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package org.autoplot.idlsupport;

import java.io.File;
import java.io.RandomAccessFile;
import java.net.URI;
import java.nio.ByteBuffer;
import java.nio.channels.FileChannel;
import java.util.Map;
import org.autoplot.datasource.AbstractDataSource;
import org.das2.qds.ArrayDataSet;
import org.das2.qds.QDataSet;
import org.das2.qds.ops.Ops;
import org.das2.util.monitor.ProgressMonitor;

/**
 * Read a variable from an IDLSav file.
 * @author jbf
 */
public class IdlsavDataSource extends AbstractDataSource {

    public IdlsavDataSource(URI uri) {
        super(uri);
    }

    @Override
    public QDataSet getDataSet(ProgressMonitor mon) throws Exception {
        File f= getFile(mon);
        
        RandomAccessFile aFile = new RandomAccessFile(f,"r");
        FileChannel inChannel = aFile.getChannel();
        long fileSize = inChannel.size();
        ByteBuffer buffer = ByteBuffer.allocate((int) fileSize);
        int bytesRead= 0;
        while ( bytesRead<fileSize ) {
            bytesRead+= inChannel.read(buffer);
        }
       
        String arg= getParam( "arg_0", "" );
        if ( arg.length()==0 ) {
            throw new IllegalArgumentException("specify a variable");
        }

        ReadIDLSav reader= new ReadIDLSav();
        
        Object v;
        
        int i= arg.indexOf('.');
        String t=arg;
        if ( i>-1 ) { // structure
            String h= t.substring(0,i);
            t= t.substring(i+1);
            v= reader.readVar( buffer, h );
            if ( !( v instanceof Map ) ) {
                throw new IllegalArgumentException("expected map for '"+h+"'");
            } else {
                i= t.indexOf('.');
                if ( i==-1 ) {
                    v= ((Map)v).get(t);
                } else {
                    throw new IllegalArgumentException("nested strctures are not supported.");
                }
            }
        } else {
            v= reader.readVar( buffer, arg );
        }
        
        if ( v==null ) {
            throw new IllegalArgumentException("unable to find variable or not supported: "+arg);
        }
        
        if ( v instanceof ReadIDLSav.ArrayData ) {
            ReadIDLSav.ArrayData arrayData= (ReadIDLSav.ArrayData)v;
            return ArrayDataSet.wrap( arrayData.array, arrayData.dims, false );
        } else if ( v instanceof Map ) { 
            throw new IllegalArgumentException("Map is not supported, select one of its tags");
        } else {
            return Ops.dataset(v);
        }
        
    }
    
}