#!/usr/bin/env bash
set -euo pipefail

# ====== CONFIG ======
# Pick a nearby Tier-1. Examples (use ONE):
#   rsync://mirror.csclub.uwaterloo.ca/archlinux/
#   rsync://mirror.constant.com/archlinux/
UPSTREAM="${UPSTREAM:-rsync://masterdistfiles.gentoo.org/gentoo/}"

# Local paths
LIVE="${LIVE:-/brimstone2/mirror/gentoo}"          # served path (symlink target)
STAGE="${STAGE:-/brimstone3/mirror-stage/gentoo}"  # staging path
LOGDIR="${LOGDIR:-/var/log/mirrors}"
LOCK="${LOCK:-/var/log/archmirror.lock}"

# rsync knobs
RSYNC_OPTS=(
  -rtlH --safe-links
  --delete-delay --delay-updates
  --partial --partial-dir=.rsync-partial
  --timeout=600 --contimeout=60
)

# Niceness (be kind to disks)
IONICE=(ionice -c2 -n7)
NICE=(nice -n 15)

mkdir -p "$STAGE" "$LIVE" "$LOGDIR"
exec 9>"$LOCK"
flock -n 9 || { echo "[$(date -Is)] another archmirror-sync is running, exiting"; exit 0; }

log() { echo "[$(date -Is)] $*"; }
log "starting sync from $UPSTREAM"

# First pass
"${IONICE[@]}" "${NICE[@]}" rsync "${RSYNC_OPTS[@]}" \
  "$UPSTREAM" "$STAGE" | tee -a "$LOGDIR/arch-sync.log"

# Quick second pass to catch files updated mid-run
"${IONICE[@]}" "${NICE[@]}" rsync "${RSYNC_OPTS[@]}" \
  "$UPSTREAM" "$STAGE" | tee -a "$LOGDIR/arch-sync.log"

# Atomic flip: make LIVE point at STAGE (symlink strategy)
# If LIVE is a directory you want to replace, serve via a symlink path like /srv/mirror/arch -> /srv/mirror-stage/arch
ln -sfn "$STAGE" "$LIVE"

# Optional: write a local "lastsync" like Arch does, helps some clients
date -u +%s > "$LIVE/lastsync"

log "sync complete; flipped LIVE -> $STAGE"