/*
 *                 Sun Public License Notice
 * 
 * The contents of this file are subject to the Sun Public License
 * Version 1.0 (the "License"). You may not use this file except in
 * compliance with the License. A copy of the License is available at
 * http://www.sun.com/
 * 
 * The Original Code is NetBeans. The Initial Developer of the Original
 * Code is Sun Microsystems, Inc. Portions Copyright 1997-2003 Sun
 * Microsystems, Inc. All Rights Reserved.
 */


package org.openide.loaders;


import java.io.IOException;
import java.io.ObjectInputStream;
import java.io.ObjectOutputStream;
import java.io.Serializable;
import java.lang.ref.WeakReference;
import java.util.ArrayList;
import java.util.Collection;
import java.util.List;

import org.openide.cookies.InstanceCookie;
import org.openide.ErrorManager;
import org.openide.filesystems.FileObject;
import org.openide.loaders.DataObject;
import org.openide.util.Lookup;
import org.openide.util.lookup.AbstractLookup;
import org.openide.util.lookup.ProxyLookup;
import org.openide.util.Task;


/** Implements a lookup, that scans a content of a folder for its
 * data objects and asks them for instance cookie, the created objects
 * are then used to for the content of the lookup.
 * 
Any instances which are in fact instances of Lookup
 * will be proxied to, permitting one file to generate many instances
 * in the lookup system easily.
 * @author  Jaroslav Tulach
 * @since 1.11
 */
public class FolderLookup extends FolderInstance {
    
    /** Lock for initiliazation of lookup. */
    private static final Object LOCK = new Object ();
    
    /** Lookup to delegate to. */
    private ProxyLkp lookup; 
    
    /** The root name of the lookup. */
    private String rootName;

    /** Indicates whether this FolderLookup is at the root of (folder)tree which 
     * we are interested in and the one which collects all items from the tree. */
    private final boolean isRoot;

    
    /** Constructs the FolderLookup for given container. A default ID prefix is 
     * used for identification of located items.
     *
     * @param df container (or folder) to work on
     */
    public FolderLookup (DataObject.Container df) {
        this (df, "FL["); // NOI18N
    }
    
    /** Constructs the FolderLookup for given container.
     * @param df container (or folder) to work on
     * @param prefix the prefix to use 
     */
    public FolderLookup (DataObject.Container df, String prefix) {
        this(df, prefix, true);
    }

    /** Constructs the FolderLookup for given container.
     * @param df container (or folder) to work on
     * @param prefix the prefix to use 
     * @param isRoot indicates whether this instance is the at the root of tree
     * in which we perform the lookup -> only this instance has lookup 
     * which collects all items from the tree */
    private FolderLookup(DataObject.Container df, String prefix, boolean isRoot) {
        super(df);
        
        this.rootName = prefix;
        this.isRoot = isRoot;
    }
    

    /** The correct class that this folder recognizes.
     * @return Proxy.Lkp class. */
    public final Class instanceClass () {
        return ProxyLkp.class;
    }
    
    /**
     * Getter for the lookup that should be used.
     * 
Serializable since 3.27.
     * @return a lookup
     */
    public final Lookup getLookup () {
        boolean inited = false;
        synchronized(LOCK) {
            if(lookup == null) {
                lookup = new ProxyLkp(this);
                inited = true;
            }
        }

        if(inited) {
            checkRecreate();
        }
                
        return lookup;
    }
    
    /** Updates the content of the lookup.
     * @param cookies updated array of instance cookies for the folder
     * @return object to represent these cookies
     *
     * @exception IOException an I/O error occured
     * @exception ClassNotFoundException a class has not been found
     */
    protected final Object createInstance(InstanceCookie[] cookies) 
    throws IOException, ClassNotFoundException {
        FolderLookupData flData = new FolderLookupData();

