/*
 * 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.sling.fsprovider.internal.mapper;

import java.io.File;
import java.io.FileInputStream;
import java.io.IOException;
import java.io.InputStream;
import java.net.MalformedURLException;
import java.net.URL;
import java.util.Calendar;
import java.util.HashMap;
import java.util.Map;

import javax.jcr.Node;

import org.apache.commons.lang3.StringUtils;
import org.apache.commons.lang3.builder.ToStringBuilder;
import org.apache.commons.lang3.builder.ToStringStyle;
import org.apache.sling.adapter.annotations.Adaptable;
import org.apache.sling.adapter.annotations.Adapter;
import org.apache.sling.api.resource.AbstractResource;
import org.apache.sling.api.resource.Resource;
import org.apache.sling.api.resource.ResourceMetadata;
import org.apache.sling.api.resource.ResourceResolver;
import org.apache.sling.api.resource.ValueMap;
import org.apache.sling.api.wrappers.DeepReadValueMapDecorator;
import org.apache.sling.contentparser.api.ParserOptions;
import org.apache.sling.fsprovider.internal.ContentFileExtensions;
import org.apache.sling.fsprovider.internal.FileStatCache;
import org.apache.sling.fsprovider.internal.FsResourceProvider;
import org.apache.sling.fsprovider.internal.mapper.jcr.FsNode;
import org.apache.sling.fsprovider.internal.mapper.valuemap.ValueMapDecorator;
import org.apache.sling.fsprovider.internal.parser.ContentFileCache;
import org.jetbrains.annotations.NotNull;
import org.jetbrains.annotations.Nullable;
import org.slf4j.Logger;
import org.slf4j.LoggerFactory;

/**
 * The <code>FileResource</code> represents a file system file or folder as
 * a Sling Resource.
 */
@Adaptable(adaptableClass=Resource.class, adapters={
    @Adapter({File.class, URL.class, ValueMap.class}),
    @Adapter(value=InputStream.class, condition="If the adaptable is a FileResource and is a readable file."),
    @Adapter(value=Node.class, condition="If the adaptable is a FileResource and is providing content in JSON or FileVault XML format.")
})
public final class FileResource extends AbstractResource {

    /**
     * The resource type for file system files mapped into the resource tree by
     * the {@link FsResourceProvider} (value is "nt:file").
     */
    static final String RESOURCE_TYPE_FILE = "nt:file";

    /**
     * The resource type for file system folders mapped into the resource tree
     * by the {@link FsResourceProvider} (value is "nt:folder").
     */
    static final String RESOURCE_TYPE_FOLDER = "nt:folder";

    // the owning resource resolver
    private final ResourceResolver resolver;

    // the path of this resource in the resource tree
    private final String resourcePath;

    // the file wrapped by this instance
    private final File file;

    // the resource metadata, assigned on demand
    private ResourceMetadata metaData;

    // the resource type, assigned on demand
    private String resourceType;
    private String resourceSuperType;

    // valuemap is build on demand
    private ValueMap valueMap;

    private final ContentFileExtensions contentFileExtensions;
    private final ContentFileCache contentFileCache;
    private final FileStatCache fileStatCache;

    private static final Logger log = LoggerFactory.getLogger(FileResource.class);

    /**
     * Creates an instance of this File system resource.
     *
     * @param resolver The owning resource resolver
     * @param resourcePath The resource path in the resource tree
     * @param file The wrapped file
     */
    FileResource(ResourceResolver resolver, String resourcePath, File file, FileStatCache fileStatCache) {
        this(resolver, resourcePath, file, null, null, fileStatCache);
    }

    FileResource(ResourceResolver resolver, String resourcePath, File file,
                 ContentFileExtensions contentFileExtensions, ContentFileCache contentFileCache,
                 FileStatCache fileStatCache) {
        this.resolver = resolver;
        this.resourcePath = resourcePath;
        this.file = file;
        this.contentFileExtensions = contentFileExtensions;
        this.contentFileCache = contentFileCache;
        this.fileStatCache = fileStatCache;
    }

    /**
     * Returns the path of this resource
     */
    public @NotNull String getPath() {
        return resourcePath;
    }

    /**
     * Returns the resource meta data for this resource containing the file
     * length, last modification time and the resource path (same as
     * {@link #getPath()}).
     */
    public @NotNull ResourceMetadata getResourceMetadata() {
        if (metaData == null) {
            metaData = new LazyModifiedDateResourceMetadata(file);
            metaData.setContentLength(file.length());
            metaData.setResolutionPath(resourcePath);
            if (fileStatCache.isDirectory(file)) {
                metaData.put(FsResourceProvider.RESOURCE_METADATA_FILE_DIRECTORY, Boolean.TRUE);
            }
        }
        return metaData;
    }

