/*++
Copyright (c) 2012 Microsoft Corporation

Module Name:

    Log.cs

Abstract:

    Z3 Managed API: Log

Author:

    Christoph Wintersteiger (cwinter) 2012-03-15

Notes:
    
--*/

using System;
using System.Diagnostics.Contracts;

namespace Microsoft.Z3
{
  /// <summary>
  /// Interaction logging for Z3.
  /// </summary>
  /// <remarks>
  /// Note that this is a global, static log and if multiple Context 
  /// objects are created, it logs the interaction with all of them.
  /// </remarks>
    [ContractVerification(true)]
    public static class Log
  {   
    private static bool m_is_open = false;

    /// <summary>
    /// Open an interaction log file.
    /// </summary>
    /// <param name="filename">the name of the file to open</param>
    /// <returns>True if opening the log file succeeds, false otherwise.</returns>
    public static bool Open(string filename)
    {
      m_is_open = true;      
      return Native.Z3_open_log(filename) == 1;
    }

    /// <summary>
    /// Closes the interaction log.
    /// </summary>
    public static void Close()
    {
      m_is_open = false;
      Native.Z3_close_log();
    }

    /// <summary>
    /// Appends the user-provided string <paramref name="s"/> to the interaction log.
    /// </summary>    
    public static void Append(string s)
    {
        Contract.Requires(isOpen());

      if (!m_is_open)
        throw new Z3Exception("Log cannot be closed.");      
      Native.Z3_append_log(s);
    }

    /// <summary>
    /// Checks whether the interaction log is opened.
    /// </summary>
    /// <returns>True if the interaction log is open, false otherwise.</returns>
        [Pure]
        public static bool isOpen()
    {
      return m_is_open;
    }
  }
}