/***********************************************************************************************************************************************************************
 * File Name: course_reading_progress.controller.js  (client)
 * Type of Program: Controller
 * Description: Tracks user reading progress through a course hierarchy (course → unit → lesson).
 *
 *   GET  /client/courses/in-progress
 *        → courses where the current user has status = 'in_progress', with lesson counts
 *
 *   GET  /client/courses/:courseId/progress
 *        → returns all progress rows for this user + course (flat, frontend builds the map)
 *
 *   POST /client/courses/:courseId/units/:unitId/lessons/:lessonId/progress
 *        → UPSERT lesson + derives + UPSERTs parent unit + course in one transaction
 *
 * Body (POST):
 *   { status: 'in_progress' | 'completed' }
 *   Defaults to 'in_progress' if omitted (on first visit).
 *
 * Author: Kenneth Obsequio (@lash0000)
 * Date Created: Jun. 21, 2026
 ***********************************************************************************************************************************************************************/
'use strict';

const R                     = require('../../utils/response.util');
const logActivity           = require('../../utils/logActivity.util');
const { upsertLessonRead }  = require('../../services/course_reading_progress.service');
const CourseReadingProgress = require('../../models/courses/course_reading_progress.mdl');
const Certificate           = require('../../models/courses/certificate.mdl');
const {
    Course, Unit, Lesson,
    UnitQuiz, CourseAssessment, QuizAttempt,
} = require('../../models/courses/courses.associations');

const notDeleted = { deletedAt: null };

// =============================================================================
// ── IN-PROGRESS COURSES — profile learning progress card ──────────────────────
// =============================================================================

// GET /client/courses/in-progress
// Returns courses the user has started but not yet completed (no certificate).
// Includes both:
//   • reading in_progress  → still working through lessons
//   • reading completed    → finished lessons but quiz / assessment still pending
// Excludes any course where the user already holds a certificate.

exports.getMyInProgressCourses = async (req, res) => {
    try {
        const userId = req.user.user_id;

        // All course-level progress rows for this user (any reading status)
        const courseRows = await CourseReadingProgress.findAll({
            where:      { user_id: userId, type: 'course' },
            attributes: ['course_id', 'status', 'last_accessed_at'],
            include: [{
                model:      Course,
                as:         'course',
                attributes: ['course_id', 'title'],
                where:      notDeleted,
                required:   true,
            }],
            order: [['last_accessed_at', 'DESC']],
        });

        if (!courseRows.length) return R.success(res, 'No courses in progress.', []);

        // Courses the user has already earned a certificate for — exclude these
        const certificates = await Certificate.findAll({
            where:      { user_id: userId },
            attributes: ['course_id'],
        });
        const certSet = new Set(certificates.map((c) => String(c.course_id)));

        const pending = courseRows.filter((r) => !certSet.has(String(r.course_id)));
        if (!pending.length) return R.success(res, 'No courses in progress.', []);

        const result = await Promise.all(pending.map(async (row) => {
            const courseId       = row.course_id;
            const readingDone    = row.status === 'completed';

            const [lessons_total, lessons_completed] = await Promise.all([
                Lesson.count({
                    include: [{
                        model:    Unit,
                        as:       'unit',
                        where:    { course_id: courseId, ...notDeleted },
                        required: true,
                    }],
                    where: notDeleted,
                }),
                CourseReadingProgress.count({
                    where: { user_id: userId, course_id: courseId, type: 'lesson', status: 'completed' },
                }),
            ]);

            // Only compute pending quiz/assessment detail when all lessons are read
            let pending_quizzes    = [];
            let pending_assessment = null;

            if (readingDone) {
                // All unit quizzes in this course
                const unitQuizzes = await UnitQuiz.findAll({
                    attributes: ['quiz_id', 'title', 'is_required', 'passing_score'],
                    include: [{
                        model:      Unit,
                        as:         'unit',
                        attributes: ['unit_id', 'title'],
                        where:      { course_id: courseId, ...notDeleted },
                        required:   true,
                    }],
                    where: notDeleted,
                });

                for (const quiz of unitQuizzes) {
                    const [hasPassed, attemptCount] = await Promise.all([
                        QuizAttempt.findOne({ where: { user_id: userId, quiz_id: quiz.quiz_id, passed: true } }),
                        QuizAttempt.count({ where: { user_id: userId, quiz_id: quiz.quiz_id } }),
                    ]);
                    if (!hasPassed) {
                        pending_quizzes.push({
                            quiz_id:       quiz.quiz_id,
                            title:         quiz.title,
                            unit_title:    quiz.unit.title,
                            is_required:   quiz.is_required,
                            passing_score: quiz.passing_score,
                            attempt_count: attemptCount,
                        });
                    }
                }

                // Course assessment
                const assessment = await CourseAssessment.findOne({
                    attributes: ['assessment_id', 'title', 'is_required', 'passing_score'],
                    where:      { course_id: courseId },
                });
                if (assessment) {
                    const [hasPassed, attemptCount] = await Promise.all([
                        QuizAttempt.findOne({ where: { user_id: userId, assessment_id: assessment.assessment_id, passed: true } }),
                        QuizAttempt.count({ where: { user_id: userId, assessment_id: assessment.assessment_id } }),
                    ]);
                    if (!hasPassed) {
                        pending_assessment = {
                            assessment_id: assessment.assessment_id,
                            title:         assessment.title,
                            is_required:   assessment.is_required,
                            passing_score: assessment.passing_score,
                            attempt_count: attemptCount,
                        };
                    }
                }
            }

            return {
                course_id:         courseId,
                title:             row.course.title,
                reading_status:    row.status,
                lessons_total,
                lessons_completed,
                last_accessed_at:  row.last_accessed_at,
                pending_quizzes,
                pending_assessment,
            };
        }));

        return R.success(res, 'In-progress courses retrieved.', result);
    } catch (err) {
        console.error('[CLIENT][COURSE READING PROGRESS][IN PROGRESS]', err);
        return R.error(res, 'Could not retrieve in-progress courses.', 500);
    }
};

