/**
 * Licensed to the Apache Software Foundation (ASF) under one or more
 * contributor license agreements.  See the NOTICE file distributed with
 * this work for additional information regarding copyright ownership.
 * The ASF licenses this file to You under the Apache License, Version 2.0
 * (the "License"); you may not use this file except in compliance with
 * the License.  You may obtain a copy of the License at
 *
 *      http://www.apache.org/licenses/LICENSE-2.0
 *
 * Unless required by applicable law or agreed to in writing, software
 * distributed under the License is distributed on an "AS IS" BASIS,
 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
 * See the License for the specific language governing permissions and
 * limitations under the License.
 */
package org.apache.camel.util;

import java.beans.PropertyEditor;
import java.beans.PropertyEditorManager;
import java.lang.reflect.Field;
import java.lang.reflect.InvocationTargetException;
import java.lang.reflect.Method;
import java.lang.reflect.Modifier;
import java.net.URI;
import java.net.URISyntaxException;
import java.util.Arrays;
import java.util.HashMap;
import java.util.Iterator;
import java.util.LinkedHashMap;
import java.util.LinkedHashSet;
import java.util.Map;
import java.util.Set;

import org.apache.camel.NoTypeConversionAvailableException;
import org.apache.camel.TypeConverter;
import org.apache.commons.logging.Log;
import org.apache.commons.logging.LogFactory;

/**
 * Helper for introspections of beans.
 */
public final class IntrospectionSupport {

    private static final transient Log LOG = LogFactory.getLog(IntrospectionSupport.class);

    /**
     * Utility classes should not have a public constructor.
     */
    private IntrospectionSupport() {
    }

    public static boolean getProperties(Object target, Map props, String optionPrefix) {
        boolean rc = false;
        if (target == null) {
            throw new IllegalArgumentException("target was null.");
        }
        if (props == null) {
            throw new IllegalArgumentException("props was null.");
        }
        if (optionPrefix == null) {
            optionPrefix = "";
        }

        Class clazz = target.getClass();
        Method[] methods = clazz.getMethods();
        for (Method method : methods) {
            String name = method.getName();
            Class type = method.getReturnType();
            Class params[] = method.getParameterTypes();
            if (name.startsWith("get") && params.length == 0 && type != null && isSettableType(type)) {
                try {
                    Object value = method.invoke(target);
                    if (value == null) {
                        continue;
                    }

                    String strValue = convertToString(value, type);
                    if (strValue == null) {
                        continue;
                    }

                    name = name.substring(3, 4).toLowerCase() + name.substring(4);
                    props.put(optionPrefix + name, strValue);
                    rc = true;
                } catch (Throwable ignore) {
                    // ignore
                }
            }
        }

        return rc;
    }

    public static Object getProperty(Object target, String prop) throws SecurityException, NoSuchMethodException, IllegalArgumentException, IllegalAccessException, InvocationTargetException {
        if (target == null) {
            throw new IllegalArgumentException("target was null.");
        }
        if (prop == null) {
            throw new IllegalArgumentException("prop was null.");
        }
        prop = prop.substring(0, 1).toUpperCase() + prop.substring(1);

        Class clazz = target.getClass();
        Method method = getPropertyGetter(clazz, prop);
        return method.invoke(target);
    }

    public static Method getPropertyGetter(Class type, String propertyName) throws NoSuchMethodException {
        Method method = type.getMethod("get" + ObjectHelper.capitalize(propertyName));
        return method;
    }

    public static boolean setProperties(Object target, Map props, String optionPrefix) throws Exception {
        boolean rc = false;
        if (target == null) {
            throw new IllegalArgumentException("target was null.");
        }
        if (props == null) {
            throw new IllegalArgumentException("props was null.");
        }

        for (Iterator iter = props.keySet().iterator(); iter.hasNext();) {
            String name = (String)iter.next();
            if (name.startsWith(optionPrefix)) {
                Object value = props.get(name);
                name = name.substring(optionPrefix.length());
                if (setProperty(target, name, value)) {
                    iter.remove();
                    rc = true;
                }
            }
        }
        return rc;
    }

    public static Map extractProperties(Map props, String optionPrefix) {
        if (props == null) {
            throw new IllegalArgumentException("props was null.");
        }

