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[beagle.git] / BeagleClient / Indexable.cs

//
// Indexable.cs
//
// Copyright (C) 2004 Novell, Inc.
//

//
// Permission is hereby granted, free of charge, to any person obtaining a
// copy of this software and associated documentation files (the "Software"),
// to deal in the Software without restriction, including without limitation
// the rights to use, copy, modify, merge, publish, distribute, sublicense,
// and/or sell copies of the Software, and to permit persons to whom the
// Software is furnished to do so, subject to the following conditions:
//
// The above copyright notice and this permission notice shall be included in
// all copies or substantial portions of the Software.
//
// THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
// IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
// FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
// AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
// LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING
// FROM, OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER
// DEALINGS IN THE SOFTWARE.
//


using System;
using System.Collections;
using System.IO;
using System.Text;
using System.Threading;
using System.Xml;
using System.Xml.Serialization;
using Beagle.Util;

namespace Beagle {

        public enum IndexableType {
                Add,
                Remove,
                PropertyChange
        }

        public enum IndexableFiltering {
                Never,           // Never try to filter this indexable, it contains no content
                AlreadyFiltered, // The readers promise to return nice clean text, so do nothing
                Automatic,       // Try to determine automatically if this needs to be filtered
                Always           // Always try to filter this indexable
        }

        public class Indexable : Versioned, IComparable {

                static private bool Debug = false;

                // This is the type of indexing operation represented by
                // this Indexable object.  We default to Add, for historical
                // reasons.
                private IndexableType type = IndexableType.Add;

                // The URI of the item being indexed.
                private Uri uri = null;

                // The URI of the parent indexable, if any.
                private Uri parent_uri = null;

                // The URI of the contents to index
                private Uri contentUri = null;

                // The URI of the hot contents to index
                private Uri hotContentUri = null;

                // Whether the content should be deleted after indexing
                private bool deleteContent = false;
                
                // File, WebLink, MailMessage, IMLog, etc.
                private String hit_type = null;

                // If applicable, otherwise set to null.
                private String mimeType = null;

                // The source backend that generated this indexable
                private string source = null;
                
                // List of Property objects
                private ArrayList properties = new ArrayList ();

                // Is this being indexed because of crawling or other
                // background activity?
                private bool crawled = true;

                // Is this object inherently contentless?
                private bool no_content = false;

                // If necessary, should we cache this object's content?
                // The cached version is used to generate snippets.
                private bool cache_content = true;

                // A stream of the content to index
                private TextReader textReader;

                // A stream of the hot content to index
                private TextReader hotTextReader;

                // A stream of binary data to filter
                private Stream binary_stream;

                // When should we try to filter this indexable?
                private IndexableFiltering filtering = IndexableFiltering.Automatic;

                // Local state: these are key/value pairs that never get serialized
                // into XML
                Hashtable local_state = new Hashtable ();

                //////////////////////////

                static private XmlSerializer our_serializer;

                static Indexable ()
                {
                        our_serializer = new XmlSerializer (typeof (Indexable));
                }

                //////////////////////////

                public Indexable (IndexableType type,
                                  Uri           uri)
                {
                        this.type = type;
                        this.uri = uri;
                        this.hit_type = "File"; // FIXME: Why do we default to this?
                }

                public Indexable (Uri uri) : this (IndexableType.Add, uri)
                { }

                public Indexable ()
                {
                        // Only used when reading from xml
                }

                public static Indexable NewFromXml (string xml)
                {
                        StringReader reader = new StringReader (xml);
                        return (Indexable) our_serializer.Deserialize (reader);
                }

                //////////////////////////

                [XmlAttribute ("Type")]
                public IndexableType Type {
                        get { return type; }
                        set { type = value; }
                }

                [XmlIgnore]
                public Uri Uri { 
                        get { return uri; }
                        set { uri = value; }
                }

