package org.apache.ibatis.reflection;

import java.lang.reflect.Constructor;
import java.lang.reflect.Field;
import java.lang.reflect.Method;
import java.lang.reflect.ReflectPermission;
import java.util.ArrayList;
import java.util.Collection;
import java.util.Collections;
import java.util.HashMap;
import java.util.Iterator;
import java.util.List;
import java.util.Locale;
import java.util.Map;

import org.apache.ibatis.reflection.invoker.GetFieldInvoker;
import org.apache.ibatis.reflection.invoker.Invoker;
import org.apache.ibatis.reflection.invoker.MethodInvoker;
import org.apache.ibatis.reflection.invoker.SetFieldInvoker;
import org.apache.ibatis.reflection.property.PropertyNamer;

/**
 * This class represents a cached set of class definition information that
 * allows for easy mapping between property names and getter/setter methods.
 */
public class Reflector {

  private static boolean classCacheEnabled = true;
  private static final String[] EMPTY_STRING_ARRAY = new String[0];
  private static final Map<Class<?>, Reflector> REFLECTOR_MAP = Collections.synchronizedMap(new HashMap<Class<?>, Reflector>());

  private Class<?> type;
  private String[] readablePropertyNames = EMPTY_STRING_ARRAY;
  private String[] writeablePropertyNames = EMPTY_STRING_ARRAY;
  private Map<String, Invoker> setMethods = new HashMap<String, Invoker>();
  private Map<String, Invoker> getMethods = new HashMap<String, Invoker>();
  private Map<String, Class<?>> setTypes = new HashMap<String, Class<?>>();
  private Map<String, Class<?>> getTypes = new HashMap<String, Class<?>>();
  private Constructor<?> defaultConstructor;

  private Map<String, String> caseInsensitivePropertyMap = new HashMap<String, String>();

  private Reflector(Class<?> clazz) {
    type = clazz;
    addDefaultConstructor(clazz);
    addGetMethods(clazz);
    addSetMethods(clazz);
    addFields(clazz);
    readablePropertyNames = getMethods.keySet().toArray(new String[getMethods.keySet().size()]);
    writeablePropertyNames = setMethods.keySet().toArray(new String[setMethods.keySet().size()]);
    for (String propName : readablePropertyNames) {
      caseInsensitivePropertyMap.put(propName.toUpperCase(Locale.ENGLISH), propName);
    }
    for (String propName : writeablePropertyNames) {
      caseInsensitivePropertyMap.put(propName.toUpperCase(Locale.ENGLISH), propName);
    }
  }

  private void addDefaultConstructor(Class<?> clazz) {
    Constructor<?>[] consts = clazz.getDeclaredConstructors();
    for (Constructor<?> constructor : consts) {
      if (constructor.getParameterTypes().length == 0) {
        if (canAccessPrivateMethods()) {
          try {
            constructor.setAccessible(true);
          } catch (Exception e) {
            // Ignored. This is only a final precaution, nothing we can do.
          }
        }
        if (constructor.isAccessible()) {
          this.defaultConstructor = constructor;
        }
      }
    }
  }

  private void addGetMethods(Class<?> cls) {
    Method[] methods = getClassMethods(cls);
    for (Method method : methods) {
      String name = method.getName();
      if (name.startsWith("get") && name.length() > 3) {
        if (method.getParameterTypes().length == 0) {
          name = PropertyNamer.methodToProperty(name);
          addGetMethod(name, method);
        }
      } else if (name.startsWith("is") && name.length() > 2) {
        if (method.getParameterTypes().length == 0) {
          name = PropertyNamer.methodToProperty(name);
          addGetMethod(name, method);
        }
      }
    }
  }

  private void addGetMethod(String name, Method method) {
    if (isValidPropertyName(name)) {
      getMethods.put(name, new MethodInvoker(method));
      getTypes.put(name, method.getReturnType());
    }
  }

  private void addSetMethods(Class<?> cls) {
    Map<String, List<Method>> conflictingSetters = new HashMap<String, List<Method>>();
    Method[] methods = getClassMethods(cls);
    for (Method method : methods) {
      String name = method.getName();
      if (name.startsWith("set") && name.length() > 3) {
        if (method.getParameterTypes().length == 1) {
          name = PropertyNamer.methodToProperty(name);
          addSetterConflict(conflictingSetters, name, method);
        }
      }
    }
    resolveSetterConflicts(conflictingSetters);
  }

