import { importModule } from '@tachybase/utils';

import _ from 'lodash';
import { QueryInterface, Sequelize } from 'sequelize';

import Database from './database';

export interface MigrationContext {
  db: Database;
  queryInterface: QueryInterface;
  sequelize: Sequelize;
}

export class Migration {
  public name: string;

  public context: { db: Database; [key: string]: any };

  constructor(context: MigrationContext) {
    this.context = context;
  }

  get db() {
    return this.context.db;
  }

  get sequelize() {
    return this.context.db.sequelize;
  }

  get queryInterface() {
    return this.context.db.sequelize.getQueryInterface();
  }

  async up() {
    // todo
  }

  async down() {
    // todo
  }
}

export interface MigrationItem {
  name: string;
  migration?: typeof Migration | string;
  context?: any;
  up?: any;
  down?: any;
}

export class Migrations {
  items = [];
  context: any;

  constructor(context: any) {
    this.context = context;
  }

  clear() {
    this.items = [];
  }

  add(item: MigrationItem) {
    const Migration = item.migration;

    if (Migration && typeof Migration === 'function') {
      const migration = new Migration({ ...this.context, ...item.context });
      migration.name = item.name;
      this.items.push(migration);
    } else {
      this.items.push(item);
    }
  }

  callback() {
    return async (ctx) => {
      return await Promise.all(
        _.sortBy(this.items, (item) => {
          const keys = item.name.split('/');
          return keys.pop() || item.name;
        }).map(async (item) => {
          if (typeof item.migration === 'string') {
            // use es module to import migration
            const Migration = await importModule(item.migration);
            const migration = new Migration({ ...this.context, ...item.context });
            migration.name = item.name;
            return migration;
          }

          return item;
        }),
      );
    };
  }
}