/*
 * Copyright (c) "Neo4j"
 * Neo4j Sweden AB [http://neo4j.com]
 *
 * This file is part of Neo4j.
 *
 * Neo4j is free software: you can redistribute it and/or modify
 * it under the terms of the GNU General Public License as published by
 * the Free Software Foundation, either version 3 of the License, or
 * (at your option) any later version.
 *
 * This program is distributed in the hope that it will be useful,
 * but WITHOUT ANY WARRANTY; without even the implied warranty of
 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
 * GNU General Public License for more details.
 *
 * You should have received a copy of the GNU General Public License
 * along with this program.  If not, see <http://www.gnu.org/licenses/>.
 */
package org.neo4j.kernel.impl.store.record;

import static org.neo4j.memory.HeapEstimator.shallowSizeOfInstance;
import static org.neo4j.memory.HeapEstimator.sizeOf;

import java.lang.reflect.Array;
import java.util.ArrayList;
import java.util.Arrays;
import java.util.Collections;
import java.util.Iterator;
import java.util.List;
import java.util.Objects;
import org.neo4j.kernel.impl.store.PropertyStore;
import org.neo4j.kernel.impl.store.PropertyType;
import org.neo4j.storageengine.api.PropertyKeyValue;
import org.neo4j.storageengine.api.cursor.StoreCursors;
import org.neo4j.values.storable.Value;

/**
 * First value block in have the following layout:
 * <pre>
 * d = data
 * x = maybe data
 * i = inlined
 * t = type
 * k = key
 * [dddd][dddd][dddd][dddd][xxxi,tttt][kkkk,kkkk][kkkk,kkkk][kkkk,kkkk]
 * </pre>
 * The rest of the blocks are pure data. In case of a long string or big array that does not fit in the blocks, we will
 * have a single value block with a pointer to dynamic record chain. The dynamic records are loaded into valueRecords, in
 * order, to provide access in a single point.
 */
public class PropertyBlock {
    private static final long SHALLOW_SIZE = shallowSizeOfInstance(PropertyBlock.class);
    public static final long HEAP_SIZE = SHALLOW_SIZE + sizeOf(new long[1]);

    /**
     * Size of one property block in a property record. One property may be composed by one or more property blocks
     * and one property record contains several property blocks.
     */
    public static final int PROPERTY_BLOCK_SIZE = Long.BYTES;

    private static final long KEY_BITMASK = 0xFFFFFFL;

    private static final int MAX_ARRAY_TOSTRING_SIZE = 4;
    private List<DynamicRecord> valueRecords;
    private long[] valueBlocks;

    public PropertyBlock() {}

    public PropertyBlock(PropertyBlock other) {
        if (other.valueBlocks != null) {
            this.valueBlocks = Arrays.copyOf(other.valueBlocks, other.valueBlocks.length);
        }
        if (other.valueRecords != null) {
            this.valueRecords = new ArrayList<>(other.valueRecords.size());
            for (DynamicRecord valueRecord : other.valueRecords) {
                this.valueRecords.add(new DynamicRecord(valueRecord));
            }
        }
    }

    public PropertyType getType() {
        return getType(false);
    }

    public PropertyType forceGetType() {
        return getType(true);
    }

    private PropertyType getType(boolean force) {
        return valueBlocks == null
                ? null
                : force
                        ? PropertyType.getPropertyTypeOrNull(valueBlocks[0])
                        : PropertyType.getPropertyTypeOrThrow(valueBlocks[0]);
    }

    public int getKeyIndexId() {
        return keyIndexId(valueBlocks[0]);
    }

    public void setKeyIndexId(int key) {
        valueBlocks[0] &= ~KEY_BITMASK;
        valueBlocks[0] |= key;
    }

    public void setSingleBlock(long value) {
        valueBlocks = new long[1];
        valueBlocks[0] = value;
        if (valueRecords != null) {
            valueRecords.clear();
        }
    }

    public void addValueRecord(DynamicRecord record) {
        if (valueRecords == null) {
            valueRecords = new ArrayList<>(1);
        }
        valueRecords.add(record);
    }

    public void setValueRecords(List<DynamicRecord> valueRecords) {
        assert this.valueRecords == null || this.valueRecords.isEmpty() : this.valueRecords.toString();
        this.valueRecords = valueRecords;
    }

    public List<DynamicRecord> getValueRecords() {
        return valueRecords != null ? valueRecords : Collections.emptyList();
    }

    public long getSingleValueBlock() {
        return valueBlocks[0];
    }

    /**
     * use this for references to the dynamic stores
     */
    public long getSingleValueLong() {
        return fetchLong(valueBlocks[0]);
    }

    public int getSingleValueInt() {
        return fetchInt(valueBlocks[0]);
    }

    public short getSingleValueShort() {
        return fetchShort(valueBlocks[0]);
    }

    public byte getSingleValueByte() {
        return fetchByte(valueBlocks[0]);
    }

    public long[] getValueBlocks() {
        return valueBlocks;
    }

    public boolean isLight() {
        return valueRecords == null || valueRecords.isEmpty();
    }

    public void setValueBlocks(long[] blocks) {
        int expectedPayloadSize = PropertyType.getPayloadSizeLongs();
        assert blocks == null || blocks.length <= expectedPayloadSize
                : "I was given an array of size " + blocks.length + ", but I wanted it to be " + expectedPayloadSize;
        this.valueBlocks = blocks;
        if (valueRecords != null) {
            valueRecords.clear();
        }
    }