  private void addSetterConflict(Map<String, List<Method>> conflictingSetters, String name, Method method) {
    List<Method> list = conflictingSetters.get(name);
    if (list == null) {
      list = new ArrayList<Method>();
      conflictingSetters.put(name, list);
    }
    list.add(method);
  }

  private void resolveSetterConflicts(Map<String, List<Method>> conflictingSetters) {
    for (String propName : conflictingSetters.keySet()) {
      List<Method> setters = conflictingSetters.get(propName);
      Method firstMethod = setters.get(0);
      if (setters.size() == 1) {
        addSetMethod(propName, firstMethod);
      } else {
        Class<?> expectedType = getTypes.get(propName);
        if (expectedType == null) {
          throw new ReflectionException("Illegal overloaded setter method with ambiguous type for property "
              + propName + " in class " + firstMethod.getDeclaringClass() + ".  This breaks the JavaBeans " +
              "specification and can cause unpredicatble results.");
        } else {
          Iterator<Method> methods = setters.iterator();
          Method setter = null;
          while (methods.hasNext()) {
            Method method = methods.next();
            if (method.getParameterTypes().length == 1
                && expectedType.equals(method.getParameterTypes()[0])) {
              setter = method;
              break;
            }
          }
          if (setter == null) {
            throw new ReflectionException("Illegal overloaded setter method with ambiguous type for property "
                + propName + " in class " + firstMethod.getDeclaringClass() + ".  This breaks the JavaBeans " +
                "specification and can cause unpredicatble results.");
          }
          addSetMethod(propName, setter);
        }
      }
    }
  }

  private void addSetMethod(String name, Method method) {
    if (isValidPropertyName(name)) {
      setMethods.put(name, new MethodInvoker(method));
      setTypes.put(name, method.getParameterTypes()[0]);
    }
  }

  private void addFields(Class<?> clazz) {
    Field[] fields = clazz.getDeclaredFields();
    for (Field field : fields) {
      if (canAccessPrivateMethods()) {
        try {
          field.setAccessible(true);
        } catch (Exception e) {
          // Ignored. This is only a final precaution, nothing we can do.
        }
      }
      if (field.isAccessible()) {
        if (!setMethods.containsKey(field.getName())) {
          // issue 379 - removed the check for final because JDK 1.5 allows
          // modification of final fields through reflection (JSR-133).  (JGB)
          addSetField(field);
        }
        if (!getMethods.containsKey(field.getName())) {
          addGetField(field);
        }
      }
    }
    if (clazz.getSuperclass() != null) {
      addFields(clazz.getSuperclass());
    }
  }

  private void addSetField(Field field) {
    if (isValidPropertyName(field.getName())) {
      setMethods.put(field.getName(), new SetFieldInvoker(field));
      setTypes.put(field.getName(), field.getType());
    }
  }

  private void addGetField(Field field) {
    if (isValidPropertyName(field.getName())) {
      getMethods.put(field.getName(), new GetFieldInvoker(field));
      getTypes.put(field.getName(), field.getType());
    }
  }

  private boolean isValidPropertyName(String name) {
    return !(name.startsWith("$") || "serialVersionUID".equals(name) || "class".equals(name));
  }

  /**
   * This method returns an array containing all methods
   * declared in this class and any superclass.
   * We use this method, instead of the simpler Class.getMethods(),
   * because we want to look for private methods as well.
   *
   * @param cls The class
   * @return An array containing all methods in this class
   */
  private Method[] getClassMethods(Class<?> cls) {
    HashMap<String, Method> uniqueMethods = new HashMap<String, Method>();
    Class<?> currentClass = cls;
    while (currentClass != null) {
      addUniqueMethods(uniqueMethods, currentClass.getDeclaredMethods());

      // we also need to look for interface methods - 
      // because the class may be abstract
      Class<?>[] interfaces = currentClass.getInterfaces();
      for (Class<?> anInterface : interfaces) {
        addUniqueMethods(uniqueMethods, anInterface.getMethods());
      }

      currentClass = currentClass.getSuperclass();
    }

    Collection<Method> methods = uniqueMethods.values();

    return methods.toArray(new Method[methods.size()]);
  }

  private void addUniqueMethods(HashMap<String, Method> uniqueMethods, Method[] methods) {
    for (Method currentMethod : methods) {
      if (!currentMethod.isBridge()) {
        String signature = getSignature(currentMethod);
        // check to see if the method is already known
        // if it is known, then an extended class must have
        // overridden a method
        if (!uniqueMethods.containsKey(signature)) {
          if (canAccessPrivateMethods()) {
            try {
              currentMethod.setAccessible(true);
            } catch (Exception e) {
              // Ignored. This is only a final precaution, nothing we can do.
            }
          }