        HashMap rc = new HashMap(props.size());

        for (Iterator iter = props.keySet().iterator(); iter.hasNext();) {
            String name = (String)iter.next();
            if (name.startsWith(optionPrefix)) {
                Object value = props.get(name);
                name = name.substring(optionPrefix.length());
                rc.put(name, value);
                iter.remove();
            }
        }

        return rc;
    }

    public static boolean setProperties(TypeConverter typeConverter, Object target, Map props) throws Exception {
        boolean rc = false;

        if (target == null) {
            throw new IllegalArgumentException("target was null.");
        }
        if (props == null) {
            throw new IllegalArgumentException("props was null.");
        }

        for (Iterator iter = props.entrySet().iterator(); iter.hasNext();) {
            Map.Entry entry = (Map.Entry)iter.next();
            if (setProperty(typeConverter, target, (String)entry.getKey(), entry.getValue())) {
                iter.remove();
                rc = true;
            }
        }

        return rc;
    }

    public static boolean setProperties(Object target, Map props) throws Exception {
        return setProperties(null, target, props);
    }

    public static boolean setProperty(TypeConverter typeConverter, Object target, String name, Object value) throws Exception {
        try {
            Class clazz = target.getClass();
            // find candidates of setter methods as there can be overloaded setters
            Set<Method> setters = findSetterMethods(typeConverter, clazz, name, value);
            if (setters.isEmpty()) {
                return false;
            }

            // loop and execute the best setter method
            Exception typeConvertionFailed = null;
            for (Method setter : setters) {
                // If the type is null or it matches the needed type, just use the value directly
                if (value == null || setter.getParameterTypes()[0].isAssignableFrom(value.getClass())) {
                    setter.invoke(target, value);
                    return true;
                } else {
                    // We need to convert it
                    try {
                        // ignore exceptions as there could be another setter method where we could type convert successfully
                        Object convertedValue = convert(typeConverter, setter.getParameterTypes()[0], value);
                        setter.invoke(target, convertedValue);
                        return true;
                    } catch (NoTypeConversionAvailableException e) {
                        typeConvertionFailed = e;
                    } catch (IllegalArgumentException e) {
                        typeConvertionFailed = e;
                    }
                    LOG.trace("Setter \"" + setter + "\" with parameter type \""
                              + setter.getParameterTypes()[0] + "\" could not be used for type conertions of " + value);
                }
            }
            // we did not find a setter method to use, and if we did try to use a type converter then throw
            // this kind of exception as the caused by will hint this error
            if (typeConvertionFailed != null) {
                throw new IllegalArgumentException("Could not find a suitable setter for property: " + name
                        + " as there isn't a setter method with same type: " + value.getClass().getCanonicalName()
                        + " nor type convertion possbile: " + typeConvertionFailed.getMessage());
            } else {
                return false;
            }
        } catch (InvocationTargetException e) {
            // lets unwrap the exception
            Throwable throwable = e.getCause();
            if (throwable instanceof Exception) {
                Exception exception = (Exception)throwable;
                throw exception;
            } else {
                Error error = (Error)throwable;
                throw error;
            }
        }
    }

    public static boolean setProperty(Object target, String name, Object value) throws Exception {
        return setProperty(null, target, name, value);
    }

    private static Object convert(TypeConverter typeConverter, Class type, Object value) throws URISyntaxException {
        if (typeConverter != null) {
            return typeConverter.convertTo(type, value);
        }
        PropertyEditor editor = PropertyEditorManager.findEditor(type);
        if (editor != null) {
            editor.setAsText(value.toString());
            return editor.getValue();
        }
        if (type == URI.class) {
            return new URI(value.toString());
        }
        return null;
    }

    private static String convertToString(Object value, Class type) throws URISyntaxException {
        PropertyEditor editor = PropertyEditorManager.findEditor(type);
        if (editor != null) {
            editor.setValue(value);
            return editor.getAsText();
        }
        if (type == URI.class) {
            return value.toString();
        }
        return null;
    }

    private static Set<Method> findSetterMethods(TypeConverter typeConverter, Class clazz, String name, Object value) {
        Set<Method> candidates = new LinkedHashSet<Method>();

        // Build the method name.
        name = "set" + ObjectHelper.capitalize(name);
        while (clazz != Object.class) {
            Method[] methods = clazz.getMethods();
            for (Method method : methods) {
                Class params[] = method.getParameterTypes();
                if (method.getName().equals(name) && params.length == 1) {
                    Class paramType = params[0];
                    if (typeConverter != null || isSettableType(paramType) || paramType.isInstance(value)) {
                        candidates.add(method);
                    }
                }
            }
            clazz = clazz.getSuperclass();
        }

        if (candidates.isEmpty()) {
            return candidates;
        } else if (candidates.size() == 1) {
            // only one
            return candidates;
        } else {
            // find the best match if possible
            if (LOG.isTraceEnabled()) {
                LOG.trace("Found " + candidates.size() + " suitable setter methods for setting " + name);
            }
            // perfer to use the one with the same instance if any exists
            for (Method method : candidates) {
                if (method.getParameterTypes()[0].isInstance(value)) {
                    if (LOG.isTraceEnabled()) {
                        LOG.trace("Method " + method + " is the best candidate as it has parameter with same instance type");
                    }
                    // retain only this method in the answer
                    candidates.clear();
                    candidates.add(method);
                    return candidates;
                }
            }
            // fallback to return what we have found as candidates so far
            return candidates;
        }
    }

    private static boolean isSettableType(Class clazz) {
        if (PropertyEditorManager.findEditor(clazz) != null) {
            return true;
        }
        if (clazz == URI.class) {
            return true;
        }
        if (clazz == Boolean.class) {
            return true;
        }
        return false;
    }

    public static String toString(Object target) {
        return toString(target, Object.class);
    }

    public static String toString(Object target, Class stopClass) {
        LinkedHashMap map = new LinkedHashMap();
        addFields(target, target.getClass(), stopClass, map);
        StringBuffer buffer = new StringBuffer(simpleName(target.getClass()));
        buffer.append(" {");
        Set entrySet = map.entrySet();
        boolean first = true;
        for (Iterator iter = entrySet.iterator(); iter.hasNext();) {
            Map.Entry entry = (Map.Entry)iter.next();
            if (first) {
                first = false;
            } else {
                buffer.append(", ");
            }
            buffer.append(entry.getKey());
            buffer.append(" = ");
            appendToString(buffer, entry.getValue());
        }
        buffer.append("}");
        return buffer.toString();
    }

    protected static void appendToString(StringBuffer buffer, Object value) {
        // if (value instanceof ActiveMQDestination) {
        // ActiveMQDestination destination = (ActiveMQDestination) value;
        // buffer.append(destination.getQualifiedName());
        // }
        // else {
        buffer.append(value);
        // }
    }

    public static String simpleName(Class clazz) {
        String name = clazz.getName();
        int p = name.lastIndexOf(".");
        if (p >= 0) {
            name = name.substring(p + 1);
        }
        return name;
    }

    private static void addFields(Object target, Class startClass, Class stopClass, LinkedHashMap map) {
        if (startClass != stopClass) {
            addFields(target, startClass.getSuperclass(), stopClass, map);
        }

        Field[] fields = startClass.getDeclaredFields();
        for (Field field : fields) {
            if (Modifier.isStatic(field.getModifiers()) || Modifier.isTransient(field.getModifiers())
                || Modifier.isPrivate(field.getModifiers())) {
                continue;
            }

            try {
                field.setAccessible(true);
                Object o = field.get(target);
                if (o != null && o.getClass().isArray()) {
                    try {
                        o = Arrays.asList((Object[])o);
                    } catch (Throwable e) {
                        // ignore
                    }
                }
                map.put(field.getName(), o);
            } catch (Throwable e) {
                LOG.debug("Error adding fields", e);
            }
        }
    }

}
