using System;
using System.Text;

/// <header>
/// <wox>
///     <version>1.0</version>
///     <author>Carlos R. Jaimez Gonzalez</author>
///     <author>Simon M. Lucas</author>
///     <site>http://woxserializer.sourceforge.net/</site>
/// </wox>
/// <wox>
///     <version>1.5</version>
///     <author>Steven M Lewis</author>
/// </wox>
/// <wox>
///     <version>2.0</version>
///     <author>George A Smith</author>
///     <svn>http://woxserializer.sourceforge.net/</svn>
///     <note>XML form for vs 2 is more compact and therefor incompatible with vs 1</note>
/// </wox>
/// </header>

namespace wox.serial
{
    public class DateTimeConverter
    {
        // The WOX format for a DateTime will be:
        //
        //                            1234567-101234567-20123
        public const string FORMAT = "yyyy/mm/dd-hh:mm:ss.nnn";
        //                            01234567-101234567-2012

        private int mYear, mMonth, mDay, mHour, mMinute, mSecond, mMillisecond;

        public DateTimeConverter()
        {
        }

        public DateTimeConverter( DateTime pDateTime )
        {
            mYear = pDateTime.Year;
            mMonth = pDateTime.Month;
            mDay = pDateTime.Day;
            mHour = pDateTime.Hour;
            mMinute = pDateTime.Minute;
            mSecond = pDateTime.Second;
            mMillisecond = pDateTime.Millisecond;
        }

        public DateTimeConverter AttemptParse( string pValue )
        {
            if ( (pValue != null) && (pValue.Length > 9) && (pValue[4] == '/') && (pValue[7] == '/') )
            {
                try
                {
                    mYear = int.Parse( pValue.Substring( 0, 4 ) );
                    mMonth = int.Parse( pValue.Substring( 5, 2 ) );
                    mDay = int.Parse( pValue.Substring( 8, 2 ) );
                    if ( CheckDoneParse( pValue, 10, '-', 2, ref mHour ) )
                    {
                        return this;
                    }
                    if ( CheckDoneParse( pValue, 13, ':', 2, ref mMinute ) )
                    {
                        return this;
                    }
                    if ( CheckDoneParse( pValue, 16, ':', 2, ref mSecond ) )
                    {
                        return this;
                    }
                    if ( pValue.Length > 19 )
                    {
                        if ( pValue.Length == 20 )
                        {
                            pValue += "?";
                        }
                        while ( pValue.Length < 23 )
                        {
                            pValue += "0";
                        }
                    }
                    if ( CheckDoneParse( pValue, 19, '.', 3, ref mMillisecond ) )
                    {
                        return this;
                    }
                    if ( pValue.Length == 23 )
                    {
                        return this;
                    }
                }
                catch ( FormatException )
                {
                    // Fall Thru...
                }
            }
            return null;
        }

        private static bool CheckDoneParse( string pValue, int pCharAt, char pSepChar, int pNumberLength, ref int pNumberVar )
        {
            if ( pValue.Length == pCharAt )
            {
                return true;
            }
            if ( (pValue.Length > (pCharAt + pNumberLength)) && (pValue[pCharAt] == pSepChar) )
            {
                pNumberVar = int.Parse( pValue.Substring( pCharAt + 1, pNumberLength ) );
            }
            return false;
        }

        public DateTime ToDateTime()
        {
            return new DateTime( mYear, mMonth, mDay, mHour, mMinute, mSecond, mMillisecond );
        }

        public override string ToString()
        {
            StringBuilder zSB = new StringBuilder();

            AddNumber( mYear, zSB, 4 );
            zSB.Append( '/' );
            AddNumber( mMonth, zSB, 2 );
            zSB.Append( '/' );
            AddNumber( mDay, zSB, 2 );

            int zMillisecond = mMillisecond;
            if ( zMillisecond != 0 )
            {
                AddHour( zSB );
                AddMinute( zSB );
                AddSecond( zSB );
                string zMilliSecs = (1000 + zMillisecond).ToString().Substring( 1 );
                while ( zMilliSecs.EndsWith( "0" ) )
                {
                    zMilliSecs = zMilliSecs.Substring( 0, zMilliSecs.Length - 1 );
                }
                zSB.Append( '.' );
                zSB.Append( zMilliSecs );
            }
            else if ( mSecond != 0 )
            {
                AddHour( zSB );
                AddMinute( zSB );
                AddSecond( zSB );
            }
            else if ( mMinute != 0 )
            {
                AddHour( zSB );
                AddMinute( zSB );
            }
            else if ( mHour != 0 )
            {
                AddHour( zSB );
            }
            return zSB.ToString();
        }

        private void AddHour( StringBuilder pSB )
        {
            pSB.Append( '-' );
            AddNumber( mHour, pSB, 2 );
        }

        private void AddMinute( StringBuilder pSB )
        {
            pSB.Append( ':' );
            AddNumber( mMinute, pSB, 2 );
        }

        private void AddSecond( StringBuilder pSB )
        {
            pSB.Append( ':' );
            AddNumber( mSecond, pSB, 2 );
        }

        private static void AddNumber( int pValue, StringBuilder pSB, int pLength )
        {
            string zValue = pValue.ToString();
            while ( zValue.Length < pLength-- )
            {
                pSB.Append( '0' );
            }
            pSB.Append( zValue );
        }
    }
}