#!/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-commit-bg
#
# SYNOPSIS
#   post-commit-bg REPOS REV
#
# ARGUMENTS
#   REPOS - the path to the Subversion repository
#   REV - the revision of the commit
#   TXN - the commit transaction that becomes the revision
#
# DESCRIPTION
#   This script performs the post-commit tasks of a Subversion repository in
#   the background.
#
#   The script does the following:
#   1. Creates an incremental revision dump of the current revision.
#   2. Update corresponding Trac environment, if relevant.
#   3. Checks the size of the revision dump. Warns if it exceeds a threshold.
#   4. If this changeset has a change to "^/svnperms.conf", install its HEAD
#      revision at "$REPOS/hooks/", or remove it from "$REPOS/hooks/" if it is
#      removed from the HEAD.
#   5. Runs "$REPOS/hooks/post-commit-bg-custom" and/or
#      "$REPOS/hooks/post-commit-background-custom", if available.
#   6. E-mails the host user account on error.
#
# ENVIRONMENT VARIABLES
#   FCM_SITE_HOME
#     The root location of site configuration.
#   FCM_SVN_HOOK_COMMIT_DUMP_DIR
#     The path to dump commit deltas. Generate a commit delta if specified.
#   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 "".)
#
# FILES
#   $REPOS/hooks/post-commit-bg-custom
#   $REPOS/hooks/post-commit-background-custom
#-------------------------------------------------------------------------------
set -eu
. "$(dirname $0)/trac_hook"

REPOS=$1
REV=$2
TXN=$3

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

main() {
    local RET_CODE=0
    local NOW=$(date -u +%FT%H:%M:%SZ)
    local AUTHOR=$(svnlook author -r "$REV" "$REPOS")
    echo "$NOW+ $REV by $AUTHOR"

    # Dump revision delta
    if [[ -n ${FCM_SVN_HOOK_COMMIT_DUMP_DIR:-} ]]; then
        if [[ ! -d "$FCM_SVN_HOOK_COMMIT_DUMP_DIR" ]]; then
            mkdir -p "$FCM_SVN_HOOK_COMMIT_DUMP_DIR" || true
        fi
        local NAME=$(basename "$REPOS")
        local DUMP="$FCM_SVN_HOOK_COMMIT_DUMP_DIR/$NAME-$REV.gz"
        local TMP_DUMP="$FCM_SVN_HOOK_COMMIT_DUMP_DIR/$NAME-$REV-tmp.gz"
        echo "svnadmin dump -r$REV --incremental --deltas $REPOS | gzip \\"
        echo "    | (dd 'conv=fsync' \"of=$TMP_DUMP\" 2>/dev/null)"
        svnadmin dump "-r$REV" --incremental --deltas "$REPOS" | gzip \
            | (dd 'conv=fsync' "of=$TMP_DUMP" 2>/dev/null) || RET_CODE=$?
        if [[ -s "${TMP_DUMP}" ]]; then
            echo "mv \"${TMP_DUMP}\" \"${DUMP}\""
            mv "${TMP_DUMP}" "${DUMP}" || RET_CODE=$?
        else
            echo "[WARN] ${NAME}-${REV}: zero dump size" >&2
            rm -f "${TMP_DUMP}"
        fi
    fi

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

    # Check size - send warning email if threshold exceeded
    local MB=1048576
    local THRESHOLD=10
    local SIZE_THRESHOLD_FILE="${REPOS}/hooks/pre-commit-size-threshold.conf"
    if [[ -f "${SIZE_THRESHOLD_FILE}" && -r "${SIZE_THRESHOLD_FILE}" ]]; then
        THRESHOLD=$(<"${SIZE_THRESHOLD_FILE}")
    fi
    local REV_FILE="${REPOS}/db/revs/$((${REV} / 1000))/${REV}"
    local REV_FILE_SIZE=$(du -b -s "${REV_FILE}" | cut -f 1)
    if ((${REV_FILE_SIZE} > ${THRESHOLD} * ${MB})); then
        echo "REV_FILE_SIZE=${REV_FILE_SIZE} # >${THRESHOLD}MB"
        RET_CODE=1
    elif ((${REV_FILE_SIZE} > ${MB})); then
        echo "REV_FILE_SIZE=${REV_FILE_SIZE} # >1MB <${THRESHOLD}MB"
        RET_CODE=1
    else
        echo "REV_FILE_SIZE=${REV_FILE_SIZE} # <1MB"
    fi

