package org.simantics.databoard.streaming;

import java.io.DataOutput;
import java.io.DataOutputStream;
import java.io.IOException;
import java.io.OutputStream;

import org.simantics.databoard.Bindings;
import org.simantics.databoard.serialization.Serializer;
import org.simantics.databoard.type.Datatype;
import org.simantics.databoard.util.binary.Endian;
import org.simantics.databoard.util.binary.UTF8;

/**
 * This is an utility class that encapsulates the databoard value encoding scheme.
 * It can be used for streaming value writing. 
 */
public class DataWriter {
    private static final Serializer DATATYPE_SERIALIZER = Bindings.getSerializerUnchecked(Bindings.getBindingUnchecked( Datatype.class ));

    private final DataOutput out;

    public DataWriter(DataOutput out) {
        this.out = out;
    }
    
    public DataWriter(OutputStream stream) {
        this.out = new DataOutputStream(stream);
    }
    
    public void writeBoolean(boolean value) throws IOException {
        out.write(value ? 1 : 0);
    }
    
    public void writeByte(byte value) throws IOException {
        out.write(value);
    }
    
    public void writeInteger(int value) throws IOException {
        out.writeInt(value);
    }
    
    public void writeLong(long value) throws IOException {
        out.writeLong(value);
    }
    
    public void writeFloat(float value) throws IOException {
        out.writeFloat(value);
    }
    
    public void writeDouble(double value) throws IOException {
        out.writeDouble(value);
    }
    
    public void writeString(String value) throws IOException {
        int utflen = UTF8.getModifiedUTF8EncodingByteLength(value);
        Endian.writeDynamicUInt32(out, utflen);
        UTF8.writeModifiedUTF(out, value);
    }
    
    public void writeDatatype(Datatype datatype) throws IOException {
        DATATYPE_SERIALIZER.serialize(out, datatype);
    }
    
    /**
     * A variable length array is started with the length
     * followed by the serialization of all elements.
     */
    public void beginVariableLengthArray(int length) throws IOException {
        out.writeInt(length);
    }
    
    /**
     * A map is started with its size followed by 
     * serialization of interleaved keys and values.
     */
    public void beginMap(int size) throws IOException {
        out.writeInt(size);
    }
    
    /**
     * An optional value that is null is written as byte 0.
     */
    public void writeOptionalNull() throws IOException {
        out.write(0);
    }
    
    /**
     * An optional value that is not null is started
     * with byte 1 followed by the actual value.
     */
    public void beginOptionalValue() throws IOException {
        out.write(1);
    }
    
    /**
     * Selects the constructor of the union type.
     * It is written as a variable length integer,
     * so the total number of tags is required.
     */
    public void writeUnionTag(int tag, int tagCount) throws IOException {
        Endian.putUInt(out, tag, tagCount-1);
    }
    
    public void writeReferenceToKnownReferableRecord(int id) throws IOException {
        out.writeInt(id);
    }
    
    public void beginUnknownReferableRecord(int id) throws IOException {
        out.writeInt(0);
        out.writeInt(id);
    }
}