AbstractModuleDescriptor

package com.atlassian.plugin.descriptors;

import com.atlassian.plugin.ModuleDescriptor;
import com.atlassian.plugin.ModulePermissionException;
import com.atlassian.plugin.Permissions;
import com.atlassian.plugin.Plugin;
import com.atlassian.plugin.PluginParseException;
import com.atlassian.plugin.RequirePermission;
import com.atlassian.plugin.Resources;
import com.atlassian.plugin.StateAware;
import com.atlassian.plugin.elements.ResourceDescriptor;
import com.atlassian.plugin.elements.ResourceLocation;
import com.atlassian.plugin.loaders.LoaderUtils;
import com.atlassian.plugin.module.LegacyModuleFactory;
import com.atlassian.plugin.module.ModuleFactory;
import com.atlassian.plugin.module.PrefixDelegatingModuleFactory;
import com.atlassian.plugin.util.ClassUtils;
import com.atlassian.plugin.util.JavaVersionUtils;
import com.atlassian.plugin.util.validation.ValidationPattern;
import com.atlassian.util.concurrent.NotNull;
import com.google.common.collect.ImmutableSet;
import com.google.common.collect.Sets;
import org.dom4j.Element;
import org.slf4j.Logger;
import org.slf4j.LoggerFactory;

import java.util.List;
import java.util.Map;
import java.util.Set;

import static com.atlassian.plugin.util.Assertions.notNull;
import static com.atlassian.plugin.util.validation.ValidationPattern.createPattern;
import static com.atlassian.plugin.util.validation.ValidationPattern.test;
import static com.google.common.base.Preconditions.checkNotNull;

public abstract class AbstractModuleDescriptor<T> implements ModuleDescriptor<T>, StateAware
{
    protected Plugin plugin;
    protected String key;
    protected String name;
    protected String moduleClassName;
    protected Class<T> moduleClass;
    private String description;
    private boolean enabledByDefault = true;
    private boolean systemModule = false;

    /**
     * @deprecated since 2.2.0
     */
    @Deprecated
    protected boolean singleton = true;
    private Map<String, String> params;
    protected Resources resources = Resources.EMPTY_RESOURCES;
    private Float minJavaVersion;
    private String i18nNameKey;
    private String descriptionKey;
    private String completeKey;
    private boolean enabled = false;
    protected final ModuleFactory moduleFactory;
    private final Logger log = LoggerFactory.getLogger(getClass());

    public AbstractModuleDescriptor(final ModuleFactory moduleFactory)
    {
        this.moduleFactory = checkNotNull(moduleFactory, "Module creator factory cannot be null");
    }

    public void init(@NotNull final Plugin plugin, @NotNull final Element element) throws PluginParseException
    {
        validate(element);

        this.plugin = notNull("plugin", plugin);
        this.key = element.attributeValue("key");
        this.name = element.attributeValue("name");
        this.i18nNameKey = element.attributeValue("i18n-name-key");
        this.completeKey = buildCompleteKey(plugin, key);
        this.description = element.elementTextTrim("description");
        this.moduleClassName = element.attributeValue("class");
        final Element descriptionElement = element.element("description");
        this.descriptionKey = (descriptionElement != null) ? descriptionElement.attributeValue("key") : null;
        params = LoaderUtils.getParams(element);

        if ("disabled".equalsIgnoreCase(element.attributeValue("state")))
        {
            enabledByDefault = false;
        }

        if ("true".equalsIgnoreCase(element.attributeValue("system")))
        {
            systemModule = true;
        }

        if (element.element("java-version") != null)
        {
            minJavaVersion = Float.valueOf(element.element("java-version").attributeValue("min"));
        }

        if ("false".equalsIgnoreCase(element.attributeValue("singleton")))
        {
            singleton = false;
        }
        else if ("true".equalsIgnoreCase(element.attributeValue("singleton")))
        {
            singleton = true;
        }
        else
        {
            singleton = isSingletonByDefault();
        }

        resources = Resources.fromXml(element);
    }

    /**
     * This is a method that module should call (in their {@link #init(Plugin, Element) init method implementation} to
     * check that permissions are correctly set on the plugin. Use the {@link RequirePermission} annotation to add
     * permissions to a module, and/or {@link #getRequiredPermissions} if you need more dynamic permissions.
     *
     * If either all permissions are allowed or this is a system module, we don't bother to check permissions
     *
     * @throws ModulePermissionException if the plugin doesn't require the necessary permissions for the module to work.
     * @see RequirePermission
     * @see #getRequiredPermissions()
     * @since 3.0
     */
    protected final void checkPermissions() throws ModulePermissionException
    {
        if (plugin.hasAllPermissions() || isSystemModule())
        {
            return;
        }

        final Sets.SetView<String> difference = Sets.difference(getAllRequiredPermissions(), plugin.getActivePermissions());
        if (!difference.isEmpty())
        {
            throw new ModulePermissionException(getCompleteKey(), difference.immutableCopy());
        }
    }

    private Set<String> getAllRequiredPermissions()
    {
        final ImmutableSet.Builder<String> permissions = ImmutableSet.builder();
        permissions.addAll(Permissions.getRequiredPermissions(this.getClass()));
        permissions.addAll(getRequiredPermissions());
        return permissions.build();
    }

