/* ==========================================================================
   librus-tui frontend - homework, attendance, messages, free days
   ========================================================================== */

"use strict";

/* ------------------------------------------------------------------ homework */

async function renderHomework(token) {
  const data = await api("/api/exams");
  if (token !== state.loadToken) return;

  const exams = (data.exams || []).slice().sort((a, b) => {
    const left = parseDate(a.Date);
    const right = parseDate(b.Date);
    return (left ? left.getTime() : Number.MAX_SAFE_INTEGER) -
      (right ? right.getTime() : Number.MAX_SAFE_INTEGER);
  });
  state.exams = exams;

  const upcoming = exams.filter((exam) => (daysUntil(exam.Date) ?? -1) >= 0).length;

  const rows = exams.length
    ? exams
        .map((exam, index) => {
          const distance = daysUntil(exam.Date);
          const dateClass = distance === null ? "" : distance < 0 ? "soft" : distance <= 1 ? "urgent" : distance <= 3 ? "soon" : "";
          const typeClass = examTagClass(exam.Type);
          const content = exam.Content ? truncate(exam.Content, 84) : "—";
          return `
            <tr data-exam="${index}" title="click for details">
              <td class="num">
                <span class="date-badge ${dateClass}">${esc(fmtDate(exam.Date))}</span>
                <div class="soft">${esc(weekdayShort(exam.Date))}</div>
              </td>
              <td class="strong">${esc(exam.Lesson || "—")}</td>
              <td><span class="tag ${typeClass}">${esc(exam.Type || "—")}</span></td>
              <td class="num">${esc(timeRange(exam.StartTime, exam.EndTime))}</td>
              <td class="soft">${esc(personName(exam.AddedBy) || "—")}</td>
              <td class="content-cell">${esc(content)}</td>
            </tr>`;
        })
        .join("")
    : "";

  $("#view").innerHTML = `
    <div class="view-inner">
      <div class="toolbar">
        <span><b>${upcoming}</b> upcoming</span>
        <span class="dim">·</span>
        <span><b>${exams.length}</b> total</span>
        <span class="grow"></span>
        <span class="dim">click a row for the full description</span>
      </div>
      <section class="panel">
        <div class="panel-title"><span>homework &amp; tests</span><span class="title-note">sorted by date</span></div>
        ${
          exams.length
            ? `<div class="table-wrap"><table class="data-table">
                <thead>
                  <tr><th>date</th><th>subject</th><th>type</th><th>time</th><th>teacher</th><th>description</th></tr>
                </thead>
                <tbody>${rows}</tbody>
              </table></div>`
            : `<div class="empty">no homework or tests</div>`
        }
      </section>
    </div>
  `;
}

function openExamDetail(index) {
  const exam = state.exams[index];
  if (!exam) return;
  const body = `
    <dl class="detail-grid">
      <dt>subject</dt><dd>${esc(exam.Lesson || "—")}</dd>
      <dt>type</dt><dd>${esc(exam.Type || "—")}</dd>
      <dt>date</dt><dd>${esc(fmtDate(exam.Date))} · ${esc(weekdayShort(exam.Date))}</dd>
      <dt>time</dt><dd>${esc(timeRange(exam.StartTime, exam.EndTime))}</dd>
      <dt>teacher</dt><dd>${esc(personName(exam.AddedBy) || "—")}</dd>
      <dt>added</dt><dd>${esc(fmtDate(exam.AddDate))}</dd>
    </dl>
    <div class="help-section">description</div>
    <p style="white-space:pre-wrap">${esc(exam.Content || "—")}</p>
  `;
  openModal(`homework · ${exam.Lesson || "—"}`, body, [{ label: "[ close ]", close: true }]);
}

/* ---------------------------------------------------------------- attendance */

async function renderAttendance(token) {
  const data = await api("/api/attendances");
  if (token !== state.loadToken) return;

  const items = (data.attendances || []).slice().sort((a, b) => {
    const left = parseDate(a.Date);
    const right = parseDate(b.Date);
    return (right ? right.getTime() : 0) - (left ? left.getTime() : 0);
  });

  const total = items.length;
  const absent = items.filter((item) => !item.isPresence).length;
  const late = items.filter((item) => /późn|spoźn|sp\./i.test(`${item.Type} ${item.Short}`)).length;
  const excused = items.filter((item) => /zwoln|zw\./i.test(`${item.Type} ${item.Short}`)).length;

