import { SafePromise, Exception } from "@rolesvillesoftware/tools/dist";

import { Calculator } from "./Calculator";
import { ExamFact, ExamQuestionFact, QuestionFact, QuestionStat, ExamStat } from "../models";
import { Logger } from "../Logger";

export class QuestionCalculator extends Calculator<{examStat: ExamStat; question: ExamQuestionFact}, QuestionStat> {
    private async getQuestionStat(examQuestion: ExamQuestionFact): Promise<QuestionStat> {
        const query = this.processResults(await SafePromise.run(() =>
            this.context.questionStat.selectOrCreate((i, b) => i.examQuestionFactId === b.examQuestionFactId, { examQuestionFactId: examQuestion.id } as QuestionStat)
        ));
        if (query.count === 0) {
            throw new Exception("Unable to create Question State record");
        }

        return query.toArray()[0];
    }

    private async getQuestionFacts(examQuestion: ExamQuestionFact): Promise<QuestionFact[]> {
        const query = this.processResults(await SafePromise.run(() =>
            this.context.questionFact
                .where((i, b) => i.questionDimId === b.questionDimId && i.examDimId === b.examDimId, examQuestion)
                .execute()
                .toPromise()
        ));
        return query.toArray();
    }
    async calculate(input?: {examStat: ExamStat; question: ExamQuestionFact}): Promise<QuestionStat> {
        if (input == null) {
            return null;
        }
        Logger.log(`\t\tLoading question facts`);
        const facts = this.processResults(await SafePromise.run(() => this.getQuestionFacts(input.question)));
        if (!facts.every((v, i) => i === 0 || v.questionDimId === facts[i - 1].questionDimId)) {
            throw new Exception("Not all question facts are for the same question.");
        }
        if (facts.length !== input.examStat.students.length) {
            throw new Exception("Exam to Question student count mis-match");
        }
        Logger.log(`\t\tRetrieving or creating question stats record`);
        const stat = this.processResults(await SafePromise.run(() => this.getQuestionStat(input.question)));

        Logger.log(`\t\tCalculating question statistics`);
        stat.populate(facts, input.examStat);
        Logger.log(`\tQuestion statistics completed`);
        return stat;
    }
}