#!/bin/sh

# === Config ===
BACKUP_NAME="$(hostname)_backup"
BACKUP_SRC="$HOME/docs $HOME/pics $HOME/code $HOME/dls"
PASSWORD_ENTRY="misc/backup-archive-password"

# Known external backup drives (UUID-based mount points)
BACKUP_DRIVE_PATHS=(
  "/run/media/opal/e1f36c5c-4775-4549-8edc-1fa4d273b82e"
  "/run/media/opal/790e21c0-77d3-4119-ad86-e9a6857fc89d"
)

# === Find first mounted backup drive ===
for path in "${BACKUP_DRIVE_PATHS[@]}"; do
  if [ -d "$path" ] && mountpoint -q "$path"; then
    DRIVE_ROOT="$path"
    break
  fi
done

if [ -z "$DRIVE_ROOT" ]; then
  echo "❌ No backup drive found."
  exit 1
fi

# === Create backup directory on drive ===
BACKUP_TARGET_DIR="$DRIVE_ROOT/backups/desktop_backups"
mkdir -p "$BACKUP_TARGET_DIR"

# === Create archive directly on the drive ===
TODAY=$(date +%F)
ARCHIVE="$BACKUP_TARGET_DIR/${BACKUP_NAME}_${TODAY}.7z"

PASSWORD=$(gopass show "$PASSWORD_ENTRY")
if [ -z "$PASSWORD" ]; then
  echo "❌ Failed to get password from gopass"
  exit 1
fi

echo "📦 Creating archive directly at $ARCHIVE..."
7z a -mhe=on -p"$PASSWORD" "$ARCHIVE" $BACKUP_SRC
if [ $? -ne 0 ]; then
  echo "❌ 7z compression failed"
  exit 1
fi

# === Retention policy ===
echo "🧹 Applying retention policy..."

BASE="${BACKUP_NAME}_"
find "$BACKUP_TARGET_DIR" -maxdepth 1 -name "${BASE}*.7z" | while read -r file; do
  fname=$(basename "$file")
  date_part=$(echo "$fname" | sed -E "s/^${BASE}([0-9]{4}-[0-9]{2}-[0-9]{2})\.7z$/\1/")

  if ! date -d "$date_part" >/dev/null 2>&1; then
    echo "⚠️  Skipping unrecognized file: $fname"
    continue
  fi

  day_of_week=$(date -d "$date_part" +%u)     # 7 = Sunday
  day_of_month=$(date -d "$date_part" +%d)    # 01 = first of month
  month_day=$(date -d "$date_part" +%m-%d)    # 01-01 = Jan 1
  age_days=$(( ( $(date +%s) - $(date -d "$date_part" +%s) ) / 86400 ))

  keep=0

  if [ "$month_day" = "01-01" ]; then
    keep=1  # yearly
  elif [ "$day_of_month" = "01" ] && [ "$age_days" -le 180 ]; then
    keep=1  # monthly
  elif [ "$day_of_week" = "7" ] && [ "$age_days" -le 28 ]; then
    keep=1  # weekly
  elif [ "$age_days" -le 3 ]; then
    keep=1  # daily
  fi

  if [ "$keep" -eq 1 ]; then
    echo "📌 Keeping: $fname"
  else
    echo "🗑 Deleting: $fname"
    rm -f "$file"
  fi
done

echo "✅ Backup complete."