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

OUT_DIR="${1:?usage: collect_backup_restore_drill.sh <out_dir>}"
mkdir -p "$OUT_DIR"

DEFAULT_GLOB="*restore*drill*.json"
DEFAULT_ROOTS=(
  "../vm-ops/60-backups"
  "../vm-skills"
)

matches=()
if [[ -n "${VMCC_RESTORE_DRILL_GLOB:-}" ]]; then
  if [[ -f "$VMCC_RESTORE_DRILL_GLOB" ]]; then
    matches+=("$VMCC_RESTORE_DRILL_GLOB")
  elif [[ -d "$VMCC_RESTORE_DRILL_GLOB" ]]; then
    while IFS= read -r -d '' file; do
      matches+=("$file")
    done < <(find "$VMCC_RESTORE_DRILL_GLOB" -type f -name "$DEFAULT_GLOB" -print0 2>/dev/null)
  else
    while IFS= read -r file; do
      matches+=("$file")
    done < <(compgen -G "$VMCC_RESTORE_DRILL_GLOB" || true)
  fi
fi

if [[ ${#matches[@]} -eq 0 ]]; then
  for root in "${DEFAULT_ROOTS[@]}"; do
    if [[ -d "$root" ]]; then
      while IFS= read -r -d '' file; do
        matches+=("$file")
      done < <(find "$root" -type f -name "$DEFAULT_GLOB" -print0 2>/dev/null)
    fi
  done
fi

file_mtime_epoch() {
  local file="$1"
  if stat -c %Y "$file" >/dev/null 2>&1; then
    stat -c %Y "$file"
  else
    stat -f %m "$file"
  fi
}

file_mtime_iso() {
  local file="$1"
  local mtime
  mtime="$(file_mtime_epoch "$file")"

  # BSD/macOS: date -r <epoch>
  if date -u -r "$mtime" "+%Y-%m-%dT%H:%M:%SZ" >/dev/null 2>&1; then
    date -u -r "$mtime" "+%Y-%m-%dT%H:%M:%SZ"
  # GNU: date -d "@<epoch>"
  elif date -u -d "@${mtime}" "+%Y-%m-%dT%H:%M:%SZ" >/dev/null 2>&1; then
    date -u -d "@${mtime}" "+%Y-%m-%dT%H:%M:%SZ"
  else
    date -u "+%Y-%m-%dT%H:%M:%SZ"
  fi
}

LATEST=""
LATEST_TS=0
for file in "${matches[@]}"; do
  if [[ -f "$file" ]]; then
    ts="$(file_mtime_epoch "$file")"
    if [[ "$ts" -gt "$LATEST_TS" || ( "$ts" -eq "$LATEST_TS" && ( -z "$LATEST" || "$file" > "$LATEST" ) ) ]]; then
      LATEST_TS="$ts"
      LATEST="$file"
    fi
  fi
done

if [[ -n "$LATEST" ]]; then
  TS="$(file_mtime_iso "$LATEST")"
  jq -n \
    --arg path "$LATEST" \
    --arg ts "$TS" \
    '{collected:true, path:$path, observed_at:$ts}' \
    > "$OUT_DIR/backup_restore_drill.json"
else
  jq -n '{collected:false, reason:"no restore drill artifacts found"}' \
    > "$OUT_DIR/backup_restore_drill.json"
fi