#!/bin/bash
#
# Gondulf SQLite Database Backup Script
# Compatible with both Podman and Docker (auto-detects)
#
# Usage: ./backup.sh [backup_dir]
#
# Environment Variables:
#   GONDULF_DATABASE_URL - Database URL (default: sqlite:////data/gondulf.db)
#   BACKUP_DIR - Backup directory (default: ./backups)
#   BACKUP_RETENTION_DAYS - Days to keep backups (default: 7)
#   COMPRESS_BACKUPS - Compress backups with gzip (default: true)
#   CONTAINER_NAME - Container name (default: gondulf)
#   CONTAINER_ENGINE - Force specific engine: podman or docker (default: auto-detect)
#

set -euo pipefail

# Auto-detect container engine
detect_container_engine() {
    if [ -n "${CONTAINER_ENGINE:-}" ]; then
        echo "$CONTAINER_ENGINE"
    elif command -v podman &> /dev/null; then
        echo "podman"
    elif command -v docker &> /dev/null; then
        echo "docker"
    else
        echo "ERROR: Neither podman nor docker found" >&2
        exit 1
    fi
}

ENGINE=$(detect_container_engine)
CONTAINER_NAME="${CONTAINER_NAME:-gondulf}"

echo "========================================="
echo "Gondulf Database Backup"
echo "========================================="
echo "Container engine: $ENGINE"
echo "Container name: $CONTAINER_NAME"
echo ""

# Configuration
DATABASE_URL="${GONDULF_DATABASE_URL:-sqlite:////data/gondulf.db}"
BACKUP_DIR="${1:-${BACKUP_DIR:-./backups}}"
RETENTION_DAYS="${BACKUP_RETENTION_DAYS:-7}"
COMPRESS="${COMPRESS_BACKUPS:-true}"

# Extract database path from URL (handle both 3-slash and 4-slash formats)
if [[ "$DATABASE_URL" =~ ^sqlite:////(.+)$ ]]; then
    # Four slashes = absolute path
    DB_PATH="/${BASH_REMATCH[1]}"
elif [[ "$DATABASE_URL" =~ ^sqlite:///(.+)$ ]]; then
    # Three slashes = relative path (assume /data in container)
    DB_PATH="/data/${BASH_REMATCH[1]}"
else
    echo "ERROR: Invalid DATABASE_URL format: $DATABASE_URL" >&2
    exit 1
fi

echo "Database path: $DB_PATH"

# Verify container is running
if ! $ENGINE ps | grep -q "$CONTAINER_NAME"; then
    echo "ERROR: Container '$CONTAINER_NAME' is not running" >&2
    echo "Start the container first with: $ENGINE start $CONTAINER_NAME" >&2
    exit 1
fi

# Create backup directory on host if it doesn't exist
mkdir -p "$BACKUP_DIR"

# Generate backup filename with timestamp
TIMESTAMP=$(date +%Y%m%d_%H%M%S)
BACKUP_FILE_CONTAINER="/tmp/gondulf_backup_${TIMESTAMP}.db"
BACKUP_FILE_HOST="$BACKUP_DIR/gondulf_backup_${TIMESTAMP}.db"

echo "Starting backup..."
echo "  Backup file: $BACKUP_FILE_HOST"
echo ""

# Perform backup using SQLite VACUUM INTO (safe hot backup)
# This creates a clean, optimized copy of the database
echo "Creating database backup (this may take a moment)..."
$ENGINE exec "$CONTAINER_NAME" sqlite3 "$DB_PATH" "VACUUM INTO '$BACKUP_FILE_CONTAINER'" || {
    echo "ERROR: Backup failed" >&2
    exit 1
}

# Copy backup out of container to host
echo "Copying backup to host..."
$ENGINE cp "$CONTAINER_NAME:$BACKUP_FILE_CONTAINER" "$BACKUP_FILE_HOST" || {
    echo "ERROR: Failed to copy backup from container" >&2
    $ENGINE exec "$CONTAINER_NAME" rm -f "$BACKUP_FILE_CONTAINER" 2>/dev/null || true
    exit 1
}

# Clean up temporary file in container
$ENGINE exec "$CONTAINER_NAME" rm -f "$BACKUP_FILE_CONTAINER"

# Verify backup was created on host
if [ ! -f "$BACKUP_FILE_HOST" ]; then
    echo "ERROR: Backup file was not created on host" >&2
    exit 1
fi

# Verify backup integrity
echo "Verifying backup integrity..."
if sqlite3 "$BACKUP_FILE_HOST" "PRAGMA integrity_check;" | grep -q "ok"; then
    echo "✓ Backup integrity check passed"
else
    echo "ERROR: Backup integrity check failed" >&2
    rm -f "$BACKUP_FILE_HOST"
    exit 1
fi

echo "✓ Backup created successfully"

# Compress backup if enabled
if [ "$COMPRESS" = "true" ]; then
    echo "Compressing backup..."
    gzip "$BACKUP_FILE_HOST"
    BACKUP_FILE_HOST="$BACKUP_FILE_HOST.gz"
    echo "✓ Backup compressed"
fi

# Calculate and display backup size
BACKUP_SIZE=$(du -h "$BACKUP_FILE_HOST" | cut -f1)
echo "Backup size: $BACKUP_SIZE"

# Clean up old backups
echo ""
echo "Cleaning up backups older than $RETENTION_DAYS days..."
DELETED_COUNT=$(find "$BACKUP_DIR" -name "gondulf_backup_*.db*" -type f -mtime +$RETENTION_DAYS -delete -print | wc -l)
if [ "$DELETED_COUNT" -gt 0 ]; then
    echo "✓ Deleted $DELETED_COUNT old backup(s)"
else
    echo "  No old backups to delete"
fi

# List current backups
echo ""
echo "Current backups:"
if ls "$BACKUP_DIR"/gondulf_backup_*.db* 1> /dev/null 2>&1; then
    ls -lht "$BACKUP_DIR"/gondulf_backup_*.db* | head -10
else
    echo "  (none)"
fi

echo ""
echo "========================================="
echo "Backup complete!"
echo "========================================="
echo "Backup location: $BACKUP_FILE_HOST"
echo "Container engine: $ENGINE"
echo ""