function load_links() {
  fetch("/api/pdf")
    .then((response) => response.json())
    .then((data) => {
      let i = 0;
      data.links.forEach((el) => {
        const select = document.getElementById("links");
        const option = document.createElement("option");
        option.value = i;
        option.text = el.split("/").pop().split(".pdf")[0];
        select.appendChild(option);
        i++;
      });
      document.getElementById("links-label").removeAttribute("aria-busy");
    })
    .catch((error) => {
      alert("Errore nel caricamento dei dati, riprova più tardi.");
      console.error("Error:", error);
    });
}

function load_teachers(id) {
  fetch(`/api/professori?id=${id}`)
    .then((response) => response.json())
    .then((data) => {
      sessionStorage.setItem("teachers", JSON.stringify(data));
      let i = 0;
      const list = document.getElementById("teachers");
      list.innerHTML = "";
      data.forEach((el) => {
        const option = document.createElement("option");
        option.value = el;
        list.appendChild(option);
        i++;
      });
      document.getElementById("teacher-label").removeAttribute("aria-busy");
    })
    .catch((error) => {
      alert("Errore nel caricamento dei dati, riprova più tardi.");
      console.error("Error:", error);
    });
}

function load_classes(id) {
  fetch(`/api/classi?id=${id}`)
    .then((response) => response.json())
    .then((data) => {
      const select = document.getElementById("year");
      for (let i = 0; i < select.children.length; i++) {
        if (!select.children[i].hasAttribute("disabled")) {
          select.removeChild(select.children[i]);
          i--;
        }
      }
      for (let i = 0; i < data.length; i++) {
        const option = document.createElement("option");
        option.value = i + 1;
        option.text = i + 1;
        select.appendChild(option);
      }
      sessionStorage.setItem("classes", JSON.stringify(data));
      document.getElementById("class-label").removeAttribute("aria-busy");
    })
    .catch((error) => {
      alert("Errore nel caricamento dei dati, riprova più tardi.");
      console.error("Error:", error);
    });
}

function make_teacher_table(id, teacher) {
  make_table(`/api/professore?id=${id}&professore=${teacher}`);
}

function make_student_table(id, student_class) {
  make_table(`/api/classe?id=${id}&classe=${student_class}`);
}

function make_table(url) {
  fetch(url)
    .then((response) => response.json())
    .then((data) => {
      for (let key in data) {
        let i = data[key].length - 1;
        while (i >= 0 && data[key][i] === "") {
          data[key].pop();
          i--;
        }
      }
      const columns = Math.max(
        ...Object.values(data).map((vettore) => vettore.length),
      );
      let table = document.getElementById("table");
      let tbody = document.createElement("tbody");
      let week = [
        "Lunedì",
        "Martedì",
        "Mercoledì",
        "Giovedì",
        "Venerdì",
        "Sabato",
      ];
      let thead = document.createElement("thead");
      let tr = document.createElement("tr");
      let th = document.createElement("th");
      th.scope = "col";
      tr.appendChild(th);
      for (let i = 0; i < columns; i++) {
        let th = document.createElement("th");
        th.scope = "col";
        th.textContent = i + 1;
        tr.appendChild(th);
      }
      thead.appendChild(tr);
      table.appendChild(thead);
      week.forEach((weekday) => {
        let tr = document.createElement("tr");
        let th = document.createElement("th");
        th.scope = "row";
        th.textContent = weekday;
        tr.appendChild(th);
        if (data[weekday] != null) {
          let inserted = 0;
          data[weekday].forEach((student_class) => {
            let td = document.createElement("td");
            td.textContent = student_class.replace(/ (?=[a-z])/g, "");
            tr.appendChild(td);
            inserted++;
          });
          while (inserted < columns) {
            let td = document.createElement("td");
            tr.appendChild(td);
            inserted++;
          }
          tbody.appendChild(tr);
        }
      });
      table.appendChild(tbody);
      document.getElementById("table").removeAttribute("aria-busy");
    })
    .catch((error) => {
      alert("Errore nel caricamento dei dati, riprova più tardi.");
      console.error("Error:", error);
    });
}

function select_pdf() {
  Cookies.set("id", document.getElementById("links").value);
  document.getElementById("form-type").removeAttribute("hidden");
}

function select_type() {
  let id = document.getElementById("links").value;
  let value = document.getElementById("type").value;
  if (value === "teacher") {
    load_teachers(id);
    document.getElementById("form-teacher").removeAttribute("hidden");
    document.getElementById("form-classes").setAttribute("hidden", "");
  } else if (value === "student") {
    load_classes(id);
    document.getElementById("form-classes").removeAttribute("hidden");
    document.getElementById("form-teacher").setAttribute("hidden", "");
  }
}

function load_section() {
  let data = JSON.parse(sessionStorage.getItem("classes"));
  let year = document.getElementById("year").value;
  const select = document.getElementById("section");
  for (let i = 0; i < select.children.length; i++) {
    if (!select.children[i].hasAttribute("disabled")) {
      select.removeChild(select.children[i]);
      i--;
    }
  }
  Object.keys(data[year - 1]).forEach((el) => {
    const option = document.createElement("option");
    option.value = el;
    option.text = el;
    select.appendChild(option);
  });
}

function load_major() {
  let data = JSON.parse(sessionStorage.getItem("classes"));
  let year = document.getElementById("year").value;
  let section = document.getElementById("section").value;
  let select = document.getElementById("major");
  for (let i = 0; i < select.children.length; i++) {
    if (!select.children[i].hasAttribute("disabled")) {
      select.removeChild(select.children[i]);
      i--;
    }
  }
  data[year - 1][section].forEach((el) => {
    const option = document.createElement("option");
    option.value = el;
    option.text = el;
    select.appendChild(option);
  });
}

function select_teacher() {
  let teacher = document.getElementById("teacher").value;
  let teachers = JSON.parse(sessionStorage.getItem("teachers"));
  if (!teachers.includes(teacher)) {
    return false;
  }
  Cookies.set("type", "teacher");
  Cookies.set("teacher", teacher);
}

function select_class() {
  Cookies.set("type", "student");
  let student_class = document.getElementById("year").value;
  student_class += document.getElementById("section").value;
  student_class += document.getElementById("major").value;
  Cookies.set("class", student_class);
}

function delete_cookies() {
  Cookies.remove("id");
  Cookies.remove("type");
  Cookies.remove("teacher");
  Cookies.remove("class");
}

if (Cookies.get("id") && Cookies.get("type")) {
  if (Cookies.get("type") === "teacher" && Cookies.get("teacher")) {
    make_teacher_table(Cookies.get("id"), Cookies.get("teacher"));
    document.getElementById("dashboard").removeAttribute("hidden");
  } else if (Cookies.get("type") === "student" && Cookies.get("class")) {
    make_student_table(Cookies.get("id"), Cookies.get("class"));
    document.getElementById("dashboard").removeAttribute("hidden");
  }
} else {
  document.getElementById("forms").removeAttribute("hidden");
  load_links();
}