import sqlite3, {Database} from "sqlite3";
import path from "path";
import os from "os";
import fs from "fs";
import CheckCache from "./CheckCache";

/**
 * @brief 设置续传缓存机制
 * 初始化的时候执行一次 之后每一个小时执行一次
 */
export default class TimeCache {

    /**
     * @brief 上次删除当时间
     * @function sql_delect_insert_status 插入上次删除的时间信息
     * @function sql_delecttime_create_table 创建时间轴的表
     * @function sql_delecttime_query_status 查询删除时间
     * @function sql_delecttime_update_status 刷新删除时间
     * */
    private static sql_delecttime_create_table = 'create table time_table ( time_name varchar PRIMARY KEY NOT NULL unique, time_value varchar)';
    private static sql_delecttime_insert_status = 'insert into time_table (time_name, time_value) values (?,?)';
    private static sql_delecttime_query_status = 'select time_value from time_table where time_name = ?';
    private static sql_delecttime_update_status = 'update time_table set time_value = ? where time_name = ?';
    private static sql_delecttime_delect_status = 'delete from time_table where time_name = ?';
    /**
     * @breif 自动过期逻辑的触发器
     * */
    private static sql_trigger_status = '';

    private _db: Database;

    private constructor(db: sqlite3.Database) {
        this._db = db;
    }

    static async build() {
        let dbDir = path.join(os.tmpdir(), 'wl_cache/');
        let dbfile = path.join(dbDir, 'index.db');
        console.log("The database file:" + dbfile + " will be created.");
        //确保目录存在
        if (!fs.existsSync(dbDir)) {
            fs.mkdirSync(dbDir);
        }

        let db = await TimeCache.initdb(dbfile);
        let obj = new TimeCache(db);
        return obj;
    }

    /**
     *  @brief 触发器 设置数据库自动过期
     *
     * */
    private static initdb(dbfile: string) {
        return new Promise<sqlite3.Database>((resolve, reject) => {
            let db = new sqlite3.Database(dbfile, err => {
                if (err !== null) {
                    console.error(dbfile + ' open failure!');
                    reject(err);
                }

                let sql = TimeCache.sql_delecttime_create_table;

                db.run(sql, e => {
                    if (e !== null) {
                        if ((e as any).errno === 1) {
                            console.debug(e.message);
                            resolve(db);
                        } else {
                            reject(e);
                        }
                    } else {
                        resolve(db);
                    }
                })
            })
        });
    }

    insert(bucket: TimeBucket) {
        return new Promise((resolve, reject) => {
            let sql = TimeCache.sql_delecttime_insert_status;

            let values: any[] = [
                bucket.time_name,
                bucket.time_value
            ];

            this._db.run(sql, values, e => {
                if (e !== null) reject(e);
                else resolve(this);
            });
        });
    }


    query(sha: string) {
        return new Promise<TimeBucket | undefined>((resolve, reject) => {
            let sql = TimeCache.sql_delecttime_query_status;
            this._db.get(sql, sha, (e, row) => {
                if (e !== null) reject(e);
                else {
                    resolve(row);
                }
            })
        });
    }

    delete(sha: string) {
        return new Promise((resolve, reject) => {
            let sql = TimeCache.sql_delecttime_delect_status;
            this._db.get(sql, sha, e => {
                if (e !== null) reject(e);
                else {
                    resolve(this);
                }
                ;
            })
        });
    }

    update(bucket: TimeBucket) {
        return new Promise((resolve, reject) => {
            let sql = TimeCache.sql_delecttime_update_status;

            let values: any[] = [
                bucket.time_name,
                bucket.time_value
            ];

            this._db.run(sql, values, e => {
                if (e !== null) reject(e);
                else resolve(this);
            });
        });
    }
}

/** 续传信息 */
export interface TimeBucket{
    time_name:       string;
    time_value:      string;
}