// =============================================================================
// ── GET PROGRESS SUMMARY ──────────────────────────────────────────────────────
// =============================================================================

// GET /client/courses/:courseId/progress/summary
// Returns a compact progress snapshot: lesson counts + percentage + course status.
// Used by the ReadCourse block to render the inline progress bar without needing
// the full flat row list.

exports.getCourseProgressSummary = async (req, res) => {
    try {
        const { courseId } = req.params;
        const userId       = req.user.user_id;

        const course = await Course.findOne({
            where:      { course_id: courseId, ...notDeleted },
            attributes: ['course_id'],
        });
        if (!course) return R.error(res, 'Course not found.', 404);

        const [lessons_total, lessons_completed, courseRow] = await Promise.all([
            Lesson.count({
                include: [{
                    model:    Unit,
                    as:       'unit',
                    where:    { course_id: courseId, ...notDeleted },
                    required: true,
                }],
                where: notDeleted,
            }),
            CourseReadingProgress.count({
                where: { user_id: userId, course_id: courseId, type: 'lesson', status: 'completed' },
            }),
            CourseReadingProgress.findOne({
                where:      { user_id: userId, course_id: courseId, type: 'course' },
                attributes: ['status'],
            }),
        ]);

        const percent = lessons_total > 0 ? Math.round((lessons_completed / lessons_total) * 100) : 0;

        return R.success(res, 'Progress summary retrieved.', {
            lessons_total,
            lessons_completed,
            percent,
            status: courseRow?.status ?? null,
        });
    } catch (err) {
        console.error('[CLIENT][COURSE READING PROGRESS][SUMMARY]', err);
        return R.error(res, 'Could not retrieve progress summary.', 500);
    }
};

// =============================================================================
// ── GET PROGRESS SNAPSHOT ─────────────────────────────────────────────────────
// =============================================================================

// GET /client/courses/:courseId/progress
// Returns all progress rows for this user+course.
// Frontend uses this to decorate the sidebar (completed checkmarks, locked states, etc.)

exports.getCourseProgress = async (req, res) => {
    try {
        const { courseId } = req.params;
        const userId       = req.user.user_id;

        const course = await Course.findOne({
            where:      { course_id: courseId, ...notDeleted },
            attributes: ['course_id'],
        });
        if (!course) return R.error(res, 'Course not found.', 404);

        const rows = await CourseReadingProgress.findAll({
            where: { user_id: userId, course_id: courseId },
            attributes: ['progress_id', 'reference_id', 'type', 'status', 'completed_at', 'last_accessed_at'],
        });

        return R.success(res, 'Course progress retrieved.', rows);
    } catch (err) {
        console.error('[CLIENT][COURSE READING PROGRESS][GET]', err);
        return R.error(res, 'Could not retrieve course progress.', 500);
    }
};

// =============================================================================
// ── UPSERT LESSON PROGRESS ────────────────────────────────────────────────────
// =============================================================================

// POST /client/courses/:courseId/units/:unitId/lessons/:lessonId/progress
// Body: { status: 'in_progress' | 'completed' }
//
// Flow:
//   1. Resolve course / unit / lesson to get their UUIDs
//   2. Delegate to upsertLessonRead — handles lesson + unit + course in one tx

exports.upsertLessonProgress = async (req, res) => {
    try {
        const { courseId, unitId, lessonId } = req.params;
        const userId = req.user.user_id;
        const status = req.body.status === 'completed' ? 'completed' : 'in_progress';

        const [course, unit, lesson] = await Promise.all([
            Course.findOne({
                where:      { course_id: courseId, ...notDeleted },
                attributes: ['course_id', 'uuid'],
            }),
            Unit.findOne({
                where:      { unit_id: unitId, course_id: courseId, ...notDeleted },
                attributes: ['unit_id', 'uuid'],
            }),
            Lesson.findOne({
                where:      { lesson_id: lessonId, unit_id: unitId, ...notDeleted },
                attributes: ['lesson_id', 'uuid'],
            }),
        ]);

        if (!course)  return R.error(res, 'Course not found.', 404);
        if (!unit)    return R.error(res, 'Unit not found.', 404);
        if (!lesson)  return R.error(res, 'Lesson not found.', 404);

        const result = await upsertLessonRead(userId, {
            courseId:     course.course_id,
            courseUuid:   course.uuid,
            unitId:       unit.unit_id,
            unitUuid:     unit.uuid,
            lessonUuid:   lesson.uuid,
            lessonStatus: status,
        });

        logActivity(userId, 'lesson_read', {
            entityType: 'lesson',
            entityId:   lesson.lesson_id,
            details:    { lesson_uuid: lesson.uuid, status },
        });

        return R.success(res, 'Progress updated.', result, 200);
    } catch (err) {
        console.error('[CLIENT][COURSE READING PROGRESS][UPSERT]', err);
        return R.error(res, 'Could not update progress.', 500);
    }
};