        // If we are root, preserve place for abstract lookup which collects items.
        // see ProxyLkp.update method.
        if(isRoot) {
            flData.lookups.add(null);
        }
        
        for (int i = 0; i < cookies.length; i++) {
            try {
                // It's either result from underlying lookup or some another lookup or it is ICItem.
                Object obj = cookies[i].instanceCreate ();

                if(obj instanceof FolderLookupData) {
                    // It's from underlying 'sub'-lookup.
                    flData.items.addAll(((FolderLookupData)obj).items);
                    flData.lookups.addAll(((FolderLookupData)obj).lookups);
                } else if(obj instanceof Lookup) {
                    flData.lookups.add(obj);
                } else {
                    // Has to be ICItem.
                    flData.items.add(obj);
                }
            } catch(IOException ex) {
                exception(ex);
            } catch(ClassNotFoundException ex) {
                exception(ex);
            }
        }

        // If this is not the root lookup just return items+lookups
        // which will be collected by root lookup.
        if(!isRoot) {
            return flData;
        }
        
        // We are root FolderLookup. Now collect all items from underlying world.
        
        // Initializes lookup.
        getLookup();

        lookup.update(flData.items, flData.lookups);
        
        return lookup;
    }
    
    /** Overrides superclass method. It returns instance
     * for DataObject&InstanceCookie 'pair'. 
     * If the instance is of FolderLookup.Lkp class it is created otherwise
     * new Lkp.ICItem created and returned.
     *
     * @param dobj the data object that is the source of the cookie
     * @param cookie the instance cookie to read the instance from
     * @exception IOException when there I/O error
     * @exception ClassNotFoundException if the class cannot be found */
    protected Object instanceForCookie(DataObject dobj, InstanceCookie cookie)
    throws IOException, ClassNotFoundException {
        boolean isLookup;
        
        if(cookie instanceof InstanceCookie.Of) {
            isLookup = ((InstanceCookie.Of)cookie).instanceOf(Lookup.class);
        } else {
            isLookup = Lookup.class.isAssignableFrom(cookie.instanceClass ());
        }

        if(isLookup) {
            // Is underlying FolderLookup create it.
            return cookie.instanceCreate();
        } else {
            return new ICItem(dobj, rootName, cookie);
        }
    }
    
    /** Folder is recognized as underlying FolderLookup which passes
     * its items to parent FolderLookup.
     * @param df the folder found
     * @return new FolderLookup
     */
    protected InstanceCookie acceptFolder (DataFolder df) {
        return new FolderLookup(df, objectName(rootName, df), false);
    }
    
    /** Container is recognized as underlying FolderLookup which passes
     * its items to parent FolderLookup.
     * @param df the container found
     * @return new FolderLookup
     */
    protected InstanceCookie acceptContainer (DataObject.Container df) {
        return new FolderLookup(
            df,
            rootName == null ? "" : rootName + "", // NOI18N
            false
        );
    }
    

    /** Starts the creation of the object in the Folder recognizer thread.
     * Doing all the lookup stuff in one thread should prevent deadlocks,
     * but because we call unknown data loaders, they obviously must be 
     * implemented in correct way.
     *
     * @param run runable to start
     * @return null, because the runnable is started immediatelly
     */
    protected final Task postCreationTask (Runnable run) {
        run.run ();
        return null;
    }
    
    /** Concatenates name of folder with name of object. Helper method.
     * @param folderName name of folder or null
     * @param obj object to concatenate
     * @return new name
     */
    private static String objectName (String name, DataObject obj) {
        if (name == null) {
            return obj.getName ();
        } else {
            return name + '/' + obj.getName ();
        }
    }
    
    /** Notifies the exception. Helper method. */
    private static void exception (Exception e) {
        ErrorManager.getDefault ().notify (ErrorManager.INFORMATIONAL, e);
    }
    private static void exception(Exception e, FileObject fo) {
        ErrorManager.getDefault().annotate(e, ErrorManager.UNKNOWN, "Bad file: " + fo, null, null, null); // NOI18N
        exception(e);
    }

    
    /** ProxyLookup delegate so we can change the lookups on fly. */
    static final class ProxyLkp extends ProxyLookup implements Serializable {
        
        private static final long serialVersionUID = 1L;

        /** FolderLookup we are associated with. */
        private transient FolderLookup fl;
        
        /** Content to control the abstract lookup. */
        private transient AbstractLookup.Content content;
        
        private transient boolean readFromStream;

        /** Constructs lookup which holds all items+lookups from underlying world.
         * @param folder FolderLookup to associate to */
        public ProxyLkp(FolderLookup folder) {
            this(folder, new AbstractLookup.Content());
        }

