/*
 * Copyright (C) 2017, Google Inc. and others
 *
 * This program and the accompanying materials are made available under the
 * terms of the Eclipse Distribution License v. 1.0 which is available at
 * https://www.eclipse.org/org/documents/edl-v10.php.
 *
 * SPDX-License-Identifier: BSD-3-Clause
 */

package org.eclipse.jgit.internal.storage.reftable;

import static org.eclipse.jgit.internal.storage.reftable.ReftableConstants.MAX_BLOCK_SIZE;

import org.eclipse.jgit.lib.Config;
import org.eclipse.jgit.lib.Repository;

/**
 * Configuration used by a reftable writer when constructing the stream.
 */
public class ReftableConfig {
	private int refBlockSize = 4 << 10;
	private int logBlockSize;
	private int restartInterval;
	private int maxIndexLevels;
	private boolean alignBlocks = true;
	private boolean indexObjects = true;

	/**
	 * Create a default configuration.
	 */
	public ReftableConfig() {
	}

	/**
	 * Create a configuration honoring the repository's settings.
	 *
	 * @param db
	 *            the repository to read settings from. The repository is not
	 *            retained by the new configuration, instead its settings are
	 *            copied during the constructor.
	 */
	public ReftableConfig(Repository db) {
		fromConfig(db.getConfig());
	}

	/**
	 * Create a configuration honoring settings in a
	 * {@link org.eclipse.jgit.lib.Config}.
	 *
	 * @param cfg
	 *            the source to read settings from. The source is not retained
	 *            by the new configuration, instead its settings are copied
	 *            during the constructor.
	 */
	public ReftableConfig(Config cfg) {
		fromConfig(cfg);
	}

	/**
	 * Copy an existing configuration to a new instance.
	 *
	 * @param cfg
	 *            the source configuration to copy from.
	 */
	public ReftableConfig(ReftableConfig cfg) {
		this.refBlockSize = cfg.refBlockSize;
		this.logBlockSize = cfg.logBlockSize;
		this.restartInterval = cfg.restartInterval;
		this.maxIndexLevels = cfg.maxIndexLevels;
		this.alignBlocks = cfg.alignBlocks;
		this.indexObjects = cfg.indexObjects;
	}

	/**
	 * Get desired output block size for references, in bytes.
	 *
	 * @return desired output block size for references, in bytes.
	 */
	public int getRefBlockSize() {
		return refBlockSize;
	}

	/**
	 * Set desired output block size for references, in bytes.
	 *
	 * @param szBytes
	 *            desired output block size for references, in bytes.
	 */
	public void setRefBlockSize(int szBytes) {
		if (szBytes > MAX_BLOCK_SIZE) {
			throw new IllegalArgumentException();
		}
		refBlockSize = Math.max(0, szBytes);
	}

	/**
	 * Get desired output block size for log entries, in bytes.
	 *
	 * @return desired output block size for log entries, in bytes. If 0 the
	 *         writer will default to {@code 2 * getRefBlockSize()}.
	 */
	public int getLogBlockSize() {
		return logBlockSize;
	}

	/**
	 * Set desired output block size for log entries, in bytes.
	 *
	 * @param szBytes
	 *            desired output block size for log entries, in bytes. If 0 will
	 *            default to {@code 2 * getRefBlockSize()}.
	 */
	public void setLogBlockSize(int szBytes) {
		if (szBytes > MAX_BLOCK_SIZE) {
			throw new IllegalArgumentException();
		}
		logBlockSize = Math.max(0, szBytes);
	}

	/**
	 * Get number of references between binary search markers.
	 *
	 * @return number of references between binary search markers.
	 */
	public int getRestartInterval() {
		return restartInterval;
	}

	/**
	 * <p>Setter for the field <code>restartInterval</code>.</p>
	 *
	 * @param interval
	 *            number of references between binary search markers. If
	 *            {@code interval} is 0 (default), the writer will select a
	 *            default value based on the block size.
	 */
	public void setRestartInterval(int interval) {
		restartInterval = Math.max(0, interval);
	}

	/**
	 * Get maximum depth of the index; 0 for unlimited.
	 *
	 * @return maximum depth of the index; 0 for unlimited.
	 */
	public int getMaxIndexLevels() {
		return maxIndexLevels;
	}

	/**
	 * Set maximum number of levels to use in indexes.
	 *
	 * @param levels
	 *            maximum number of levels to use in indexes. Lower levels of
	 *            the index respect {@link #getRefBlockSize()}, and the highest
	 *            level may exceed that if the number of levels is limited.
	 */
	public void setMaxIndexLevels(int levels) {
		maxIndexLevels = Math.max(0, levels);
	}

	/**
	 * Whether the writer should align blocks.
	 *
	 * @return {@code true} if the writer should align blocks.
	 */
	public boolean isAlignBlocks() {
		return alignBlocks;
	}

	/**
	 * Whether blocks are written aligned to multiples of
	 * {@link #getRefBlockSize()}.
	 *
	 * @param align
	 *            if {@code true} blocks are written aligned to multiples of
	 *            {@link #getRefBlockSize()}. May increase file size due to NUL
	 *            padding bytes added between blocks. Default is {@code true}.
	 */
	public void setAlignBlocks(boolean align) {
		alignBlocks = align;
	}

	/**
	 * Whether the writer should index object to ref.
	 *
	 * @return {@code true} if the writer should index object to ref.
	 */
	public boolean isIndexObjects() {
		return indexObjects;
	}

	/**
	 * Whether the reftable may include additional storage to efficiently map
	 * from {@code ObjectId} to reference names.
	 *
	 * @param index
	 *            if {@code true} the reftable may include additional storage to
	 *            efficiently map from {@code ObjectId} to reference names. By
	 *            default, {@code true}.
	 */
	public void setIndexObjects(boolean index) {
		indexObjects = index;
	}

	/**
	 * Update properties by setting fields from the configuration.
	 *
	 * If a property's corresponding variable is not defined in the supplied
	 * configuration, then it is left unmodified.
	 *
	 * @param rc
	 *            configuration to read properties from.
	 */
	public void fromConfig(Config rc) {
		refBlockSize = rc.getInt("reftable", "blockSize", refBlockSize); //$NON-NLS-1$ //$NON-NLS-2$
		logBlockSize = rc.getInt("reftable", "logBlockSize", logBlockSize); //$NON-NLS-1$ //$NON-NLS-2$
		restartInterval = rc.getInt("reftable", "restartInterval", restartInterval); //$NON-NLS-1$ //$NON-NLS-2$
		maxIndexLevels = rc.getInt("reftable", "indexLevels", maxIndexLevels); //$NON-NLS-1$ //$NON-NLS-2$
		alignBlocks = rc.getBoolean("reftable", "alignBlocks", alignBlocks); //$NON-NLS-1$ //$NON-NLS-2$
		indexObjects = rc.getBoolean("reftable", "indexObjects", indexObjects); //$NON-NLS-1$ //$NON-NLS-2$
	}
}