#! /bin/bash

SOLO_LAD_DIR=/var/lib/waagent/Microsoft.Azure.Diagnostics.LinuxDiagnostic-*
OMS_LAD_DIR=/var/opt/microsoft/omsagent/LAD

OMS_UNINSTALL_AGENT=uninstall.sh

WAAGENT_DIR=/var/lib/waagent
WAAGENT_XML=$WAAGENT_DIR/Microsoft.EnterpriseCloud.Monitoring.OmsAgentForLinux.*.manifest.xml

STOPPED_WAAGENT=0

# error codes
UNSUPPORTED_PKG_INSTALLER=66
UNSUPPORTED_SERVICE_CONTROLLER=67
UNSUPPORTED_WAAGENT_NAME=68
UNINSTALL_AGENT_MISSING=69


# $1 - exit status
call_exit()
{
    echo "Purge script exiting with code $1"
    exit $1
}

ulinux_detect_installer()
{
    INSTALLER=""

    # Detect based on distribution
    if [ -f "/etc/debian_version" ]; then # Ubuntu, Debian
        INSTALLER="DPKG"
    elif [ -f "/etc/redhat-release" ]; then # RHEL, CentOS, Oracle
        INSTALLER="RPM"
    elif [ -f "/etc/os-release" ]; then # Possibly SLES, openSUSE
        grep PRETTY_NAME /etc/os-release | sed 's/PRETTY_NAME=//g' | tr -d '="' | grep -qi suse
        if [ $? == 0 ]; then
            INSTALLER="RPM"
        fi
    fi

    # Fall back on detection via package manager availability
    if [ "$INSTALLER" = "" ]; then
        if [ -x "$(command -v dpkg)" ]; then
            INSTALLER="DPKG"
        elif [ -x "$(command -v rpm)" ]; then
            INSTALLER="RPM"
        fi
    fi

    if [ "$INSTALLER" = "" ]; then
        echo "Error: This system does not have a supported package manager" >&2
        echo "Supported Sytems: 'DPKG' & 'RPM'" >&2
        echo "Cannot purge without a supported package manager" >&2
        call_exit $UNSUPPORTED_PKG_INSTALLER
    fi
}

ulinux_detect_servicecontroller()
{
    CONTROLLER=""

    # Detect based on systemd
    if which systemctl > /dev/null 2>&1; then
        CONTROLLER="systemctl"
    # Fall back on detection via filepath
    else
        if   [ -f "/bin/systemctl" ]; then
            CONTROLLER="systemctl"
        elif [ -f "/sbin/service" ]; then
            CONTROLLER="service"
        elif [ -f "/usr/sbin/invoke-rc.d" ]; then
            CONTROLLER="invoke-rc.d"
        fi
    fi

    if [ "$CONTROLLER" = "" ]; then
        echo "Error: This system does not have a supported service controller" >&2
        echo "Supported Systems: 'systemctl', 'service', and 'invoke-rc'" >&2
        echo "Cannot purge without a supported service controller" >&2
        call_exit $UNSUPPORTED_SERVICE_CONTROLLER
    fi
}

# $1 - The name of the package to check as to whether it's installed
check_if_pkg_is_installed()
{
    if [ "$INSTALLER" = "DPKG" ]; then
        dpkg -s $1 2> /dev/null | grep Status | grep " installed" 1> /dev/null
    else
        rpm -q $1 > /dev/null 2>&1
    fi

    return $?
}

# $1 - The name of the package to be uninstalled
pkg_rm()
{
    if [ "$1" != "" ]; then
        echo "----- Removing package: $1 -----"
        if [ "$INSTALLER" = "DPKG" ]; then
            dpkg --purge ${1}
        else
            rpm --erase ${1}
        fi
        if [ $? -ne 0 ]; then
            echo "----- Ignore previous errors for package: $1 -----"
        fi
    fi
}

check_service_running()
{
    if [ "$CONTROLLER" = "systemctl" ]; then
        systemctl status $WAAGENT_NAME 2> /dev/null | grep Active | grep " active (running)" 1> /dev/null
    elif [ "$CONTROLLER" = "service" ]; then
        service $WAAGENT_NAME status 2> /dev/null | grep $1 | grep "is running..." 1> /dev/null
    else
        invoke-rc.d $WAAGENT_NAME status 2> /dev/null | grep $1 | grep "start/running" 1> /dev/null
    fi

    return $?
}

check_waagent_name()
{
    WAAGENT_NAME=""

    if [ "$CONTROLLER" = "systemctl" ]; then
        if systemctl status waagent > /dev/null 2>&1; then
            WAAGENT_NAME="waagent"
        elif systemctl status walinuxagent > /dev/null 2>&1; then
            WAAGENT_NAME="walinuxagent"
        fi
    else
        if $CONTROLLER waagent status > /dev/null 2>&1; then
            WAAGENT_NAME="waagent"
        elif $CONTROLLER walinuxagent status > /dev/null 2>&1; then
            WAAGENT_NAME="walinuxagent"
        fi
    fi