    /**
     * Returns the resource resolver which cause this resource object to be
     * created.
     */
    public @NotNull ResourceResolver getResourceResolver() {
        return resolver;
    }

    public String getResourceSuperType() {
        if (resourceSuperType == null) {
            resourceSuperType = getValueMap().get("sling:resourceSuperType", String.class);
        }
        return resourceSuperType;
    }

    public @NotNull String getResourceType() {
        if (resourceType == null) {
            ValueMap props = getValueMap();
            resourceType = props.get("sling:resourceType", String.class);
            if (resourceType == null) {
                // fallback to jcr:primaryType when resource type not set
                resourceType = props.get("jcr:primaryType", String.class);
            }
        }
        return resourceType;
    }

    /**
     * Returns an adapter for this resource. This implementation supports
     * <code>File</code>, <code>InputStream</code> and <code>URL</code>
     * plus those supported by the adapter manager.
     */
    @Override
    @SuppressWarnings({ "unchecked", "null" })
    public @Nullable <AdapterType> AdapterType adaptTo(@NotNull Class<AdapterType> type) {
        if (type == File.class) {
            return (AdapterType) file;
        }
        else if (type == InputStream.class) {
            if (fileStatCache.isFile(file) && file.canRead()) {
                try {
                    return (AdapterType) new FileInputStream(file);
                }
                catch (IOException ioe) {
                    log.info("adaptTo: Cannot open a stream on the file " + file, ioe);
                }
            }
            else {
                log.debug("adaptTo: File {} is not a readable file", file);
            }
        }
        else if (type == URL.class) {
            try {
                return (AdapterType) file.toURI().toURL();
            }
            catch (MalformedURLException mue) {
                log.info("adaptTo: Cannot convert the file path " + file + " to an URL", mue);
            }
        }
        else if (type == ValueMap.class) {
            return (AdapterType) getValueMap();
        }
        else if (type == Node.class) {
            ContentFile contentFile = getNodeDescriptorContentFile();
            if (contentFile != null) {
                // support a subset of JCR API for content file resources
                return (AdapterType)new FsNode(contentFile, getResourceResolver());
            }
        }
        return super.adaptTo(type);
    }

    @Override
    public String toString() {
        return new ToStringBuilder(this, ToStringStyle.SHORT_PREFIX_STYLE)
                .append("path", resourcePath)
                .append("file", file.getPath())
                .append("resourceType", getResourceType())
                .build();
    }

    @Override
    public ValueMap getValueMap() {
        if (valueMap == null) {
            // this resource simulates nt:file/nt:folder behavior by returning it as resource type
            // we should simulate the corresponding JCR properties in a value map as well
            if (fileStatCache.exists(file) && file.canRead()) {
                Map<String,Object> props = new HashMap<String, Object>();
                props.put("jcr:primaryType", fileStatCache.isFile(file) ? RESOURCE_TYPE_FILE : RESOURCE_TYPE_FOLDER);
                props.put("jcr:createdBy", "system");

                Calendar lastModifed = Calendar.getInstance();
                lastModifed.setTimeInMillis(file.lastModified());
                props.put("jcr:created", lastModifed);

                // overlay properties with those from node descriptor content file, if it exists
                ContentFile contentFile = getNodeDescriptorContentFile();
                if (contentFile != null) {
                    for (Map.Entry<String, Object> entry : contentFile.getValueMap().entrySet()) {
                        // skip primary type if it is the default type assigned by contentparser when none is defined
                        if (StringUtils.equals(entry.getKey(), "jcr:primaryType")
                                && StringUtils.equals((String)entry.getValue(), ParserOptions.DEFAULT_PRIMARY_TYPE)) {
                            continue;
                        }
                        props.put(entry.getKey(), entry.getValue());
                    }
                }

                valueMap = new DeepReadValueMapDecorator(this, new ValueMapDecorator(props));
            }
        }
        return valueMap;
    }

    private ContentFile getNodeDescriptorContentFile() {
        if (contentFileExtensions == null || contentFileCache == null) {
            return null;
        }
        for (String fileNameSuffix : contentFileExtensions.getSuffixes()) {
            File fileWithSuffix = new File(file.getPath() + fileNameSuffix);
            if (fileStatCache.exists(fileWithSuffix) && fileWithSuffix.canRead()) {
                return new ContentFile(fileWithSuffix, resourcePath, null, contentFileCache);
            }
        }
        return null;
    }

}