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

: "${DRY_RUN:=}"   # set DRY_RUN=1 to preview deletions

log() { printf '[%(%F %T)T] %s\n' -1 "$*" >&2; }

# Function to create symlink for snapshots
create_symlink() {
  local osname="$1"     # e.g. almalinux
  local release="$2"    # e.g. 9.6
  local repository="$3" # e.g. appstream
  local basepath="$4"   # e.g. /shared/apps/packagerepo
  local label="$5"      # monthly|weekly|daily
  local date_value="$6" # YYYYMMDD for the snapshot to promote

  local snap_path="${basepath}/snap/${osname}/${release}/${repository}-${date_value}"
  local symlink_target="${basepath}/snap/${osname}/${release}/${repository}-${label}"

  if [[ -d "$snap_path" ]]; then
    ln -sfn "$snap_path" "$symlink_target"
    log "Symlink set: ${symlink_target} -> ${snap_path}"
    return 0
  else
    log "Snapshot path does not exist: $snap_path"
    return 1
  fi
}

# Cleanup snapshot directories older than a cutoff date (YYYYMMDD)
cleanup_older_than_monthly() {
  local osname="$1"
  local release="$2"
  local repository="$3"
  local basepath="$4"
  local cutoff_date="$5"  # newly promoted monthly date, YYYYMMDD

  local root="${basepath}/snap/${osname}/${release}"
  local pattern="${repository}-"[0-9][0-9][0-9][0-9][0-9][0-9][0-9][0-9]

  shopt -s nullglob
  for dir in "${root}"/${pattern}; do
    # Skip symlinks and non-directories
    [[ -L "$dir" ]] && continue
    [[ -d "$dir" ]] || continue

    # Extract the date suffix
    local name base datepart
    name="$(basename -- "$dir")"
    base="${name%-????????}"     # remove last 8 chars
    datepart="${name#${base}-}"  # after "<repo>-"

    # Only act on valid YYYYMMDD dates
    if [[ "$datepart" =~ ^[0-9]{8}$ ]]; then
      if [[ "$datepart" -lt "$cutoff_date" ]]; then
        if [[ -n "${DRY_RUN}" ]]; then
          log "[DRY_RUN] Would remove: $dir"
        else
          log "Removing: $dir"
          rm -rf --one-file-system -- "$dir"
        fi
      fi
    fi
  done
  shopt -u nullglob
}

# Determine which snapshot to promote based on the passed argument
case "${1:-}" in
  monthly)
    promote_date=$(date --date="$(date +%Y%m01) -1 month" +%Y%m%d)
    ;;
  weekly)
    promote_date=$(date --date="last Sunday" +%Y%m%d)
    ;;
  daily)
    promote_date=$(date --date="yesterday" +%Y%m%d)
    ;;
  *)
    echo "Usage: $0 {monthly|weekly|daily}"
    exit 1
    ;;
esac

label="$1"

# Process each repo conf
for conf in /etc/reposync/conf.d/*.conf; do
  # shellcheck disable=SC1090
  source "$conf"

  # Expecting these vars in the conf: OSNAME, RELEASE, REPOSITORY, BASEPATH
  : "${OSNAME:?missing OSNAME in $conf}"
  : "${RELEASE:?missing RELEASE in $conf}"
  : "${REPOSITORY:?missing REPOSITORY in $conf}"
  : "${BASEPATH:?missing BASEPATH in $conf}"

  # 1) Promote the symlink for this label
  if create_symlink "$OSNAME" "$RELEASE" "$REPOSITORY" "$BASEPATH" "$label" "$promote_date"; then
    # 2) If monthly, clean up older snapshot dirs for this repo
    if [[ "$label" == "monthly" ]]; then
      cleanup_older_than_monthly "$OSNAME" "$RELEASE" "$REPOSITORY" "$BASEPATH" "$promote_date"
    fi
  else
    log "Skipping cleanup for ${OSNAME}/${RELEASE}/${REPOSITORY} due to missing ${REPOSITORY}-${promote_date}"
  fi
done