import { Calculator, QuestionCalculator } from "./";
import { ExamStat, ExamQuestionFact, QuestionStat } from "../models";
import { SafePromise, Exception } from "@rolesvillesoftware/tools/dist";
import { Logger } from "../Logger";

export class QuestionsCalculator extends Calculator<ExamStat, QuestionStat[]> {
    private async getExamQuestions(exam: ExamStat): Promise<ExamQuestionFact[]> {
        const result = this.processResults(await SafePromise.run(() =>
            this.context.examQuestionFact
                .where((i, b) => i.examDimId == b.examDimId, exam)
                .execute()
                .toPromise()
        ));
        return result.toArray();
    }

    async calculate(input?: ExamStat): Promise<QuestionStat[]> {
        const questionStats = new Array<QuestionStat>();

        if (input == null) {
            return null;
        }

        Logger.log(`Loading questions`);
        const questions = this.processResults(await SafePromise.run(() => this.getExamQuestions(input)));
        if (questions == null || questions.length === 0) {
            throw new Exception(`No questions to process for exam ${input.id}`);
        }
        const calculator = Calculator.initialize(QuestionCalculator, this.context);

        Logger.log(`Exam questions: ${questions.length}`);
        for (const question of questions) {
            Logger.log(`\tCalculating question ${question.questionNo} - ${question.questionDimId} - ${question.id}`);
            var questionStat = this.processResults(await SafePromise.run(() => calculator.calculate({ examStat: input, question: question})));
            questionStats.push(questionStat);
        }
        Logger.log(`Calculating FEV and PEV`);

        Logger.log(`Calculating question statistics completed`);
        return questionStats.filter(item => item != null);
    }
}