package ibxm;
import java.io.*;
public class ScreamTracker3 {
        private static final int[] effect_map = new int[] {
                0xFF,
                0x25, /* A: Set Speed.*/
                0x0B, /* B: Pattern Jump.*/
                0x0D, /* C: Pattern Break.*/
                0x0A, /* D: Volume Slide.*/
                0x02, /* E: Portamento Down.*/
                0x01, /* F: Portamento Up.*/
                0x03, /* G: Tone Portamento.*/
                0x04, /* H: Vibrato.*/
                0x1D, /* I: Tremor.*/
                0x00, /* J: Arpeggio.*/
                0x06, /* K: Vibrato + Volume Slide.*/
                0x05, /* L: Tone Portamento + Volume Slide.*/
                0xFF, /* M: */
                0xFF, /* N: */
                0x09, /* O: Sample Offset.*/
                0xFF, /* P: */
                0x1B, /* Q: Retrig + Volume Slide.*/
                0x07, /* R: Tremolo.*/
                0x0E, /* S: Extended Effects.*/
                0x0F, /* T: Set Tempo.*/
                0x24, /* U: Fine Vibrato.*/
                0x10, /* V: Set Global Volume. */
                0xFF, 0xFF, 0xFF, 0xFF, 0xFF,
                0xFF, 0xFF, 0xFF, 0xFF
        };
        private static final int[] effect_s_map = new int[] {
                0x00, /* 0: Set Filter.*/
                0x03, /* 1: Glissando.*/
                0x05, /* 2: Set Fine Tune.*/
                0x04, /* 3: Set Vibrato Waveform.*/
                0x07, /* 4: Set Tremolo Waveform.*/
                0xFF, /* 5: */
                0xFF, /* 6: */
                0xFF, /* 7: */
                0x08, /* 8: Set Panning.*/
                0xFF, /* 9: */
                0x09, /* A: Stereo Control.*/
                0x06, /* B: Pattern Loop.*/
                0x0C, /* C: Note Cut.*/
                0x0D, /* D: Note Delay.*/
                0x0E, /* E: Pattern Delay.*/
                0x0F  /* F: Invert Loop.*/
        };
        public static boolean is_s3m( byte[] header_96_bytes ) {
                String s3m_identifier;
                s3m_identifier = ascii_text( header_96_bytes, 44, 4 );
                return s3m_identifier.equals( "SCRM" );
        }
        public static Module load_s3m( byte[] header_96_bytes, DataInput data_input ) throws IOException {
                int num_pattern_orders, num_instruments, num_patterns, num_channels;
                int flags, tracker_version, master_volume, panning, channel_config, sequence_length;
                int instrument_idx, pattern_idx, channel_idx, order_idx, panning_offset;
                boolean signed_samples, stereo_mode, default_panning;
                int[] channel_map, sequence;
                byte[] s3m_file;
                Module module;
                Instrument instrument;
                s3m_file = read_s3m_file( header_96_bytes, data_input );
                module = new Module();
                module.song_title = ascii_text( s3m_file, 0, 28 );
                num_pattern_orders = get_num_pattern_orders( s3m_file );
                num_instruments = get_num_instruments( s3m_file );
                num_patterns = get_num_patterns( s3m_file );
                flags = unsigned_short_le( s3m_file, 38 );
                tracker_version = unsigned_short_le( s3m_file, 40 );
                if( ( flags & 0x40 ) == 0x40 || tracker_version == 0x1300 ) {
                        module.fast_volume_slides = true;
                }
                signed_samples = false;
                if( unsigned_short_le( s3m_file, 42 ) == 0x01 ) {
                        signed_samples = true;
                }
                module.global_volume = s3m_file[ 48 ] & 0xFF;
                module.default_speed = s3m_file[ 49 ] & 0xFF;
                module.default_tempo = s3m_file[ 50 ] & 0xFF;
                master_volume = s3m_file[ 51 ] & 0x7F;
                module.channel_gain = ( master_volume << IBXM.FP_SHIFT ) >> 7;
                stereo_mode = ( s3m_file[ 51 ] & 0x80 ) == 0x80;
                default_panning = ( s3m_file[ 53 ] & 0xFF ) == 0xFC;
                channel_map = new int[ 32 ];
                num_channels = 0;
                for( channel_idx = 0; channel_idx < 32; channel_idx++ ) {
                        channel_config = s3m_file[ 64 + channel_idx ] & 0xFF;
                        channel_map[ channel_idx ] = -1;
                        if( channel_config < 16 ) {
                                channel_map[ channel_idx ] = num_channels;
                                num_channels += 1;
                        }
                }
                module.set_num_channels( num_channels );
                panning_offset = 96 + num_pattern_orders + num_instruments * 2 + num_patterns * 2;
                for( channel_idx = 0; channel_idx < 32; channel_idx++ ) {
                        channel_config = s3m_file[ 64 + channel_idx ] & 0xFF;           
                        if( channel_map[ channel_idx ] >= 0 ) {
                                panning = 128;
                                if( stereo_mode ) {
                                        if( channel_config < 8 ) {
