script.js

document.addEventListener("DOMContentLoaded", function () {
  let allData = {};
  const searchBranchContainer = document.getElementById("search-parameters-branch");
  const searchSemesterContainer = document.getElementById("search-parameters-semester");
  const searchSubjectContainer = document.getElementById("search-parameters-subject");
  const branchFilter = document.getElementById("branch-filter");
  const semesterFilter = document.getElementById("semester-filter");
  const subjectFilter = document.getElementById("subject-filter");
  const notesContainer = document.getElementById("notes-container");
  const themeToggleButton = document.getElementById('themeToggle');
  const hamburger = document.getElementById("hamburger");
  const navMenu = document.querySelector(".navbar-center");
  const signUp = document.querySelector(".signup-btn");

  const subjectMap = {
    "CSE": ["Maths", "DBMS", "OS", "DSA"],
    "CSE AIML": ["AI", "ML", "Python"],
    "CSE IOT": ["IoT Fundamentals", "Sensors", "Microcontrollers"],
    "CSE DS": ["Data Science Basics", "Statistics", "Python for DS"]
  };

  let notesData = [];

  function createDropdown(container, id, defaultText, options) {
    container.innerHTML = '';
    const select = document.createElement("select");
    select.id = id;
    select.className = "search-parameters-select";
    const defaultOption = document.createElement("option");
    defaultOption.disabled = true;
    defaultOption.selected = true;
    defaultOption.innerHTML = defaultText;
    select.appendChild(defaultOption);
    options.forEach(opt => {
      const option = document.createElement("option");
      option.value = opt;
      option.innerHTML = opt;
      select.appendChild(option);
    });
    container.appendChild(select);
    return select;
  }

  function updateSemesters() {
    const selectedBranch = document.getElementById("selectBranch").value;
    let semesterNames = [];
    searchSemesterContainer.innerHTML = '';
    searchSubjectContainer.innerHTML = '';
    const branchData = allData.branches.find(b => b.name === selectedBranch);
    if (branchData && branchData.semesters) {
      semesterNames = branchData.semesters.map(sem => sem.semester);
    }
    const semesterSelect = createDropdown(searchSemesterContainer, "selectSemester", "Select Semester", semesterNames);
    semesterSelect.addEventListener("change", updateSubjects);
  }

  function updateSubjects() {
    const selectedBranch = document.getElementById("selectBranch").value;
    const selectedSemester = document.getElementById("selectSemester").value;
    let subjectNames = [];
    searchSubjectContainer.innerHTML = '';
    const branchData = allData.branches.find(b => b.name === selectedBranch);
    if (branchData && branchData.semesters) {
      const semesterData = branchData.semesters.find(sem => sem.semester == selectedSemester);
      if (semesterData && semesterData.subjects) {
        subjectNames = semesterData.subjects.map(sub => Object.values(sub)[0]).sort((a, b) => a.localeCompare(b));
      }
    }
    createDropdown(searchSubjectContainer, "selectSubject", "Select Subject", subjectNames);
  }

  fetch("data/search_parameters/parameters.json")
    .then(res => res.json())
    .then(data => {
      allData = data;
      const branchNames = allData.branches.map(b => b.name);
      const branchSelect = createDropdown(searchBranchContainer, "selectBranch", "Select Branch", branchNames);
      branchSelect.addEventListener("change", updateSemesters);
    })
    .catch(error => console.error("Error fetching parameters:", error));

  // Typewriter Effect
  const words = ["Branch", "Semester", "Subject", "Year"];
  let currentWordIndex = 0;
  let charIndex = 0;
  let isDeleting = false;
  function typeWriterEffect() {
    const currentWord = words[currentWordIndex];
    const typewriterElement = document.getElementById('typeWriterText');
    if (!typewriterElement) return;
    if (isDeleting) {
      typewriterElement.textContent = currentWord.substring(0, charIndex - 1);
      charIndex--;
    } else {
      typewriterElement.textContent = currentWord.substring(0, charIndex + 1);
      charIndex++;
    }
    let typeSpeed = isDeleting ? 75 : 150;
    if (!isDeleting && charIndex === currentWord.length) {
      typeSpeed = 2000;
      isDeleting = true;
    } else if (isDeleting && charIndex === 0) {
      isDeleting = false;
      currentWordIndex = (currentWordIndex + 1) % words.length;
      typeSpeed = 500;
    }
    setTimeout(typeWriterEffect, typeSpeed);
  }
  typeWriterEffect();

