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package org.jnbt;

/*
 * JNBT License
 * 
 * Copyright (c) 2010 Graham Edgecombe
 * All rights reserved.
 * 
 * Redistribution and use in source and binary forms, with or without
 * modification, are permitted provided that the following conditions are met:
 * 
 *     * Redistributions of source code must retain the above copyright notice,
 *       this list of conditions and the following disclaimer.
 *       
 *     * Redistributions in binary form must reproduce the above copyright
 *       notice, this list of conditions and the following disclaimer in the
 *       documentation and/or other materials provided with the distribution.
 *       
 *     * Neither the name of the JNBT team nor the names of its
 *       contributors may be used to endorse or promote products derived from
 *       this software without specific prior written permission.
 * 
 * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS "AS IS"
 * AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
 * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
 * ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT HOLDER OR CONTRIBUTORS BE
 * LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR
 * CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF
 * SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS
 * INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN
 * CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE)
 * ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE
 * POSSIBILITY OF SUCH DAMAGE. 
 */
import com.google.common.io.LittleEndianDataInputStream;

import java.io.*;
import java.util.ArrayList;
import java.util.HashMap;
import java.util.List;
import java.util.Map;

/**
 * This class reads NBT, or
 * Named Binary Tag streams, and produces an object graph of
 * subclasses of the Tag object.
 * 
 * The NBT format was created by Markus Persson, and the specification may
 * be found at 
 * http://www.minecraft.net/docs/NBT.txt.
 * @author Graham Edgecombe
 *
 */
public final class NBTInputStream implements Closeable {

    /**
     * The data input stream.
     */
    private final DataInput is;

    /**
     * Creates a new NBTInputStream, which will source its data
     * from the specified input stream, which is assumed to contain big
     * endian data, or if the input stream is already a {@link DataInput}
     * stream, the stream's default byte order.
     *
     * @param is The input stream.
     */
    public NBTInputStream(InputStream is) {
        if (is instanceof DataInput) {
            this.is = (DataInput) is;
        } else {
            this.is = new DataInputStream(is);
        }
    }

    /**
     * Creates a new NBTInputStream, which will source its data
     * from the specified input stream.
     *
     * @param is The input stream.
     * @param littleEndian Whether the stream contains little endian data.
     */
    public NBTInputStream(InputStream is, boolean littleEndian) {
        this.is = littleEndian ? new LittleEndianDataInputStream(is) : new DataInputStream(is);
    }

    /**
     * Reads an NBT tag from the stream.
     * @return The tag that was read.
     * @throws IOException if an I/O error occurs.
     */
    public Tag readTag() throws IOException {
        return readTag(0);
    }

    /**
     * Reads an NBT from the stream.
     * @param depth The depth of this tag.
     * @return The tag that was read.
     * @throws IOException if an I/O error occurs.
     */
    private Tag readTag(int depth) throws IOException {
        int type = is.readByte() & 0xFF;

        String name;
        if (type != NBTConstants.TYPE_END) {
            int nameLength = is.readShort() & 0xFFFF;
            byte[] nameBytes = new byte[nameLength];
            is.readFully(nameBytes);
            name = new String(nameBytes, NBTConstants.CHARSET);
        } else {
            name = "";
        }

        return readTagPayload(type, name, depth);
    }

    /**
     * Reads the payload of a tag, given the name and type.
     * @param type The type.
     * @param name The name.
     * @param depth The depth.
     * @return The tag.
     * @throws IOException if an I/O error occurs.
     */
    private Tag readTagPayload(int type, String name, int depth) throws IOException {
        switch (type) {
            case NBTConstants.TYPE_END:
//                if (depth == 0) {
//                    throw new IOException("TAG_End found without a TAG_Compound/TAG_List tag preceding it.");
//                } else {
                    return new EndTag();
//                }
            case NBTConstants.TYPE_BYTE:
                return new ByteTag(name, is.readByte());
            case NBTConstants.TYPE_SHORT:
                return new ShortTag(name, is.readShort());
            case NBTConstants.TYPE_INT:
                return new IntTag(name, is.readInt());
            case NBTConstants.TYPE_LONG:
                return new LongTag(name, is.readLong());
            case NBTConstants.TYPE_FLOAT:
                return new FloatTag(name, is.readFloat());
            case NBTConstants.TYPE_DOUBLE:
                return new DoubleTag(name, is.readDouble());
            case NBTConstants.TYPE_BYTE_ARRAY:
                int length = is.readInt();
                byte[] bytes = new byte[length];
                is.readFully(bytes);
                return new ByteArrayTag(name, bytes);
            case NBTConstants.TYPE_STRING:
                length = is.readShort();
                bytes = new byte[length];
                is.readFully(bytes);
                return new StringTag(name, new String(bytes, NBTConstants.CHARSET));
            case NBTConstants.TYPE_LIST:
                int childType = is.readByte();
                length = is.readInt();

                List tagList = new ArrayList<>();
                for (int i = 0; i < length; i++) {
                    Tag tag = readTagPayload(childType, "", depth + 1);
                    if (tag instanceof EndTag) {
                        throw new IOException("TAG_End not permitted in a list.");
                    }
                    tagList.add(tag);
                }

                return new ListTag(name, NBTUtils.getTypeClass(childType), tagList);
            case NBTConstants.TYPE_COMPOUND:
                Map tagMap = new HashMap<>();
                while (true) {
                    Tag tag = readTag(depth + 1);
                    if (tag instanceof EndTag) {
                        break;
                    } else {
                        tagMap.put(tag.getName(), tag);
                    }
                }

                return new CompoundTag(name, tagMap);
            case NBTConstants.TYPE_INT_ARRAY:
                length = is.readInt();
                int[] values = new int[length];
                for (int i = 0; i < length; i++) {
                    values[i] = is.readInt();
                }
                return new IntArrayTag(name, values);
            case NBTConstants.TYPE_LONG_ARRAY:
                length = is.readInt();
                long[] longs = new long[length];
                for (int i = 0; i < length; i++) {
                    longs[i] = is.readLong();
                }
                return new LongArrayTag(name, longs);
            default:
                throw new IOException("Invalid tag type: " + type + ".");
        }
    }

    public void close() throws IOException {
        ((InputStream) is).close();
    }
}