                [XmlAttribute ("Uri")]
                public string UriString {
                        get { return UriFu.UriToEscapedString (uri); }
                        set { uri = UriFu.EscapedStringToUri (value); }
                }

                [XmlIgnore]
                public Uri ParentUri { 
                        get { return parent_uri; }
                        set { parent_uri = value; }
                }

                [XmlAttribute ("ParentUri")]
                public string ParentUriString {
                        get {
                                if (parent_uri == null)
                                        return null;

                                return UriFu.UriToEscapedString (parent_uri);
                        }

                        set {
                                if (value == null)
                                        parent_uri = null;
                                else
                                        parent_uri = UriFu.EscapedStringToUri (value);
                        }
                }

                [XmlIgnore]
                public Uri ContentUri {
                        get { return contentUri != null ? contentUri : Uri; }
                        set { contentUri = value; }
                }

                [XmlAttribute ("ContentUri")]
                public string ContentUriString {
                        get { return UriFu.UriToEscapedString (ContentUri); }
                        set { contentUri = UriFu.EscapedStringToUri (value); } 
                }

                [XmlIgnore]
                private Uri HotContentUri {
                        get { return hotContentUri; }
                        set { hotContentUri = value; }
                }
                
                [XmlAttribute ("HotContentUri")]
                public string HotContentUriString {
                        get { return HotContentUri != null ? UriFu.UriToEscapedString (HotContentUri) : ""; }
                        set { hotContentUri = (value != "") ? UriFu.EscapedStringToUri (value) : null; }
                }

                [XmlIgnore]
                public Uri DisplayUri {
                        get { return uri.Scheme == GuidFu.UriScheme ? ContentUri : Uri; }
                }

                [XmlAttribute]
                public bool DeleteContent {
                        get { return deleteContent; }
                        set { deleteContent = value; }
                }

                [XmlAttribute]
                public String HitType {
                        get { return  hit_type; }
                        set { hit_type = value; }
                }

                [XmlAttribute]
                public String MimeType {
                        get { return mimeType; }
                        set { mimeType = value; }
                }

                [XmlAttribute]
                public string Source {
                        get { return source; }
                        set { source = value; }
                }

                [XmlIgnore]
                public bool IsNonTransient {
                        get { return ! DeleteContent && ContentUri.IsFile && ParentUri == null; }
                }

                [XmlAttribute]
                public bool Crawled {
                        get { return crawled; }
                        set { crawled = value; }
                }

                [XmlAttribute]
                public bool NoContent {
                        get { return no_content; }
                        set { no_content = value; }
                }

                [XmlAttribute]
                public bool CacheContent {
                        get { return cache_content; }
                        set { cache_content = value; }
                }

                [XmlAttribute]
                public IndexableFiltering Filtering {
                        get { return filtering; }
                        set { filtering = value; }
                }

                [XmlIgnore]
                public IDictionary LocalState {
                        get { return local_state; }
                }

                //////////////////////////

                public void Cleanup ()
                {
                        if (DeleteContent) {
                                if (contentUri != null) {
                                        if (Debug)
                                                Logger.Log.Debug ("Cleaning up {0}", contentUri.LocalPath);

                                        try {
                                                File.Delete (contentUri.LocalPath);
                                        } catch { 
                                                // It might be gone already, so catch the exception.
                                        }

                                        contentUri = null;
                                }

                                if (hotContentUri != null) {
                                        if (Debug)
                                                Logger.Log.Debug ("Cleaning up {0}", hotContentUri.LocalPath);

                                        try {
                                                File.Delete (hotContentUri.LocalPath);
                                        } catch {
                                                // Ditto
                                        }

                                        hotContentUri = null;
                                }
                        }
                }

                private Stream StreamFromUri (Uri uri)
                {
                        Stream stream = null;

                        if (uri != null && uri.IsFile && ! no_content) {
                                stream = new FileStream (uri.LocalPath,
                                                         FileMode.Open,
                                                         FileAccess.Read,
                                                         FileShare.Read);
                        }

