using System;
using System.Collections.Generic;
using Unosquare.Swan.Exceptions;

namespace Unosquare.Swan.Networking.Ldap {
  /// <summary>
  /// Encapsulates optional additional parameters or constraints to be applied to
  /// an Ldap operation.
  /// When included with LdapConstraints or LdapSearchConstraints
  /// on an LdapConnection or with a specific operation request, it is
  /// sent to the server along with operation requests.
  /// </summary>
  public class LdapControl {
    /// <summary>
    /// Initializes a new instance of the <see cref="LdapControl"/> class.
    /// Constructs a new LdapControl object using the specified values.
    /// </summary>
    /// <param name="oid">The OID of the control, as a dotted string.</param>
    /// <param name="critical">True if the Ldap operation should be discarded if
    /// the control is not supported. False if
    /// the operation can be processed without the control.</param>
    /// <param name="values">The control-specific data.</param>
    /// <exception cref="ArgumentException">An OID must be specified.</exception>
    public LdapControl(String oid, Boolean critical, SByte[] values) {
      if(oid == null) {
        throw new ArgumentException("An OID must be specified");
      }

      this.Asn1Object = new RfcControl(
          oid,
          new Asn1Boolean(critical),
          values == null ? null : new Asn1OctetString(values));
    }

    /// <summary>
    /// Returns the identifier of the control.
    /// </summary>
    /// <value>
    /// The identifier.
    /// </value>
    public String Id => this.Asn1Object.ControlType.StringValue();

    /// <summary>
    /// Returns whether the control is critical for the operation.
    /// </summary>
    /// <value>
    ///   <c>true</c> if critical; otherwise, <c>false</c>.
    /// </value>
    public Boolean Critical => this.Asn1Object.Criticality.BooleanValue();

    internal static RespControlVector RegisteredControls { get; } = new RespControlVector(5);

    internal RfcControl Asn1Object {
      get;
    }

    /// <summary>
    /// Registers a class to be instantiated on receipt of a control with the
    /// given OID.
    /// Any previous registration for the OID is overridden. The
    /// controlClass must be an extension of LdapControl.
    /// </summary>
    /// <param name="oid">The object identifier of the control.</param>
    /// <param name="controlClass">A class which can instantiate an LdapControl.</param>
    public static void Register(String oid, Type controlClass)
        => RegisteredControls.RegisterResponseControl(oid, controlClass);

    /// <summary>
    ///     Returns the control-specific data of the object.
    /// </summary>
    /// <returns>
    ///     The control-specific data of the object as a byte array,
    ///     or null if the control has no data.
    /// </returns>
    public SByte[] GetValue() => this.Asn1Object.ControlValue?.ByteValue();

    internal void SetValue(SByte[] controlValue) => this.Asn1Object.ControlValue = new Asn1OctetString(controlValue);
  }

  /// <summary>
  /// Represents a simple bind request.
  /// </summary>
  /// <seealso cref="Unosquare.Swan.Networking.Ldap.LdapMessage" />
  public class LdapBindRequest : LdapMessage {
    /// <summary>
    /// Initializes a new instance of the <see cref="LdapBindRequest"/> class.
    /// Constructs a simple bind request.
    /// </summary>
    /// <param name="version">The Ldap protocol version, use Ldap_V3.
    /// Ldap_V2 is not supported.</param>
    /// <param name="dn">If non-null and non-empty, specifies that the
    /// connection and all operations through it should
    /// be authenticated with dn as the distinguished
    /// name.</param>
    /// <param name="password">If non-null and non-empty, specifies that the
    /// connection and all operations through it should
    /// be authenticated with dn as the distinguished
    /// name and passwd as password.</param>
    public LdapBindRequest(Int32 version, String dn, SByte[] password)
        : base(LdapOperation.BindRequest, new RfcBindRequest(version, dn, password)) {
    }

    /// <summary>
    /// Retrieves the Authentication DN for a bind request.
    /// </summary>
    /// <value>
    /// The authentication dn.
    /// </value>
    public String AuthenticationDN => this.Asn1Object.RequestDn;

    /// <inheritdoc />
    public override String ToString() => this.Asn1Object.ToString();
  }

  /// <summary>
  /// Encapsulates a continuation reference from an asynchronous search operation.
  /// </summary>
  /// <seealso cref="Unosquare.Swan.Networking.Ldap.LdapMessage" />
  internal class LdapSearchResultReference : LdapMessage {
    /// <summary>
    /// Initializes a new instance of the <see cref="LdapSearchResultReference"/> class.
    /// Constructs an LdapSearchResultReference object.
    /// </summary>
    /// <param name="message">The LdapMessage with a search reference.</param>
    internal LdapSearchResultReference(RfcLdapMessage message)
        : base(message) {
    }

