emilepharand/Babilonia

import type {Database} from 'sqlite';
import type {Idea} from '../model/ideas/idea';
import type SettingsManager from '../model/settings/settingsManager';
import type IdeaManager from '../model/ideas/ideaManager';

// Knows which ideas need to be provided to the user to practice
// Handles the logic for providing ideas to practice
// Provides ideas for the user to practice them
export default class PracticeManager {
    private readonly ideasAlreadyGiven = new Set<number>();

    constructor(private readonly db: Database,
        private readonly ideaManager: IdeaManager,
        private readonly settingsManager: SettingsManager) {}

    public async getNextIdea(): Promise<Idea | undefined> {
        let idea: Idea = (await this.db.get(await this.buildNextIdeaIdQuery()))!;
        if (idea === undefined) {
            if (this.ideasAlreadyGiven.size === 0) {
                return undefined;
            }
            this.ideasAlreadyGiven.clear();
            idea = (await this.db.get(await this.buildNextIdeaIdQuery()))!;
        }
        this.ideasAlreadyGiven.add(idea.id);
        return this.ideaManager.getIdea(idea.id);
    }

    public clear(): void {
        this.ideasAlreadyGiven.clear();
    }

    private async buildNextIdeaIdQuery(): Promise<string> {
        let query = `select id from ideas where id in
    (select ideaId from expressions
    join languages on expressions.languageId = languages.id
    where isPractice = false)
    and id in
    (select ideaId from expressions
    join languages on expressions.languageId = languages.id
    ${await this.settingsManager.isPracticeOnlyNotKnown() ? 'and expressions.known = "0"' : ''}
    where isPractice = true)
    and id not in
    (${Array.from(this.ideasAlreadyGiven).join(',')})`;
        if (await this.settingsManager.isRandomPractice()) {
            query += ' order by random() ';
        } else {
            query += ' order by ideas.id ';
        }
        query += ' limit 1 ';
        return query;
    }
}