/*
 *  jDTAUS Banking API
 *  Copyright (C) 2005 Christian Schulte
 *  <cs@schulte.it>
 *
 *  This library is free software; you can redistribute it and/or
 *  modify it under the terms of the GNU Lesser General Public
 *  License as published by the Free Software Foundation; either
 *  version 2.1 of the License, or any later version.
 *
 *  This library is distributed in the hope that it will be useful,
 *  but WITHOUT ANY WARRANTY; without even the implied warranty of
 *  MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
 *  Lesser General Public License for more details.
 *
 *  You should have received a copy of the GNU Lesser General Public
 *  License along with this library; if not, write to the Free Software
 *  Foundation, Inc., 51 Franklin St, Fifth Floor, Boston, MA  02110-1301  USA
 *
 */
package org.jdtaus.banking;

import java.lang.ref.Reference;
import java.lang.ref.SoftReference;
import java.text.DecimalFormat;
import java.text.ParseException;
import java.text.ParsePosition;
import java.util.Collections;
import java.util.HashMap;
import java.util.Map;

/**
 * Unique identifier to a particular bank account at a german bank.
 * <p>A Kontonummer is a positive integer with a maximum of ten digits.</p>
 *
 * @author <a href="mailto:cs@schulte.it">Christian Schulte</a>
 * @version $JDTAUS: Kontonummer.java 8661 2012-09-27 11:29:58Z schulte $
 */
public final class Kontonummer extends Number implements Comparable
{

    /**
     * Constant for the electronic format of a Kontonummer.
     * <p>The electronic format of a Kontonummer is a ten digit number with leading zeros omitted (e.g. 6789).</p>
     */
    public static final int ELECTRONIC_FORMAT = 4001;

    /**
     * Constant for the letter format of a Kontonummer.
     * <p>The letter format of a Kontonummer is a ten digit number with leading zeros omitted separated by spaces
     * between the first three digits and the second three digits, the second three digits and the third three digits,
     * and between the third three digits and the lastdigit (e.g. 123 456 789 0).</p>
     */
    public static final int LETTER_FORMAT = 4002;

    /** Maximum number of digits of a Kontonummer. */
    public static final int MAX_DIGITS = 10;

    /** Maximum number of characters of a Kontonummer. */
    public static final int MAX_CHARACTERS = 13;

    /** {@code 10^0..10^9}. */
    private static final double[] EXP10 =
    {
        1, 10, 100, 1000, 10000, 100000, 1000000, 10000000, 100000000,
        1000000000
    };

    /** Serial version UID for backwards compatibility with 1.0.x classes. */
    private static final long serialVersionUID = 3117245365189973632L;

    /** Used to cache instances. */
    private static volatile Reference cacheReference = new SoftReference( null );

    /**
     * German account code.
     * @serial
     */
    private long kto;

    /**
     * Creates a new {@code Kontonummer} instance.
     *
     * @param accountCode The number to create an instance from.
     *
     * @throws IllegalArgumentException if {@code accountCode} is negative, zero or greater than 9999999999.
     *
     * @see #checkKontonummer(Number)
     */
    private Kontonummer( final Number accountCode )
    {
        if ( !Kontonummer.checkKontonummer( accountCode ) )
        {
            throw new IllegalArgumentException( accountCode.toString() );
        }

        this.kto = accountCode.longValue();
    }

    /**
     * Parses text from a string to produce a {@code Kontonummer}.
     * <p>The method attempts to parse text starting at the index given by {@code pos}. If parsing succeeds, then the
     * index of {@code pos} is updated to the index after the last character used (parsing does not necessarily use all
     * characters up to the end of the string), and the parsed value is returned. The updated {@code pos} can be used to
     * indicate the starting point for the next call to this method.</p>
     *
     * @param accountCode A Kontonummer in either electronic or letter format.
     * @param pos A {@code ParsePosition} object with index and error index information as described above.
     *
     * @return The parsed value, or {@code null} if the parse fails.
     *
     * @throws NullPointerException if either {@code accountCode} or {@code pos} is {@code null}.
     */
    public static Kontonummer parse( final String accountCode, final ParsePosition pos )
    {
        if ( accountCode == null )
        {
            throw new NullPointerException( "accountCode" );
        }
        if ( pos == null )
        {
            throw new NullPointerException( "pos" );
        }

