#!/bin/bash
#-------------------------------------------------------------------------------
# (C) British Crown Copyright 2006-17 Met Office.
#
# This file is part of FCM, tools for managing and building source code.
#
# FCM 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 3 of the License, or
# (at your option) any later version.
#
# FCM 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 FCM. If not, see <http://www.gnu.org/licenses/>.
#-------------------------------------------------------------------------------
# NAME
#   post-revprop-change-bg
#
# SYNOPSIS
#   post-revprop-change-bg REPOS REV PROP_AUTHOR PROP_NAME ACTION
#
# ARGUMENTS
#   REPOS - the path to the Subversion repository
#   REV - the revision relevant for the property
#   PROP_AUTHOR - the author of this property change
#   PROP_NAME - the name of the property, should only be "svn:log"
#   ACTION - the action of the property change, should only be "M"
#
# DESCRIPTION
#   This script performs the post-revprop-change tasks of a Subversion
#   repository in the background.
#
#   The script does the following:
#   1. Write diff between old and new property.
#   2. Update corresponding Trac environment, if relevant.
#   3. E-mails the host user account on error.
#   4. E-mails the changeset author if property author is not changeset author.
#
# ENVIRONMENT VARIABLES
#   FCM_SVN_HOOK_TRAC_ROOT_DIR
#     The root directories of Trac environments. Update corresponding Trac
#     environment if specified.
#   FCM_SVN_HOOK_REPOS_SUFFIX
#     A suffix that should be removed from the basename of REPOS to get the
#     name of the Trac environment. (Default is "".)
#-------------------------------------------------------------------------------
set -eu
. "$(dirname $0)/trac_hook"

REPOS=$1
REV=$2
PROP_AUTHOR=$3
PROP_NAME=$4
ACTION=$5

export PATH=${PATH:-'/usr/local/bin:/bin:/usr/bin'}:$(dirname $0)
THIS=$(basename $0)
USER=${USER:-$(whoami)}
LOG_TMP=$(mktemp "$REPOS/log/$THIS.log.XXXXXXXXXX")
NAME=$(basename "$REPOS")

main() {
    local RET_CODE=0
    local NOW=$(date -u +%FT%H:%M:%SZ)
    echo "$NOW+ $ACTION $PROP_NAME @$REV by $PROP_AUTHOR"

    # Diff old/new in log
    local OLD_FILE=$(mktemp "$REPOS/log/$THIS.$REV.XXXXXXXXXX.old")
    cat >"$OLD_FILE"
    local DIFF_FILE=$(mktemp "$REPOS/log/$THIS.$REV.XXXXXXXXXX.diff")
    {
        echo "$NOW+ $ACTION $PROP_NAME @$REV by $PROP_AUTHOR"
        printf '=%.0s' {1..72}
        echo
    } >"$DIFF_FILE"
    svnlook pg -r "$REV" --revprop "$REPOS" "$PROP_NAME" \
        | diff -u --label="old-value" --label="new-value" "$OLD_FILE" - \
        | tee -a "$DIFF_FILE"

    # Email to changeset author if not the same as property change author
    REV_AUTHOR=$(svnlook author -r "$REV" "$REPOS")
    if [[ "$REV_AUTHOR" != "$PROP_AUTHOR" ]]; then
        SUBJECT="-s$(basename $REPOS)@$REV [$ACTION $PROP_NAME] by $PROP_AUTHOR"
        FROM=
        if [[ -n ${FCM_SVN_HOOK_NOTIFICATION_FROM:-} ]]; then
            FROM="-r${FCM_SVN_HOOK_NOTIFICATION_FROM:-}"
        fi
        ADDRS=$(fcm-user-to-email "$REV_AUTHOR" "$PROP_AUTHOR" 2>'/dev/null')
        mail "$FROM" "$SUBJECT" "$ADDRS" <"$DIFF_FILE" || true
    fi
    rm -f "$OLD_FILE" "$DIFF_FILE"

    # Resync Trac
    trac_hook "$REPOS" "$REV" modified || RET_CODE=$?

    echo "RET_CODE=$RET_CODE"
    return $RET_CODE
}

if ! main 1>$LOG_TMP 2>&1 && [[ -n ${FCM_SVN_HOOK_ADMIN_EMAIL:-} ]]; then
    mail -s "[ERROR $THIS] $NAME" "$FCM_SVN_HOOK_ADMIN_EMAIL" <"$LOG_TMP" \
        || true
fi

cat "$LOG_TMP"
rm -f "$LOG_TMP"
exit