const mongoose = require("mongoose");
const express = require("express");
const Course = require("../mongoose/models/courses");

const usersRouter = new express.Router();

// Get all courses
usersRouter.get("/courses/get", async (req, res) => {
  try {
    const courses = await Course.find({});
    res.status(200).send(courses);
  } catch (error) {
    res.status(400).send({ error: "Failed to fetch courses" });
  }
});

// Enroll in a course
usersRouter.post("/courses/enroll/:id", async (req, res) => {
  try {
    const course = await Course.findById(req.params.id);
    if (!course) {
      return res.status(404).send({ error: "Course not found" });
    }
    if (course.isApplied) {
      return res.status(403).send({ error: "Already enrolled in this course" });
    }
    course.isApplied = true;
    await course.save();
    res.status(200).send({ message: "Enrolled successfully" });
  } catch (error) {
    res.status(400).send({ error: "Failed to enroll in the course" });
  }
});

// Drop a course
usersRouter.delete("/courses/drop/:id", async (req, res) => {
  try {
    const course = await Course.findById(req.params.id);
    if (!course) {
      return res.status(404).send({ error: "Course not found" });
    }
    if (!course.isApplied) {
      return res.status(403).send({ error: "Cannot drop an unenrolled course" });
    }
    course.isApplied = false;
    await course.save();
    res.status(200).send({ message: "Dropped the course successfully" });
  } catch (error) {
    res.status(400).send({ error: "Failed to drop the course" });
  }
});

// Rate a course
usersRouter.patch("/courses/rating/:id", async (req, res) => {
  try {
    const { rating } = req.body;
    if (!rating || rating < 1 || rating > 5) {
      return res.status(400).send({ error: "Invalid rating" });
    }

    const course = await Course.findById(req.params.id);
    if (!course) {
      return res.status(404).send({ error: "Course not found" });
    }
    if (!course.isApplied) {
      return res.status(403).send({ error: "Cannot rate an unenrolled course" });
    }

    if (course.isRated) {
      return res.status(403).send({ error: "Course has already been rated" });
    }

    // Update course rating
    const totalRating = course.rating * course.noOfRatings;
    const newTotalRating = totalRating + rating;
    course.noOfRatings += 1;
    course.rating = (newTotalRating / course.noOfRatings).toFixed(1);
    course.isRated = true;
    await course.save();

    res.status(200).send({ message: "Rating added successfully" });
  } catch (error) {
    res.status(400).send({ error: "Failed to rate the course" });
  }
});

module.exports = usersRouter;