using System;
using System.Collections.Generic;
using System.Linq;

namespace Unosquare.Swan.Networking.Ldap {
  /// <summary>
  /// An LdapSearchResults object is returned from a synchronous search
  /// operation. It provides access to all results received during the
  /// operation (entries and exceptions).
  /// </summary>
  /// <seealso cref="LdapConnection.Search"></seealso>
  public sealed class LdapSearchResults {
    private readonly List<RfcLdapMessage> _messages;
    private readonly Int32 _messageId;

    /// <summary>
    /// Initializes a new instance of the <see cref="LdapSearchResults" /> class.
    /// </summary>
    /// <param name="messages">The messages.</param>
    /// <param name="messageId">The message identifier.</param>
    internal LdapSearchResults(List<RfcLdapMessage> messages, Int32 messageId) {
      this._messages = messages;
      this._messageId = messageId;
    }

    /// <summary>
    /// Returns a count of the items in the search result.
    /// Returns a count of the entries and exceptions remaining in the object.
    /// If the search was submitted with a batch size greater than zero,
    /// getCount reports the number of results received so far but not enumerated
    /// with next().  If batch size equals zero, getCount reports the number of
    /// items received, since the application thread blocks until all results are
    /// received.
    /// </summary>
    /// <value>
    /// The count.
    /// </value>
    public Int32 Count => new List<RfcLdapMessage>(this._messages)
        .Count(x => x.MessageId == this._messageId && GetResponse(x) is LdapSearchResult);

    /// <summary>
    /// Reports if there are more search results.
    /// </summary>
    /// <returns>
    /// true if there are more search results.
    /// </returns>
    public Boolean HasMore() => new List<RfcLdapMessage>(this._messages)
        .Any(x => x.MessageId == this._messageId && GetResponse(x) is LdapSearchResult);

    /// <summary>
    /// Returns the next result as an LdapEntry.
    /// If automatic referral following is disabled or if a referral
    /// was not followed, next() will throw an LdapReferralException
    /// when the referral is received.
    /// </summary>
    /// <returns>
    /// The next search result as an LdapEntry.
    /// </returns>
    /// <exception cref="ArgumentOutOfRangeException">Next - No more results.</exception>
    public LdapEntry Next() {
      IEnumerable<RfcLdapMessage> list = new List<RfcLdapMessage>(this._messages)
          .Where(x => x.MessageId == this._messageId);

      foreach(RfcLdapMessage item in list) {
        _ = this._messages.Remove(item);
        LdapMessage response = GetResponse(item);

        if(response is LdapSearchResult result) {
          return result.Entry;
        }
      }

      throw new ArgumentOutOfRangeException(nameof(Next), "No more results");
    }

    private static LdapMessage GetResponse(RfcLdapMessage item) {
      switch(item.Type) {
        case LdapOperation.SearchResponse:
          return new LdapSearchResult(item);
        case LdapOperation.SearchResultReference:
          return new LdapSearchResultReference(item);
        default:
          return new LdapResponse(item);
      }
    }
  }
}