#!/bin/bash
#
#   CDM: The Console Display Manager
#
#   Copyright (C) 2009-2011, Daniel J Griffiths <ghost1227@archlinux.us>
#   Thanks to:
#
#       Andrwe          beta-testing and submitting the fix for the all
#                       important X incrementation function
#       brisbin33       code cleanup
#       tigrmesh        finding a critical issue with the gnome-session handler
#       Profjim         several incredibly useful patches
#       lambchops468    consolekit and hibernation patches
#       CasperVector    Massive rearchitecturing and code sanitation
#
#   This program 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 2 of the License, or
#   (at your option) any later version.
#   
#   This program 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 this program; if not, write to the Free Software
#   Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston,
#   MA 02110-1301, USA.

name=$(basename "$0")
longname='Console Display Manager'
ver='0.6'

trap '' SIGINT SIGTSTP

# Helper functions.

warn() { (printf ' \033[01;33m*\033[00m '; echo "$name: $*") > /dev/stderr; }
error() { (printf ' \033[01;31m*\033[00m '; echo "$name: $*") > /dev/stderr; }
exitnormal() { exit 0; }
exiterror() { sleep 1; exit 1; }
yesno()
{
    [ -z "$1" ] && return 1
    eval value=\$${1}

    case "$value" in
        [Yy][Ee][Ss]|[Tt][Rr][Uu][Ee]|[Oo][Nn]|1) return 0;; 
        [Nn][Oo]|[Ff][Aa][Ll][Ss][Ee]|[Oo][Ff][Ff]|0) return 1;; 
        *) warn "Invalid value for \`$1'; falling back to \`no' for now.";;
    esac
}

# Source cdm configurations.

if [[ -n "$1" ]]; then
    if [[ -f "$1" ]]
    then
        source "$1"
    else
        error "config file \`$1' does not exist."
        exiterror
    fi
elif [[ -f "$HOME/.cdmrc" ]]; then
    source "$HOME/.cdmrc"
elif [[ -f /etc/cdmrc ]]; then
    source /etc/cdmrc
fi

# Default options.

binlist=${binlist:-()}
namelist=${namelist:-()}
flaglist=${flaglist:-()}
dialogrc=${dialogrc:-}
countfrom=${countfrom:-0}
display=${display:-0}
xtty=${xtty:-7}
locktty=${locktty:-no}
serverargs=${serverargs:-'-nolisten tcp'}
consolekit=${consolekit:-yes}
cktimeout=${cktimeout:-30}

# Offer all available sessions in /etc/X11/Sessions,
# if binlist if not explicitly set in cdmrc.

if [[ "$binlist" == "()" ]]; then
    binlist=($(ls /etc/X11/Sessions))
    flaglist=($(sed 's/[[:digit:]]\+/X/g' <<< ${!flaglist[*]}))
    namelist=(${binlist[@]^})
fi

# Generate the main menu.
menu=()
for ((count = 0; count < ${#namelist[@]}; count++)); do
    menu=("${menu[@]}" "$((count+countfrom))" "${namelist[${count}]}")
done

# Override dialog display if only one option is available.
if [[ "$count" == 1 ]]; then
    binindex=0
else
    # Display selection dialog.
    binindex=$(
        DIALOGRC="$dialogrc" dialog --colors --stdout \
        --backtitle "${longname} v${ver}" \
        --ok-label ' Select ' --cancel-label ' Exit ' \
        --menu 'Select session' 0 0 0 "${menu[@]}"
    )
    if [[ $? != 0 ]]; then
        clear
        exitnormal
    fi
fi

# Run $bin according to its flag.
let binindex-=countfrom
bin="${binlist[${binindex}]}"
case ${flaglist[$binindex]} in
    # *C*onsole programs.
    [Cc])
        clear
        # If $bin is a login shell, it might `exec' cdm again, causing an endless
        # loop. To solve this problem, export $CDM_SPAWN when `exec'ing $bin and
        # only let the shell automatically `exec' cdm when $CDM_SPAWN is not set.
        # See also the example shell profile file shipped with the cdm package.

        # Also untrap SIGINT and SIGTSTP before spawning process: If this is not
        # done, *ANY* child process of *ANY* child (bash) shell will completely
        # ignore SIGINT, which is rather confusing, and cannot be undone.

        trap - SIGINT SIGTSTP
        CDM_SPAWN=$$ exec $bin
        ;;

    # *X* programs.
    [Xx])
        clear

        # If X is already running and locktty=yes, activate it
        if $(yesno locktty); then
            if xdpyinfo -display ":$display.0" &> /dev/null; then
                chvt "$((display+xtty))"
                exitnormal
            fi
        fi

        # Get the first empty display.
        display=0
        while ((display < 7)); do
            if dpyinfo=$(xdpyinfo -display ":$display.0" 2>&1 1>/dev/null) ||
                # Display is in use by another user.
                [[ "$dpyinfo" == 'No protocol specified'* ]] ||
                # Invalid MIT cookie.
                [[ "$dpyinfo" == 'Invalid MIT'* ]]
            then
                let display+=1
            else
                break
            fi
        done

        # run X in current tty
        if [[ $xtty == "keep" ]]; then
            vt=$(tty)
            vt=${vt#/dev/}
            if [[ $vt != tty* ]]; then
                error "error: invalid TTY"
                exiterror
            fi
            vt=${vt#tty}
        else
            vt=$((xtty+display))
        fi

        serverargs=":${display} $serverargs vt$vt"

        $(yesno consolekit) && launchflags="-c -t $cktimeout"
        if ! eval cdm-xlaunch $launchflags -- $bin -- $serverargs; then
            warn "\`cdm-xlaunch' exited unsuccessfully."
            exiterror
        else
            exitnormal
        fi
        ;;

    *)
        error "unknown flag: \`${flaglist[$binindex]}'."
        exiterror
        ;;
esac

# vim:set ts=4 sw=4 et: