/**
 *  Licensed to the Apache Software Foundation (ASF) under one
 *  or more contributor license agreements.  See the NOTICE file
 *  distributed with this work for additional information
 *  regarding copyright ownership.  The ASF licenses this file
 *  to you under the Apache License, Version 2.0 (the
 *  "License"); you may not use this file except in compliance
 *  with the License.  You may obtain a copy of the License at
 *  
 *    http://www.apache.org/licenses/LICENSE-2.0
 *  
 *  Unless required by applicable law or agreed to in writing,
 *  software distributed under the License is distributed on an
 *  "AS IS" BASIS, WITHOUT WARRANTIES OR CONDITIONS OF ANY
 *  KIND, either express or implied.  See the License for the
 *  specific language governing permissions and limitations
 *  under the License. 
 *  
 */
package org.apache.kerby.asn1.type;

import org.apache.kerby.asn1.Asn1;
import org.apache.kerby.asn1.Asn1FieldInfo;
import org.apache.kerby.asn1.EnumType;
import org.apache.kerby.asn1.TaggingOption;
import org.apache.kerby.asn1.UniversalTag;

import java.io.IOException;
import java.nio.ByteBuffer;

public class Asn1Choice extends AbstractAsn1Type<Asn1Type> {

    private Asn1FieldInfo[] fieldInfos;
    private Asn1Type[] fields;

    public Asn1Choice(Asn1FieldInfo[] fieldInfos) {
        super(UniversalTag.CHOICE);
        setValue(this);
        this.fieldInfos = fieldInfos.clone();
        this.fields = new Asn1Type[fieldInfos.length];
    }

    @Override
    protected int encodingBodyLength() {
        for (int i = 0; i < fields.length; ++i) {
            AbstractAsn1Type<?> field = (AbstractAsn1Type<?>) fields[i];
            if (field != null) {
                if (fieldInfos[i].isTagged()) {
                    TaggingOption taggingOption = fieldInfos[i].getTaggingOption();
                    return field.taggedEncodingLength(taggingOption);
                } else {
                    return field.encodingLength();
                }
            }
        }
        return 0;
    }

    @Override
    protected void encodeBody(ByteBuffer buffer) {
        for (int i = 0; i < fields.length; ++i) {
            Asn1Type field = fields[i];
            if (field != null) {
                if (fieldInfos[i].isTagged()) {
                    TaggingOption taggingOption = fieldInfos[i].getTaggingOption();
                    field.taggedEncode(buffer, taggingOption);
                } else {
                    field.encode(buffer);
                }
                break;
            }
        }
    }

    @Override
    public void decode(ByteBuffer content) throws IOException {
        int foundPos = -1;
        Asn1Item item = (Asn1Item) Asn1.decode(content);
        for (int i = 0; i < fieldInfos.length; ++i) {
            if (item.isContextSpecific()) {
                if (fieldInfos[i].getTagNo() == item.tagNo()) {
                    foundPos = i;
                    break;
                }
            } else {
                initField(i);
                if (fields[i].tag().equals(item.tag())) {
                    foundPos = i;
                    break;
                } else {
                    fields[i] = null;
                }
            }
        }
        if (foundPos == -1) {
            throw new RuntimeException("Unexpected item with (tagFlags, tagNo): ("
                    + item.tag() + ", " + item.tagNo() + ")");
        }

        if (!item.isFullyDecoded()) {
            AbstractAsn1Type<?> fieldValue = (AbstractAsn1Type<?>) fields[foundPos];
            if (item.isContextSpecific()) {
                item.decodeValueWith(fieldValue, fieldInfos[foundPos].getTaggingOption());
            } else {
                item.decodeValueWith(fieldValue);
            }
        }
        fields[foundPos] = item.getValue();
    }

    protected void decodeBody(ByteBuffer content) throws IOException {
        // Not used
    }

    private void initField(int idx) {
        try {
            fields[idx] = fieldInfos[idx].getType().newInstance();
        } catch (Exception e) {
            throw new IllegalArgumentException("Bad field info specified at index of " + idx, e);
        }
    }

    protected <T extends Asn1Type> T getFieldAs(EnumType index, Class<T> t) {
        Asn1Type value = fields[index.getValue()];
        if (value == null) {
            return null;
        }
        return (T) value;
    }

    protected void setFieldAs(EnumType index, Asn1Type value) {
        fields[index.getValue()] = value;
    }

    protected String getFieldAsString(int index) {
        Asn1Type value = fields[index];
        if (value == null) {
            return null;
        }

        if (value instanceof Asn1String) {
            return ((Asn1String) value).getValue();
        }

        throw new RuntimeException("The targeted field type isn't of string");
    }

    protected byte[] getFieldAsOctets(EnumType index) {
        Asn1OctetString value = getFieldAs(index, Asn1OctetString.class);
        if (value != null) {
            return value.getValue();
        }
        return null;
    }

    protected void setFieldAsOctets(EnumType index, byte[] bytes) {
        Asn1OctetString value = new Asn1OctetString(bytes);
        setFieldAs(index, value);
    }

    protected Integer getFieldAsInteger(EnumType index) {
        Asn1Integer value = getFieldAs(index, Asn1Integer.class);
        if (value != null) {
            return value.getValue().intValue();
        }
        return null;
    }

    protected void setFieldAsInt(EnumType index, int value) {
        setFieldAs(index, new Asn1Integer(value));
    }
}