                        return stream;
                }

                private TextReader ReaderFromUri (Uri uri)
                {
                        Stream stream = StreamFromUri (uri);

                        if (stream == null)
                                return null;

                        return new StreamReader (stream);
                }
                                

                public TextReader GetTextReader ()
                {
                        if (NoContent)
                                return null;

                        if (textReader == null)
                                textReader = ReaderFromUri (ContentUri);

                        return textReader;
                }
                
                public void SetTextReader (TextReader reader)
                { 
                        textReader = reader;
                }

                public TextReader GetHotTextReader ()
                {
                        if (NoContent)
                                return null;

                        if (hotTextReader == null)
                                hotTextReader = ReaderFromUri (HotContentUri);
                        return hotTextReader;
                }

                public void SetHotTextReader (TextReader reader)
                {
                        hotTextReader = reader;
                }

                public Stream GetBinaryStream ()
                {
                        if (NoContent)
                                return null;

                        if (binary_stream == null)
                                binary_stream = StreamFromUri (ContentUri);

                        return binary_stream;
                }

                public void SetBinaryStream (Stream stream)
                {
                        binary_stream = stream;
                }

                [XmlArrayItem (ElementName="Property", Type=typeof (Property))]
                public ArrayList Properties {
                        get { return properties; }
                }

                public void AddProperty (Property prop) {
                        if (prop != null) {
                                
                                if (type == IndexableType.PropertyChange && ! prop.IsMutable)
                                        throw new ArgumentException ("Non-mutable properties aren't allowed in this indexable");

                                // If this is a mutable property, make sure that
                                // we don't already contain another mutable property
                                // with the same name.  If we do, replace it.
                                if (prop.IsMutable) {
                                        for (int i = 0; i < properties.Count; ++i) {
                                                Property other_prop = properties [i] as Property;
                                                if (other_prop.IsMutable && prop.Key == other_prop.Key) {
                                                        properties [i] = prop;
                                                        return;
                                                }
                                        }
                                }

                                properties.Add (prop);
                        }
                }

                public bool HasProperty (string keyword) {
                        foreach (Property property in properties)
                                if (property.Key == keyword)
                                        return true;

                        return false;
                }

                // This doesn't check if it makes sense to actually
                // merge the two indexables: it just does it.
                public void Merge (Indexable other)
                {
                        this.Timestamp = other.Timestamp;

                        foreach (Property prop in other.Properties)
                                this.AddProperty (prop);

                        foreach (DictionaryEntry entry in other.local_state)
                                this.local_state [entry.Key] = entry.Value;
                }

                //////////////////////////

                public void SetChildOf (Indexable parent)
                {
                        this.ParentUri = parent.Uri;

                        if (!this.ValidTimestamp)
                                this.Timestamp = parent.Timestamp;

                        // FIXME: Set all of the parent's properties on the
                        // child so that we get matches against the child
                        // that otherwise would match only the parent, at
                        // least until we have proper RDF support.
                        foreach (Property prop in parent.Properties) {
                                Property new_prop = (Property) prop.Clone ();
                                new_prop.Key = "parent:" + new_prop.Key;
                                this.AddProperty (new_prop);
                        }
                }

                //////////////////////////

                public override string ToString () 
                {
                        StringWriter writer = new StringWriter ();
                        our_serializer.Serialize (writer, this);
                        writer.Close ();
                        return writer.ToString ();
                }

                //////////////////////////

                const int BUFFER_SIZE = 8192;

                private static char [] GetCharBuffer ()
                {
                        LocalDataStoreSlot slot;
                        slot = Thread.GetNamedDataSlot ("Char Buffer");

                        object obj;
                        char [] buffer;
                        obj = Thread.GetData (slot);
                        if (obj == null) {
                                buffer = new char [BUFFER_SIZE];
                                Thread.SetData (slot, buffer);
                        } else {
                                buffer = (char []) obj; 
                        }

