#!/bin/bash
#
# Script to backup (export), restore (import), or restore-and-rename a SAP HANA schema.
# It automatically detects the number of available CPU threads to optimize operations.
# Designed for both interactive use and cronjob automation.
#
# ETomi 2025

# --- Configuration ---
hdbsql_path="/usr/sap/hdbclient/hdbsql"

# -- HANA Secure User Store Key --
user_key="CRONKEY"

# --- Validation ---
for cmd in hdbsql hdbuserstore tar gzip nproc pv mkdir chmod date; do
    tool_path="$(dirname "$hdbsql_path")/$cmd"
    if ! command -v $cmd &> /dev/null && [ ! -f "$tool_path" ]; then
        echo "❌ Error: Required command '$cmd' is not found in your PATH or at '$tool_path'."
        exit 1
    fi
done

if [ "$#" -lt 2 ]; then
    echo "❌ Error: Not enough arguments."
    echo ""
    echo "Usage: $0 <action> <arguments...>"
    echo ""
    echo "Actions:"
    echo "  setup-key <key_name>                      - Interactively create a secure user store key"
    echo "  backup <schema> <path> [--compress] [--timestamp] - Export a schema, optionally compress and/or add a timestamp"
    echo "  restore <schema> <path>                     - Import a schema from a path"
    echo "  restore-rename <schema> <new_schema> <path> - Import and rename a schema"
    exit 1
fi

action=$1
threads=$(nproc --all)

# --- Functions ---
confirm_action() {
    if [ "$TERM" != "dumb" ] && [ -t 0 ]; then
        read -p "❓ Are you sure you want to proceed with the '$1' operation? (y/n): " -n 1 -r
        echo ""
        if [[ ! $REPLY =~ ^[Yy]$ ]]; then
            echo "🛑 Operation cancelled by user."
            exit 1
        fi
    fi
}

execute_sql() {
    local command_to_run=$1
    local action_name=$2

    echo "⚙️  Executing SQL: $command_to_run"
    $hdbsql_path -U $user_key "$command_to_run"

    if [ $? -ne 0 ]; then
        echo "❌ Failure! The '$action_name' command failed. Please check the logs."
        exit 1
    fi
}

# --- Main Logic ---
# The setup-key action is handled first as it doesn't need all global variables.
if [ "$action" == "setup-key" ]; then
    if [ "$#" -ne 2 ]; then
        echo "❌ Error: Invalid arguments for 'setup-key'."
        echo "Usage: $0 setup-key <key_name>"
        exit 1
    fi
    key_name=$2
    hdbuserstore_path="$(dirname "$hdbsql_path")/hdbuserstore"

    echo "--- Interactive Secure User Store Key Setup ---"
    read -p "Enter HANA host [localhost]: " hdb_host
    hdb_host=${hdb_host:-localhost}

    read -p "Enter instance number [00]: " hdb_instance
    hdb_instance=${hdb_instance:-00}
    hdb_port="3${hdb_instance}15"

    read -p "Enter tenant database name [NDB]: " hdb_tenant
    hdb_tenant=${hdb_tenant:-NDB}

    read -p "Enter database user [SYSTEM]: " hdb_user
    hdb_user=${hdb_user:-SYSTEM}

    read -sp "Enter password for '$hdb_user': " hdb_pass
    echo ""
    if [ -z "$hdb_pass" ]; then
        echo "❌ Error: Password cannot be empty."
        exit 1
    fi

    connection_string="${hdb_host}:${hdb_port}@${hdb_tenant}"
    echo "-------------------------------------"
    echo "Key Name:          $key_name"
    echo "Connection String: $connection_string"
    echo "Database User:     $hdb_user"
    echo "-------------------------------------"
    confirm_action "create key '$key_name'"

    echo "▶️ Creating secure store key..."
    $hdbuserstore_path SET "$key_name" "$connection_string" "$hdb_user" "$hdb_pass"

    if [ $? -eq 0 ]; then
        echo "✅ Success! Key '$key_name' created. You can now set 'user_key=\"$key_name\"' at the top of this script."
    else
        echo "❌ Failure! Could not create key '$key_name'. Please check the details and try again."
        exit 1
    fi
    exit 0
fi