                                                panning = 64;
                                        } else {
                                                panning = 192;
                                        }
                                }
                                if( default_panning ) {
                                        flags = s3m_file[ panning_offset + channel_idx ] & 0xFF;
                                        if( ( flags & 0x20 ) == 0x20 ) {
                                                panning = ( flags & 0x0F ) << 4;
                                        }
                                }
                                module.set_initial_panning( channel_map[ channel_idx ], panning );
                        }
                }
                sequence = read_s3m_sequence( s3m_file );
                module.set_sequence_length( sequence.length );
                for( order_idx = 0; order_idx < sequence.length; order_idx++ ) {
                        module.set_sequence( order_idx, sequence[ order_idx ] );
                }
                module.set_num_instruments( num_instruments );
                for( instrument_idx = 0; instrument_idx < num_instruments; instrument_idx++ ) {
                        instrument = read_s3m_instrument( s3m_file, instrument_idx, signed_samples );
                        module.set_instrument( instrument_idx + 1, instrument );
                }
                module.set_num_patterns( num_patterns );
                for( pattern_idx = 0; pattern_idx < num_patterns; pattern_idx++ ) {
                        module.set_pattern( pattern_idx, read_s3m_pattern( s3m_file, pattern_idx, channel_map ) );
                }
                return module;
        }
        private static int[] read_s3m_sequence( byte[] s3m_file ) {
                int num_pattern_orders, sequence_length;
                int sequence_idx, order_idx, pattern_order;
                int[] sequence;
                num_pattern_orders = get_num_pattern_orders( s3m_file );
                sequence_length = 0;
                for( order_idx = 0; order_idx < num_pattern_orders; order_idx++ ) {
                        pattern_order = s3m_file[ 96 + order_idx ] & 0xFF;
                        if( pattern_order == 255 ) {
                                break;
                        } else if( pattern_order < 254 ) {
                                sequence_length += 1;
                        }
                }
                sequence = new int[ sequence_length ];
                sequence_idx = 0;
                for( order_idx = 0; order_idx < num_pattern_orders; order_idx++ ) {
                        pattern_order = s3m_file[ 96 + order_idx ] & 0xFF;
                        if( pattern_order == 255 ) {
                                break;
                        } else if( pattern_order < 254 ) {
                                sequence[ sequence_idx ] = pattern_order;
                                sequence_idx += 1;
                        }
                }
                return sequence;
        }
        private static Instrument read_s3m_instrument( byte[] s3m_file, int instrument_idx, boolean signed_samples ) {
                int instrument_offset;
                int sample_data_offset, sample_data_length;
                int loop_start, loop_length, sample_idx, amplitude;
                Instrument instrument;
                Sample sample;
                short[] sample_data;
                instrument_offset = get_instrument_offset( s3m_file, instrument_idx );
                instrument = new Instrument();
                instrument.name = ascii_text( s3m_file, instrument_offset + 48, 28 );
                sample = new Sample();
                if( s3m_file[ instrument_offset ] == 1 ) {
                        sample_data_length = get_sample_data_length( s3m_file, instrument_offset );
                        loop_start = unsigned_short_le( s3m_file, instrument_offset + 20 );
                        loop_length = unsigned_short_le( s3m_file, instrument_offset + 24 ) - loop_start;
                        sample.volume = s3m_file[ instrument_offset + 28 ] & 0xFF;
                        if( s3m_file[ instrument_offset + 30 ] != 0 ) {
                                throw new IllegalArgumentException( "ScreamTracker3: Packed samples not supported!" );
                        }
                        if( ( s3m_file[ instrument_offset + 31 ] & 0x01 ) == 0 ) {
                                loop_length = 0;
                        }
                        sample.c2_rate = unsigned_short_le( s3m_file, instrument_offset + 32 );
                        sample_data = new short[ sample_data_length ];
                        sample_data_offset = get_sample_data_offset( s3m_file, instrument_offset );
                        if( signed_samples ) {
                                for( sample_idx = 0; sample_idx < sample_data_length; sample_idx++ ) {
                                        amplitude = s3m_file[ sample_data_offset + sample_idx ] << 8;