    /**
     * <p>The set of additionally required permissions. This is useful for dynamic permissions depending on module
     * configuration. One might prefer the {@link RequirePermission} annotation otherwise for 'static' permissions.
     * <p>Default implementation returns an empty set
     * @return the set of additionally required permissions.
     * @see RequirePermission
     * @see #checkPermissions()
     * @since 3.0
     */
    protected Set<String> getRequiredPermissions()
    {
        return ImmutableSet.of();
    }

    /**
     * Validates the element, collecting the rules from
     * {@link #provideValidationRules(ValidationPattern)}
     *
     * @param element The configuration element
     * @since 2.2.0
     */
    private void validate(final Element element)
    {
        notNull("element", element);
        final ValidationPattern pattern = createPattern();
        provideValidationRules(pattern);
        pattern.evaluate(element);
    }

    /**
     * Provides validation rules for the pattern
     *
     * @param pattern The validation pattern
     * @since 2.2.0
     */
    protected void provideValidationRules(final ValidationPattern pattern)
    {
        pattern.rule(test("@key").withError("The key is required"));
    }

    /**
     * Override this for module descriptors which don't expect to be able to
     * load a class successfully
     *
     * @param plugin
     * @param element
     * @deprecated Since 2.1.0, use {@link #loadClass(Plugin,String)} instead
     */
    @Deprecated
    protected void loadClass(final Plugin plugin, final Element element) throws PluginParseException
    {
        loadClass(plugin, element.attributeValue("class"));
    }

    /**
     * Loads the module class that this descriptor provides, and will not
     * necessarily be the implementation class. Override this for module
     * descriptors whose type cannot be determined via generics.
     *
     * @param clazz The module class name to load
     * @throws IllegalStateException If the module class cannot be determined
     *             and the descriptor doesn't define a module type via generics
     */
    protected void loadClass(final Plugin plugin, final String clazz) throws PluginParseException
    {
        if (moduleClassName != null)
        {
            if (moduleFactory instanceof LegacyModuleFactory) // not all plugins have to have a class
            {
                moduleClass = ((LegacyModuleFactory) moduleFactory).getModuleClass(moduleClassName, this);
            }

            // This is only here for backwards compatibility with old code that
            // uses {@link
            // com.atlassian.plugin.PluginAccessor#getEnabledModulesByClass(Class)}
            else if (moduleFactory instanceof PrefixDelegatingModuleFactory)
            {
                moduleClass = ((PrefixDelegatingModuleFactory) moduleFactory).guessModuleClass(moduleClassName, this);
            }
        }
        // If this module has no class, then we assume Void
        else
        {
            moduleClass = (Class<T>) Void.class;
        }

        // Usually is null when a prefix is used in the class name
        if (moduleClass == null)
        {
            try
            {

                Class moduleTypeClass = null;
                try
                {
                    moduleTypeClass = ClassUtils.getTypeArguments(AbstractModuleDescriptor.class, getClass()).get(0);
                }
                catch (RuntimeException ex)
                {
                    log.debug("Unable to get generic type, usually due to Class.forName() problems", ex);
                    moduleTypeClass = getModuleReturnClass();
                }
                moduleClass = moduleTypeClass;
            }
            catch (final ClassCastException ex)
            {
                throw new IllegalStateException("The module class must be defined in a concrete instance of " + "ModuleDescriptor and not as another generic type.");
            }

            if (moduleClass == null)
            {
                throw new IllegalStateException("The module class cannot be determined, likely because it needs a concrete "
                    + "module type defined in the generic type it passes to AbstractModuleDescriptor");
            }
        }
    }

    Class<?> getModuleReturnClass()
    {
        try
        {
            return getClass().getMethod("getModule").getReturnType();
        }
        catch (NoSuchMethodException e)
        {
            throw new IllegalStateException("The getModule() method is missing (!) on " + getClass());
        }
    }

    /**
     * Build the complete key based on the provided plugin and module key. This
     * method has no side effects.
     *
     * @param plugin The plugin for which the module belongs
     * @param moduleKey The key for the module
     * @return A newly constructed complete key, null if the plugin is null
     */
    private String buildCompleteKey(final Plugin plugin, final String moduleKey)
    {
        if (plugin == null)
        {
            return null;
        }

        final StringBuffer completeKeyBuffer = new StringBuffer(32);
        completeKeyBuffer.append(plugin.getKey()).append(":").append(moduleKey);
        return completeKeyBuffer.toString();
    }

