/*
 * Copyright 2014 Red Hat, Inc.
 *
 *  All rights reserved. This program and the accompanying materials
 *  are made available under the terms of the Eclipse Public License v1.0
 *  and Apache License v2.0 which accompanies this distribution.
 *
 *  The Eclipse Public License is available at
 *  http://www.eclipse.org/legal/epl-v10.html
 *
 *  The Apache License v2.0 is available at
 *  http://www.opensource.org/licenses/apache2.0.php
 *
 *  You may elect to redistribute this code under either of these licenses.
 */

package io.vertx.ext.web.sstore.impl;

import io.vertx.core.VertxException;
import io.vertx.core.buffer.Buffer;
import io.vertx.core.shareddata.Shareable;
import io.vertx.core.shareddata.impl.ClusterSerializable;
import io.vertx.ext.auth.VertxContextPRNG;
import io.vertx.ext.web.impl.Utils;
import io.vertx.ext.web.sstore.AbstractSession;

import java.lang.reflect.InvocationTargetException;
import java.nio.charset.Charset;
import java.nio.charset.StandardCharsets;
import java.util.Map;
import java.util.concurrent.ConcurrentHashMap;

/**
 * @author <a href="http://tfox.org">Tim Fox</a>
 */
public class SharedDataSessionImpl extends AbstractSession implements ClusterSerializable, Shareable {

  private static final Charset UTF8 = StandardCharsets.UTF_8;

  private static final byte TYPE_LONG = 1;
  private static final byte TYPE_INT = 2;
  private static final byte TYPE_SHORT = 3;
  private static final byte TYPE_BYTE = 4;
  private static final byte TYPE_DOUBLE = 5;
  private static final byte TYPE_FLOAT = 6;
  private static final byte TYPE_CHAR = 7;
  private static final byte TYPE_BOOLEAN = 8;
  private static final byte TYPE_STRING = 9;
  private static final byte TYPE_BUFFER = 10;
  private static final byte TYPE_BYTES = 11;
  private static final byte TYPE_CLUSTER_SERIALIZABLE = 13;

  /**
   * Important note: This constructor (even though not referenced anywhere) is required for serialization purposes. Do
   * not remove.
   */
  public SharedDataSessionImpl() {
    super();
  }

  public SharedDataSessionImpl(VertxContextPRNG random) {
    super(random);
  }

  public SharedDataSessionImpl(VertxContextPRNG random, long timeout, int length) {
    super(random, timeout, length);
  }

  @Override
  public void writeToBuffer(Buffer buff) {
    byte[] bytes = id().getBytes(UTF8);
    buff.appendInt(bytes.length).appendBytes(bytes);
    buff.appendLong(timeout());
    buff.appendLong(lastAccessed());
    buff.appendInt(version());
    // use cache
    Buffer dataBuf = writeDataToBuffer();
    buff.appendBuffer(dataBuf);
  }

  @Override
  public int readFromBuffer(int pos, Buffer buffer) {
    int len = buffer.getInt(pos);
    pos += 4;
    byte[] bytes = buffer.getBytes(pos, pos + len);
    pos += len;
    setId(new String(bytes, UTF8));
    setTimeout(buffer.getLong(pos));
    pos += 8;
    setLastAccessed(buffer.getLong(pos));
    pos += 8;
    setVersion(buffer.getInt(pos));
    pos += 4;
    pos = readDataFromBuffer(pos, buffer);
    return pos;
  }

