#!/bin/bash

# BASICS ***************************************************************
# enable extended globbing
shopt -qs extglob

# VARS *****************************************************************
scriptName="${0##*/}"
scriptDir=$(readlink -f "${0%/*}")
scriptVersion=1.1
scriptLock="$scriptDir/$scriptName.pid"
scriptPipe="$scriptDir/$scriptName.fifo"

# FUNCS ****************************************************************
getScreenConfig() {
    local wmctrld=$(wmctrl -d | sed 's/\*//g')

    # desktop geometry
    dX=${wmctrld##*DG: } && dX=${dX%%x*}
    dY=${wmctrld#*x} && dY=${dY%% *}

    # viewport geometry
    vX=${wmctrld##*WA: } && vX=${vX#* } && vX=${vX%%x*}
    vY=${wmctrld##*x} && vY=${vY%% *}

    # viewport config
    (( vRows=dX/vX , vCols=dY/vY, vTotal=vRows*vCols ))

    # current viewport
    cvX=${wmctrld##*VP: } && cvY=${cvX#*,}
    cvX=${cvX%%,*} && cvY=${cvY%% *}

    # verbosity
    [[ "$1" == "-v" ]] && {
        echo "Geometry: desktop $dX"x"$dY, viewport: $vX"x"$vY"
        echo "Viewports: $vRows"h \* "$vCols"v = "$vTotal total"
        echo "Current viewport: "$(getV $cvX $cvY)" ($cvX,$cvY)"
    }
}

getX() {
    echo $(( (($1 - 1) % vRows) * vX ))
}

getY() {
    echo $(( (($1 - 1) / vRows) * (vY + 1) ))
}

getV() {
    echo $(( ($1 / vX) + (( $2 / (vY + 1) ) * vRows) + 1 ))
}

gotoViewport() {
    (( $1 > 0 && $1 <= vTotal )) && {
        echo "$FUNCNAME: switching to viewport $1 ("$(getX $1),$(getY $1)")"
        wmctrl -o $(getX $1),$(getY $1)
        return $?
    }
    echo "$FUNCNAME: parameter may be an integer between 1 and $vTotal, got $1"
    return 1
}

gotoWindow() {
    wmctrl -a "$1" && {
        echo "$FUNCNAME: switching to window \"$1\" - viewport "$(getV $cvX $cvY)" ($cvX,$cvY)"
        return $?
    }
    echo "$FUNCNAME: couldn't find a window named \"$1\""
    return 1
}

cmdGoto() {
    ! (( $# )) && echo "$FUNCNAME: need parameters, accepting \$1=viewport|(+|-)viewport|windowname" && return 1
    (( $# > 1 )) && echo "$FUNCNAME: extra parameters, accepting \$1=viewport|(+|-)viewport|windowname" && return 1

    case "$1" in
        # viewport
        +([[:digit:]])) gotoViewport "$1" ;;
        # viewport offset
        @(-|+)+([[:digit:]]))
            getScreenConfig
            local remainder=$(( ($(getV $cvX $cvY) + ($1)) % vTotal ))
            gotoViewport $(( (remainder ? 0 : vTotal) + remainder ))
        ;;
        # window
        *) gotoWindow "$1" ;;
    esac
    return $?
}

cmdRotate() {
    ! (( $# )) && echo "$FUNCNAME: need parameters, accepting \$1=delay \$2=(+|-)step" && return 1
    (( $# > 2 )) && echo "$FUNCNAME: extra parameters, accepting \$1=delay \$2=(+|-)step" && return 1
    [[ "${1//*([[:digit:]])}" ]] && echo "$FUNCNAME: \"$1\" is not a positive integer" && return 1
    [[ "${2//@(-|+)*([[:digit:]])}" ]] && echo "$FUNCNAME: \"$2\" is not a positive step" && return 1

    echo "$FUNCNAME: setting rotation interval to $1 seconds"
    # if there is a rotation loop running, finish it
    [[ "${rotPID+defined}" ]] && cmdStop
    doRotate "$@" &
    rotPID=$!
    return $?
}

cmdStop() {
    [[ ! "${rotPID+defined}" ]] && echo "$FUNCNAME: there isn't any rotation loop running" && return 1
    (($#>1)) && echo "$FUNCNAME: extra parameters, accepting \$1=viewport|(+|-)viewport|nombre-ventana" && return 1

    # if there is a rotation loop running, finish it
    echo "$FUNCNAME: finishing rotation $rotPID"
    kill -15 $rotPID &
    unset rotPID

    # we have a goto
    [[ $1 ]] && cmdGoto "$1"

    return $?
}

doRotate() {
    echo "$FUNCNAME ($BASHPID): starting rotation..."
    trap "trap - TERM && echo $FUNCNAME \($BASHPID\): exiting... && exit 0" TERM
    while sleep $1; do cmdGoto ${2-+1}; done
}

doInit() {
    echo "$FUNCNAME: initializing..."

    # lock
    (set -o noclobber; echo "$$" > "$scriptLock") &>/dev/null || {
        # lock found
        echo "$FUNCNAME: found lockfile, checking if the process is alive..."

        # here goes a check using "cmd pid"

        kill -0 $(cat "$scriptLock") &>/dev/null && \
        echo "$FUNCNAME: found a running proceess with ID " $(cat "$scriptLock")", saliendo..." && exit 0

        # dead pid: clean up
        rm -f $scriptPipe &>/dev/null
        echo "$$" >| "$scriptLock"
    }

    # pipe (connect stdin too)
    mknod "$scriptPipe" p

    # traps
    trap "doExit" INT TERM EXIT
}

doExit() {
    echo "$FUNCNAME: exiting..."

    # if there is a rotation loop running, finish it
    [[ "${rotPID+defined}" ]] && cmdStop

    # delete lock and exit
    rm -fv "$scriptLock" "$scriptPipe"
    exit $?
}

getInput() {
    echo "$scriptName: waiting for commands"
#    while read -ep"-> " line; do
    while true; do
        read line < "$scriptPipe"
        case "$line" in
            @(goto|rotate|stop)*(+([[:space:]])*)) cmd${line^} ;;
            quit) doExit ;;
            pid) echo $$ ;;
            *) echo "$scriptName: unknown command: $line" ;;
        esac
    done
}

# MAIN *****************************************************************
doInit
getScreenConfig -v
getInput

scriptname &

echo "command" > pipe

cat>pipe