                                        sample_data[ sample_idx ] = ( short ) ( amplitude << 8 );
                                }
                        } else {
                                for( sample_idx = 0; sample_idx < sample_data_length; sample_idx++ ) {
                                        amplitude = ( s3m_file[ sample_data_offset + sample_idx ] & 0xFF ) - 128;
                                        sample_data[ sample_idx ] = ( short ) ( amplitude << 8 );
                                }
                        }
                        sample.set_sample_data( sample_data, loop_start, loop_length, false );
                }
                instrument.set_num_samples( 1 );
                instrument.set_sample( 0, sample );
                return instrument;
        }
       
        private static Pattern read_s3m_pattern( byte[] s3m_file, int pattern_idx, int[] channel_map ) {
                int pattern_offset;
                int num_channels, num_notes;
                int row_idx, channel_idx, note_idx;
                int token, key, volume_column, effect, effect_param;
                byte[] pattern_data;
                Pattern pattern;
                num_channels = 0;
                for( channel_idx = 0; channel_idx < 32; channel_idx++ ) {
                        if( channel_map[ channel_idx ] >= num_channels ) {
                                num_channels = channel_idx + 1;
                        }
                }
                num_notes = num_channels * 64;
                pattern_data = new byte[ num_notes * 5 ];
                row_idx = 0;
                pattern_offset = get_pattern_offset( s3m_file, pattern_idx ) + 2;
                while( row_idx < 64 ) {
                        token = s3m_file[ pattern_offset ] & 0xFF;
                        pattern_offset += 1;
                        if( token > 0 ) {
                                channel_idx = channel_map[ token & 0x1F ];
                                note_idx = ( num_channels * row_idx + channel_idx ) * 5;
                                if( ( token & 0x20 ) == 0x20 ) {
                                        /* Key + Instrument.*/
                                        if( channel_idx >= 0 ) {
                                                key = s3m_file[ pattern_offset ] & 0xFF;
                                                if( key == 255 ) {
                                                        key = 0;
                                                } else if( key == 254 ) {
                                                        key = 97;
                                                } else {
                                                        key = ( ( key & 0xF0 ) >> 4 ) * 12 + ( key & 0x0F ) + 1;
                                                        while( key > 96 ) {
                                                                key = key - 12;
                                                        }
                                                }
                                                pattern_data[ note_idx ] = ( byte ) key;
                                                pattern_data[ note_idx + 1 ] = s3m_file[ pattern_offset + 1 ];
                                        }
                                        pattern_offset += 2;
                                }
                                if( ( token & 0x40 ) == 0x40 ) {
                                        /* Volume.*/
                                        if( channel_idx >= 0 ) {
                                                volume_column = ( s3m_file[ pattern_offset ] & 0xFF ) + 0x10;
                                                pattern_data[ note_idx + 2 ] = ( byte ) volume_column;
                                        }
                                        pattern_offset += 1;
                                }
                                if( ( token & 0x80 ) == 0x80 ) {
                                        /* Effect + Param.*/
                                        if( channel_idx >= 0 ) {
                                                effect = s3m_file[ pattern_offset ] & 0xFF;
                                                effect_param = s3m_file[ pattern_offset + 1 ] & 0xFF;
                                                effect = effect_map[ effect & 0x1F ];
                                                if( effect == 0xFF ) {
                                                        effect = 0;
                                                        effect_param = 0;
                                                }
                                                if( effect == 0x0E ) {
                                                        effect = effect_s_map[ ( effect_param & 0xF0 ) >> 4 ];
                                                        effect_param = effect_param & 0x0F;
                                                        switch( effect ) {
                                                                case 0x08:
                                                                        effect = 0x08;
                                                                        effect_param = effect_param << 4;
                                                                        break;
                                                                case 0x09:
                                                                        effect = 0x08;
                                                                        if( effect_param > 7 ) {
                                                                                effect_param -= 8;
                                                                        } else {
                                                                                effect_param += 8;
                                                                        }
                                                                        break;
                                                                case 0xFF:
                                                                        effect = 0;
                                                                        effect_param = 0;
                                                                        break;
                                                                default:
                                                                        effect_param = ( ( effect & 0x0F ) << 4 ) | ( effect_param & 0x0F );
                                                                        effect = 0x0E;
                                                                        break;
                                                        }
                                                }
                                                pattern_data[ note_idx + 3 ] = ( byte ) effect;
                                                pattern_data[ note_idx + 4 ] = ( byte ) effect_param;
                                        }
                                        pattern_offset += 2;
                                }
                        } else {
                                row_idx += 1;
                        }
                }
                pattern = new Pattern();
                pattern.num_rows = 64;
                pattern.set_pattern_data( pattern_data );
                return pattern;
        }
        private static byte[] read_s3m_file( byte[] header_96_bytes, DataInput data_input ) throws IOException {
                int s3m_file_length;
                int num_pattern_orders, num_instruments, num_patterns;
                int instrument_idx, pattern_idx;
                int instrument_offset, sample_data_offset, pattern_offset;
                byte[] s3m_file;
                if( !is_s3m( header_96_bytes ) ) {
                        throw new IllegalArgumentException( "ScreamTracker3: Not an S3M file!" );
                }
                s3m_file = header_96_bytes;
                s3m_file_length = header_96_bytes.length;
                num_pattern_orders = get_num_pattern_orders( s3m_file );
                num_instruments = get_num_instruments( s3m_file );
                num_patterns = get_num_patterns( s3m_file );
                s3m_file_length += num_pattern_orders;
                s3m_file_length += num_instruments * 2;
                s3m_file_length += num_patterns * 2;
                /* Read enough of file to calculate the length.*/
                s3m_file = read_more( s3m_file, s3m_file_length, data_input );
                for( instrument_idx = 0; instrument_idx < num_instruments; instrument_idx++ ) {
                        instrument_offset = get_instrument_offset( s3m_file, instrument_idx );
                        instrument_offset += 80;
                        if( instrument_offset > s3m_file_length ) {
                                s3m_file_length = instrument_offset;
                        }
                }
                for( pattern_idx = 0; pattern_idx < num_patterns; pattern_idx++ ) {
                        pattern_offset = get_pattern_offset( s3m_file, pattern_idx );
                        pattern_offset += 2;
                        if( pattern_offset > s3m_file_length ) {
                                s3m_file_length = pattern_offset;
                        }
                }
                s3m_file = read_more( s3m_file, s3m_file_length, data_input );
                /* Read rest of file.*/
                for( instrument_idx = 0; instrument_idx < num_instruments; instrument_idx++ ) {
                        instrument_offset = get_instrument_offset( s3m_file, instrument_idx );
                        sample_data_offset = get_sample_data_offset( s3m_file, instrument_offset );
                        sample_data_offset += get_sample_data_length( s3m_file, instrument_offset );
                        if( sample_data_offset > s3m_file_length ) {
                                s3m_file_length = sample_data_offset;
                        }
                }