        /** Constructs lookup. */
        private ProxyLkp(FolderLookup folder, AbstractLookup.Content content) {
            super(new Lookup[] {new AbstractLookup(content)});
            
            this.fl = folder;
            this.content = content;
        }
        
        public String toString() {
            return "FolderLookup.lookup[\"" + fl.rootName + "\"]";
        }
        
        private void writeObject (ObjectOutputStream oos) throws IOException {
            Lookup[] ls = getLookups();
            for (int i = 0; i < ls.length; i++) {
                oos.writeObject(ls[i]);
            }
            oos.writeObject(null);
            oos.writeObject (fl.folder);
            oos.writeObject (fl.rootName);
            oos.writeObject (content);
        }
        
        private void readObject (ObjectInputStream ois) throws IOException, ClassNotFoundException {
            List ls = new ArrayList(); // List
            Lookup l;
            while ((l = (Lookup)ois.readObject()) != null) {
                ls.add(l);
            }
            Lookup[] arr = (Lookup[])ls.toArray(new Lookup[ls.size()]);
            DataFolder df = (DataFolder)ois.readObject ();
            String root = (String)ois.readObject ();
            
            fl = new FolderLookup (df, root, true);
            fl.lookup = this;
            
            content = (AbstractLookup.Content)ois.readObject ();
            
            setLookups (arr);

            readFromStream = true;
            org.openide.util.RequestProcessor.getDefault ().post (fl, 0, Thread.MIN_PRIORITY);
        }
        
        
        /** Updates internal data. 
         * @param items Items to assign to all pairs
         * @param lookups delegates to delegate to (first item is null)
         */
        public void update(Collection items, List lookups) {
            readFromStream = false;
            
            // remember the instance lookup 
            Lookup pairs = getLookups ()[0];

            // changes the its content
            content.setPairs (items);
            if (fl.err().isLoggable(ErrorManager.INFORMATIONAL)) fl.err ().log ("Changed pairs: " + items); // NOI18N

            lookups.set(0, pairs);

            Lookup[] arr = (Lookup[])lookups.toArray (new Lookup[lookups.size ()]);
            setLookups (arr);
            if (fl.err().isLoggable(ErrorManager.INFORMATIONAL)) fl.err ().log ("Changed lookups: " + lookups); // NOI18N
        }
        
        /** Waits before the processing of changes is finished. */
        protected void beforeLookup (Template template) {
            if (readFromStream) {
                // ok
                return;
            }
            
            // do not wait in folder recognizer, but in all other cases
            if (!FolderList.isFolderRecognizerThread ()) {
                fl.instanceFinished ();
            }
        }
        
        /** Mostly for testing purposes, to allow the tests to wait
         * for the scan to finished after deserialization.
         */
        public void waitFinished () {
            fl.waitFinished ();
        }

    } // End of ProxyLkp class.
    
    
    /** Item that delegates to InstanceCookie. Item which 
     * the internal lookup data structure is made from. */
    private static final class ICItem extends AbstractLookup.Pair implements Serializable {
        static final long serialVersionUID = 10L;

        /** when deserialized only primary file is stored */
        private FileObject fo;
        
        private transient InstanceCookie ic;
        /** source data object */
        private transient DataObject obj;
        /** reference to created object */
        private transient WeakReference ref;
        /** root folder */
        private String rootName;

        /** Constructs new item. */
        public ICItem (DataObject obj, String rootName, InstanceCookie ic) {
            this.ic = ic;
            this.obj = obj;
            this.rootName = rootName;
            this.fo = obj.getPrimaryFile();
        }
        
        /** Initializes the item
         */
        public void init () {
            if (ic != null) return;

            if (obj == null) {
                try {
                    obj = DataObject.find(fo);
                } catch (DataObjectNotFoundException donfe) {
                    ic = new BrokenInstance("File: " + fo.getPath(), donfe); // NOI18N
                    return;
                }
            }
            
            ic = (InstanceCookie)obj.getCookie (InstanceCookie.class);
            if (ic == null) {
                ic = new BrokenInstance("File: " + fo.getPath(), null); // NOI18N
            }
        }
            