                        return buffer;
                }

                private static byte [] GetByteBuffer ()
                {
                        LocalDataStoreSlot slot;
                        slot = Thread.GetNamedDataSlot ("Byte Buffer");

                        object obj;
                        byte [] buffer;
                        obj = Thread.GetData (slot);
                        if (obj == null) {
                                buffer = new byte [BUFFER_SIZE];
                                Thread.SetData (slot, buffer);
                        } else {
                                buffer = (byte []) obj; 
                        }

                        return buffer;
                }

                //////////////////////////

                private static Uri TextReaderToTempFileUri (TextReader reader)
                {
                        if (reader == null)
                                return null;

                        string filename = Path.GetTempFileName ();
                        FileStream fileStream = File.OpenWrite (filename);

                        // When we dump the contents of an indexable into a file, we
                        // expect to use it again soon.
                        FileAdvise.PreLoad (fileStream);

                        // Make sure the temporary file is only readable by the owner.
                        // FIXME: There is probably a race here.  Could some malicious program
                        // do something to the file between creation and the chmod?
                        Mono.Unix.Native.Syscall.chmod (filename, (Mono.Unix.Native.FilePermissions) 256);

                        BufferedStream bufferedStream = new BufferedStream (fileStream);
                        StreamWriter writer = new StreamWriter (bufferedStream);


                        char [] buffer;
                        buffer = GetCharBuffer ();

                        int read;
                        do {
                                read = reader.Read (buffer, 0, buffer.Length);
                                if (read > 0)
                                        writer.Write (buffer, 0, read);
                        } while (read > 0);
                        
                        writer.Close ();

                        return UriFu.PathToFileUri (filename);
                }

                private static Uri BinaryStreamToTempFileUri (Stream stream)
                {
                        if (stream == null)
                                return null;

                        string filename = Path.GetTempFileName ();
                        FileStream fileStream = File.OpenWrite (filename);

                        // When we dump the contents of an indexable into a file, we
                        // expect to use it again soon.
                        FileAdvise.PreLoad (fileStream);

                        // Make sure the temporary file is only readable by the owner.
                        // FIXME: There is probably a race here.  Could some malicious program
                        // do something to the file between creation and the chmod?
                        Mono.Unix.Native.Syscall.chmod (filename, (Mono.Unix.Native.FilePermissions) 256);

                        BufferedStream bufferedStream = new BufferedStream (fileStream);

                        byte [] buffer;
                        buffer = GetByteBuffer ();

                        int read;
                        do {
                                read = stream.Read (buffer, 0, buffer.Length);
                                if (read > 0)
                                        bufferedStream.Write (buffer, 0, read);
                        } while (read > 0);

                        bufferedStream.Close ();

                        return UriFu.PathToFileUri (filename);
                }

                public void StoreStream () {
                        if (textReader != null) {
                                ContentUri = TextReaderToTempFileUri (textReader);

                                if (Debug)
                                        Logger.Log.Debug ("Storing text content from {0} in {1}", Uri, ContentUri);

                                DeleteContent = true;
                        } else if (binary_stream != null) {
                                ContentUri = BinaryStreamToTempFileUri (binary_stream);

                                if (Debug)
                                        Logger.Log.Debug ("Storing binary content from {0} in {1}", Uri, ContentUri);

                                DeleteContent = true;
                        }

                        if (hotTextReader != null) {
                                HotContentUri = TextReaderToTempFileUri (hotTextReader);

                                if (Debug)
                                        Logger.Log.Debug ("Storing hot content from {0} in {1}", Uri, HotContentUri);

                                DeleteContent = true;
                        }
                }

                //////////////////////////

                public override int GetHashCode ()
                {
                        return (uri != null ? uri.GetHashCode () : 0) ^ type.GetHashCode ();
                }

                public int CompareTo (object obj)
                {
                        Indexable other = (Indexable) obj;
                        return DateTime.Compare (this.Timestamp, other.Timestamp);
                }
        }
}