#!/bin/sh -e

BACKUP_PATH=${BACKUP_PATH:-$1}
INSTANCE="$(echo "${INSTANCE:-${TAG}}" | envsubst)"
KEEP_ARGS=${KEEP_ARGS:-"--keep-hourly 12 --keep-daily 7 --keep-monthly 3"}
RESTIC_REPOSITORY="$(echo "${RESTIC_REPOSITORY}" | envsubst)"
export RESTIC_REPOSITORY

PUSHGATEWAY_URL=${PUSHGATEWAY_URL:-"http://prometheus-pushgateway.monitoring.svc.cluster.local:9091"}

log_info() {
    echo "[INFO] $*"
}

log_warn() {
    echo "[WARN] $*" >&2
}

echo > /tmp/metrics
ts_start=$(date +%s)

log_info "Initializing restic"
ts=$(date +%s)
restic cat config --no-lock >/dev/null || {
    log_warn "Repository ${RESTIC_REPOSITORY} does not exist, creating";
    restic init;
}
echo "restic_init_duration $(echo "$(date +%s) - $ts" | bc)" >> /tmp/metrics

log_info "Cleaning stale locks"
ts=$(date +%s)
restic unlock
echo "restic_unlock_duration $(echo "$(date +%s) - $ts" | bc)" >> /tmp/metrics

log_info "Running restic backup"
ts=$(date +%s)
# TODO: parent snapshot detection might fail so it's on our own, https://github.com/restic/restic/issues/2246
restic backup --verbose --no-scan --tag "${TAG}" --parent "$(restic snapshots --tag "${TAG}" -g paths,tags --path ${BACKUP_PATH} --json | jq -r ".[].snapshots | max_by(.time) | .short_id")" ${BACKUP_PATH}
echo "restic_backup_duration $(echo "$(date +%s) - $ts" | bc)" >> /tmp/metrics

log_info "Cleaning up old snapshots"
ts=$(date +%s)
restic forget --prune --tag "${TAG}" -g paths,tags ${KEEP_ARGS}
echo "restic_forget_duration $(echo "$(date +%s) - $ts" | bc)" >> /tmp/metrics

# Metrics
log_info "Collecting metrics"
ts=$(date +%s)
restic stats --json latest | tee /tmp/stats.json
restic snapshots --json latest | tee /tmp/snapshots.json
echo "restic_stats_duration $(echo "$(date +%s) - $ts" | bc)" >> /tmp/metrics

echo "restic_total_duration $(echo "$(date +%s) - $ts_start" | bc)" >> /tmp/metrics

log_info "Sending metrics to pushgateway"
jq -r '"restic_stats_total_size_bytes \(.total_size)\nrestic_stats_total_file_count \(.total_file_count)"' < /tmp/stats.json >> /tmp/metrics
jq -r 'max_by(.time) | .time | sub(".[0-9]+Z$"; "Z") | fromdate | "restic_stats_last_snapshot_timestamp \(.)"' < /tmp/snapshots.json >> /tmp/metrics
curl --data-binary @- "${PUSHGATEWAY_URL}/metrics/job/backup/instance/${INSTANCE}" < /tmp/metrics