#!/bin/sh
#
# Dummy external solver to communicate with OpenFOAM via externalCoupled
# functionObject
#
# Functionality is hard-coded for this particular test case
# - patch temperatures increased by 1K on each step
#
cd ${0%/*} || exit 1    # Run from this directory

# Check for unassigned variables
set -u

echo "Executing dummy external solver"

commsDir="comms"
regionGroupName="heater_topAir"
patchGroupName="coupleGroup"
fieldName="T"

lockFile="${commsDir}/OpenFOAM.lock"
dataFile="${commsDir}/${regionGroupName}/${patchGroupName}/${fieldName}"
waitSec=5
timeOut=100
nSteps=1000 # maximum number of time steps. Note: should be more than
            # number of iterations on the OpenFOAM side
refGrad=0
valueFraction=1


# Remove any old junk
\rm -f $lockFile 2>/dev/null

log()
{
    echo "External: $@"
}

init()
{
    log "initialisation: creating ${dataFile}.in"

    # Hard-coded for patch of size 8 (heater/minY)
    n1=8
    refValue1=500
    touch "${dataFile}.in"
    log "initialisation: adding $n1 data elements with refValue $refValue1"
    for i in $(seq 1 $n1); do
        echo "$refValue1 $refGrad $valueFraction" >> "${dataFile}.in"
    done

    # Hard-coded for patch of size 40 (topAir/minX)
    n2=40
    refValue2=300
    log "initialisation: adding $n2 data elements with refValue $refValue2"
    for i in $(seq 1 $n2); do
        echo "$refValue2 $refGrad $valueFraction" >> "${dataFile}.in"
    done

    # Create lock file to pass control to OpenFOAM
    touch ${lockFile}
}


# create the comms directory
mkdir -p ${commsDir}/${regionGroupName}/${patchGroupName}

# tutorial case employs the 'initByExternalOption', so we need to provide
# the initial values
init


totalWait=0
step=0
while [ $step -lt $nSteps ]
do
    if [ -f $lockFile ]
    then
        if grep -q "status=done" ${lockFile}
        then
             log "found lock file ${lockFile} with 'status=done' - finished"
             break
        elif [ -s $lockFile ]
        then
             log "found lock file ${lockFile} containing '$(cat $lockFile)' - waiting"
        else
             log "found lock file ${lockFile} - waiting"
        fi

        totalWait=$(expr $totalWait + $waitSec)
        if [ $totalWait -gt $timeOut ]
        then
            log "timeout"
            break
        else
            sleep $waitSec
        fi
    else
        totalWait=0
        step=$(expr $step + 1)
        log "step $step"
        log "lock not present - taking control"

        log "sleeping for $waitSec secs to simulate external process"
        sleep $waitSec

        log "updating ${dataFile}.in from ${dataFile}.out"

        awk '{if( $1 != "#" ){print $1+1 " 0 1"}}' \
            ${dataFile}.out >| ${dataFile}.in

        log "creating lock file ${lockFile}"
        touch ${lockFile}
    fi
done

log "done"

# Remove the lock file too
\rm -f $lockFile 2>/dev/null

#------------------------------------------------------------------------------