/*******************************************************************************
 * Copyright (c) 2006, 2007 IBM Corporation and others.
 * All rights reserved. This program and the accompanying materials
 * are made available under the terms of the Eclipse Public License v1.0
 * which accompanies this distribution, and is available at
 * http://www.eclipse.org/legal/epl-v10.html
 *
 * Contributors:
 *     IBM Corporation - initial API and implementation
 * Port to the D programming language:
 *     Frank Benoit <benoit@tionex.de>
 *******************************************************************************/
module dwtx.jface.fieldassist.FieldDecorationRegistry;

import dwtx.jface.fieldassist.FieldDecoration;

import tango.util.collection.HashMap;

import dwt.graphics.Image;
import dwtx.jface.resource.ImageDescriptor;
import dwtx.jface.resource.ImageRegistry;
import dwtx.jface.resource.JFaceResources;

import dwt.dwthelper.utils;

/**
 * FieldDecorationRegistry is a common registry used to define shared field
 * decorations within an application. Unlike resource registries, the
 * FieldDecorationRegistry does not perform any lifecycle management of the
 * decorations.
 * </p>
 * <p>
 * Clients may specify images for the decorations in several different ways.
 * Images may be described by their image id in a specified
 * {@link ImageRegistry}. In this case, the life cycle of the image is managed
 * by the image registry, and the decoration registry will not attempt to obtain
 * an image from the image registry until the decoration is actually requested.
 * In cases where the client has access to an already-created image, the image
 * itself can be specified when registering the decoration. In this case, the
 * life cycle should be managed by the specifying client.
 * </p>
 *
 * @see FieldDecoration
 * @see ImageRegistry
 *
 * @since 3.2
 */
public class FieldDecorationRegistry {

    /**
     * Decoration id for the decoration that should be used to cue the user that
     * content proposals are available.
     */
    public static const String DEC_CONTENT_PROPOSAL = "DEC_CONTENT_PROPOSAL"; //$NON-NLS-1$

    /**
     * Decoration id for the decoration that should be used to cue the user that
     * a field is required.
     */
    public static const String DEC_REQUIRED = "DEC_REQUIRED"; //$NON-NLS-1$

    /**
     * Decoration id for the decoration that should be used to cue the user that
     * a field has an error.
     */
    public static const String DEC_ERROR = "DEC_ERROR"; //$NON-NLS-1$

    /**
     * Decoration id for the decoration that should be used to cue the user that
     * a field has a warning.
     */
    public static const String DEC_WARNING = "DEC_WARNING"; //$NON-NLS-1$

    /**
     * Decoration id for the decoration that should be used to cue the user that
     * a field has additional information.
     *
     * @since 3.3
     */
    public static const String DEC_INFORMATION = "DEC_INFORMATION"; //$NON-NLS-1$

    /**
     * Decoration id for the decoration that should be used to cue the user that
     * a field has an error with quick fix available.
     *
     * @since 3.3
     */
    public static const String DEC_ERROR_QUICKFIX = "DEC_ERRORQUICKFIX"; //$NON-NLS-1$

    /*
     * Image id's
     */
    private static const String IMG_DEC_FIELD_CONTENT_PROPOSAL = "dwtx.jface.fieldassist.IMG_DEC_FIELD_CONTENT_PROPOSAL"; //$NON-NLS-1$

    private static const String IMG_DEC_FIELD_REQUIRED = "dwtx.jface.fieldassist.IMG_DEC_FIELD_REQUIRED"; //$NON-NLS-1$

    private static const String IMG_DEC_FIELD_ERROR = "dwtx.jface.fieldassist.IMG_DEC_FIELD_ERROR"; //$NON-NLS-1$

    private static const String IMG_DEC_FIELD_ERROR_QUICKFIX = "dwtx.jface.fieldassist.IMG_DEC_FIELD_ERROR_QUICKFIX"; //$NON-NLS-1$

    private static const String IMG_DEC_FIELD_WARNING = "dwtx.jface.fieldassist.IMG_DEC_FIELD_WARNING"; //$NON-NLS-1$

    private static const String IMG_DEC_FIELD_INFO = "dwtx.jface.fieldassist.IMG_DEC_FIELD_INFO"; //$NON-NLS-1$

    /*
     * Declare images and decorations immediately.
     */
    private static void static_this(FieldDecorationRegistry reg) {
        ImageRegistry imageRegistry = JFaceResources.getImageRegistry();

