#!/bin/bash

#-----------------------------------------------------------
#
# Get proper disk to install OS
#
# 1. Check all partitions list in /proc/partitions, whether 
#    there is disk had OS installed. Select the one with the
#    smallest WWN.
# 2. Check all disks list in /proc/partitions, sort them by
#    WWN and driver type, select the first one.
# 3. Select the default one: /dev/sda.   
#
# Output: /tmp/install_disk
#
#-----------------------------------------------------------

install_disk=""
rm /tmp/install_disk

# Check if any disk have installed OS
if [ -z "$install_disk" ]; then

    entries=$(awk -F ' '  '{print $4}' /proc/partitions | grep -v "name")
    
    for entry in $entries; do

        dev_type=$(udevadm info --query=property --name=/dev/$entry | grep -i "DEVTYPE" | awk -F = '{print $2}' | tr A-Z a-z)
        
        if [ "$dev_type" == "disk" ]; then
            disks=$disks"$entry"
        elif [ "$dev_type" == "partition" ]; then
            partitions=$partitions"$entry"
        fi

    done

    for partition in $partitions; do

        echo Check the partition $partition >> /tmp/getinstalldisk_log

        if [ -e "/tmp/tmp_${partition%%[0-9]*}" ]; then
            echo The disk had OS installed, check next partition. >> /tmp/getinstalldisk_log
            continue
        fi

        mkdir -p /tmp/mymount;

        fs_type=$(udevadm info --query=property --name=/dev/$partition | grep -i "FS_TYPE" | awk -F = '{print $2}')

        rc=255

        # mount partition based on fs type, if fs_type is swap, do not mount it, jump to next partition.
        if [ -z "$fs_type" ]; then
            mount /dev/$partition /tmp/mymount 
            rc=$?
        elif [ "$fs_type" != "swap" ]; then
            mount -t $fs_type /dev/$partition /tmp/mymount 
            rc=$?
        fi

        if [ $rc -eq 0 ]; then

            ker_dir="/tmp/mymount"            
            
            if [ -d /tmp/mymount/boot ]; then
                ker_dir="/tmp/mymount/boot"
            fi

            for i in $ker_dir/vmlinuz*; do
                disk_part=${partition%%[0-9]*}
                disk_wwn=$(udevadm info --query=property --name=$disk_part | grep '\<ID_WWN\>' | cut -d "=" -f2 | tr A-Z a-z)
                disk_array=$disk_array"$disk_part $disk_wwn\n"
                touch /tmp/tmp_$disk_part
                break
            done
             
            echo -e The partition $partition has kernel file. >> /tmp/getinstalldisk_log

            umount /tmp/mymount || echo $partition umount failed. >> /tmp/getinstalldisk_log
        else
            echo Partition $partition mount failed or the partition is swap. >> /tmp/getinstalldisk_log
        fi
    done
    
    if [ "$disk_array" ]; then    
        echo -e The disk_array: >> /tmp/getinstalldisk_log
        echo -e $disk_array >> /tmp/getinstalldisk_log

        install_disk=/dev/$(echo -e $disk_array | grep -v "^$" | sort -t : -k 2 -b | cut -d " " -f1 | head -n 1)
   
        echo -e The install_disk is $install_disk. >> /tmp/getinstalldisk_log
    fi
    rm -f /tmp/tmp_*;
    rmdir /tmp/mymount;
fi

# Sort all disks based on their WWN and driver type, choose the first one
if [ -z "$install_disk" ]; then
    
    rm -f /tmp/tmp_*;

    for disk in $disks; do

        disk_wwn=$(udevadm info --query=property --name=$disk | grep '\<ID_WWN\>' | cut -d "=" -f2 | tr A-Z a-z)
 
        if [ "$disk_wwn" ]; then

            disk_driver=$(udevadm info --attribute-walk --name=$disk | grep DRIVERS| grep -v '""'| grep -v '"sd"'| head -n 1| sed -e 's/[^"]*"//' -e 's/"//' | tr A-Z a-z)

            echo -e The disk $disk information: disk_wwn=$disk_wwn disk_driver=$disk_driver. >> /tmp/getinstalldisk_log

            case "$disk_driver" in

            "ata_piix4"|"PMC MaxRAID"|"ahci"|"megaraid_sas")
                echo "$disk $disk_wwn" >> /tmp/tmp_firstdisks
                echo "Add disk:" $disk $driver $disk_wwn " into firstdisks" >> tmp/tmp/getinstalldisk_log
                ;;
            "mptsas"|"mpt2sas"|"mpt3sas")
                echo "$disk $disk_wwn" >> /tmp/tmp_seconddisks
                echo "Add disk:" $disk $driver $disk_wwn " into seconddisks" >> tmp/tmp/getinstalldisk_log
                ;;
            *)
                echo "$disk $disk_wwn" >> /tmp/tmp_thirddisks
                echo "Add disk:" $disk $driver $disk_wwn " into thirddisks" >> tmp/tmp/getinstalldisk_log
                ;;
 
            esac
        fi
    done

    for seq in first second third; do
        if [ -s /tmp/tmp_${seq}disks ]; then
            install_file="/tmp/tmp_${seq}disks"
            break
        fi
    done
        

    if [ "$install_file" ] && [ -s $install_file ]; then
        install_disk=/dev/$(cat $install_file | grep -v "^$" | sort -t : -k 2 -b | cut -d " " -f1 | head -n 1)
        echo -e The install_disk is $install_disk by sorting WWN and DRIVER. >> /tmp/getinstalldisk_log
        rm -f /tmp/tmp_*;
    fi
      
fi

# Cannot find proper disk for OS install, select the default one "/dev/sda"
if [ -z "$install_disk" ]; then
    install_disk="/dev/sda"
    echo -e The default install_disk is $install_disk. >> /tmp/getinstalldisk_log
fi

# Output the result to /tmp/install_disk file
echo $install_disk > /tmp/install_disk