import { Request, Response } from 'express';
import { createQuestion, deleteQuestion, getAllQuestions, getAnswersByQuestion, getQuestion } from '../services/questions.js';
import { QuestionDTO, QuestionId } from '../interfaces/question.js';
import { FALLBACK_LANG, FALLBACK_SEQ_NUM } from '../config.js';
import { LearningObjectIdentifier } from '../entities/content/learning-object-identifier.js';
import { Language } from '../entities/content/language.js';

function getObjectId(req: Request, res: Response): LearningObjectIdentifier | null {
    const { hruid, version } = req.params;
    const lang = req.query.lang;

    if (!hruid || !version) {
        res.status(400).json({ error: 'Missing required parameters.' });
        return null;
    }

    return {
        hruid,
        language: (lang as Language) || FALLBACK_LANG,
        version: +version,
    };
}

function getQuestionId(req: Request, res: Response): QuestionId | null {
    const seq = req.params.seq;
    const learningObjectIdentifier = getObjectId(req, res);

    if (!learningObjectIdentifier) {
        return null;
    }

    return {
        learningObjectIdentifier,
        sequenceNumber: seq ? Number(seq) : FALLBACK_SEQ_NUM,
    };
}

export async function getAllQuestionsHandler(req: Request, res: Response): Promise<void> {
    const objectId = getObjectId(req, res);
    const full = req.query.full === 'true';

    if (!objectId) {
        return;
    }

    const questions = await getAllQuestions(objectId, full);

    if (!questions) {
        res.status(404).json({ error: `Questions not found.` });
    } else {
        res.json({ questions: questions });
    }
}

export async function getQuestionHandler(req: Request, res: Response): Promise<void> {
    const questionId = getQuestionId(req, res);

    if (!questionId) {
        return;
    }

    const question = await getQuestion(questionId);

    if (!question) {
        res.status(404).json({ error: `Question not found.` });
    } else {
        res.json(question);
    }
}

export async function getQuestionAnswersHandler(req: Request, res: Response): Promise<void> {
    const questionId = getQuestionId(req, res);
    const full = req.query.full === 'true';

    if (!questionId) {
        return;
    }

    const answers = await getAnswersByQuestion(questionId, full);

    if (!answers) {
        res.status(404).json({ error: `Questions not found` });
    } else {
        res.json({ answers: answers });
    }
}

export async function createQuestionHandler(req: Request, res: Response): Promise<void> {
    const questionDTO = req.body as QuestionDTO;

    if (!questionDTO.learningObjectIdentifier || !questionDTO.author || !questionDTO.content) {
        res.status(400).json({ error: 'Missing required fields: identifier and content' });
        return;
    }

    const question = await createQuestion(questionDTO);

    if (!question) {
        res.status(400).json({ error: 'Could not create question' });
    } else {
        res.json(question);
    }
}

export async function deleteQuestionHandler(req: Request, res: Response): Promise<void> {
    const questionId = getQuestionId(req, res);

    if (!questionId) {
        return;
    }

    const question = await deleteQuestion(questionId);

    if (!question) {
        res.status(400).json({ error: 'Could not find nor delete question' });
    } else {
        res.json(question);
    }
}
