#!/bin/bash
#
# Gondulf SQLite Database Restore Script
# Compatible with both Podman and Docker (auto-detects)
#
# Usage: ./restore.sh <backup_file>
#
# CAUTION: This will REPLACE the current database!
#          A safety backup will be created before restoration.
#

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
}

# Check arguments
if [ $# -ne 1 ]; then
    echo "Usage: $0 <backup_file>"
    echo ""
    echo "Example:"
    echo "  $0 ./backups/gondulf_backup_20251120_120000.db.gz"
    echo "  $0 ./backups/gondulf_backup_20251120_120000.db"
    echo ""
    exit 1
fi

BACKUP_FILE="$1"
ENGINE=$(detect_container_engine)
CONTAINER_NAME="${CONTAINER_NAME:-gondulf}"

echo "========================================="
echo "Gondulf Database Restore"
echo "========================================="
echo "Container engine: $ENGINE"
echo "Container name: $CONTAINER_NAME"
echo "Backup file: $BACKUP_FILE"
echo ""
echo "⚠️  WARNING: This will REPLACE the current database!"
echo ""

# Validate backup file exists
if [ ! -f "$BACKUP_FILE" ]; then
    echo "ERROR: Backup file not found: $BACKUP_FILE" >&2
    exit 1
fi

# Configuration
DATABASE_URL="${GONDULF_DATABASE_URL:-sqlite:////data/gondulf.db}"

# Extract database path from URL
if [[ "$DATABASE_URL" =~ ^sqlite:////(.+)$ ]]; then
    DB_PATH="/${BASH_REMATCH[1]}"
elif [[ "$DATABASE_URL" =~ ^sqlite:///(.+)$ ]]; then
    DB_PATH="/data/${BASH_REMATCH[1]}"
else
    echo "ERROR: Invalid DATABASE_URL format: $DATABASE_URL" >&2
    exit 1
fi

echo "Database path in container: $DB_PATH"

# Check if container is running
CONTAINER_RUNNING=false
if $ENGINE ps | grep -q "$CONTAINER_NAME"; then
    CONTAINER_RUNNING=true
    echo "Container status: running"
    echo ""
    echo "⚠️  Container is running. It will be stopped during restoration."
    read -p "Continue? [y/N] " -n 1 -r
    echo
    if [[ ! $REPLY =~ ^[Yy]$ ]]; then
        echo "Restore cancelled."
        exit 0
    fi

    echo "Stopping container..."
    $ENGINE stop "$CONTAINER_NAME"
else
    echo "Container status: stopped"
fi

# Decompress if needed
TEMP_FILE=""
RESTORE_FILE=""
if [[ "$BACKUP_FILE" == *.gz ]]; then
    echo "Decompressing backup..."
    TEMP_FILE=$(mktemp)
    gunzip -c "$BACKUP_FILE" > "$TEMP_FILE"
    RESTORE_FILE="$TEMP_FILE"
    echo "✓ Decompressed to temporary file"
else
    RESTORE_FILE="$BACKUP_FILE"
fi

# Verify backup integrity before restore
echo "Verifying backup integrity..."
if ! sqlite3 "$RESTORE_FILE" "PRAGMA integrity_check;" | grep -q "ok"; then
    echo "ERROR: Backup integrity check failed" >&2
    [ -n "$TEMP_FILE" ] && rm -f "$TEMP_FILE"
    exit 1
fi
echo "✓ Backup integrity verified"

# Create temporary container to access volume if container is stopped
if [ "$CONTAINER_RUNNING" = false ]; then
    echo "Creating temporary container to access volume..."
    TEMP_CONTAINER="${CONTAINER_NAME}_restore_temp"
    $ENGINE run -d --name "$TEMP_CONTAINER" \
        -v gondulf_data:/data \
        alpine:latest sleep 300
    CONTAINER_NAME="$TEMP_CONTAINER"
fi

# Create safety backup of current database
echo "Creating safety backup of current database..."
SAFETY_BACKUP_CONTAINER="/data/gondulf_pre_restore_$(date +%Y%m%d_%H%M%S).db"
if $ENGINE exec "$CONTAINER_NAME" test -f "$DB_PATH" 2>/dev/null; then
    $ENGINE exec "$CONTAINER_NAME" cp "$DB_PATH" "$SAFETY_BACKUP_CONTAINER" || {
        echo "WARNING: Failed to create safety backup" >&2
    }
    echo "✓ Safety backup created: $SAFETY_BACKUP_CONTAINER"
else
    echo "  No existing database found (first time setup)"
fi

# Copy restore file into container
RESTORE_FILE_CONTAINER="/tmp/restore_db.tmp"
echo "Copying backup to container..."
$ENGINE cp "$RESTORE_FILE" "$CONTAINER_NAME:$RESTORE_FILE_CONTAINER"

# Perform restore
echo "Restoring database..."
$ENGINE exec "$CONTAINER_NAME" sh -c "cp '$RESTORE_FILE_CONTAINER' '$DB_PATH'"

# Verify restored database
echo "Verifying restored database..."
if $ENGINE exec "$CONTAINER_NAME" sqlite3 "$DB_PATH" "PRAGMA integrity_check;" | grep -q "ok"; then
    echo "✓ Restored database integrity verified"
else
    echo "ERROR: Restored database integrity check failed" >&2
    echo "Attempting to restore from safety backup..."

    if $ENGINE exec "$CONTAINER_NAME" test -f "$SAFETY_BACKUP_CONTAINER" 2>/dev/null; then
        $ENGINE exec "$CONTAINER_NAME" cp "$SAFETY_BACKUP_CONTAINER" "$DB_PATH"
        echo "✓ Reverted to safety backup"
    fi

    # Clean up
    $ENGINE exec "$CONTAINER_NAME" rm -f "$RESTORE_FILE_CONTAINER"
    [ -n "$TEMP_FILE" ] && rm -f "$TEMP_FILE"

    # Stop temporary container if created
    if [ "$CONTAINER_RUNNING" = false ]; then
        $ENGINE stop "$TEMP_CONTAINER" 2>/dev/null || true
        $ENGINE rm "$TEMP_CONTAINER" 2>/dev/null || true
    fi

    exit 1
fi

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

# Clean up temporary decompressed file on host
[ -n "$TEMP_FILE" ] && rm -f "$TEMP_FILE"

# Stop and remove temporary container if we created one
if [ "$CONTAINER_RUNNING" = false ]; then
    echo "Cleaning up temporary container..."
    $ENGINE stop "$TEMP_CONTAINER" 2>/dev/null || true
    $ENGINE rm "$TEMP_CONTAINER" 2>/dev/null || true
    CONTAINER_NAME="${CONTAINER_NAME%_restore_temp}"  # Restore original name
fi

# Restart original container if it was running
if [ "$CONTAINER_RUNNING" = true ]; then
    echo "Starting container..."
    $ENGINE start "$CONTAINER_NAME"
    echo "Waiting for container to be healthy..."
    sleep 5
fi

echo ""
echo "========================================="
echo "Restore complete!"
echo "========================================="
echo "Backup restored from: $BACKUP_FILE"
echo "Safety backup location: $SAFETY_BACKUP_CONTAINER"
echo ""
echo "Next steps:"
echo "1. Verify the application is working correctly"
echo "2. Once verified, you may delete the safety backup with:"
echo "   $ENGINE exec $CONTAINER_NAME rm $SAFETY_BACKUP_CONTAINER"
echo ""