        Kontonummer ret = null;
        boolean sawSpace = false;
        boolean failed = false;
        final ParsePosition fmtPos = new ParsePosition( 0 );
        final int len = accountCode.length();
        final int startIndex = pos.getIndex();
        final int maxIndex = startIndex + MAX_CHARACTERS;
        final StringBuffer digits = new StringBuffer( MAX_DIGITS );
        int mode = ELECTRONIC_FORMAT;
        int part = 0;
        int partStart = 0;
        int partEnd = 2;
        int digit = 0;
        int i = startIndex;

        for ( ; i < len && i < maxIndex && digits.length() < MAX_DIGITS; i++ )
        {
            final char c = accountCode.charAt( i );

            if ( Character.isDigit( c ) )
            {
                sawSpace = false;

                if ( mode == LETTER_FORMAT )
                {
                    if ( digit < partStart || digit > partEnd )
                    {
                        failed = true;
                    }
                    else
                    {
                        digits.append( c );
                    }
                }
                else
                {
                    digits.append( c );
                }

                digit++;
            }
            else if ( c == ' ' )
            {
                if ( sawSpace || i == startIndex || ( mode == ELECTRONIC_FORMAT && digit != 3 ) )
                {
                    failed = true;
                }
                else
                {
                    mode = LETTER_FORMAT;
                    switch ( part )
                    {
                        case 0:
                            partStart = 3;
                            partEnd = 5;
                            break;
                        case 1:
                            partStart = 6;
                            partEnd = 8;
                            break;
                        case 2:
                            partStart = 9;
                            partEnd = 9;
                            break;
                        default:
                            failed = true;
                            break;
                    }
                    part++;

                    if ( digit < partStart || digit > partEnd )
                    {
                        failed = true;
                    }
                }

                sawSpace = true;
            }
            else
            {
                failed = true;
            }

            if ( failed )
            {
                pos.setErrorIndex( i );
                break;
            }
        }

        if ( !failed )
        {
            final Number num = new DecimalFormat( "##########" ).parse( digits.toString(), fmtPos );

            if ( num != null && fmtPos.getErrorIndex() == -1 )
            {
                final String key = num.toString();
                ret = (Kontonummer) getCache().get( key );

                if ( ret == null )
                {
                    if ( !Kontonummer.checkKontonummer( num ) )
                    {
                        pos.setErrorIndex( startIndex );
                        ret = null;
                    }
                    else
                    {
                        pos.setIndex( i );
                        ret = new Kontonummer( num );
                        getCache().put( key, ret );
                    }
                }
                else
                {
                    pos.setIndex( i );
                }
            }
            else
            {
                pos.setErrorIndex( startIndex );
            }
        }

        return ret;
    }

    /**
     * Parses text from the beginning of the given string to produce a {@code Kontonummer}.
     * <p>Unlike the {@link #parse(String, ParsePosition)} method this method throws a {@code ParseException} if
     * {@code accountCode} cannot be parsed or is of invalid length.</p>
     *
     * @param accountCode A Kontonummer in either electronic or letter format.
     *
     * @return The parsed value.
     *
     * @throws NullPointerException if {@code accountCode} is {@code null}.
     * @throws ParseException if the parse fails or {@code accountCode} is of invalid length.
     */
    public static Kontonummer parse( final String accountCode ) throws ParseException
    {
        if ( accountCode == null )
        {
            throw new NullPointerException( "accountCode" );
        }

        Kontonummer kto = (Kontonummer) getCache().get( accountCode );
        if ( kto == null )
        {
            final ParsePosition pos = new ParsePosition( 0 );
            kto = Kontonummer.parse( accountCode, pos );
            if ( kto == null || pos.getErrorIndex() != -1 || pos.getIndex() < accountCode.length() )
            {
                throw new ParseException( accountCode, pos.getErrorIndex() != -1 ? pos.getErrorIndex() : pos.getIndex() );
            }
            else
            {
                getCache().put( accountCode, kto );
            }
        }