        // Define the images used in the standard decorations.
        imageRegistry.put(IMG_DEC_FIELD_CONTENT_PROPOSAL, ImageDescriptor.createFromFile(
            getImportData!("dwtx.jface.fieldassist.images.contassist_ovr.gif")));//$NON-NLS-1$
        imageRegistry.put(IMG_DEC_FIELD_ERROR, ImageDescriptor.createFromFile(
            getImportData!("dwtx.jface.fieldassist.images.error_ovr.gif")));//$NON-NLS-1$

        imageRegistry.put(IMG_DEC_FIELD_WARNING, ImageDescriptor.createFromFile(
            getImportData!("dwtx.jface.fieldassist.images.warn_ovr.gif")));//$NON-NLS-1$

        imageRegistry.put(IMG_DEC_FIELD_REQUIRED, ImageDescriptor.createFromFile(
            getImportData!("dwtx.jface.fieldassist.images.required_field_cue.gif")));//$NON-NLS-1$

        imageRegistry.put(IMG_DEC_FIELD_ERROR_QUICKFIX, ImageDescriptor.createFromFile(
            getImportData!("dwtx.jface.fieldassist.images.errorqf_ovr.gif")));//$NON-NLS-1$

        imageRegistry.put(IMG_DEC_FIELD_INFO, ImageDescriptor.createFromFile(
            getImportData!("dwtx.jface.fieldassist.images.info_ovr.gif")));//$NON-NLS-1$

        // Define the standard decorations. Some do not have standard
        // descriptions. Use null in these cases.
        reg
                .registerFieldDecoration(
                        DEC_CONTENT_PROPOSAL,
                        JFaceResources
                                .getString("FieldDecorationRegistry.contentAssistMessage"), //$NON-NLS-1$
                        IMG_DEC_FIELD_CONTENT_PROPOSAL, imageRegistry);

        reg.registerFieldDecoration(
                DEC_ERROR,
                JFaceResources
                        .getString("FieldDecorationRegistry.errorMessage"), //$NON-NLS-1$
                IMG_DEC_FIELD_ERROR, imageRegistry);

        reg.registerFieldDecoration(
                DEC_ERROR_QUICKFIX,
                JFaceResources
                        .getString("FieldDecorationRegistry.errorQuickFixMessage"), //$NON-NLS-1$
                IMG_DEC_FIELD_ERROR_QUICKFIX, imageRegistry);

        reg.registerFieldDecoration(DEC_WARNING, null,
                IMG_DEC_FIELD_WARNING, imageRegistry);

        reg.registerFieldDecoration(DEC_INFORMATION, null,
                IMG_DEC_FIELD_INFO, imageRegistry);

        reg
                .registerFieldDecoration(
                        DEC_REQUIRED,
                        JFaceResources
                                .getString("FieldDecorationRegistry.requiredFieldMessage"), //$NON-NLS-1$
                        IMG_DEC_FIELD_REQUIRED, imageRegistry);

    }

    /*
     * Data structure that holds onto the decoration image info and description,
     * and can produce a decorator on request.
     */
    class Entry {
        private String description;

        private String imageId;

        private ImageRegistry imageRegistry;

        private Image image;

        private FieldDecoration decoration;

        this(String description, String imageId, ImageRegistry registry) {
            this.description = description;
            this.imageId = imageId;
            this.imageRegistry = registry;
        }

        this(String description, Image image) {
            this.description = description;
            this.image = image;
        }

        FieldDecoration getDecoration() {
            if (decoration is null) {
                if (image is null) {
                    if (imageRegistry is null) {
                        imageRegistry = JFaceResources.getImageRegistry();
                    }
                    image = imageRegistry.get(imageId);
                }
                decoration = new FieldDecoration(image, description);
            }
            // Null out all other fields now that the decoration has an image
            description = null;
            imageId = null;
            imageRegistry = null;
            image = null;

            return decoration;
        }
    }

    /**
     * Default instance of the registry. Applications may install their own
     * registry.
     */
    private static FieldDecorationRegistry defaultInstance;

    /**
     * Maximum width and height used by decorations in this registry. Clients
     * may use these values to reserve space in dialogs for decorations or to
     * adjust layouts so that decorated and non-decorated fields line up.
     */
    private int maxDecorationWidth = 0;
    private int maxDecorationHeight = 0;

    private HashMap!(String,Object) /* <String id, FieldDecoration> */decorations;

    /**
     * Get the default FieldDecorationRegistry.
     *
     * @return the singleton FieldDecorationRegistry that is used to manage
     *         shared field decorations.
     */
    public static FieldDecorationRegistry getDefault() {
        if (defaultInstance is null) {
            synchronized(FieldDecorationRegistry.classinfo){
                if (defaultInstance is null) {
                    defaultInstance = new FieldDecorationRegistry();
                    static_this(defaultInstance);
                }
            }
        }
        return defaultInstance;
    }

    /**
     * Set the default FieldDecorationRegistry.
     *
     * @param defaultRegistry
     *            the singleton FieldDecorationRegistry that is used to manage
     *            shared field decorations.
     */
    public static void setDefault(FieldDecorationRegistry defaultRegistry) {
        defaultInstance = defaultRegistry;
    }