# --- Actions (Backup/Restore) ---
echo "ℹ️ Detected $threads available CPU threads to use for the operation."

case "$action" in
    backup)
        if [ "$#" -lt 3 ] || [ "$#" -gt 5 ]; then
            echo "❌ Error: Invalid arguments for 'backup'."
            echo "Usage: $0 backup <schema_name> <path> [--compress] [--timestamp]"
            exit 1
        fi
        
        schema=$2
        path=$3
        compress_flag=false
        timestamp_flag=false

        # Loop through optional arguments to handle any order
        for arg in "${@:4}"; do
            case "$arg" in
                --compress)
                    compress_flag=true
                    ;;
                --timestamp)
                    timestamp_flag=true
                    ;;
                *)
                    echo "❌ Error: Invalid option '$arg'. Valid options are '--compress' or '--timestamp'."
                    exit 1
                    ;;
            esac
        done

        # Add timestamp to path if flag is set
        if [ "$timestamp_flag" = true ]; then
            timestamp=$(date +'%Y%m%d_%H%M%S')
            path="${path}_${timestamp}"
        fi

        echo "ℹ️  Creating backup directory: $path"
        mkdir -p "$path" && chmod 777 "$path"
        if [ $? -ne 0 ]; then
            echo "❌ Failure! Could not create or set permissions for directory '$path'."
            exit 1
        fi

        echo "▶️ Starting BACKUP (EXPORT) for schema '$schema' to '$path'..."
        sql_command="EXPORT \"$schema\".\"*\" AS BINARY INTO '$path' WITH REPLACE THREADS $threads;"
        execute_sql "$sql_command" "$action"
        echo "✅ SQL Export completed successfully."

        if [ "$compress_flag" = true ]; then
            echo "▶️ Compressing backup directory: $path"
            archive_file="${path}.tar.gz"
            total_size=$(du -sb "$path" | awk '{print $1}')
            tar cf - -C "$(dirname "$path")" "$(basename "$path")" | pv -s "$total_size" | gzip > "$archive_file"
            if [ $? -eq 0 ]; then
                echo "✅ Compression successful: $archive_file"
                echo "🗑️ Removing original backup directory..."
                rm -rf "$path"
            else
                echo "❌ Failure! Compression failed."
                exit 1
            fi
        fi
        ;;

    restore)
        if [ "$#" -ne 3 ]; then
            echo "❌ Error: Invalid arguments for 'restore'."
            echo "Usage: $0 restore <schema_name> <path>"
            exit 1
        fi
        schema=$2
        path=$3
        confirm_action "restore"
        echo "▶️ Starting RESTORE (IMPORT) for schema '$schema' from '$path'..."
        sql_command="IMPORT \"$schema\".\"*\" AS BINARY FROM '$path' WITH IGNORE EXISTING THREADS $threads;"
        execute_sql "$sql_command" "$action"
        echo "✅ Success! The '$action' operation completed."
        ;;

    restore-rename)
        if [ "$#" -ne 4 ]; then
            echo "❌ Error: Invalid arguments for 'restore-rename'."
            echo "Usage: $0 restore-rename <schema_name> <new_schema_name> <path>"
            exit 1
        fi
        schema=$2
        new_schema=$3
        path=$4
        confirm_action "restore-rename"
        echo "▶️ Starting RESTORE & RENAME for schema '$schema' from '$path' to '$new_schema'..."
        sql_command="IMPORT \"$schema\".\"*\" AS BINARY FROM '$path' WITH IGNORE EXISTING THREADS $threads RENAME SCHEMA \"$schema\" TO \"$new_schema\";"
        execute_sql "$sql_command" "$action"
        echo "✅ Success! The '$action' operation completed."
        ;;

    *)
        echo "❌ Error: Invalid action '$action'."
        echo "Valid actions are 'backup', 'restore', 'restore-rename', or 'setup-key'."
        exit 1
        ;;
esac

exit 0