        return kto;
    }

    /**
     * Returns an instance for the Kontonummer identified by the given number.
     *
     * @param accountCode A number identifying a Kontonummer.
     *
     * @return An instance for {@code accountCode}.
     *
     * @throws NullPointerException if {@code accountCode} is {@code null}.
     * @throws IllegalArgumentException if {@code accountCode} is negative, zero or greater than 9999999999.
     *
     * @see #checkKontonummer(Number)
     */
    public static Kontonummer valueOf( final Number accountCode )
    {
        if ( accountCode == null )
        {
            throw new NullPointerException( "accountCode" );
        }

        final String key = accountCode.toString();
        Kontonummer ret = (Kontonummer) getCache().get( key );
        if ( ret == null )
        {
            ret = new Kontonummer( accountCode );
            getCache().put( key, ret );
        }

        return ret;
    }

    /**
     * Parses text from the beginning of the given string to produce a {@code Kontonummer}.
     * <p>Unlike the {@link #parse(String)} method this method throws an {@code IllegalArgumentException} if
     * {@code accountCode} cannot be parsed or is of invalid length.</p>
     *
     * @param accountCode A Kontonummer in either electronic or letter format.
     *
     * @return The parsed value.
     *
     * @throws NullPointerException if {@code accountCode} is {@code null}.
     * @throws IllegalArgumentException if the parse fails or {@code accountCode} is of invalid length.
     */
    public static Kontonummer valueOf( final String accountCode )
    {
        try
        {
            return Kontonummer.parse( accountCode );
        }
        catch ( final ParseException e )
        {
            throw (IllegalArgumentException) new IllegalArgumentException( accountCode ).initCause( e );
        }
    }

    /**
     * Checks a given number to conform to a Kontonummer.
     *
     * @param accountCode The number to check.
     *
     * @return {@code true} if {@code accountCode} is a valid Kontonummer; {@code false} if not.
     */
    public static boolean checkKontonummer( final Number accountCode )
    {
        boolean valid = accountCode != null;

        if ( valid )
        {
            final long num = accountCode.longValue();
            valid = num > 0L && num < 10000000000L;
        }

        return valid;
    }

    /**
     * Returns this Kontonummer as an int value.
     *
     * @return This Kontonummer as an int value.
     */
    public int intValue()
    {
        return (int) this.kto;
    }

    /**
     * Returns this Kontonummer as a long value.
     *
     * @return This Kontonummer as a long value.
     */
    public long longValue()
    {
        return this.kto;
    }

    /**
     * Returns this Kontonummer as a float value.
     *
     * @return This Kontonummer as a float value.
     */
    public float floatValue()
    {
        return this.kto;
    }

    /**
     * Returns this Kontonummer as a double value.
     *
     * @return This Kontonummer as a double value.
     */
    public double doubleValue()
    {
        return this.kto;
    }

    /**
     * Formats a Kontonummer and appends the resulting text to the given string buffer.
     *
     * @param style The style to use ({@code ELECTRONIC_FORMAT} or {@code LETTER_FORMAT}).
     * @param toAppendTo The buffer to which the formatted text is to be appended.
     *
     * @return The value passed in as {@code toAppendTo}.
     *
     * @throws NullPointerException if {@code toAppendTo} is {@code null}.
     * @throws IllegalArgumentException if {@code style} is neither {@code ELECTRONIC_FORMAT} nor {@code LETTER_FORMAT}.
     *
     * @see #ELECTRONIC_FORMAT
     * @see #LETTER_FORMAT
     */
    public StringBuffer format( final int style, final StringBuffer toAppendTo )
    {
        if ( toAppendTo == null )
        {
            throw new NullPointerException( "toAppendTo" );
        }
        if ( style != Kontonummer.ELECTRONIC_FORMAT && style != Kontonummer.LETTER_FORMAT )
        {
            throw new IllegalArgumentException( Integer.toString( style ) );
        }

        final int[] digits = Kontonummer.toDigits( this.kto );
        for ( int i = digits.length - 1, lastDigit = 0; i >= 0; i-- )
        {
            if ( digits[i] != 0 || lastDigit > 0 )
            {
                toAppendTo.append( digits[i] );
                lastDigit++;
            }

            if ( style == Kontonummer.LETTER_FORMAT && ( lastDigit == 3 || lastDigit == 6 || lastDigit == 9 ) )
            {
                toAppendTo.append( ' ' );
            }
        }

        return toAppendTo;
    }

    /**
     * Formats a Kontonummer to produce a string. Same as
     * <blockquote>
     * {@link #format(int, StringBuffer) format<code>(style, new StringBuffer()).toString()</code>}
     * </blockquote>
     *
     * @param style The style to use ({@code ELECTRONIC_FORMAT} or {@code LETTER_FORMAT}).
     *
     * @return The formatted string.
     *
     * @throws IllegalArgumentException if {@code style} is neither {@code ELECTRONIC_FORMAT} nor {@code LETTER_FORMAT}.
     *
     * @see #ELECTRONIC_FORMAT
     * @see #LETTER_FORMAT
     */
    public String format( final int style )
    {
        return this.format( style, new StringBuffer() ).toString();
    }

