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

SCRIPT_DIR="$(cd "$(dirname "${BASH_SOURCE[0]}")" && pwd)"
# shellcheck source=backup.env
source "$SCRIPT_DIR/backup.env"

# ==============================================================================
# RESTORE-SPECIFIC CONFIGURATION
# ==============================================================================
BACKUP_GROUP="host/${HOSTNAME}"       # <backup-type>/<backup-id>
ARCHIVE_NAME="${HOSTNAME}-root.pxar"  # archive created by backup.sh

usage() {
    cat >&2 <<'EOF'
Usage:
  restore.sh [mount] [MOUNTPOINT] [SNAPSHOT]
      FUSE-mount a snapshot for browsing or restoring single files.

  restore.sh restore TARGET [PATTERN ...] [--snapshot SNAPSHOT]
      Bulk-restore files/directories into TARGET. Faster than the FUSE
      mount for many files. PATTERN is a glob matched against paths inside
      the archive (e.g. "var/vmail/example.com/*"); repeatable. With no
      PATTERN the whole archive is extracted.

  restore.sh shell [--snapshot SNAPSHOT]
      Interactive shell to browse the backup and selectively restore files.

  Without SNAPSHOT (or --snapshot), you are prompted to pick one from a
  list of available snapshots (default: the most recent).
EOF
    exit 1
}

# Prints a snapshot reference on stdout. When stdin is a TTY and there is more
# than one snapshot, shows a numbered menu (newest first) and prompts.
select_snapshot() {
    local -a snaps
    mapfile -t snaps < <(
        proxmox-backup-client snapshot list "$BACKUP_GROUP" \
            --ns "$BACKUP_NS" --output-format json \
            | jq -r 'sort_by(."backup-time") | reverse | .[] | "\(."backup-type")/\(."backup-id")/\(."backup-time" | todateiso8601)"'
    )

    if [ "${#snaps[@]}" -eq 0 ]; then
        echo "error: no snapshots found in group $BACKUP_GROUP" >&2
        exit 1
    fi

    # Non-interactive (piped/cron): use the latest without prompting.
    if [ ! -t 0 ]; then
        printf '%s\n' "${snaps[0]}"
        return
    fi

    echo "Available snapshots:" >&2
    local i
    for i in "${!snaps[@]}"; do
        printf '  %d) %s\n' "$((i + 1))" "${snaps[$i]}" >&2
    done

    local choice=""
    read -r -p "Select a snapshot [1-${#snaps[@]}] (default 1): " choice

    choice="${choice:-1}"
    case "$choice" in
        *[!0-9]*) echo "error: invalid selection: $choice" >&2; exit 1 ;;
    esac

    local idx=$((choice - 1))
    if [ "$idx" -lt 0 ] || [ "$idx" -ge "${#snaps[@]}" ]; then
        echo "error: selection out of range: $choice" >&2
        exit 1
    fi

    printf '%s\n' "${snaps[$idx]}"
}

CMD="mount"
case "${1:-}" in
    mount|restore|shell) CMD="$1"; shift ;;
esac

case "$CMD" in
    mount)
        MOUNTPOINT="${1:-/mnt/pbs-restore}"
        SNAPSHOT="${2:-}"
        [ -z "$SNAPSHOT" ] && SNAPSHOT="$(select_snapshot)"

        if mountpoint -q "$MOUNTPOINT" 2>/dev/null; then
            echo "error: already mounted at $MOUNTPOINT" >&2
            exit 1
        fi

        mkdir -p "$MOUNTPOINT"

        echo "Snapshot:   $SNAPSHOT"
        echo "Archive:    $ARCHIVE_NAME"
        echo "Mountpoint: $MOUNTPOINT"

        # The client daemonizes by default, so its exit code only tells us
        # whether it started; verify the FUSE mount actually appears.
        proxmox-backup-client mount "$SNAPSHOT" "$ARCHIVE_NAME" "$MOUNTPOINT" \
            --ns "$BACKUP_NS" \
            --keyfile "$ENCRYPTION_KEY_FILE"

        for _ in $(seq 1 100); do
            mountpoint -q "$MOUNTPOINT" 2>/dev/null && break
            sleep 0.1
        done
        mountpoint -q "$MOUNTPOINT" 2>/dev/null \
            || { echo "error: mount did not appear" >&2; exit 1; }

        echo
        echo "Mounted at $MOUNTPOINT. Copy out the files you need, then unmount:"
        echo "    umount $MOUNTPOINT"
        ;;

    restore)
        TARGET="${1:-}"
        [ -n "$TARGET" ] || usage
        shift

        PATTERNS=()
        SNAPSHOT=""
        while [ $# -gt 0 ]; do
            case "$1" in
                --snapshot) SNAPSHOT="${2:-}"; [ -n "$SNAPSHOT" ] || usage; shift 2 ;;
                *) PATTERNS+=("$1"); shift ;;
            esac
        done

        [ -z "$SNAPSHOT" ] && SNAPSHOT="$(select_snapshot)"

        mkdir -p "$TARGET"

        echo "Snapshot: $SNAPSHOT"
        echo "Archive:  $ARCHIVE_NAME"
        echo "Target:   $TARGET"
        [ "${#PATTERNS[@]}" -gt 0 ] && printf 'Patterns: %s\n' "${PATTERNS[*]}"

        ARGS=(restore "$SNAPSHOT" "$ARCHIVE_NAME" "$TARGET" --ns "$BACKUP_NS" --keyfile "$ENCRYPTION_KEY_FILE")
        for p in "${PATTERNS[@]}"; do
            ARGS+=(--pattern "$p")
        done

        proxmox-backup-client "${ARGS[@]}"

        echo
        echo "Restored into $TARGET"
        ;;

    shell)
        SNAPSHOT=""
        while [ $# -gt 0 ]; do
            case "$1" in
                --snapshot) SNAPSHOT="${2:-}"; [ -n "$SNAPSHOT" ] || usage; shift 2 ;;
                *) usage ;;
            esac
        done

        [ -z "$SNAPSHOT" ] && SNAPSHOT="$(select_snapshot)"

        exec proxmox-backup-client catalog shell "$SNAPSHOT" "$ARCHIVE_NAME" \
            --ns "$BACKUP_NS" \
            --keyfile "$ENCRYPTION_KEY_FILE"
        ;;

    *)
        usage
        ;;
esac