#!/bin/bash

## Improved version of the script at https://askubuntu.com/a/1068932
##
## Disables the Evolution mail program's services by moving the services files
## to another directory.
##
## This must be run as root.
##

myname=$(basename "$0")

promp_usage()
{
    echo "Usage: $myname ( --enable | --disable )"
    exit 1
}

if [ $# -ne 1 ]
then
    promp_usage
fi

SERVICES_HOME="/usr/share/dbus-1/services"
DISABLED_DIR="$SERVICES_HOME/disabled"


die()
{
    local errorCode=$1
    local errorMessage="$2"

    echo "$errorMessage"
    exit $errorCode
}

check_assumptions()
{
    # Make sure that we are running as root and that the
    # services directory didn't change!
    if ! [ $(id -u) = 0 ]; then
        die -1 "Script must be run as root or sudo.  Exiting..."
    fi

    if [ ! -d "$SERVICES_HOME" ]; then
        die -2 "Services directory $SERVICES_HOME does not exist.  Exiting..."
    fi
}

find_evolution_services()
{
    find "$SERVICES_HOME" -maxdepth 1 \
                          -type f \
                          -name "org.gnome.evolution.dataserver.*" \
                          ! -name "*.bak" \
                          -printf "%f\0"
}

disable-services()
{
    mkdir -p "$DISABLED_DIR"

    find_evolution_services | while IFS= read -r -d $'\0' servicename
    do
        # Tell dpkg/apt to update the file in DISABLED_DIR instead
        # of the one in SERVICES_HOME
        dpkg-divert --quiet --divert "$DISABLED_DIR/$servicename" --rename --add "$SERVICES_HOME/$servicename" \
            || die -3 "Unable to divert service $servicename."

        ln -snf /dev/null  "$SERVICES_HOME/$servicename"
        echo "Disabled service $servicename"
    done

    echo "All evolution services have been disabled."
    echo "Please restart for changes to take effect."
}

enable-services()
{
    local servicename servicefile
    for servicename in AddressBook Calendar Sources UserPrompter
    do
        local servicefile=org.gnome.evolution.dataserver."$servicename".service
        rm "$SERVICES_HOME/$servicefile"
        dpkg-divert --rename --remove "$SERVICES_HOME/$servicefile"
    done
}

check_assumptions
case "$1" in
    --enable) enable-services ;;
    --disable) disable-services ;;
    *) promp_usage ;;
esac