#!/usr/bin/env bash
# 백업 스크립트 공통 유틸

log_ts() { date '+%Y-%m-%dT%H:%M:%S%z'; }

# 오래된 YYYYMMDD 백업 디렉터리 삭제
# 사용: prune_old_backups "$BACKUP_ROOT" "$RETENTION_DAYS"
prune_old_backups() {
  local backup_root="$1"
  local retention_days="$2"
  local cutoff removed=0 base day entry

  [[ "$retention_days" =~ ^[0-9]+$ ]] || return 0
  [[ "$retention_days" -le 0 ]] && return 0

  if date -d "1 day ago" +%Y%m%d >/dev/null 2>&1; then
    cutoff=$(date -d "${retention_days} days ago" +%Y%m%d)
  else
    cutoff=$(date -v-"${retention_days}"d +%Y%m%d)
  fi

  shopt -s nullglob
  for entry in "$backup_root"/*; do
    [[ -d "$entry" ]] || continue
    base=$(basename "$entry")
    [[ "$base" == "latest" ]] && continue
    if [[ "$base" =~ ^([0-9]{8}) ]]; then
      day="${BASH_REMATCH[1]}"
      if [[ "$day" < "$cutoff" ]]; then
        rm -rf "$entry"
        removed=$((removed + 1))
        echo "[$(log_ts)] retention: removed $entry (backup date $day < cutoff $cutoff)"
      fi
    fi
  done
  shopt -u nullglob
  echo "[$(log_ts)] retention: pruned ${removed} dir(s); keeping backups from ${cutoff} onward (${retention_days} days)"
}

resolve_run_dir() {
  local component="$1"
  local stamp="${BACKUP_STAMP:-$(date +%Y%m%d)}"
  local root="${BACKUP_DIR:-$REPO_ROOT/backup}"

  if [[ -n "${BACKUP_RUN_DIR:-}" ]]; then
    RUN_DIR="$BACKUP_RUN_DIR/$component"
  else
    RUN_DIR="$root/$stamp/$component"
  fi
  mkdir -p "$RUN_DIR"
}

update_latest_link() {
  local component="$1"
  local root="${BACKUP_DIR:-$REPO_ROOT/backup}"
  local stamp="${BACKUP_STAMP:-$(date +%Y%m%d)}"
  local target

  if [[ -n "${BACKUP_RUN_DIR:-}" ]]; then
    target="$BACKUP_RUN_DIR/$component"
  else
    target="$root/$stamp/$component"
  fi

  ln -sfn "$target" "$root/latest/$component"
}