vm

#!/bin/bash -ue
#
# 'vmscripts' low-level VM management scripts main call entry point
#
# Copyright © 2015 Thilo Fromm. Released under the terms of the GNU GLP v3.
#
#    vmscripts 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 3 of the License, or
#    (at your option) any later version.
#
#    vmscripts 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 vmscripts. If not, see <http://www.gnu.org/licenses/>.#
#


#     MODULES API
#   ===============
#
# - modules must be in the current PATH
# - modules are named 'vm-<modname>.sh'
# - modules *MUST* immplement at least a main function like
#
#  vm_<modname>() {
#       # main entry function of module
#  }
#
# -----------------
#
# - modules *MAY* implement these utility functions:
#
#   <modname>_usage() {
#       echo "Usage: vm <modname> ...."
#   }
#
#   -----
#
#   <modname>_complete() {
#       # auto-complete helper for the module
#   }
#
#   -----
#
# - modules *MAY* define command line arguments for use with auto completion,
#    e.g.:
#
# <modname>_shortopts="-i -d -s -M -m" 
# <modname>_longopts="--iso --disk --disk-size --move --mem"
#
#   -----
# 
# - modules *MAY* define one global variable determining the importance of the
#   <vm-name> argument:
#
#  vmscripts_prereq=""
#
#  Values:
#    'none'      - VM name must neither be provided nor needs the VM to exist
#    'name'      - A VM name must be provided
#    'exist'     - A name must be provided and the corresponding VM must exist
#    'inactive'  - The VM specified by the <name> argument must be powered off
#    'active'    - The VM specified by the <name> argument must be up + running
# 
# -----------------
#
# Variables defined and exported by "vm" main entry script
# - basically, look at setup_env() below
# - also, all values from the config and the run time config

#
# Variables and Functions to be used by modules
#

VM_CONFIG_PATH="$HOME/.vmscripts"
[ ! -d "$VM_CONFIG_PATH" ] && mkdir -p "$VM_CONFIG_PATH"
export VM_CONFIG_PATH
# ----

usage() {
    local ret=0
    echo
    if [ $# -ge 1 ] ; then
        echo " vm $vm_cmd: $@"
        echo
        ret=1
    fi
    ${vm_cmd}_usage
    echo
    exit $ret
}
# ----

die() {
    echo                >&2
    echo "ERROR: $@"    >&2
    echo                >&2
    exit 1
}
# ----

write_rtconf() {
    echo "$1=\"$2\"" >> "$vm_rtconf"
}
# ----

#
# 'vm' script internal Variables and Functions
#

function source_with_defaults() {
    local cmd="$1"
    local script=$(which "vm-${cmd}.sh" 2>/dev/null)
    [ -z "$script" ] && return 1

    vmscripts_prereq="none"
    eval "${cmd}_usage()    { return ; }"
    eval "${cmd}_complete() { return 1; }"
    eval "${cmd}_longopts=''"
    eval "${cmd}_shortopts=''"
    source "$script"
}
# ----

vm_usage() {
    local ret=0
    echo
    if [ $# -ge 1 ] ; then
        echo " $@"
            ret=1
    fi
    echo " Usage:"
    echo "    vm <creat|prepare|ls|slink|start|ports|iodir|attach|ssh|off|purge>"
    echo
    exit $ret
}
# ----

setup_env() {
    vm_name="$1"
    vm_path="$VM_CONFIG_PATH/$vm_name"

    local vm_prefix="$vm_path/$vm_name"

    vm_disk_image="${vm_prefix}.img"
    vm_iso_image="${vm_prefix}.iso"

    vm_iodir="${vm_prefix}-io"

    vm_pidfile="${vm_prefix}.pid"
    vm_logfile="${vm_prefix}.log"

    vm_rtconf="${vm_prefix}.run"
    vm_config="${vm_prefix}.cfg"

    # source static and run time config if present
    [ -f "$vm_config" ] && source "$vm_config"
    [ -f "$vm_rtconf" ] && source "$vm_rtconf"

    [ -z "${netmode-}" ] && netmode="hidden"
    
    vm_tools_initialized="YES"

    export vm_name vm_path vm_disk_image vm_iso_image vm_pidfile \
           vm_logfile vm_rtconf vm_config vm_tools_initialized write_rtconf \
           vm_iodir
}
# ----

initialize_command() {
    local cmd="$1"

    source_with_defaults "$cmd" || \
        vm_usage  "Unknown command '$vm_cmd'."

    # check VM name command line option
    [ "$vmscripts_prereq" = "none" ] && return

    [ -z "$vm_name" ] &&    \
        usage "This command takes a mandatory <name> argument"
    [ "$vmscripts_prereq" = "name" ] && return

    vm ls | grep -qw "$vm_name" || \
        usage "Unknown VM ${vm_name}. Try 'vm ls' to get a list."
    [ "$vmscripts_prereq" = "exist" ] && return

    case "$vmscripts_prereq" in
    active)
        vm ls -a | grep -qw "$vm_name" || \
            usage "VM ${vm_name} is currently inactive. Try starting it with 'vm start $vm_name'."
            ;;
    inactive)
        vm ls | grep '(active)' | grep -qw "$vm_name" && \
            usage "VM ${vm_name} is currently active. Try shutting it down with 'vm off $vm_name'."
            ;;
    esac

    return 0
}
# ----

vm_complete() {
    local cword="$1"; shift
    local words=( $@ )
    local cur="${words[$cword]-}"
    local opts="creat prepare ls slink start ports iodir attach ssh off purge"

    [ $cword -eq 1 ] && { compgen -W "${opts}" -- ${cur}; return; }

    local cmd="${words[1]}"
    source_with_defaults "$cmd" || return
    
    while true; do
        [ $cword -eq 2 ] && case $vmscripts_prereq in
            exist)
                compgen -W "$(vm ls                  \
                                | awk '{print $1}')" -- ${cur}; break ;;
            inactive)
                compgen -W "$(vm ls                  \
                                | grep -v '(active)' \
                                | awk '{print $1}')" -- ${cur}; break ;;
            active)
                compgen -W "$(vm ls -a               \
                                | awk '{print $1}')" -- ${cur}; break ;;
        esac
        break
    done

    [ $cword -le 2 -a "$vmscripts_prereq" != "none" -o $cword -le 1 ] && return

    opts="$(eval echo \$${cmd}_shortopts) $(eval echo \$${cmd}_longopts)"
    if [ -n "$opts" ] && ! ${cmd}_complete "$cword" $@ ; then
        compgen -W "${opts}" -- $cur
    fi
}
# ----

vm_main() {
    vm_name=""
    vm_cmd=""

    [ $# -lt 1 ] && vm_usage "No command provided."
    [ "$1" = "-h" ] && vm_usage
    [ "$1" = "complete" ] && { shift; vm_complete $@; exit; }

    vm_cmd="$1"; shift
    export vm_cmd

    setup_env "${1-}"
    local script=$(which "vm-${vm_cmd}.sh" 2>/dev/null)

    initialize_command "$vm_cmd"
    [ "${1-}" = "-h" ] && usage

    vm_${vm_cmd} "$@"
}
# ----

if [ `basename "$0"` = "vm" ] ; then
    vm_main "$@"
else
    true
fi