/*
 * Copyright 2012, 2013 Red Hat, Inc.
 *
 * This file is part of Thermostat.
 *
 * Thermostat 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 2, or (at your
 * option) any later version.
 *
 * Thermostat 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 Thermostat; see the file COPYING.  If not see
 * <http://www.gnu.org/licenses/>.
 *
 * Linking this code with other modules is making a combined work
 * based on this code.  Thus, the terms and conditions of the GNU
 * General Public License cover the whole combination.
 *
 * As a special exception, the copyright holders of this code give
 * you permission to link this code with independent modules to
 * produce an executable, regardless of the license terms of these
 * independent modules, and to copy and distribute the resulting
 * executable under terms of your choice, provided that you also
 * meet, for each linked independent module, the terms and conditions
 * of the license of that module.  An independent module is a module
 * which is not derived from or based on this code.  If you modify
 * this code, you may extend this exception to your version of the
 * library, but you are not obligated to do so.  If you do not wish
 * to do so, delete this exception statement from your version.
 */

package com.redhat.thermostat.backend.system;

import java.io.BufferedReader;
import java.io.IOException;
import java.net.InetAddress;
import java.net.UnknownHostException;
import java.util.logging.Level;
import java.util.logging.Logger;

import com.redhat.thermostat.agent.utils.ProcDataSource;
import com.redhat.thermostat.common.Size;
import com.redhat.thermostat.common.Size.Unit;
import com.redhat.thermostat.common.utils.LoggingUtils;
import com.redhat.thermostat.storage.core.WriterID;
import com.redhat.thermostat.storage.model.HostInfo;
import com.redhat.thermostat.utils.hostname.HostName;

public class HostInfoBuilder {

    private static final Logger logger = LoggingUtils.getLogger(HostInfoBuilder.class);

    public static final String FALLBACK_LOCAL_HOSTNAME = "localhost";

    static class HostCpuInfo {
        public final String model;
        public final int count;

        public HostCpuInfo(String model, int count) {
            this.count = count;
            this.model = model;
        }
    }

    static class HostOsInfo {
        public final String kernel;
        public final String distribution;

        public HostOsInfo(String kernel, String distribution) {
            this.kernel = kernel;
            this.distribution = distribution;
        }
    }

    static class HostMemoryInfo {
        public final Size totalMemory;

        public HostMemoryInfo(Size totalMemory) {
            this.totalMemory = totalMemory;
        }
    }

    private final ProcDataSource dataSource;
    private final WriterID writerId;

    public HostInfoBuilder(ProcDataSource dataSource, WriterID writerId) {
        this.dataSource = dataSource;
        this.writerId = writerId;
    }

    public HostInfo build() {
        String hostname = getHostName();
        HostCpuInfo cpuInfo = getCpuInfo();
        HostMemoryInfo memoryInfo = getMemoryInfo();
        long totalMemorySize = (long) memoryInfo.totalMemory.convertTo(Unit.B).getValue();
        HostOsInfo osInfo = getOsInfo();
        String wId = writerId.getWriterID();
        return new HostInfo(wId, hostname, osInfo.distribution, osInfo.kernel, cpuInfo.model, cpuInfo.count, totalMemorySize);
    }

    HostCpuInfo getCpuInfo() {
        final String KEY_PROCESSOR_ID = "processor";
        final String KEY_CPU_MODEL = "model name";
        int cpuCount = 0;
        String cpuModel = null;
        try (BufferedReader bufferedReader = new BufferedReader(dataSource.getCpuInfoReader())) {
            String line = null;
            while ((line = bufferedReader.readLine()) != null) {
                if (line.startsWith(KEY_PROCESSOR_ID)) {
                    cpuCount++;
                } else if (line.startsWith(KEY_CPU_MODEL)) {
                    cpuModel = line.substring(line.indexOf(":") + 1).trim();
                }
            }
        } catch (IOException ioe) {
            logger.log(Level.WARNING, "unable to read cpu info");
        }

        logger.log(Level.FINEST, "cpuModel: " + cpuModel);
        logger.log(Level.FINEST, "cpuCount: " + cpuCount);

        return new HostCpuInfo(cpuModel, cpuCount);
    }

    HostMemoryInfo getMemoryInfo() {
        Size totalMemory = null;
        try (BufferedReader bufferedReader = new BufferedReader(dataSource.getMemInfoReader())) {
            String[] memTotalParts = bufferedReader.readLine().split(" +");
            long data = Long.valueOf(memTotalParts[1]);
            String units = memTotalParts[2];
            if (units.equals("kB")) {
                totalMemory = new Size(data, Size.Unit.KiB);
            }
        } catch (IOException ioe) {
            logger.log(Level.WARNING, "unable to read memory info");
        }

        logger.log(Level.FINEST, "totalMemory: " + totalMemory.toString());
        return new HostMemoryInfo(totalMemory);
    }

    HostOsInfo getOsInfo() {
        return getOsInfo(DistributionInformation.get());
    }

    HostOsInfo getOsInfo(DistributionInformation distroInfo) {
        String osName = distroInfo.getName() + " " + distroInfo.getVersion();
        logger.log(Level.FINEST, "osName: " + osName);

        String osKernel = System.getProperty("os.name") + " " + System.getProperty("os.version");
        logger.log(Level.FINEST, "osKernel: " + osKernel);

        return new HostOsInfo(osKernel, osName);
    }

    String getHostName() {
        String hostname = null;
        
        try {
            InetAddress localAddress = null;
            localAddress = InetAddress.getLocalHost();
            hostname = getHostName(localAddress);
        } catch (UnknownHostException uhe) {
            logger.log(Level.WARNING, "unable to get hostname", uhe);
        }
        
        // if fails, try to get hostname without dns lookup
        if (hostname == null) {
            hostname = HostName.getLocalHostName();
        }
        
        // still null, use localhost
        if (hostname == null) {
            hostname = FALLBACK_LOCAL_HOSTNAME;

        }
        
        return hostname;
    }

    String getHostName(InetAddress localAddress) {
        String hostname = localAddress.getCanonicalHostName();
        logger.log(Level.FINEST, "hostname: " + hostname);
        return hostname;
    }

}