    if [ "$WAAGENT_NAME" = "" ]; then
        echo "Error: This system does not have a recognized version of waagent" >&2
        echo "Supported Version Names: 'waagent' and 'walinuxagent'" >&2
        echo "Cannot purge without a recognized version of waagent" >&2
        call_exit $UNSUPPORTED_WAAGENT_NAME
    fi
}

stop_waagent()
{
    if check_service_running; then
        if [ "$CONTROLLER" = "systemctl" ]; then
            systemctl stop $WAAGENT_NAME
        else
            $CONTROLLER $WAAGENT_NAME stop
        fi

        if [ $? -ne 0 ]; then
            echo "----- ERROR OCCURRED -----"
            echo "Error in stopping waagent"
        else
            STOPPED_WAAGENT=1
        fi
    fi
}

restart_waagent()
{
    if [ $STOPPED_WAAGENT -eq 1 ]; then
        if [ "$CONTROLLER" = "systemctl" ]; then
            systemctl restart $WAAGENT_NAME
        else
            $CONTROLLER $WAAGENT_NAME restart
        fi

        if [ $? -ne 0 ]; then
            echo "----- ERROR OCCURRED -----"
            echo "Error in restarting waagent"
        else
            STOPPED_WAAGENT=0
        fi
    fi
}

# $1 - The name of the user to be removed (if it exists)
user_rm()
{
    if id $1 > /dev/null 2>&1; then
        echo "----- Removing user: $1 -----"
        userdel -r $1
    fi
    if [ $? -ne 0 ]; then
        echo "----- Ignore previous errors for removing user: $1 -----"
    fi
}

# $1 - The name of the group to be removed (if it exists)
group_rm()
{
    if id -g $1 > /dev/null 2>&1; then
        echo "----- Removing group: $1 -----"
        groupdel $1
    fi
    if [ $? -ne 0 ]; then
        echo "----- Ignore previous errors for removing group: $1 -----"
    fi
}

# $1 - The name of the directory to delete (if it exists)
dir_rm()
{
    if [ -d $1 ]; then
        # get package name
        d=${1%*/}       # remove the trailing "/"
        pkg=${d##*/}    # grab the folder name (aka the package name)
        pkg_rm pkg
        # remove directory if still exists
        if [ -d $1 ]; then
            rm -rf $1
        fi
    fi
}



##### PURGE SCRIPT FOLLOWS #####

# check that we're running as root
if [ `id -u` -ne 0 ]; then
    echo "In order to successfully purge the agent, this script needs to be run as root."
    echo "Please run this script with 'sudo' in front in order to purge the agent."
    call_exit 1
fi

ulinux_detect_installer
ulinux_detect_servicecontroller
check_waagent_name

# REMOVE LAD
check_if_pkg_is_installed lad-mdsd
LAD_MDSD_INSTALLED=$?
if [ $LAD_MDSD_INSTALLED -eq 0 ]; then
    echo "--------------------------------------------------------------------------------"
    echo "WARNING: LAD is currently installed on the machine."
    echo "  Purging OMS without purging LAD may not fully succeed, because LAD has a dependency on OMS."
    echo "  In order to successfully purge OMS, LAD must be purged as well."
    while : ; do
        read -p "Do you wish to continue with purging? (y/n): " continue_lad
        if [ "$continue_lad" = "y" ]; then
            echo "Continuing with purge..."
            echo "--------------------------------------------------------------------------------"
            break
        elif [ "$continue_lad" = "n" ]; then
            echo "Exiting without purging..."
            call_exit 0
        else
            echo "Unknown input. Please type 'y' (yes) or 'n' (no) to proceed."
        fi
    done

    # continuing with LAD purge
    echo "Please go to portal.azure.com and uninstall the LAD extension."
    echo "Go to Azure Portal -> Virtual Machines -> <vm_name> -> Settings -> Extensions"
    echo "and then click the '...' in the LinuxDiagnostic row and click 'Uninstall'"
    echo "---------- IMPORTANT NOTE ----------"
    echo "If you have a policy or ASC set up to push the OMS Extension to the machine, it"
    echo "will quickly re-install the extension. To ensure that this doesn't occur, please"
    echo "make sure to resume the script immediately after the extension is uninstalled"
    echo "via portal."
    echo "------------------------------------"
    read -p "Press enter to proceed once the LAD Extension is uninstalled." toss2
    echo ""

    # remove LAD directories
    echo "---------- Removing LAD directories ----------"
    for d in $SOLO_LAD_DIR
    do
        dir_rm d
    done

    if [ -d $OMS_LAD_DIR ]; then
        dir_rm $OMS_LAD_DIR
    fi

    # remove LAD package
    check_if_pkg_is_installed lad-mdsd
    if [ $? -eq 0 ]; then
        pkg_rm lad-mdsd
    fi

    # remove MDSD package
    check_if_pkg_is_installed mdsd
    MDSD_INSTALLED=$?
    if [ $MDSD_INSTALLED -eq 0 ]; then
        pkg_rm mdsd
    fi

    echo "LAD successfully purged!"
fi


# REMOVE OMS
echo "--------------------------------------------------------------------------------"
echo "------------------------------ STARTING OMS PURGE ------------------------------"
echo "--------------------------------------------------------------------------------"
echo ""