    /**
     * A property block can take a variable size of bytes in a property record.
     * This method returns the size of this block in bytes, including the header
     * size. This does not include dynamic records.
     *
     * @return The size of this block in bytes, including the header.
     */
    public int getSize() {
        // Currently each block is a multiple of 8 in size
        return valueBlocks == null ? 0 : valueBlocks.length * PROPERTY_BLOCK_SIZE;
    }

    @Override
    public String toString() {
        StringBuilder result = new StringBuilder("PropertyBlock[");
        PropertyType type = getType();
        if (valueBlocks != null) {
            result.append("blocks=").append(valueBlocks.length).append(',');
        }
        result.append(type == null ? "<unknown type>" : type.name()).append(',');
        result.append("key=").append(valueBlocks == null ? "?" : Integer.toString(getKeyIndexId()));
        if (type != null) {
            switch (type) {
                case STRING:
                case ARRAY:
                    result.append(",firstDynamic=").append(getSingleValueLong());
                    break;
                default:
                    Object value = type.value(this, null, null).asObject();
                    if (value != null && value.getClass().isArray()) {
                        int length = Array.getLength(value);
                        StringBuilder buf = new StringBuilder(
                                        value.getClass().getComponentType().getSimpleName())
                                .append('[');
                        for (int i = 0; i < length && i <= MAX_ARRAY_TOSTRING_SIZE; i++) {
                            if (i != 0) {
                                buf.append(',');
                            }
                            buf.append(Array.get(value, i));
                        }
                        if (length > MAX_ARRAY_TOSTRING_SIZE) {
                            buf.append(",...");
                        }
                        value = buf.append(']');
                    }
                    result.append(",value=").append(value);
                    break;
            }
        }
        if (!isLight()) {
            result.append(",ValueRecords[");
            Iterator<DynamicRecord> recIt = valueRecords.iterator();
            while (recIt.hasNext()) {
                result.append(recIt.next());
                if (recIt.hasNext()) {
                    result.append(',');
                }
            }
            result.append(']');
        }
        result.append(']');
        return result.toString();
    }

    public boolean hasSameContentsAs(PropertyBlock other) {
        // Assumption (which happens to be true) that if a heavy (long string/array) property
        // changes it will get another id, making the valueBlocks values differ.
        return Arrays.equals(valueBlocks, other.valueBlocks);
    }

    public Value newPropertyValue(PropertyStore propertyStore, StoreCursors cursors) {
        return getType().value(this, propertyStore, cursors);
    }

    public PropertyKeyValue newPropertyKeyValue(PropertyStore propertyStore, StoreCursors cursors) {
        int propertyKeyId = getKeyIndexId();
        return new PropertyKeyValue(propertyKeyId, getType().value(this, propertyStore, cursors));
    }

    public static int keyIndexId(long valueBlock) {
        // [][][][][][kkkk,kkkk][kkkk,kkkk][kkkk,kkkk]
        return (int) (valueBlock & KEY_BITMASK);
    }

    public static long fetchLong(long valueBlock) {
        return (valueBlock & 0xFFFFFFFFF0000000L) >>> 28;
    }

    public static int fetchInt(long valueBlock) {
        return (int) ((valueBlock & 0x0FFFFFFFF0000000L) >>> 28);
    }

    public static short fetchShort(long valueBlock) {
        return (short) ((valueBlock & 0x00000FFFF0000000L) >>> 28);
    }

    public static byte fetchByte(long valueBlock) {
        return (byte) ((valueBlock & 0x0000000FF0000000L) >>> 28);
    }

    public static boolean valueIsInlined(long valueBlock) {
        // [][][][][   i,tttt][kkkk,kkkk][kkkk,kkkk][kkkk,kkkk]
        return (valueBlock & 0x10000000L) > 0;
    }

    @Override
    public boolean equals(Object o) {
        if (this == o) {
            return true;
        }
        if (o == null || getClass() != o.getClass()) {
            return false;
        }
        PropertyBlock that = (PropertyBlock) o;
        return Objects.equals(valueRecords, that.valueRecords) && Arrays.equals(valueBlocks, that.valueBlocks);
    }

    @Override
    public int hashCode() {
        int result = Objects.hash(valueRecords);
        result = 31 * result + Arrays.hashCode(valueBlocks);
        return result;
    }
}