    /**
     * The default implementation disables the module if it's still enabled, and unreference the plugin.
     * Override this if your plugin needs to clean up when it's been removed,
     * and call super.destroy(Plugin) before returning.
     */
    public void destroy()
    {
        destroy(plugin);
    }

    @Deprecated
    public void destroy(final Plugin plugin)
    {
        if (enabled)
        {
            this.disabled();
        }
    }

    public boolean isEnabledByDefault()
    {
        return enabledByDefault && satisfiesMinJavaVersion();
    }

    public boolean isSystemModule()
    {
        return systemModule;
    }

    /**
     * @deprecated Since 2.2.0
     */
    @Deprecated
    public boolean isSingleton()
    {
        return singleton;
    }

    /**
     * @deprecated Since 2.2.0
     */
    @Deprecated
    protected boolean isSingletonByDefault()
    {
        return true;
    }

    /**
     * Check that the module class of this descriptor implements a given
     * interface, or extends a given class.
     *
     * @param requiredModuleClazz The class this module's class must implement
     *            or extend.
     * @throws PluginParseException If the module class does not implement or
     *             extend the given class.
     */
    final protected void assertModuleClassImplements(final Class<T> requiredModuleClazz) throws PluginParseException
    {
        if (!enabled)
        {
            throw new PluginParseException("Plugin module " + getKey() + " not enabled");
        }
        if (!requiredModuleClazz.isAssignableFrom(getModuleClass()))
        {
            throw new PluginParseException("Given module class: " + getModuleClass().getName() + " does not implement " + requiredModuleClazz.getName());
        }
    }

    public String getCompleteKey()
    {
        return completeKey;
    }

    public String getPluginKey()
    {
        return getPlugin().getKey();
    }

    public String getKey()
    {
        return key;
    }

    public String getName()
    {
        return name;
    }

    public Class<T> getModuleClass()
    {
        return moduleClass;
    }

    public abstract T getModule();

    public String getDescription()
    {
        return description;
    }

    public Map<String, String> getParams()
    {
        return params;
    }

    public String getI18nNameKey()
    {
        return i18nNameKey;
    }

    public String getDescriptionKey()
    {
        return descriptionKey;
    }

    public List<ResourceDescriptor> getResourceDescriptors()
    {
        return resources.getResourceDescriptors();
    }

    public List<ResourceDescriptor> getResourceDescriptors(final String type)
    {
        return resources.getResourceDescriptors(type);
    }

    public ResourceLocation getResourceLocation(final String type, final String name)
    {
        return resources.getResourceLocation(type, name);
    }

    public ResourceDescriptor getResourceDescriptor(final String type, final String name)
    {
        return resources.getResourceDescriptor(type, name);
    }

    public Float getMinJavaVersion()
    {
        return minJavaVersion;
    }

    public boolean satisfiesMinJavaVersion()
    {
        if (minJavaVersion != null)
        {
            return JavaVersionUtils.satisfiesMinVersion(minJavaVersion);
        }
        return true;
    }

    /**
     * Sets the plugin for the ModuleDescriptor
     *
     * @param plugin The plugin to set for this descriptor.
     */
    public void setPlugin(final Plugin plugin)
    {
        this.completeKey = buildCompleteKey(plugin, key);
        this.plugin = plugin;
    }

    /**
     * @return The plugin this module descriptor is associated with.
     */
    public Plugin getPlugin()
    {
        return plugin;
    }

    @Override
    public boolean equals(Object obj)
    {
        return new ModuleDescriptors.EqualsBuilder().descriptor(this).isEqualTo(obj);
    }

    @Override
    public int hashCode()
    {
        return new ModuleDescriptors.HashCodeBuilder().descriptor(this).toHashCode();
    }

    @Override
    public String toString()
    {
        return getCompleteKey() + " (" + getDescription() + ")";
    }

    /**
     * Enables the descriptor by loading the module class. Classes overriding
     * this method MUST call super.enabled() before their own enabling code.
     *
     * @since 2.1.0
     */
    public void enabled()
    {
        loadClass(plugin, moduleClassName);
        enabled = true;
    }

    /**
     * Disables the module descriptor. Classes overriding this method MUST call
     * super.disabled() after their own disabling code.
     */
    public void disabled()
    {
        enabled = false;
        moduleClass = null;
    }

    /**
     * @return The defined module class name
     * @since 3.0
     */
    protected String getModuleClassName()
    {
        return moduleClassName;
    }
}