# Check if installed via extension
ls /var/lib/waagent | grep -i Microsoft.EnterpriseCloud.Monitoring.OmsAgentForLinux- > /dev/null 2>&1
EXTENSION_INSTALLED=$?
if [ $EXTENSION_INSTALLED -eq 0 ]; then
    echo ""
    echo "Please go to portal.azure.com and uninstall the OMS extension and its dependencies."
    echo "Go to Azure Portal -> Virtual Machines -> <vm_name> -> Settings -> Extensions"
    echo "and then click the '...' in the OMSAgentForLinux row and click 'Uninstall'"
    echo "(Do this as well with the DependencyAgentLinux row)"
    echo "---------- IMPORTANT NOTE ----------"
    echo "If you have a policy or ASC set up to push the OMS Extension to the machine, it"
    echo "will quickly re-install the extension. To ensure that this doesn't occur, please"
    echo "make sure to resume the script immediately after the extension is uninstalled"
    echo "via portal."
    echo "------------------------------------"
    read -p "Press enter to proceed once the OMS Extension is uninstalled." toss2
    echo ""
fi

# run OMS purge command
echo "---------- Downloading OMS Uninstall Script ----------"
if [ ! -f $OMS_UNINSTALL_AGENT ]; then
    wget https://raw.githubusercontent.com/microsoft/OMS-Agent-for-Linux/master/installer/scripts/uninstall.sh
    if [ $? -ne 0 ]; then
        echo "Error accessing Github to download the uninstall script for the OMS Agent" >&2
        echo "Please ensure that this machine can connect to the following URL:" >&2
        echo "  https://raw.githubusercontent.com/microsoft/OMS-Agent-for-Linux/master/installer/scripts/uninstall.sh" >&2
        echo "Or ensure the uninstall.sh script is available in the same directory as this script." >&2
        call_exit $UNINSTALL_AGENT_MISSING
    fi
fi
echo ""

echo "---------- Running OMS Uninstall Script ----------"
chmod +x uninstall.sh
./uninstall.sh P

# remove OMS Extension info

if [ -f $WAAGENT_XML ]; then
    STOPPED_WAAGENT=1
    echo "Temporarily stopping waagent..."
    stop_waagent

    echo "Removing OMS Extension files..."
    rm -rf $WAAGENT_XML
fi

# remove directories (if they exist)
echo "---------- Removing all relevant directories ----------"
dir_rm /etc/opt/microsoft/auoms
dir_rm /etc/opt/microsoft/dependency-agent
dir_rm /etc/opt/microsoft/omsagent
dir_rm /etc/opt/microsoft/scx
if [ "$(ls -A /etc/opt/microsoft 2>/dev/null  |wc -w)" = "0" ]; then
    dir_rm /etc/opt/microsoft
fi

dir_rm /opt/microsoft/auoms
dir_rm /opt/microsoft/dependency-agent
dir_rm /opt/microsoft/omsagent
dir_rm /opt/microsoft/omsconfig
dir_rm /opt/microsoft/scx
if [ "$(ls -A /opt/microsoft 2>/dev/null  |wc -w)" = "0" ]; then
    dir_rm /opt/microsoft
fi

dir_rm /var/opt/microsoft/auoms
dir_rm /var/opt/microsoft/dependency-agent
dir_rm /var/opt/microsoft/omsagent
dir_rm /var/opt/microsoft/omsconfig
dir_rm /var/opt/microsoft/scx
if [ "$(ls -A /var/opt/microsoft 2>/dev/null  |wc -w)" = "0" ]; then
    dir_rm /var/opt/microsoft
fi

dir_rm /etc/opt/omi
dir_rm /opt/omi
dir_rm /var/opt/omi

if [ $EXTENSION_INSTALLED -eq 0 ]; then
    for d in /var/lib/waagent/Microsoft.EnterpriseCloud.Monitoring.OmsAgentForLinux-*
    do
        dir_rm d
    done
fi

echo ""

echo "---------- Removing Users and Groups ----------"
user_rm omsagent
user_rm omi
user_rm nxautomation

group_rm omiusers
group_rm omi
group_rm omsagent
group_rm nxautomation
echo ""

if [ $STOPPED_WAAGENT -eq 1 ]; then
    echo "Restarting waagent..."
    restart_waagent
fi

echo ""
echo "--------------------------------------------------------------------------------"
echo "OMS Agent should be fully purged!"
echo "(If you see a lot of errors above, try running the script again.)"
echo "In order to reinstall the agent, either:"
echo "  - Wait for Azure Security Center to provision the VM (if it is active)"
echo "  - Manually connect the VM to the workspace (Azure Log Analytics - > Workspace -> Virtual Machines -> VM_name -> Connect)"
echo "  - Install+onboard via shell bundle using the onboard_agent.sh file:"
echo "    $ wget https://raw.githubusercontent.com/Microsoft/OMS-Agent-for-Linux/master/installer/scripts/onboard_agent.sh"
echo "    $ sudo sh ./onboard_agent.sh -w <workspace_id> -s <shared_key>"
echo "Thank you!"
call_exit 0