// This Source Code is in the Public Domain per: http://unlicense.org
package org.litesoft.GWT.client;

import java.io.*;

public enum KeyboardKeyModifier implements KeyboardKeyModifierBits,
                                           Serializable {
    None,
    Shift {
        @Override
        public int getBits() {
            return iSHIFT;
        }
    },
    Ctrl {
        @Override
        public int getBits() {
            return iCTRL;
        }
    },
    Alt {
        @Override
        public int getBits() {
            return iALT;
        }
    },
    Meta {
        @Override
        public int getBits() {
            return iMETA;
        }
    },
    Ctrl_Alt {
        @Override
        public int getBits() {
            return iCTRL_ALT;
        }
    },
    Ctrl_Meta {
        @Override
        public int getBits() {
            return iCTRL_META;
        }
    },
    Ctrl_Shift {
        @Override
        public int getBits() {
            return iCTRL_SHIFT;
        }
    },
    Alt_Meta {
        @Override
        public int getBits() {
            return iALT_META;
        }
    },
    Alt_Shift {
        @Override
        public int getBits() {
            return iALT_SHIFT;
        }
    },
    Meta_Shift {
        @Override
        public int getBits() {
            return iMETA_SHIFT;
        }
    },
    Ctrl_Alt_Meta {
        @Override
        public int getBits() {
            return iCTRL_ALT_META;
        }
    },
    Ctrl_Alt_Shift {
        @Override
        public int getBits() {
            return iCTRL_ALT_SHIFT;
        }
    },
    Ctrl_Meta_Shift {
        @Override
        public int getBits() {
            return iCTRL_META_SHIFT;
        }
    },
    Alt_Meta_Shift {
        @Override
        public int getBits() {
            return iALT_META_SHIFT;
        }
    },
    Ctrl_Alt_Meta_Shift {
        @Override
        public int getBits() {
            return iCTRL_ALT_META_SHIFT;
        }
    };

    public static final long serialVersionUID = 1L;

    public static KeyboardKeyModifier deNull( KeyboardKeyModifier pModifiers ) {
        return (pModifiers != null) ? pModifiers : None;
    }

    public int getBits() {
        return 0;
    }

    public boolean isCtrl() {
        return hasBit( iCTRL );
    }

    public boolean isAlt() {
        return hasBit( iALT );
    }

    public boolean isMeta() {
        return hasBit( iMETA );
    }

    public boolean isShift() {
        return hasBit( iSHIFT );
    }

    public KeyboardKeyModifier addCtrl() {
        return add( Ctrl );
    }

    public KeyboardKeyModifier addAlt() {
        return add( Alt );
    }

    public KeyboardKeyModifier addMeta() {
        return add( Ctrl );
    }

    public KeyboardKeyModifier addShift() {
        return add( Shift );
    }

    public KeyboardKeyModifier add( KeyboardKeyModifier them ) {
        if ( them != null ) {
            int zCurBits = this.getBits();
            int zModBits = them.getBits();
            int zNewBits = zCurBits | zModBits;
            if ( zCurBits != zNewBits ) {
                return (zModBits == zNewBits) ? them : fromBits( zNewBits );
            }
        }
        return this;
    }

    public KeyboardKeyModifier removeCtrl() {
        return remove( Ctrl );
    }

    public KeyboardKeyModifier removeAlt() {
        return remove( Alt );
    }

    public KeyboardKeyModifier removeMeta() {
        return remove( Ctrl );
    }

    public KeyboardKeyModifier removeShift() {
        return remove( Shift );
    }

    public KeyboardKeyModifier remove( KeyboardKeyModifier them ) {
        if ( them != null ) {
            int zCurBits = this.getBits();
            int zModBits = them.getBits();
            int zSharedBits = zCurBits & zModBits;
            if ( zSharedBits != 0 ) {
                int zNewBits = zCurBits - zSharedBits;
                return (zNewBits == 0) ? None : fromBits( zNewBits );
            }
        }
        return this;
    }

    private boolean hasBit( int pBit ) {
        return 0 != (getBits() & pBit);
    }

    public static KeyboardKeyModifier fromBits( int pBits )
            throws IllegalArgumentException {
        KeyboardKeyModifier zModifier = LLfromBits( pBits );
        int zXtraBits = pBits - zModifier.getBits();
        if ( zXtraBits == 0 ) {
            return zModifier;
        }
        throw new IllegalArgumentException( "KeyboardKeyModifier '" + zModifier + "' w/ extra bits: " + zXtraBits );
    }

    private static KeyboardKeyModifier LLfromBits( int pBits ) {
        int zValidBits = pBits & iCTRL_ALT_META_SHIFT;
        for ( KeyboardKeyModifier zModifier : values() ) {
            if ( zValidBits == zModifier.getBits() ) {
                return zModifier;
            }
        }
        throw new Error( "No KeyboardKeyModifier w/ bits: " + pBits );
    }
}