#region
/* -----------------------------------------------------------------------
 * <copyright file="CollectionExtensions.cs" company="GRNet">
 * 
 * Copyright 2011-2012 GRNET S.A. All rights reserved.
 *
 * Redistribution and use in source and binary forms, with or
 * without modification, are permitted provided that the following
 * conditions are met:
 *
 *   1. Redistributions of source code must retain the above
 *      copyright notice, this list of conditions and the following
 *      disclaimer.
 *
 *   2. Redistributions in binary form must reproduce the above
 *      copyright notice, this list of conditions and the following
 *      disclaimer in the documentation and/or other materials
 *      provided with the distribution.
 *
 *
 * THIS SOFTWARE IS PROVIDED BY GRNET S.A. ``AS IS'' AND ANY EXPRESS
 * OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED
 * WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR
 * PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL GRNET S.A OR
 * CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL,
 * SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT
 * LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF
 * USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED
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 * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN
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 * </copyright>
 * -----------------------------------------------------------------------
 */
#endregion
using System.Collections.Concurrent;
using System.Diagnostics.Contracts;
using Pithos.Interfaces;

namespace Pithos.Core.Agents
{
    using System;
    using System.Collections.Generic;
    using System.Linq;
    using System.Text;

    /// <summary>
    /// Extension methods for collections
    /// </summary>
    public static class CollectionExtensions
    {
        /// <summary>
        /// Remove the first message in a queue that matches the predicate
        /// </summary>
        /// <param name="predicate">The condition to match</param>
        /// <remarks>Removes the first message that matches the predicate by dequeing all 
        /// messages and re-enqueing all except the first matching message</remarks>
        public static void RemoveFirst<TMessage>(this ConcurrentQueue<TMessage> queue, Func<TMessage, bool> predicate)
        {
            //Can this work? Dequeue all items 
            //and then enqueue everything except the filtered items

            //Possible problems: 
            //* A matching item may be dequeued between one TryDequeue and the next
            var temp = new Queue<TMessage>();
            TMessage message;
            var alreadyFound = false;
            while (queue.TryDequeue(out message))
            {
                if (!predicate(message) || alreadyFound)
                    temp.Enqueue(message);
                else
                {
                    alreadyFound = true;
                }
            }

            queue.AddFromEnumerable(temp);
        }


        public static IEnumerable<ObjectInfo> FilterBelow(this IEnumerable<ObjectInfo> infos,List<Uri> filterUris  )
        {
            if (filterUris == null)
                return infos;
            if (filterUris.Count == 0)
                return infos;
            //Allow all objects whose Uris start with any of the filters            
            var filteredUris = from info in infos
                                  where filterUris.Any(f => info.Uri.IsAtOrBelow(f)) 
                                  select info;            
            return filteredUris;
        }

        public static IEnumerable<ObjectInfo> FilterDirectlyBelow(this IEnumerable<ObjectInfo> infos,List<Uri> filterUris  )
        {
            if (filterUris == null)
                return infos;
            if (filterUris.Count == 0)
                return infos;
            //Allow all objects whose Uris start with any of the filters            
            var filteredUris = from info in infos
                                  where filterUris.Any(f => info.Uri.IsAtOrDirectlyBelow(f)) 
                                  select info;            
            return filteredUris;
        }

        public static bool IsAtOrBelow(this Uri target,Uri root)
        {
            Contract.Requires(root != null);
            Contract.Requires(target != null);

            var targetSegments = target.Segments;
            var rootSegments = root.Segments;

            return InnerAtOrBelow(targetSegments, rootSegments);
        }

        private static bool InnerAtOrBelow(string[] targetSegments, string[] rootSegments)
        {
            //If the uri is shorter than the root, no point in comparing
            if (targetSegments.Length < rootSegments.Length)
                return false;
            //If the uri is below the root, it should match the root's segments one by one
            //If there is any root segment that doesn't match its corresponding target segment,
            //the target is not below the root
            var mismatch = rootSegments
                .Where((t, i) => !String.Equals(targetSegments[i], t))
                .Any();
            return !mismatch;
        }


        public static bool IsAtOrDirectlyBelow(this Uri target,Uri root)
        {
            Contract.Requires(root!=null);
            Contract.Requires(target!=null);

            return
                //If the target is directly below the root, it will have exactly 
                //one segment more than the root            
                target.Segments.Length == root.Segments.Length + 1
                //Ensure that the candidate target is indeed below the root
                && target.IsAtOrBelow(root);
        }

        public static bool IsAtOrBelow(this string targetPath, string rootPath)
        {
            Contract.Requires(!String.IsNullOrWhiteSpace(targetPath));
            Contract.Requires(!String.IsNullOrWhiteSpace(rootPath));

            var targetSegments = targetPath.Split('\\');
            var rootSegments = rootPath.Split('\\');

            return InnerAtOrBelow(targetSegments, rootSegments);
        }

        public static bool IsAtOrDirectlyBelow(this string targetPath, string rootPath)
        {
            Contract.Requires(!String.IsNullOrWhiteSpace(targetPath));
            Contract.Requires(!String.IsNullOrWhiteSpace(rootPath));

            var targetSegments = targetPath.Split('\\');
            var rootSegments = rootPath.Split('\\');

            return
                //If the target is directly below the root, it will have exactly 
                //one segment more than the root            
                targetSegments.Length == rootSegments.Length + 1
                //Ensure that the candidate target is indeed below the root
                && InnerAtOrBelow(targetSegments, rootSegments);
        }
    }
}