/*******************************************************************************
 *
 * Copyright (c) 2004-2009, Oracle Corporation
 *
 * All rights reserved. This program and the accompanying materials
 * are made available under the terms of the Eclipse Public License v1.0
 * which accompanies this distribution, and is available at
 * http://www.eclipse.org/legal/epl-v10.html
 *
 * Contributors:
 *
 *
 *
 *
 *******************************************************************************/ 

package hudson.node_monitors;

import hudson.FilePath.FileCallable;
import hudson.model.Computer;
import hudson.remoting.VirtualChannel;
import hudson.Util;
import hudson.slaves.OfflineCause;
import hudson.node_monitors.DiskSpaceMonitorDescriptor.DiskSpace;

import java.io.File;
import java.io.IOException;
import java.io.Serializable;
import java.math.BigDecimal;
import java.text.ParseException;
import java.util.Locale;

import org.kohsuke.stapler.export.ExportedBean;
import org.kohsuke.stapler.export.Exported;

/**
 * {@link AbstractNodeMonitorDescriptor} for {@link NodeMonitor} that checks a
 * free disk space of some directory.
 *
 * @author Kohsuke Kawaguchi
 */
/*package*/ abstract class DiskSpaceMonitorDescriptor extends AbstractNodeMonitorDescriptor<DiskSpace> {

    /**
     * Value object that represents the disk space.
     */
    @ExportedBean
    public static final class DiskSpace extends OfflineCause implements Serializable {

        @Exported
        public final long size;
        private boolean triggered;

        public DiskSpace(long size) {
            this.size = size;
        }

        @Override
        public String toString() {
            return String.valueOf(size);
        }

        /**
         * Gets GB left.
         */
        public String getGbLeft() {
            long space = size;
            space /= 1024L;   // convert to KB
            space /= 1024L;   // convert to MB

            return new BigDecimal(space).scaleByPowerOfTen(-3).toPlainString();
        }

        /**
         * Returns the HTML representation of the space.
         */
        public String toHtml() {
            long space = size;
            space /= 1024L;   // convert to KB
            space /= 1024L;   // convert to MB
            if (triggered) {
                // less than a GB
                return Util.wrapToErrorSpan(new BigDecimal(space).scaleByPowerOfTen(-3).toPlainString() + "GB");
            }

            return space / 1024 + "GB";
        }

        /**
         * Sets whether this disk space amount should be treated as outside the
         * acceptable conditions or not.
         */
        protected void setTriggered(boolean triggered) {
            this.triggered = triggered;
        }

        /**
         * Parses a human readable size description like "1GB", "0.5m", etc.
         * into {@link DiskSpace}
         *
         * @throws ParseException If failed to parse.
         */
        public static DiskSpace parse(String size) throws ParseException {
            size = size.toUpperCase(Locale.ENGLISH).trim();
            if (size.endsWith("B")) // cut off 'B' from KB, MB, etc.
            {
                size = size.substring(0, size.length() - 1);
            }

            long multiplier = 1;

            // look for the size suffix. The goal here isn't to detect all invalid size suffix,
            // so we ignore double suffix like "10gkb" or anything like that.
            String suffix = "KMGT";
            for (int i = 0; i < suffix.length(); i++) {
                if (size.endsWith(suffix.substring(i, i + 1))) {
                    multiplier = 1;
                    for (int j = 0; j <= i; j++) {
                        multiplier *= 1024;
                    }
                    size = size.substring(0, size.length() - 1);
                }
            }

            return new DiskSpace((long) (Double.parseDouble(size.trim()) * multiplier));
        }
        private static final long serialVersionUID = 2L;
    }

    protected DiskSpace monitor(Computer c) throws IOException, InterruptedException {
        return getFreeSpace(c);
    }

    /**
     * Computes the free size.
     */
    protected abstract DiskSpace getFreeSpace(Computer c) throws IOException, InterruptedException;

    protected static final class GetUsableSpace implements FileCallable<DiskSpace> {

        public DiskSpace invoke(File f, VirtualChannel channel) throws IOException {
            try {
                long s = f.getUsableSpace();
                if (s <= 0) {
                    return null;
                }
                return new DiskSpace(s);
            } catch (LinkageError e) {
                // pre-mustang
                return null;
            }
        }
        private static final long serialVersionUID = 1L;
    }
}