  // Theme Toggle
  if (themeToggleButton) {
    themeToggleButton.addEventListener('click', () => {
      const html = document.documentElement;
      const currentTheme = html.getAttribute('data-theme') || 'light';
      const newTheme = currentTheme === 'dark' ? 'light' : 'dark';
      html.setAttribute('data-theme', newTheme);
      localStorage.setItem('theme', newTheme);
    });
  }
  (function initTheme() {
    const savedTheme = localStorage.getItem('theme');
    const prefersDark = window.matchMedia && window.matchMedia('(prefers-color-scheme: dark)').matches;
    document.documentElement.setAttribute('data-theme', savedTheme || (prefersDark ? 'dark' : 'light'));
  })();

  if (hamburger && navMenu) {
    hamburger.addEventListener("click", () => {
      navMenu.classList.toggle("show");
      signUp.classList.toggle("show");
    });
    document.addEventListener('click', function (event) {
      if (!navMenu.contains(event.target) && !hamburger.contains(event.target)) {
        navMenu.classList.remove('show');
        signUp.classList.remove('show');
      }
    });
  }

  fetch("data/notes.json")
    .then(res => res.json())
    .then(data => {
      notesData = data;
      updateFilterSubjects("");
      displayNotes(notesData);
      runQuerySearch();
    });

  function updateFilterSubjects(branch) {
    subjectFilter.innerHTML = '<option value="">All Subjects</option>';
    const subjects = subjectMap[branch] || [].concat(...Object.values(subjectMap));
    [...new Set(subjects)].sort((a, b) => a.localeCompare(b)).forEach(sub => {
      const opt = document.createElement("option");
      opt.value = sub;
      opt.textContent = sub;
      subjectFilter.appendChild(opt);
    });
  }

  function displayNotes(notes) {
    notesContainer.innerHTML = notes.length === 0 ? "<p>No notes found.</p>" : "";
    const bookmarked = JSON.parse(localStorage.getItem("bookmarkedNotes") || "[]");
    notes.sort((a, b) => a.title.toLowerCase().localeCompare(b.title.toLowerCase())).forEach(note => {
      const card = document.createElement("div");
      card.className = "note-card";
      const isBookmarked = bookmarked.includes(note.title);
      card.innerHTML = `
        <div>
          <h3>${note.title}</h3>
          <p><strong>Branch:</strong> ${note.branch}</p>
          <p><strong>Semester:</strong> ${note.semester}</p>
          <p><strong>Subject:</strong> ${note.subject}</p>
          <div class="rating" data-id="${note.title}">
            ${[1, 2, 3, 4, 5].map(i => `<span class="star" data-value="${i}">&#9733;</span>`).join('')}
          </div>
        </div>
        <div class="mark">
          <a href="${note.link}" target="_blank" download>Download</a>
          <button class="bookmark-btn ${isBookmarked ? 'bookmarked' : ''}" data-id="${note.title}">
            ${isBookmarked ? "★ Bookmarked" : "☆ Bookmark"}
          </button>
        </div>
      `;
      notesContainer.appendChild(card);
    });

    document.querySelectorAll(".bookmark-btn").forEach(btn => {
      btn.addEventListener("click", () => {
        const id = btn.getAttribute("data-id");
        let bookmarks = JSON.parse(localStorage.getItem("bookmarkedNotes") || "[]");
        if (bookmarks.includes(id)) {
          bookmarks = bookmarks.filter(b => b !== id);
          btn.textContent = "☆ Bookmark";
          btn.classList.remove("bookmarked");
        } else {
          bookmarks.push(id);
          btn.textContent = "★ Bookmarked";
          btn.classList.add("bookmarked");
        }
        localStorage.setItem("bookmarkedNotes", JSON.stringify(bookmarks));
      });
    });

    document.querySelectorAll(".rating").forEach(rating => {
      const noteId = rating.dataset.id;
      const saved = localStorage.getItem(`rating_${noteId}`);
      if (saved) highlightStars(rating, saved);
      rating.querySelectorAll(".star").forEach(star => {
        star.addEventListener("click", () => {
          const value = star.dataset.value;
          localStorage.setItem(`rating_${noteId}`, value);
          highlightStars(rating, value);
        });
      });
    });

    function highlightStars(container, rating) {
      const stars = container.querySelectorAll(".star");
      stars.forEach(star => {
        star.classList.toggle("filled", star.dataset.value <= rating);
      });
    }
  }

  [branchFilter, semesterFilter, subjectFilter].forEach(filter => {
    filter.addEventListener("change", () => {
      const branchVal = branchFilter.value;
      if (filter === branchFilter) updateFilterSubjects(branchVal);
      const filtered = notesData.filter(note =>
        (branchVal === "" || note.branch === branchVal) &&
        (semesterFilter.value === "" || note.semester === semesterFilter.value) &&
        (subjectFilter.value === "" || note.subject === subjectFilter.value)
      );
      displayNotes(filtered);
    });
  });

  function runQuerySearch() {
    const urlParams = new URLSearchParams(window.location.search);
    const query = urlParams.get("query")?.trim().toLowerCase();
    if (query) {
      const notes = document.querySelectorAll(".note-card");
      let matchFound = false;
      notes.forEach(note => {
        const content = note.textContent.toLowerCase();
        const show = content.includes(query);
        note.style.display = show ? "block" : "none";
        if (show) matchFound = true;
      });
      if (!matchFound) {
        const msg = document.createElement("p");
        msg.textContent = `No notes found for "${query}"`;
        msg.style.color = "red";
        msg.style.fontWeight = "bold";
        msg.style.marginTop = "20px";
        document.getElementById("notes-container").appendChild(msg);
      }
    }
  }
});