import sqlite3, { Database, Statement } from 'sqlite3';
import os from 'os';
import path from 'path';
import fs from 'fs';

export default class TaskStatus {
    private static sql_create_table = 'create table checkpoint ('
        + 'md5 varchar PRIMARY KEY NOT NULL unique, '
        + 'media_id varchar, '
        + 'file_size mediumint, '
        + 'object_key varchar, '
        + 'part_size mediumint, '
        + 'upload_id varchar )';
    private static sql_insert_status = 'insert into checkpoint '
        + '( md5, media_id, file_size, object_key, part_size, upload_id ) values (?,?,?,?,?,?)';
    private static sql_delete_status = 'delete from checkpoint where md5 = ?';
    private static sql_query_status = 'select md5,media_id,file_size,object_key,part_size,upload_id from checkpoint where md5 = ?';

    private _db: Database;

    static async build() {
        let dbDir = path.join(os.tmpdir(), 'wl_status/');
        let dbfile = path.join(dbDir, 'index.db');
        //确保目录存在
        if (!fs.existsSync(dbDir)) {
            fs.mkdirSync(dbDir);
        }

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

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

    insert(checkpoint: StatusCheckpoint) {
        return new Promise((resolve, reject) => {
            let sql = TaskStatus.sql_insert_status;

            let values: any[] = [
                checkpoint.md5,
                checkpoint.media_id,
                checkpoint.file_size,
                checkpoint.object_key,
                checkpoint.part_size,
                checkpoint.upload_id
            ];

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

    delete(md5: string) {
        return new Promise((resolve, reject) => {
            let sql = TaskStatus.sql_delete_status;
            this._db.get(sql, md5, e => {
                if (e !== null) reject(e);
                else {
                    resolve(this);
                };
            })
        });
    }

    query(md5: string) {
        return new Promise<StatusCheckpoint | undefined>((resolve, reject) => {
            let sql = TaskStatus.sql_query_status;
            this._db.get(sql, md5, (e, row) => {
                if (e !== null) reject(e);
                else {
                    resolve(row);
                }
            })
        });
    }

    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 = TaskStatus.sql_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);
                    }
                })
            })
        });
    }
}

/** 上传状态检查点 */
export interface StatusCheckpoint {
    md5: string;
    media_id: string;
    file_size: number;
    object_key: string;
    part_size: number;
    upload_id: string;
}