import util from "util";
import fs from "graceful-fs";
import glob from "glob";
import path from "path";
import {config} from "../config";
import Logger from "../logger";
import {Database, open, Statement} from "sqlite";
import * as sqlite3 from "sqlite3";
import {RunResult, SqlType, TypedDatabase} from "../types";

const pglob = util.promisify(glob);
const pReadFile = util.promisify(fs.readFile);

/**
 * Typesafe database wrapper.
 *
 * @see Database
 */
class DatabasePromiseWrapper implements TypedDatabase {
    private db: Promise<Database>;

    constructor() {
        this.db = new Promise<Database>((resolve, reject) => {
            open({
                filename: config.server.databaseFile,
                driver: sqlite3.Database,
            })
                .then(resolve)
                .catch(reject);
        });
        this.db.catch(err => {
            Logger.tag('database', 'init').error('Error initializing database: ', err);
            process.exit(1);
        });
    }

    async on(event: string, listener: any): Promise<void> {
        const db = await this.db;
        db.on(event, listener);
    }

    async run(sql: SqlType, ...params: any[]): Promise<RunResult> {
        const db = await this.db;
        return db.run(sql, ...params);
    }

    async get<T>(sql: SqlType, ...params: any[]): Promise<T | undefined> {
        const db = await this.db;
        return await db.get<T>(sql, ...params);
    }

    async each<T>(sql: SqlType, callback: (err: any, row: T) => void): Promise<number>;
    async each<T>(sql: SqlType, param1: any, callback: (err: any, row: T) => void): Promise<number>;
    async each<T>(sql: SqlType, param1: any, param2: any, callback: (err: any, row: T) => void): Promise<number>;
    async each<T>(sql: SqlType, param1: any, param2: any, param3: any, callback: (err: any, row: T) => void): Promise<number>;
    async each<T>(sql: SqlType, ...params: any[]): Promise<number> {
        const db = await this.db;
        // @ts-ignore
        return await db.each.apply(db, arguments);
    }

    async all<T>(sql: SqlType, ...params: any[]): Promise<T[]> {
        const db = await this.db;
        return (await db.all<T[]>(sql, ...params));
    }

    async exec(sql: SqlType, ...params: any[]): Promise<void> {
        const db = await this.db;
        return await db.exec(sql, ...params);
    }

    async prepare(sql: SqlType, ...params: any[]): Promise<Statement> {
        const db = await this.db;
        return await db.prepare(sql, ...params);
    }
}

async function applyPatch(db: TypedDatabase, file: string): Promise<void> {
    Logger.tag('database', 'migration').info('Checking if patch need to be applied: %s', file);

    const contents = await pReadFile(file);
    const version = path.basename(file, '.sql');

    const row = await db.get('SELECT * FROM schema_version WHERE version = ?', version);
    if (row) {
        // patch is already applied. skip!
        Logger.tag('database', 'migration').info('Patch already applied, skipping: %s', file);
        return
    }

    const sql = 'BEGIN TRANSACTION;\n' +
        contents.toString() + '\n' +
        'INSERT INTO schema_version (version) VALUES (\'' + version + '\');\n' +
        'END TRANSACTION;';

    await db.exec(sql);

    Logger.tag('database', 'migration').info('Patch successfully applied: %s', file);
}

async function applyMigrations(db: TypedDatabase): Promise<void> {
    Logger.tag('database', 'migration').info('Migrating database...');

    const sql = 'BEGIN TRANSACTION; CREATE TABLE IF NOT EXISTS schema_version (\n' +
        '    version VARCHAR(255) PRIMARY KEY ASC,\n' +
        '    applied_at DATETIME DEFAULT CURRENT_TIMESTAMP NOT NULL\n' +
        '); END TRANSACTION;';

    await db.exec(sql);

    const files = await pglob(__dirname + '/patches/*.sql');
    for (const file of files) {
        await applyPatch(db, file)
    }
}

export const db: TypedDatabase = new DatabasePromiseWrapper();

export async function init(): Promise<void> {
    Logger.tag('database').info('Setting up database: %s', config.server.databaseFile);
    await db.on('profile', (sql: string, time: number) => Logger.tag('database').profile('[%sms]\t%s', time, sql));

    try {
        await applyMigrations(db);
    } catch (error) {
        Logger.tag('database').error('Error migrating database:', error);
        throw error;
    }
}