#!/bin/sh
#
# Automatically select a display configuration based on connected devives
#
# Stefan Tomanek <stefan.tomanek@wertarbyte.de>
#
# requires disper, the command line display switcher:
# http://willem.engen.nl/projects/disper/
#
#
# How to use:
#
# Save your current display configuration and setup with
# auto-disper --save mobil
#
# Connect an additional display, configure your setup and save it
# auto-disper --save docked
#
# Now auto-disper can detect which hardware setup is active: # auto-disper
# mobile
# docked (detected)
#
# To automatically reload your setup, just append --change to the command line
#
# To manually load a profile, you can use the --load <profile> option.
#
# To prevent a profile from being loaded, place a script call "block" in its
# directory. The script is evaluated before the screen setup is inspected, and
# in case of it returning a value of 0 the profile is skipped. This can be used
# to query the status of a docking station you are about to leave.
#
# If no suitable profile can be identified, the current configuration is kept.
# To change this behaviour and switch to a fallback configuration, specify
# --default <profile>
#
# Another script called "postswitch "can be placed in the directory
# ~/.auto-disper as well as in all profile directories: The scripts are
# executed after a mode switch has taken place and can notify window managers
# or other applications about it.

DISPER=/usr/bin/disper
PROFILES=~/.auto-disper/

CHANGE_PROFILE=0
DEFAULT_PROFILE=""
SAVE_PROFILE=""

blocked() {
    local PROFILE="$1"
    [ ! -x "$PROFILES/$PROFILE/block" ] && return 1

    "$PROFILES/$PROFILE/block"  "$PROFILE"
}

load() {
    local PROFILE="$1"
    if [ "$CHANGE_PROFILE" -eq 1 ]; then
        echo " -> loading profile $PROFILE"
        $DISPER -i < "$PROFILES/$PROFILE/config"

        [ -x "$PROFILES/$PROFILE/postswitch" ] && \
            "$PROFILES/$PROFILE/postswitch" "$PROFILE"
        [ -x "$PROFILES/postswitch" ] && \
            "$PROFILES/postswitch" "$PROFILE"
    fi
}

# process parameters
OPTS=$(getopt -n auto-disper -o s:l:d:c --long change,default:,save:,load: -- "$@")
if [ $? != 0 ] ; then echo "Terminating..." >&2 ; exit 1 ; fi
eval set -- "$OPTS"

while true; do
    case "$1" in
        -c|--change) CHANGE_PROFILE=1; shift ;;
        -d|--default) DEFAULT_PROFILE="$2"; shift 2 ;;
        -s|--save) SAVE_PROFILE="$2"; shift 2 ;;
        -l|--load) LOAD_PROFILE="$2"; shift 2 ;;
        --) shift; break ;;
        *) echo "Error: $1"; exit 1;;
    esac
done

CURRENT_SETUP="$($DISPER -l | grep '^display ')"

if [ -n "$SAVE_PROFILE" ]; then
    echo "Saving current configuration as profile '${SAVE_PROFILE}'"
    mkdir -p "$PROFILES/$SAVE_PROFILE"
    echo "$CURRENT_SETUP" > "$PROFILES/$SAVE_PROFILE/setup"
    $DISPER -p > "$PROFILES/$SAVE_PROFILE/config"
    exit 0
fi

if [ -n "$LOAD_PROFILE" ]; then
    CHANGE_PROFILE=1 load "$LOAD_PROFILE"
    exit $?
fi

for SETUP_FILE in $PROFILES/*/setup; do
    if ! [ -e $SETUP_FILE ]; then
        break
    fi
    PROFILE="$(basename $(dirname "$SETUP_FILE"))"
    echo -n "$PROFILE"

    if blocked "$PROFILE"; then
        echo " (blocked)"
        continue
    fi

    FILE_SETUP="$(cat "$PROFILES/$PROFILE/setup")"
    if [ "$CURRENT_SETUP" = "$FILE_SETUP" ]; then
        echo " (detected)"
        load "$PROFILE"
        # found the profile, exit with success
        exit 0
    else
        echo ""
    fi
done

# we did not find the profile, load default
if [ -n "$DEFAULT_PROFILE" ]; then
    echo "No suitable profile detected, falling back to $DEFAULT_PROFILE"
    load "$DEFAULT_PROFILE"
fi
exit 1