#!/bin/bash
#################################################################################################
# title         :git-myshellconfig-checkout                                                     #
# description   :checkout git detached HEAD                                                     #
# author        :Jakobus Schürz                                                                 #
# changes by    :Jakobus Schürz                                                                 #
# created       :17.01.2019                                                                     #
# updated       :28.10.2020                                                                     #
# version       :2.0                                                                            #
# usage         :git myshellconfig-checkout [-h]                                                #
# notes         :                                                                               #
#################################################################################################

[ -z "${SGIT+x}" ] && SGIT=git
    [ -z "${MYSHELLCONFIG_LOGDIR+x}" ]                  && export MYSHELLCONFIG_LOGDIR="${HOME}/logs"
    [ -z "${MYSHELLCONFIG_LOGFILE+x}" ]                 && export MYSHELLCONFIG_LOGFILE="${MYSHELLCONFIG_LOGDIR}/myshellconfig.log"
#MYSHELLCONFIG_LOGDIR="./logs"
#MYSHELLCONFIG_LOGFILE="${MYSHELLCONFIG_LOGDIR}/git.log"
[ -d "${MYSHELLCONFIG_LOGDIR}" ] || mkdir -p "${MYSHELLCONFIG_LOGDIR}"
[ -z "${MYSHELLCONFIG_GIT_REMOTE_NAME+x}" ] && export MYSHELLCONFIG_GIT_REMOTE_NAME=origin
[ -z "${MYSHELLCONFIG_GIT_BRANCH+x}" ] && export MYSHELLCONFIG_GIT_BRANCH=master

gitupdateend() {
cat << EOF >> "${MYSHELLCONFIG_LOGFILE}"

+-----ENDE git update repo $(date) ---------------------------------+
 
EOF
}

ENTRY
cat << EOF >> "${MYSHELLCONFIG_LOGFILE}"
+-----BEGINN git update repo $(date) -------------------------------+
EOF

case $1 in
    -h)
        # Headless repo local
        PRE="${MYSHELLCONFIG_GIT_REMOTE_NAME}"
        ;;
    -s)
        dosubmodupdate="true"
        ;;
    *)
        PRE=""
        ;;
esac
# If TAG is set, checkout is always headless. 
[ -z "${MYSHELLCONFIG_GIT_TAG:+x}" ] || { export MYSHELLCONFIG_GIT_BRANCH=${MYSHELLCONFIG_GIT_TAG}; export PRE=""; }

# Output
#echo -n " remote: ${MYSHELLCONFIG_GIT_REMOTE_NAME}, branch: ${MYSHELLCONFIG_GIT_BRANCH}: "

# Check for updates in submodules only if last check was INTERVALL hours in the past
updated=$(cat ${MYSHELLCONFIG_BASE%/}${MYSHELLCONFIG_BASE:+/}.last_update_submodules 2>/dev/null || echo 0 )
if [ $updated -lt $(date --date="${MYSHELLCONFIG_GIT_SUBMODULES_UPDATE_INTERVALL} hours ago" "+%s") ]; then
    dosubmodupdate="true"
fi
    
#echo $SGIT fetch ${MYSHELLCONFIG_GIT_REMOTE_NAME} -p 1>&2 
$SGIT fetch ${dosubmodupdate:+--recurse-submodules} ${MYSHELLCONFIG_GIT_REMOTE_NAME} -p  2>>"${MYSHELLCONFIG_LOGFILE}"|| { logwarn fetch failed; gitupdateend; exit 1; }
if ${dosubmodupdate:-false}; then 
    date "+%s" > ${MYSHELLCONFIG_BASE%/}${MYSHELLCONFIG_BASE:+/}.last_update_submodules
fi

echo "Check for local changes:" >> "${MYSHELLCONFIG_LOGFILE}"
if $SGIT diff-index --ignore-submodules --exit-code HEAD -- >> "${MYSHELLCONFIG_LOGFILE}" ; then
    cat << EOF >> "${MYSHELLCONFIG_LOGFILE}"
    no changes in local repo
    $SGIT checkout repo ${PRE}${PRE:+/}${MYSHELLCONFIG_GIT_BRANCH}
EOF
    $SGIT checkout ${PRE}${PRE:+/}${MYSHELLCONFIG_GIT_BRANCH} 1>>"${MYSHELLCONFIG_LOGFILE}" 2>>"${MYSHELLCONFIG_LOGFILE}"|| { gitupdateend; exit 2; }
    $SGIT merge FETCH_HEAD 1>>"${MYSHELLCONFIG_LOGFILE}" 2>>"${MYSHELLCONFIG_LOGFILE}"|| { gitupdateend; exit 3; }
else
    logwarn -n "    Lokale Änderungen festgestellt:"
    echo "    Siehe Logfile ${MYSHELLCONFIG_LOGFILE}" >&2
    cat << EOF >> "${MYSHELLCONFIG_LOGFILE}"
    um die Änderung zurückzusetzen bitte

      $SGIT checkout \$FILENAME

    oder um alle lokalen Änderungen auf einmal zurückzusetzen:

      $SGIT checkout .

    ausführen

    Die Änderungen sind:
    $($SGIT diff-index HEAD --|awk '{print $5, $6}')
    $($SGIT diff-index -p HEAD --)
EOF

    gitupdateend
    exit 4

fi

logwarn "   repo synced"

if ${MYSHELLCONFIG_GIT_SUBMODULES_UPDATE-${MYSHELLCONFIG_GIT_SUBMODULES_UPDATE_DEFAULT-true}}; then
    if ${dosubmodupdate:-false}; then 
        logdebug "$($SGIT submodule update --remote)"
        logdebug "$($SGIT commit -a -m 'update submodules')"
        date "+%s" > ${MYSHELLCONFIG_BASE%/}${MYSHELLCONFIG_BASE:+/}.last_update_submodules
        logwarn "   submodules synced"
    fi
else
    loginfo -n ", submodules not synced"
    logdebug "Do not update submodules. It's denied by environment MYSHELLCONFIG_GIT_UPDATE_SUBMODULES: ${MYSHELLCONFIG_GIT_SUBMODULES_UPDATE-${MYSHELLCONFIG_GIT_SUBMODULES_UPDATE_DEFAULT-true}}"
fi

EXIT
exit $rc