    /// <summary>
    /// Returns any URLs in the object.
    /// </summary>
    /// <value>
    /// The referrals.
    /// </value>
    public String[] Referrals {
      get {
        Asn1Object[] references = ((RfcSearchResultReference)this.Message.Response).ToArray();
        String[] srefs = new String[references.Length];
        for(Int32 i = 0; i < references.Length; i++) {
          srefs[i] = ((Asn1OctetString)references[i]).StringValue();
        }

        return srefs;
      }
    }
  }

  internal class LdapResponse : LdapMessage {
    internal LdapResponse(RfcLdapMessage message)
        : base(message) {
    }

    public String ErrorMessage => ((IRfcResponse)this.Message.Response).GetErrorMessage().StringValue();

    public String MatchedDN => ((IRfcResponse)this.Message.Response).GetMatchedDN().StringValue();

    public LdapStatusCode ResultCode => this.Message.Response is RfcSearchResultEntry ||
                                        (IRfcResponse)this.Message.Response is RfcIntermediateResponse
        ? LdapStatusCode.Success
        : (LdapStatusCode)((IRfcResponse)this.Message.Response).GetResultCode().IntValue();

    internal LdapException Exception {
      get; set;
    }

    internal void ChkResultCode() {
      if(this.Exception != null) {
        throw this.Exception;
      }

      switch(this.ResultCode) {
        case LdapStatusCode.Success:
        case LdapStatusCode.CompareTrue:
        case LdapStatusCode.CompareFalse:
          break;
        case LdapStatusCode.Referral:
          throw new LdapException(
              "Automatic referral following not enabled",
              LdapStatusCode.Referral,
              this.ErrorMessage);
        default:
          throw new LdapException(this.ResultCode.ToString().Humanize(), this.ResultCode, this.ErrorMessage, this.MatchedDN);
      }
    }
  }

  /// <summary>
  /// The RespControlVector class implements extends the
  /// existing Vector class so that it can be used to maintain a
  /// list of currently registered control responses.
  /// </summary>
  internal class RespControlVector : List<RespControlVector.RegisteredControl> {
    private readonly Object _syncLock = new Object();

    public RespControlVector(Int32 cap)
        : base(cap) {
    }

    public void RegisterResponseControl(String oid, Type controlClass) {
      lock(this._syncLock) {
        this.Add(new RegisteredControl(this, oid, controlClass));
      }
    }

    /// <summary>
    /// Inner class defined to create a temporary object to encapsulate
    /// all registration information about a response control.
    /// </summary>
    internal class RegisteredControl {
      public RegisteredControl(RespControlVector enclosingInstance, String oid, Type controlClass) {
        this.EnclosingInstance = enclosingInstance;
        this.MyOid = oid;
        this.MyClass = controlClass;
      }

      internal Type MyClass {
        get;
      }

      internal String MyOid {
        get;
      }


      [System.Diagnostics.CodeAnalysis.SuppressMessage("Codequalität", "IDE0052:Ungelesene private Member entfernen", Justification = "<Ausstehend>")]
      private RespControlVector EnclosingInstance {
        get;
      }
    }
  }

  /// <summary>
  /// Represents and Ldap Bind Request.
  /// <pre>
  /// BindRequest ::= [APPLICATION 0] SEQUENCE {
  /// version                 INTEGER (1 .. 127),
  /// name                    LdapDN,
  /// authentication          AuthenticationChoice }
  /// </pre></summary>
  /// <seealso cref="Unosquare.Swan.Networking.Ldap.Asn1Sequence" />
  /// <seealso cref="IRfcRequest" />
  internal sealed class RfcBindRequest
      : Asn1Sequence, IRfcRequest {
    [System.Diagnostics.CodeAnalysis.SuppressMessage("Codequalität", "IDE0052:Ungelesene private Member entfernen", Justification = "<Ausstehend>")]
    private readonly SByte[] _password;
    private static readonly Asn1Identifier Id = new Asn1Identifier(LdapOperation.BindRequest);

    public RfcBindRequest(Int32 version, String name, SByte[] password)
        : base(3) {
      this._password = password;
      this.Add(new Asn1Integer(version));
      this.Add(name);
      this.Add(new RfcAuthenticationChoice(password));
    }

    public Asn1Integer Version {
      get => (Asn1Integer)this.Get(0);
      set => this.Set(0, value);
    }

    public Asn1OctetString Name {
      get => (Asn1OctetString)this.Get(1);
      set => this.Set(1, value);
    }

    public RfcAuthenticationChoice AuthenticationChoice {
      get => (RfcAuthenticationChoice)this.Get(2);
      set => this.Set(2, value);
    }

    public override Asn1Identifier GetIdentifier() => Id;

    public String GetRequestDN() => ((Asn1OctetString)this.Get(1)).StringValue();
  }
}