  private Buffer writeDataToBuffer() {
    Buffer buffer = Buffer.buffer();
    if (isEmpty()) {
      buffer.appendInt(0);
    } else {
      final Map<String, Object> data = data();
      buffer.appendInt(data.size());
      for (Map.Entry<String, Object> entry : data.entrySet()) {
        String key = entry.getKey();
        byte[] keyBytes = key.getBytes(UTF8);
        buffer.appendInt(keyBytes.length).appendBytes(keyBytes);
        Object val = entry.getValue();
        if (val instanceof Long) {
          buffer.appendByte(TYPE_LONG).appendLong((long) val);
        } else if (val instanceof Integer) {
          buffer.appendByte(TYPE_INT).appendInt((int) val);
        } else if (val instanceof Short) {
          buffer.appendByte(TYPE_SHORT).appendShort((short) val);
        } else if (val instanceof Byte) {
          buffer.appendByte(TYPE_BYTE).appendByte((byte) val);
        } else if (val instanceof Double) {
          buffer.appendByte(TYPE_DOUBLE).appendDouble((double) val);
        } else if (val instanceof Float) {
          buffer.appendByte(TYPE_FLOAT).appendFloat((float) val);
        } else if (val instanceof Character) {
          buffer.appendByte(TYPE_CHAR).appendShort((short) ((Character) val).charValue());
        } else if (val instanceof Boolean) {
          buffer.appendByte(TYPE_BOOLEAN).appendByte((byte) ((boolean) val ? 1 : 0));
        } else if (val instanceof String) {
          byte[] bytes = ((String) val).getBytes(UTF8);
          buffer.appendByte(TYPE_STRING).appendInt(bytes.length).appendBytes(bytes);
        } else if (val instanceof Buffer) {
          Buffer buff = (Buffer) val;
          buffer.appendByte(TYPE_BUFFER).appendInt(buff.length()).appendBuffer(buff);
        } else if (val instanceof byte[]) {
          byte[] bytes = (byte[]) val;
          buffer.appendByte(TYPE_BYTES).appendInt(bytes.length).appendBytes(bytes);
        } else if (val instanceof ClusterSerializable) {
          buffer.appendByte(TYPE_CLUSTER_SERIALIZABLE);
          String className = val.getClass().getName();
          byte[] classNameBytes = className.getBytes(UTF8);
          buffer.appendInt(classNameBytes.length).appendBytes(classNameBytes);
          ((ClusterSerializable) val).writeToBuffer(buffer);
        } else {
          if (val != null) {
            throw new IllegalStateException("Invalid type for data in session: " + val.getClass());
          }
        }
      }
    }
    return buffer;
  }

  private int readDataFromBuffer(int pos, Buffer buffer) {
    try {
      int entries = buffer.getInt(pos);
      pos += 4;
      if (entries > 0) {
        final Map<String, Object> data = new ConcurrentHashMap<>(entries);

        for (int i = 0; i < entries; i++) {
          int keylen = buffer.getInt(pos);
          pos += 4;
          byte[] keyBytes = buffer.getBytes(pos, pos + keylen);
          pos += keylen;
          String key = new String(keyBytes, UTF8);
          byte type = buffer.getByte(pos++);
          Object val;
          switch (type) {
            case TYPE_LONG:
              val = buffer.getLong(pos);
              pos += 8;
              break;
            case TYPE_INT:
              val = buffer.getInt(pos);
              pos += 4;
              break;
            case TYPE_SHORT:
              val = buffer.getShort(pos);
              pos += 2;
              break;
            case TYPE_BYTE:
              val = buffer.getByte(pos);
              pos++;
              break;
            case TYPE_FLOAT:
              val = buffer.getFloat(pos);
              pos += 4;
              break;
            case TYPE_DOUBLE:
              val = buffer.getDouble(pos);
              pos += 8;
              break;
            case TYPE_CHAR:
              short s = buffer.getShort(pos);
              pos += 2;
              val = (char) s;
              break;
            case TYPE_BOOLEAN:
              byte b = buffer.getByte(pos);
              pos++;
              val = b == 1;
              break;
            case TYPE_STRING:
              int len = buffer.getInt(pos);
              pos += 4;
              byte[] bytes = buffer.getBytes(pos, pos + len);
              val = new String(bytes, UTF8);
              pos += len;
              break;
            case TYPE_BUFFER:
              len = buffer.getInt(pos);
              pos += 4;
              bytes = buffer.getBytes(pos, pos + len);
              val = Buffer.buffer(bytes);
              pos += len;
              break;
            case TYPE_BYTES:
              len = buffer.getInt(pos);
              pos += 4;
              val = buffer.getBytes(pos, pos + len);
              pos += len;
              break;
            case TYPE_CLUSTER_SERIALIZABLE:
              int classNameLen = buffer.getInt(pos);
              pos += 4;
              byte[] classNameBytes = buffer.getBytes(pos, pos + classNameLen);
              pos += classNameLen;
              String className = new String(classNameBytes, UTF8);
              Class<?> clazz = Utils.getClassLoader().loadClass(className);
              if (!ClusterSerializable.class.isAssignableFrom(clazz)) {
                throw new ClassCastException(new String(classNameBytes) + " is not assignable from ClusterSerializable");
              }
              ClusterSerializable obj = (ClusterSerializable) clazz.getDeclaredConstructor().newInstance();
              pos = obj.readFromBuffer(pos, buffer);
              val = obj;
              break;
            default:
              throw new IllegalStateException("Invalid serialized type: " + type);
          }
          data.put(key, val);
        }
        setData(data);
      }
      return pos;
    } catch (ClassNotFoundException | NoSuchMethodException | IllegalAccessException | InvocationTargetException | InstantiationException e) {
      throw new VertxException(e);
    }
  }
}