                for( pattern_idx = 0; pattern_idx < num_patterns; pattern_idx++ ) {
                        pattern_offset = get_pattern_offset( s3m_file, pattern_idx );
                        pattern_offset += get_pattern_length( s3m_file, pattern_offset );
                        pattern_offset += 2;
                        if( pattern_offset > s3m_file_length ) {
                                s3m_file_length = pattern_offset;
                        }
                }
                s3m_file = read_more( s3m_file, s3m_file_length, data_input );
                return s3m_file;
        }
        private static int get_num_pattern_orders( byte[] s3m_file ) {
                int num_pattern_orders;
                num_pattern_orders = unsigned_short_le( s3m_file, 32 );
                return num_pattern_orders;
        }
        private static int get_num_instruments( byte[] s3m_file ) {
                int num_instruments;
                num_instruments = unsigned_short_le( s3m_file, 34 );
                return num_instruments;
        }
       
        private static int get_num_patterns( byte[] s3m_file ) {
                int num_patterns;
                num_patterns = unsigned_short_le( s3m_file, 36 );
                return num_patterns;
        }
        private static int get_instrument_offset( byte[] s3m_file, int instrument_idx ) {
                int instrument_offset, pointer_offset;
                pointer_offset = 96 + get_num_pattern_orders( s3m_file );
                instrument_offset = unsigned_short_le( s3m_file, pointer_offset + instrument_idx * 2 ) << 4;
                return instrument_offset;
        }
        private static int get_sample_data_offset( byte[] s3m_file, int instrument_offset ) {
                int sample_data_offset;
                sample_data_offset = 0;
                if( s3m_file[ instrument_offset ] == 1 ) {
                        sample_data_offset = ( s3m_file[ instrument_offset + 13 ] & 0xFF ) << 20;
                        sample_data_offset |= unsigned_short_le( s3m_file, instrument_offset + 14 ) << 4;
                }
                return sample_data_offset;
        }
        private static int get_sample_data_length( byte[] s3m_file, int instrument_offset ) {
                int sample_data_length;
                sample_data_length = 0;
                if( s3m_file[ instrument_offset ] == 1 ) {
                        sample_data_length = unsigned_short_le( s3m_file, instrument_offset + 16 );
                }
                return sample_data_length;
        }
        private static int get_pattern_offset( byte[] s3m_file, int pattern_idx ) {
                int pattern_offset, pointer_offset;
                pointer_offset = 96 + get_num_pattern_orders( s3m_file );
                pointer_offset += get_num_instruments( s3m_file ) * 2;
                pattern_offset = unsigned_short_le( s3m_file, pointer_offset + pattern_idx * 2 ) << 4;
                return pattern_offset;
        }
        private static int get_pattern_length( byte[] s3m_file, int pattern_offset ) {
                int pattern_length;
                pattern_length = unsigned_short_le( s3m_file, pattern_offset );
                return pattern_length;
        }
        private static byte[] read_more( byte[] old_data, int new_length, DataInput data_input ) throws IOException {
                byte[] new_data;
                new_data = old_data;
                if( new_length > old_data.length ) {
                        new_data = new byte[ new_length ];
                        System.arraycopy( old_data, 0, new_data, 0, old_data.length );
                        try {
                                data_input.readFully( new_data, old_data.length, new_data.length - old_data.length );
                        } catch( EOFException e ) {
                                System.out.println( "ScreamTracker3: Module has been truncated!" );
                        }
                }
                return new_data;
        }
        private static int unsigned_short_le( byte[] buffer, int offset ) {
                int value;
                value = buffer[ offset ] & 0xFF;
                value = value | ( ( buffer[ offset + 1 ] & 0xFF ) << 8 );
                return value;
        }
        private static String ascii_text( byte[] buffer, int offset, int length ) {
                int idx, chr;
                byte[] string_buffer;
                String string;
                string_buffer = new byte[ length ];
                for( idx = 0; idx < length; idx++ ) {
                        chr = buffer[ offset + idx ];
                        if( chr < 32 ) {
                                chr = 32;
                        }
                        string_buffer[ idx ] = ( byte ) chr;
                }
                try {
                        string = new String( string_buffer, 0, length, "ISO-8859-1" );
                } catch( UnsupportedEncodingException e ) {
                        string = "";
                }
                return string;
        }
}