known "nasty classes", deserialization of which is considered dangerous
     * and should (and is) prevented by default.
     */
    protected final static Set<String> DEFAULT_NO_DESER_CLASS_NAMES;
    static {
        Set<String> s = new HashSet<String>();
        // Courtesy of [https://github.com/kantega/notsoserial]:
        // (and wrt [databind#1599])
        s.add("org.apache.commons.collections.functors.InvokerTransformer");
        s.add("org.apache.commons.collections.functors.InstantiateTransformer");
        s.add("org.apache.commons.collections4.functors.InvokerTransformer");
        s.add("org.apache.commons.collections4.functors.InstantiateTransformer");
        s.add("org.codehaus.groovy.runtime.ConvertedClosure");
        s.add("org.codehaus.groovy.runtime.MethodClosure");
        s.add("org.springframework.beans.factory.ObjectFactory");
        s.add("com.sun.org.apache.xalan.internal.xsltc.trax.TemplatesImpl");
        s.add("org.apache.xalan.xsltc.trax.TemplatesImpl");
        // [databind#1680]: may or may not be problem, take no chance
        s.add("com.sun.rowset.JdbcRowSetImpl");
        // [databind#1737]; JDK provided
        s.add("java.util.logging.FileHandler");
        s.add("java.rmi.server.UnicastRemoteObject");
        // [databind#1737]; 3rd party
//s.add("org.springframework.aop.support.AbstractBeanFactoryPointcutAdvisor"); // deprecated by [databind#1855]
        s.add("org.springframework.beans.factory.config.PropertyPathFactoryBean");
        s.add("com.mchange.v2.c3p0.JndiRefForwardingDataSource");
        s.add("com.mchange.v2.c3p0.WrapperConnectionPoolDataSource");
        // [databind#1855]: more 3rd party
        s.add("org.apache.tomcat.dbcp.dbcp2.BasicDataSource");
        s.add("com.sun.org.apache.bcel.internal.util.ClassLoader");
        DEFAULT_NO_DESER_CLASS_NAMES = Collections.unmodifiableSet(s);
    }

    /**
     * Set of class names of types that are never to be deserialized.
     */
    protected Set<String> _cfgIllegalClassNames = DEFAULT_NO_DESER_CLASS_NAMES;

    private final static SubTypeValidator instance = new SubTypeValidator();

    protected SubTypeValidator() { }

    public static SubTypeValidator instance() { return instance; }

    public void validateSubType(DeserializationContext ctxt, JavaType type) throws JsonMappingException
    {
        // There are certain nasty classes that could cause problems, mostly
        // via default typing -- catch them here.
        final Class<?> raw = type.getRawClass();
        String full = raw.getName();

        main_check:
        do {
            if (_cfgIllegalClassNames.contains(full)) {
                break;
            }

            // 18-Dec-2017, tatu: As per [databind#1855], need bit more sophisticated handling
            //    for some Spring framework types
            // 05-Jan-2017, tatu: ... also, only applies to classes, not interfaces
            if (!raw.isInterface() && full.startsWith(PREFIX_STRING)) {
                for (Class<?> cls = raw; (cls != null) && (cls != Object.class); cls = cls.getSuperclass()){
                    String name = cls.getSimpleName();
                    // looking for "AbstractBeanFactoryPointcutAdvisor" but no point to allow any is there?
                    if ("AbstractPointcutAdvisor".equals(name)
                            // ditto  for "FileSystemXmlApplicationContext": block all ApplicationContexts
                            || "AbstractApplicationContext".equals(name)) {
                        break main_check;
                    }
                }
            }
            return;
        } while (false);

        throw JsonMappingException.from(ctxt,
                String.format("Illegal type (%s) to deserialize: prevented for security reasons", full));
    }
}