  const rows = items.length
    ? items
        .map((item) => {
          const isLate = /późn|spoźn|sp\./i.test(`${item.Type} ${item.Short}`);
          const tagClass = !item.isPresence ? "tag-red" : isLate ? "tag-amber" : "tag-green";
          return `
            <tr>
              <td class="num">${esc(fmtDate(item.Date))}</td>
              <td class="strong">${esc(item.Lesson || "—")}</td>
              <td><span class="tag ${tagClass}">${esc(item.Short || "?")} ${esc(item.Type || "")}</span></td>
              <td class="soft">${esc(personName(item.AddedBy) || "—")}</td>
              <td class="num presence ${item.isPresence ? "yes" : "no"}">${item.isPresence ? "present" : "absent"}</td>
            </tr>`;
        })
        .join("")
    : "";

  $("#view").innerHTML = `
    <div class="view-inner">
      <div class="att-summary">
        <div class="att-tile"><div class="value">${total}</div><div class="label">entries</div></div>
        <div class="att-tile"><div class="value">${Math.max(0, total - absent)}</div><div class="label">present</div></div>
        <div class="att-tile absent"><div class="value">${absent}</div><div class="label">absences</div></div>
        <div class="att-tile late"><div class="value">${late}</div><div class="label">late · ${excused} excused</div></div>
      </div>
      <section class="panel">
        <div class="panel-title"><span>attendance register</span><span class="title-note">${total} entries</span></div>
        ${
          items.length
            ? `<div class="table-wrap"><table class="data-table">
                <thead><tr><th>date</th><th>subject</th><th>type</th><th>teacher</th><th>status</th></tr></thead>
                <tbody>${rows}</tbody>
              </table></div>`
            : `<div class="empty">no attendance entries</div>`
        }
      </section>
    </div>
  `;
}

/* ------------------------------------------------------------------ messages */

async function renderMessages(token) {
  const data = await api("/api/messages");
  if (token !== state.loadToken) return;

  state.messages = data.messages || [];
  state.messageCache.clear();
  state.messageIndex = state.messages.length ? 0 : -1;

  $("#view").innerHTML = `
    <div class="view-inner">
      <div class="messages-layout">
        <section class="panel">
          <div class="panel-title">
            <span>inbox</span>
            <span class="title-note">${state.messages.length} messages</span>
          </div>
          <div class="message-list" id="message-list"></div>
        </section>
        <div class="panel" id="message-reader"></div>
      </div>
    </div>
  `;

  renderMessageList();

  if (state.messageIndex >= 0) {
    loadMessage(state.messageIndex);
  } else {
    $("#message-reader").innerHTML = `
      <div class="panel-title"><span>reader</span></div>
      <div class="empty">inbox empty</div>`;
  }
}

function renderMessageList() {
  const list = $("#message-list");
  if (!list) return;
  if (!state.messages.length) {
    list.innerHTML = `<div class="empty">no messages</div>`;
    return;
  }
  list.innerHTML = state.messages
    .map(
      (message, index) => `
      <button class="message-item ${index === state.messageIndex ? "active" : ""}" type="button" data-message="${index}">
        <div class="msg-top">
          <span class="msg-from">${esc(message.from || "unknown")}</span>
          <span class="msg-date">${esc(message.date || "")}</span>
        </div>
        <div class="msg-subject">${esc(message.subject || "(no subject)")}</div>
      </button>`
    )
    .join("");
}

function highlightMessageList() {
  $$("#message-list .message-item").forEach((element, index) => {
    element.classList.toggle("active", index === state.messageIndex);
  });
  const active = $("#message-list .message-item.active");
  if (active) active.scrollIntoView({ block: "nearest" });
}

function selectMessage(index) {
  if (!state.messages.length) return;
  const next = Math.max(0, Math.min(state.messages.length - 1, index));
  if (next === state.messageIndex) return;
  state.messageIndex = next;
  highlightMessageList();
  loadMessage(next);
}

function moveMessage(delta) {
  if (!state.messages.length) return;
  selectMessage(state.messageIndex + delta);
}

async function loadMessage(index, force = false) {
  const message = state.messages[index];
  const reader = $("#message-reader");
  if (!message || !reader) return;

  const token = ++state.messageToken;
  const link = message.link;

  if (!force && state.messageCache.has(link)) {
    renderMessageDetail(state.messageCache.get(link), index);
    return;
  }

  reader.innerHTML = `
    <div class="panel-title"><span>reader</span><span class="title-note">loading…</span></div>
    <div class="loading">[..] opening message…</div>`;

