/*
 * Copyright (C) 2025 Jakub Žitník
 *
 * This program is free software: you can redistribute it and/or modify
 * it under the terms of the GNU General Public License as published by
 * the Free Software Foundation, either version 3 of the License, or
 * (at your option) any later version.
 *
 * This program is distributed in the hope that it will be useful,
 * but WITHOUT ANY WARRANTY; without even the implied warranty of
 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
 * GNU General Public License for more details.
 */

import axios from "axios";
import { CookieJar } from "tough-cookie";
import { wrapper } from "axios-cookiejar-support";
import * as cheerio from "cheerio";
import { URLSearchParams } from "url";
import fs from "fs";

const BASE = "https://www.spsejecna.cz";
const PATHS = {
  SET_ROLE: "/user/role",
  LOGIN: "/user/login",
  TEACHERS: "/ucitel",
  TEACHER: teacherCode => `/ucitel/${teacherCode}`
};
const DB_PATH = "db/persistent/timetables.json";

const jar = new CookieJar();

const client = wrapper(axios.create({
  baseURL: BASE,
  jar,
  withCredentials: true,
  headers: {
    "User-Agent": "Mozilla/5.0 (Windows NT 10.0; Win64; x64; rv:120.0) Gecko/20100101 Firefox/120.0",
    "Accept": "text/html,application/xhtml+xml,application/xml;q=0.9,*/*;q=0.8"
  }
}));

globalThis.File = class File {};

async function login(username, password) {
  await client.get("/");

  await client.get(PATHS.SET_ROLE, {
    params: { role: "student" }
  });

  const token3Res = await client.get("/");
  const token3 = token3Res.data.match(/"token3"\s+value="(\d+)"/)[1];

  const form = new URLSearchParams();
  form.append('user', username);
  form.append('pass', password);
  form.append('token3', token3);
  form.append('submit', 'Přihlásit+se');

  try {
    const response = await client.post(PATHS.LOGIN, form.toString(), {
      headers: {
        "Content-Type": "application/x-www-form-urlencoded"
      },
      maxRedirects: 0
    });

    if (response.status == 200) {
      console.log("INVALID CREDENTIALS!");
      process.exit(1);
    }
  } catch {}
}

async function getAllTeacherCodes() {
  const list = new Set();
  const response = await client.get(PATHS.TEACHERS);
  const $ = cheerio.load(response.data);

  $("main .contentLeftColumn li, main .contentRightColumn li").each((_, el) => {
    const link = $(el).find("a");
    const href = link.attr("href");

    if (href) {
      const key = href.split("/").pop().toLowerCase();
      list.add(key);
    }
  });

  return list;
}

async function constructSchedules(allTeachers) {
  const classes = {};

  function setupClass(className) {
    function generateArray(width, height) {
      return Array.from({ length: height }, () => Array.from({ length: width }, () => []));
    }
    classes[className] = generateArray(10, 5);
  }

  let idk = 0;
  for (const key of allTeachers) {
    idk++;
    const response = await client.get(PATHS.TEACHER(key));
    const $ = cheerio.load(response.data);

    const tbody = $('table.timetable > tbody');
    if (!tbody.length) {
      console.log(`ERROR: ${key}`)
      continue;
    }

    tbody.find('tr').slice(1).each((dayIndex, tr) => {
      const $tr = $(tr);
      
      let currentHour = 0;

      $tr.find('td').each((_, td) => {
        const $td = $(td);
        
        const colspan = parseInt($td.attr('colspan') || '1', 10);

        const $subject = $td.find('span.subject');
        const $class = $td.find('span.class');
        const $group = $td.find('span.group');
        const $room = $td.find('a.room');
        const $employee = $td.find('a.employee');

        const hasData = $subject.length && $class.length && $room.length && $employee.length;
        
        let cellData = null;
        let classText = '';

        if (hasData) {
           classText = $class.text().trim();
           cellData = {
            subject: $subject.text().trim(),
            title: $subject.attr('title')?.trim() || '',
            group: $group.length ? $group.text().trim() : null,
            room: $room.text().trim(),
            teacher: {
              code: $employee.text().trim().toLowerCase(),
              name: $employee.attr('title')?.trim() || ''
            }
          };
        }

        for (let i = 0; i < colspan; i++) {
          if (currentHour >= 10) {
            break; 
          }

          if (hasData && cellData) {
            if (classes[classText] === undefined) {
              setupClass(classText);
            }
            
            classes[classText][dayIndex][currentHour].push(cellData);
          }

          currentHour++; 
        }
      });
    });
    
    console.log(`DONE: ${idk}/${allTeachers.size}`)
  }

  return classes;
}

await login(process.env.USERNAME, process.env.PASSWORD);
const allTeachers = await getAllTeacherCodes();
const schedule = await constructSchedules(allTeachers)
const str = JSON.stringify(schedule);

fs.writeFileSync(DB_PATH, str, {
  encoding: "utf8"
});