    /**
     * Construct a FieldDecorationRegistry.
     */
    public this() {
        decorations = new HashMap!(String,Object);
        maxDecorationWidth = 0;
        maxDecorationHeight = 0;
    }

    /**
     * Get the maximum width (in pixels) of any decoration retrieved so far in
     * the registry. This value changes as decorations are added and retrieved.
     * This value can be used by clients to reserve space or otherwise compute
     * margins when aligning non-decorated fields with decorated fields.
     *
     * @return the maximum width in pixels of any accessed decoration
     */
    public int getMaximumDecorationWidth() {
        return maxDecorationWidth;
    }

    /**
     * Get the maximum height (in pixels) of any decoration retrieved so far in
     * the registry. This value changes as decorations are added and retrieved.
     * This value can be used by clients to reserve space or otherwise compute
     * margins when aligning non-decorated fields with decorated fields.
     *
     *
     * @return the maximum height in pixels of any accessed decoration
     */
    public int getMaximumDecorationHeight() {
        return maxDecorationHeight;
    }

    /**
     * Registers a field decoration using the specified id. The lifecyle of the
     * supplied image should be managed by the client. That is, it will never be
     * disposed by this registry and the decoration should be removed from the
     * registry if the image is ever disposed elsewhere.
     *
     * @param id
     *            the String id used to identify and access the decoration.
     * @param description
     *            the String description to be used in the decoration, or
     *            <code>null</code> if the decoration has no description.
     * @param image
     *            the image to be used in the decoration
     */
    public void registerFieldDecoration(String id, String description,
            Image image) {
        decorations.add(id, new Entry(description, image));
        // Recompute the maximums since this might be a replacement
        recomputeMaximums();
    }

    /**
     * Registers a field decoration using the specified id. An image id of an
     * image located in the default JFaceResources image registry is supplied.
     * The image will not be created until the decoration is requested.
     *
     * @param id
     *            the String id used to identify and access the decoration.
     * @param description
     *            the String description to be used in the decoration, or
     *            <code>null</code> if the decoration has no description. *
     * @param imageId
     *            the id of the image in the JFaceResources image registry that
     *            is used for this decorator
     */
    public void registerFieldDecoration(String id, String description,
            String imageId) {
        decorations.add(id, new Entry(description, imageId, JFaceResources
                .getImageRegistry()));
        // Recompute the maximums as this could be a replacement of a previous
        // image.
        recomputeMaximums();
    }

    /**
     * Registers a field decoration using the specified id. An image id and an
     * image registry are supplied. The image will not be created until the
     * decoration is requested.
     *
     * @param id
     *            the String id used to identify and access the decoration.
     * @param description
     *            the String description to be used in the decoration, or
     *            <code>null</code> if the decoration has no description. *
     * @param imageId
     *            the id of the image in the supplied image registry that is
     *            used for this decorator
     * @param imageRegistry
     *            the registry used to obtain the image
     */
    public void registerFieldDecoration(String id, String description,
            String imageId, ImageRegistry imageRegistry) {
        decorations.add(id, new Entry(description, imageId, imageRegistry));
        // Recompute the maximums since this could be a replacement
        recomputeMaximums();
    }

    /**
     * Unregisters the field decoration with the specified id. No lifecycle
     * management is performed on the decoration's image. This message has no
     * effect if no field decoration with the specified id was previously
     * registered.
     * </p>
     * <p>
     * This method need not be called if the registered decoration's image is
     * managed in an image registry. In that case, leaving the decoration in the
     * registry will do no harm since the image will remain valid and will be
     * properly disposed when the application is shut down. This method should
     * be used in cases where the caller intends to dispose of the image
     * referred to by the decoration, or otherwise determines that the
     * decoration should no longer be used.
     *
     * @param id
     *            the String id of the decoration to be unregistered.
     */
    public void unregisterFieldDecoration(String id) {
        decorations.removeKey(id);
        recomputeMaximums();
    }

    /**
     * Returns the field decoration registered by the specified id .
     *
     * @param id
     *            the String id used to access the decoration.
     * @return the FieldDecoration with the specified id, or <code>null</code>
     *         if there is no decoration with the specified id.
     */
    public FieldDecoration getFieldDecoration(String id) {
        Object entry = decorations.get(id);
        if (entry is null) {
            return null;
        }
        return (cast(Entry) entry).getDecoration();

    }

    /*
     * The maximum decoration width and height must be recomputed. Typically
     * called in response to adding, removing, or replacing a decoration.
     */
    private void recomputeMaximums() {
        maxDecorationHeight = 0;
        maxDecorationWidth = 0;
        foreach( k,v; decorations ){
            Image image = (cast(Entry)v).getDecoration().getImage();
            if (image !is null) {
                maxDecorationHeight = Math.max(maxDecorationHeight, image.getBounds().height);
                maxDecorationWidth = Math.max(maxDecorationWidth, image.getBounds().width);
            }
        }

    }
}