    /**
     * Formats a Kontonummer to produce a string. Same as
     * <blockquote>
     * {@link #format(int) kontonummer.format(ELECTRONIC_FORMAT)}
     * </blockquote>
     *
     * @param kontonummer The {@code Kontonummer} instance to format.
     *
     * @return The formatted string.
     *
     * @throws NullPointerException if {@code kontonummer} is {@code null}.
     */
    public static String toString( final Kontonummer kontonummer )
    {
        if ( kontonummer == null )
        {
            throw new NullPointerException( "kontonummer" );
        }

        return kontonummer.format( ELECTRONIC_FORMAT );
    }

    /**
     * Creates an array holding the digits of {@code number}.
     *
     * @param number The number to return the digits for.
     *
     * @return An array holding the digits of {@code number}.
     */
    private static int[] toDigits( final long number )
    {
        int i;
        int j;
        long subst;
        final int[] ret = new int[ MAX_DIGITS ];

        for ( i = MAX_DIGITS - 1; i >= 0; i-- )
        {
            for ( j = i + 1, subst = 0L; j < MAX_DIGITS; j++ )
            {
                subst += ret[j] * EXP10[j];
            }
            ret[i] = (int) Math.floor( ( number - subst ) / EXP10[i] );
        }

        return ret;
    }

    /**
     * Creates a string representing the properties of the instance.
     *
     * @return A string representing the properties of the instance.
     */
    private String internalString()
    {
        return new StringBuffer( 500 ).append( "{accountCode=" ).append( this.kto ).append( '}' ).toString();
    }

    /**
     * Gets the current cache instance.
     *
     * @return Current cache instance.
     */
    private static Map getCache()
    {
        Map cache = (Map) cacheReference.get();
        if ( cache == null )
        {
            cache = Collections.synchronizedMap( new HashMap( 1024 ) );
            cacheReference = new SoftReference( cache );
        }

        return cache;
    }

    /**
     * Compares this object with the specified object for order. Returns a negative integer, zero, or a positive integer
     * as this object is less than, equal to, or greater than the specified object.<p>
     *
     * @param o The Object to be compared.
     * @return A negative integer, zero, or a positive integer as this object is less than, equal to, or greater than
     * the specified object.
     *
     * @throws NullPointerException if {@code o} is {@code null}.
     * @throws ClassCastException if the specified object's type prevents it from being compared to this Object.
     */
    public int compareTo( final Object o )
    {
        if ( o == null )
        {
            throw new NullPointerException( "o" );
        }
        if ( !( o instanceof Kontonummer ) )
        {
            throw new ClassCastException( o.getClass().getName() );
        }

        int result = 0;
        final Kontonummer that = (Kontonummer) o;

        if ( !this.equals( that ) )
        {
            result = this.kto > that.kto ? 1 : -1;
        }

        return result;
    }

    /**
     * Indicates whether some other object is equal to this one.
     *
     * @param o The reference object with which to compare.
     *
     * @return {@code true} if this object is the same as {@code o}; {@code false} otherwise.
     */
    public boolean equals( final Object o )
    {
        boolean equal = o == this;

        if ( !equal && o instanceof Kontonummer )
        {
            equal = this.kto == ( (Kontonummer) o ).kto;
        }

        return equal;
    }

    /**
     * Returns a hash code value for this object.
     *
     * @return A hash code value for this object.
     */
    public int hashCode()
    {
        return (int) ( this.kto ^ ( this.kto >>> 32 ) );
    }

    /**
     * Returns a string representation of the object.
     *
     * @return A string representation of the object.
     */
    public String toString()
    {
        return super.toString() + this.internalString();
    }

}