          uniqueMethods.put(signature, currentMethod);
        }
      }
    }
  }

  private String getSignature(Method method) {
    StringBuffer sb = new StringBuffer();
    sb.append(method.getName());
    Class<?>[] parameters = method.getParameterTypes();
    for (int i = 0; i < parameters.length; i++) {
      if (i == 0) {
        sb.append(':');
      } else {
        sb.append(',');
      }
      sb.append(parameters[i].getName());
    }
    return sb.toString();
  }

  private static boolean canAccessPrivateMethods() {
    try {
      SecurityManager securityManager = System.getSecurityManager();
      if (null != securityManager) {
        securityManager.checkPermission(new ReflectPermission("suppressAccessChecks"));
      }
    } catch (SecurityException e) {
      return false;
    }
    return true;
  }

  /**
   * Gets the name of the class the instance provides information for
   *
   * @return The class name
   */
  public Class<?> getType() {
    return type;
  }

  public Constructor<?> getDefaultConstructor() {
    if (defaultConstructor != null) {
      return defaultConstructor;
    } else {
      throw new ReflectionException("There is no default constructor for " + type);
    }
  }

  public Invoker getSetInvoker(String propertyName) {
    Invoker method = setMethods.get(propertyName);
    if (method == null) {
      throw new ReflectionException("There is no setter for property named '" + propertyName + "' in '" + type + "'");
    }
    return method;
  }

  public Invoker getGetInvoker(String propertyName) {
    Invoker method = getMethods.get(propertyName);
    if (method == null) {
      throw new ReflectionException("There is no getter for property named '" + propertyName + "' in '" + type + "'");
    }
    return method;
  }

  /**
   * Gets the type for a property setter
   *
   * @param propertyName - the name of the property
   * @return The Class of the propery setter
   */
  public Class<?> getSetterType(String propertyName) {
    Class<?> clazz = setTypes.get(propertyName);
    if (clazz == null) {
      throw new ReflectionException("There is no setter for property named '" + propertyName + "' in '" + type + "'");
    }
    return clazz;
  }

  /**
   * Gets the type for a property getter
   *
   * @param propertyName - the name of the property
   * @return The Class of the propery getter
   */
  public Class<?> getGetterType(String propertyName) {
    Class<?> clazz = getTypes.get(propertyName);
    if (clazz == null) {
      throw new ReflectionException("There is no getter for property named '" + propertyName + "' in '" + type + "'");
    }
    return clazz;
  }

  /**
   * Gets an array of the readable properties for an object
   *
   * @return The array
   */
  public String[] getGetablePropertyNames() {
    return readablePropertyNames;
  }

  /**
   * Gets an array of the writeable properties for an object
   *
   * @return The array
   */
  public String[] getSetablePropertyNames() {
    return writeablePropertyNames;
  }

  /**
   * Check to see if a class has a writeable property by name
   *
   * @param propertyName - the name of the property to check
   * @return True if the object has a writeable property by the name
   */
  public boolean hasSetter(String propertyName) {
    return setMethods.keySet().contains(propertyName);
  }

  /**
   * Check to see if a class has a readable property by name
   *
   * @param propertyName - the name of the property to check
   * @return True if the object has a readable property by the name
   */
  public boolean hasGetter(String propertyName) {
    return getMethods.keySet().contains(propertyName);
  }

  public String findPropertyName(String name) {
    return caseInsensitivePropertyMap.get(name.toUpperCase(Locale.ENGLISH));
  }

  /**
   * Gets an instance of ClassInfo for the specified class.
   *
   * @param clazz The class for which to lookup the method cache.
   * @return The method cache for the class
   */
  public static Reflector forClass(Class<?> clazz) {
    if (classCacheEnabled) {
      synchronized (clazz) {
        Reflector cached = REFLECTOR_MAP.get(clazz);
        if (cached == null) {
          cached = new Reflector(clazz);
          REFLECTOR_MAP.put(clazz, cached);
        }
        return cached;
      }
    } else {
      return new Reflector(clazz);
    }
  }

  public static void setClassCacheEnabled(boolean classCacheEnabled) {
    Reflector.classCacheEnabled = classCacheEnabled;
  }

  public static boolean isClassCacheEnabled() {
    return classCacheEnabled;
  }
}