    # Install commit.conf and svnperms.conf, if necessary
    local NAME=$(basename "${REPOS}")
    if [[ -n "${FCM_SVN_HOOK_REPOS_SUFFIX:-}" ]]; then
        NAME="${NAME%${FCM_SVN_HOOK_REPOS_SUFFIX}}"
    fi
    local CHANGED=$(svnlook changed -r "${REV}" "${REPOS}")
    local FILE=
    for FILE in 'commit.conf' 'svnperms.conf'; do
        # Ignore if there is a site override
        if [[ -n "${FCM_SITE_HOME:-}" \
            && -e "${FCM_SITE_HOME:-}/svn-hooks/${NAME}/${FILE}" ]]
        then
            continue
        fi
        if grep -q "^....${FILE}\$" <<<"${CHANGED}"; then
            # Don't specify revision, so always look at latest.
            if svnlook filesize "${REPOS}" "${FILE}" >/dev/null 2>&1; then
                echo "svnlook cat ${REPOS} ${FILE} >${REPOS}/hooks/${FILE}"
                svnlook cat "${REPOS}" "${FILE}" >"${REPOS}/hooks/${FILE}"
            else
                echo "rm -f ${REPOS}/hooks/${FILE}"
                rm -f "${REPOS}/hooks/${FILE}"
            fi
        fi
    done

    # If relevant, notify owners
    local COMMIT_CONFIG="${REPOS}/hooks/commit.conf"
    if grep -q 'notify-owner' "$COMMIT_CONFIG" 2>/dev/null; then
        local ADDRS=$('post-commit-bg-notify-who' "$REPOS" "$REV" "$TXN")
        if [[ -n $ADDRS ]]; then
            SUBJECT="-s$(basename $REPOS)@$REV by $AUTHOR"
            FROM=
            if [[ -n ${FCM_SVN_HOOK_NOTIFICATION_FROM:-} ]]; then
                FROM="-r${FCM_SVN_HOOK_NOTIFICATION_FROM:-}"
            fi
            echo -n "svn log -v -r \"$REV\" \"file://$REPOS\""
            echo " | mail \"$FROM\" \"$SUBJECT\" \"$ADDRS\""
            svn log -v -r "$REV" "file://$REPOS" \
                | mail "$FROM" "$SUBJECT" "$ADDRS"
        fi
    fi

    # Custom hook
    local CUSTOM_HOOK=
    for CUSTOM_HOOK in \
        "$REPOS/hooks/$THIS-custom" \
        "$REPOS/hooks/post-commit-background-custom"
    do
        if [[ -x "$CUSTOM_HOOK" ]]; then
            echo "$CUSTOM_HOOK $REPOS $REV $TXN"
            "$CUSTOM_HOOK" "$REPOS" "$REV" "$TXN" || RET_CODE=$?
        fi
    done

    echo "RET_CODE=$RET_CODE"
    return $RET_CODE
}

if ! main 1>$LOG_REV 2>&1; then
    if [[ -n ${FCM_SVN_HOOK_ADMIN_EMAIL:-} ]]; then
        mail -s "[$THIS] $REPOS@$REV" "$FCM_SVN_HOOK_ADMIN_EMAIL" <"$LOG_REV" \
            || true
    fi
fi
cat "$LOG_REV"
rm -f "$LOG_REV"
exit
