import { IRecordFilter, ITaskFilter } from "../@types/task";
import { Prisma, PrismaClient } from "@prisma/client";
/**
 * CRUD tasks in the sqlite db file
 */
export declare class DB {
    private static instance;
    /**
     * Create or get exist instance of this class
     */
    static init(): DB;
    /**
     * Instance of PrismaClient
     */
    conn: PrismaClient | undefined;
    /**
     * Restore unfinished tasks from database if the program was terminated
     */
    loadUnfinshedTasks(): Promise<void>;
    /**
     * Write a new task info into the database
     * @param taskName For example: Count
     * @param taskDescription For example: Execute 3 arrow functions to print Count + index on the terminal
     * @param executeTime The returned formatted datetime string from scheduleTask, for example: "2024-12-30 17:00:00"
     */
    createTask(taskName: string, taskDescription: string, executeTime: string, data: string): Promise<{
        id: number;
        taskName: string;
        taskDescription: string;
        data: string;
        executeTime: Date;
        startTime: Date | null;
        finishTime: Date | null;
    }>;
    /**
     * Mark a executing task as started
     * @param taskId The created task's id of method createTask
     */
    startTask(taskId: number): Promise<void>;
    /**
     * Mark a executed task as finished
     * @param taskId The created task's id of method createTask
     */
    finishTask(taskId: number): Promise<void>;
    /**
     * Executing a task item successfully
     * @param taskId The primary key of a task
     * @param itemId The id of each item in the request body's data field
     * @param itemValue The stringified value of the item
     */
    markItemSuccessful(taskId: number, itemId: string, itemValue: string): Promise<void>;
    /**
     * Executing a task item failed
     * @param taskId The primary key of a task
     * @param itemId The id of each item in the request body's data field
     * @param itemValue The stringified value of the item
     */
    markItemFailed(taskId: number, itemId: string, itemValue: string, errorMessage: string): Promise<void>;
    /**
     * To filter the task from database
     * @param filter The object consist of conditions, the example below shows the tasks finished during 2025-01-02
     * @example {"finish":  {"after": "2025-01-02", "before": "2025-01-03"}}
     */
    getTasks(filter: ITaskFilter): Promise<{
        id: number;
        taskName: string;
        taskDescription: string;
        executeTime: Date;
        startTime: Date | null;
        finishTime: Date | null;
    }[]>;
    /**
     * To delete the task and all related records
     * @param taskId Primary key of a task record
     */
    deleteTaskById(taskId: number): Promise<Prisma.BatchPayload | undefined>;
    /**
     * To reschedule waiting state task
     * @param taskId Primary key of a task record
     * @param executeTime The new executeTime for reschedule task
     * @returns
     */
    rescheduleTask(taskId: number, executeTime: Date): Promise<{
        isSuccessful: boolean;
        updatedTask: {
            id: number;
            taskName: string;
            taskDescription: string;
            executeTime: Date;
            startTime: Date | null;
            finishTime: Date | null;
        };
    }>;
    /**
     * To filter the records from database
     * @param filter The object consist of conditions, the example below shows the records finished during 2025-01-02
     * @example {"finish":  {"after": "2025-01-02", "before": "2025-01-03"}}
     */
    getRecords(filter: IRecordFilter): Promise<{
        error: string | null;
        id: number;
        finishTime: Date;
        itemId: string;
        itemValue: string;
        task: {
            id: number;
            taskName: string;
            taskDescription: string;
        };
    }[]>;
}