        /**
         * Fake instance cookie.
         * Used in case a file had an instance in a previous session but now does not
         * (or the data object could not even be created correctly).
         */
        private static final class BrokenInstance implements InstanceCookie.Of {
            private final String message;
            private final Exception ex;
            public BrokenInstance(String message, Exception ex) {
                this.message = message;
                this.ex = ex;
            }
            public String instanceName() {
                return "java.lang.Object"; // NOI18N
            }
            private ClassNotFoundException die() {
                if (ex != null) {
                    return new ClassNotFoundException(message, ex);
                } else {
                    return new ClassNotFoundException(message);
                }
            }
            public Class instanceClass() throws IOException, ClassNotFoundException {
                throw die();
            }
            public Object instanceCreate() throws IOException, ClassNotFoundException {
                throw die();
            }
            public boolean instanceOf(Class type) {
                return false;
            }
        }


        /** The class of the result item.
         * @return the class of the item
         */
        protected boolean instanceOf (Class clazz) {
            init ();
            
            if (ic instanceof InstanceCookie.Of) {
                // special handling for special cookies
                InstanceCookie.Of of = (InstanceCookie.Of)ic;
                return of.instanceOf (clazz);
            }

            // handling of normal instance cookies
            try {
                return clazz.isAssignableFrom (ic.instanceClass ());
            } catch (ClassNotFoundException ex) {
                exception(ex, fo);
            } catch (IOException ex) {
                exception(ex, fo);
            }
            return false;
        }

        /** The class of the result item.
         * @return the instance of the object or null if it cannot be created
         */
        public Object getInstance() {
            init ();
            
            try {
                Object obj = ic.instanceCreate();
                ref = new WeakReference (obj);
                return obj;
            } catch (ClassNotFoundException ex) {
                exception(ex, fo);
            } catch (IOException ex) {
                exception(ex, fo);
            }
            return null;
        }

        /** Hash code is the InstanceCookie's code. */
        public int hashCode () {
            init ();
            
            return System.identityHashCode (ic);
        }

        /** Two items are equal if they point to the same cookie. */
        public boolean equals (Object obj) {
            if (obj instanceof ICItem) {
                ICItem i = (ICItem)obj;
                i.init ();
                init ();
                return ic == i.ic;
            }
            return false;
        }

        /** An identity of the item.
         * @return string representing the item, that can be used for
         *   persistance purposes to locate the same item next time */
        public String getId() {
            init ();

            if (obj == null) {
                // Deser problems.
                return ""; // NOI18N
            }
            
            return objectName(rootName, obj);
        }

        /** Display name is extracted from name of the objects node. */
        public String getDisplayName () {
            init ();
            
            if (obj == null) {
                // Deser problems.
                return ""; // NOI18N
            }
            
            return obj.getNodeDelegate ().getDisplayName ();
        }

        /** Method that can test whether an instance of a class has been created
         * by this item.
         *
         * @param obj the instance
         * @return if the item has already create an instance and it is the same
         *  as obj.
         */
        protected boolean creatorOf(Object obj) {
            WeakReference w = ref;
            if (w != null && w.get () == obj) {
                return true;
            }
            if (this.obj instanceof InstanceDataObject) {
                return ((InstanceDataObject)this.obj).creatorOf (obj);
            }
            return false;
        }

        /** The class of this item.
         * @return the correct class
         */
        public Class getType() {
            init ();
            
            try {
                return ic.instanceClass ();
            } catch (IOException ex) {
                // ok, no class available
            } catch (ClassNotFoundException ex) {
                // ok, no class available
            }
            return Object.class;
        }

    } // End of ICItem class.

    
    /** Data structure which holds ICItem's and Lookup's got
     * from current folder and underlying sub-folders making it possible to
     * pass to parent folder together. */
    private static class FolderLookupData {

        /** Collection of ICItem's found in current 
         * folder and its sub-folders. */
        private Collection items;
        
        /** List of Lookup's found in current folder
         * and its sub-folders. */
        private List lookups;
        
        
        /** Constructs data structure with inited fields. */
        public FolderLookupData() {
            items = new ArrayList(30);
            lookups = new ArrayList(5);
        }
        
    } // End of FolderLookupData class.
}