#!/bin/sh
#
# Define and install a libvirt domain
#
# Copyright 2013 Guilhem Moulin <guilhem@fripost.org>
#
# Licensed under the GNU GPL version 3 or higher.
#

set -ue
root=$(dirname "$0")

help() {
    cat >&2 <<-EOF
		Usage:
		  $0 install <libvirt domain> [<QEMU image>]
		      Install the given domain, using the given image (created if
		      necessary) as a disk.
		  $0 view <libvirt domain>
		      Open a connection to a running domain using the Spice protocol
	EOF
    exit 1
}

get_XML_attribute() {
    local domain="$1" object="$2" attribute="$3"

    /usr/bin/virsh dumpxml "$domain" \
    | /usr/bin/xmlstarlet sel -t -m /domain/"$object" -v @"$attribute"
}
add_net_section() {
    local net="${3:-$network}" section="$1" xml="$2"
    /usr/bin/virsh net-update "$net" add "$section" --xml "$xml" --live --config
}

doesExist() {
    /usr/bin/virsh -r list --all --name | grep -qxF "$1"
}
isActive() {
    /usr/bin/virsh -r list       --name | grep -qxF "$1"
}

install() {
    [ $# -eq 1 -o $# -eq 2 ] || help
    local name=$1
    local disk=${2:-$root/images/${name}.qcow2}

    local darch version=$(sed -n 's/^VERSION\s*=\s*//p' $root/../preseed/Makefile)
    case "${ARCH:=$(/bin/uname -m)}" in
        i386|i686) darch=i386;;
        x86_64)    darch=amd64;;
        *)         darch=$ARCH;;
    esac
    local cdrom="$root/../preseed/dist/$darch/debian-$version-$darch-netinst-preseeded.iso"

    if doesExist "$name"; then
        echo "Error: Domain $name already exists. If you want to replace the domain, run" >&2
        echo >&2
        isActive "$name" && echo "    virsh destroy  $name" >&2
        echo "    virsh undefine $name" >&2
        exit 1
    fi
    if ! [ -f "$cdrom" -a -r "$cdrom" ]; then
        cat >&2 <<- EOF
			Error: '$cdrom' does not exist or is not readable.
			To create the preseeded image, run

			    cd $root/../preseed
			    ARCH=$darch make iso-preseed
		EOF
        exit 1
    fi

    grep -q '^kvm\s' /proc/modules || echo 'WARN: KVM not available!' >&2

    if ! [ -r "$disk" -a -r "$disk" ]; then
        local size=12G
        echo "Creating (sparse) $size disk image '$disk'" >&2
        /usr/bin/qemu-img create -f "${disk##*.}" \
            -o size="$size",preallocation=metadata "$disk"
    fi

    # TODO: the bus should be chosen at random among sata,ide,scsi,usb
    # TODO: test EFI: http://www.linux-kvm.org/page/OVMF
    local network=default
    /usr/bin/virt-install -q \
        --name      "$name" \
        --arch      "$ARCH" \
        --ram       128 \
        --cdrom     "$cdrom" \
        --disk      "$disk",cache=writeback,bus=sata \
        --network   network=$network \
        --graphics  spice

    # Attribute the next available IP. You may also want to add a domain
    # section, e.g., <domain name='libvirt.example.org'/>, and prepend
    # the DNS IP to /etc/resolv.conf.
    # Cf. http://libvirt.org/formatnetwork.html
    local mac ip
    mac=$(get_XML_attribute "$name" devices/interface/mac address)
    ip=$( /usr/bin/virsh net-dumpxml $network \
        | /usr/bin/xmlstarlet sel -t -m /network/ip/dhcp/host -n -v @ip \
        | sed '/^\s*$/d' \
        | sort -n \
        | tail -1 )
    [ -n "$ip" ] || \
    ip=$( /usr/bin/virsh net-dumpxml $network \
        | /usr/bin/xmlstarlet sel -t -m /network/ip -v @address )
    ip=${ip%.*}.$(( 1 + ${ip##*.} ))
    add_net_section ip-dhcp-host "<host mac='$mac' name='$name' ip='$ip'/>"
    add_net_section dns-host     "<host ip='$ip'><hostname>$name</hostname></host>"

    cat >&2 <<- EOF
		Domain '$name' has been created, and has been attributed the IP $ip.
		As you can see in

		    virsh list

		it should now be up and running. To open a graphical console, run

		    $0 view $name
	EOF
}

view(){
    [ $# -eq 1 ] || help
    local domain="$1"

    if ! doesExist "$domain"; then
        cat >&2 <<- EOF
			Error: Domain $domain does not exist. To create it, run

			  ./virt install $domain
		EOF
        exit 1
    elif ! isActive "$domain"; then
        echo "Error: Domain $domain is not active" >&2
        exit 1
    fi

    local type=$(get_XML_attribute "$domain" devices/graphics type)
    local port=$(get_XML_attribute "$domain" devices/graphics port) || true

    if [ "$type" != spice -o -z "$port" ]; then
        echo "Error: Could not find a valid Spice server on domain '$domain'." >&2
        exit 1
    fi
    /usr/bin/spicec -h 127.0.0.1 -p $port
}

command="${1:-}"
shift;

case "$command" in
    install|view) $command "$@";;
    *) help
esac