  try {
    const detail = await api(`/api/message?link=${encodeURIComponent(link)}`);
    if (token !== state.messageToken) return;
    state.messageCache.set(link, detail);
    renderMessageDetail(detail, index);
    setStatus(`[ok] message ${index + 1}/${state.messages.length}`, "ok");
  } catch (error) {
    if (token !== state.messageToken) return;
    reader.innerHTML = `
      <div class="panel-title"><span>reader</span><span class="title-note">error</span></div>
      <div class="error-message">${esc(error.message)}</div>`;
    toast(error.message, "err");
  }
}

function renderMessageDetail(detail, index) {
  const reader = $("#message-reader");
  if (!reader) return;

  const attachments = (detail.attachments || [])
    .map((attachment) => {
      const link = attachment.nice || attachment.source || "";
      return `
        <a class="attachment" href="/api/download?link=${encodeURIComponent(link)}" download>
          <span>[&darr;]</span>
          <span>${esc(attachment.name || link || "attachment")}</span>
          <span class="size-hint">download</span>
        </a>`;
    })
    .join("");

  const readState = detail.read
    ? `<span class="tag tag-dim">read: ${esc(detail.read)}</span>`
    : "";

  reader.innerHTML = `
    <div class="panel-title">
      <span>reader</span>
      <span class="title-note">${index + 1} / ${state.messages.length}</span>
    </div>
    <div class="reader-head">
      <h2 class="reader-subject">${esc(detail.subject || "(no subject)")}</h2>
      <div class="reader-meta">
        <span>from <b>${esc(detail.from || "unknown")}</b></span>
        <span>${esc(detail.date || "")}</span>
        ${readState}
      </div>
    </div>
    <div class="message-body">${detail.content || `<div class="empty">message body is empty</div>`}</div>
    ${
      attachments
        ? `<div class="attachments"><div class="attachments-title">attachments</div>${attachments}</div>`
        : ""
    }
  `;
  reader.scrollTop = 0;
}

/* ----------------------------------------------------------------- free days */

async function renderFreedays(token) {
  const [free, conferences] = await Promise.all([
    api("/api/freedays"),
    api("/api/conferences").catch(() => null),
  ]);
  if (token !== state.loadToken) return;

  const school = (free.school || [])
    .slice()
    .sort((a, b) => (parseDate(a.DateFrom) || 0) - (parseDate(b.DateFrom) || 0));
  const teachers = (free.teachers || [])
    .slice()
    .sort((a, b) => (parseDate(a.DateFrom) || 0) - (parseDate(b.DateFrom) || 0));
  const conf = (conferences && conferences.conferences) || [];

  const schoolRows = school.length
    ? school
        .map((item) => {
          const distance = daysUntil(item.DateFrom);
          const past = distance !== null && distance < 0;
          return `
            <div class="free-item" ${past ? 'style="opacity:.55"' : ""}>
              <div>
                <div class="free-name">${esc(item.Name || "free day")}</div>
                <div class="conf-meta">${esc(fmtDate(item.DateFrom))} → ${esc(fmtDate(item.DateTo))}</div>
              </div>
              <span class="countdown ${countdownClass(item.DateFrom)}">${esc(countdownLabel(item.DateFrom))}</span>
            </div>`;
        })
        .join("")
    : `<div class="empty">no free days</div>`;

  const teacherRows = teachers.length
    ? teachers
        .map((item) => {
          const teacher = personName(item.Teacher) || "teacher";
          const times = item.TimeFrom
            ? ` · ${esc(shortTime(item.TimeFrom))}–${esc(shortTime(item.TimeTo))}`
            : "";
          return `
            <div class="free-item">
              <div>
                <div class="free-name">${esc(teacher)}</div>
                <div class="conf-meta">${esc(fmtDate(item.DateFrom))} → ${esc(fmtDate(item.DateTo))}${times}</div>
              </div>
              <span class="countdown ${countdownClass(item.DateFrom)}">${esc(countdownLabel(item.DateFrom))}</span>
            </div>`;
        })
        .join("")
    : `<div class="empty">no teacher absences</div>`;

  const confRows = conf.length
    ? conf
        .map(
          (item) => `
          <div class="conf-item">
            <div class="conf-name">${esc(item.Name || "conference")}</div>
            <div class="conf-meta">${esc(item.Topic || "")}</div>
            <div class="conf-meta">${esc(fmtDate(item.Date))} · ${esc(shortTime(item.Time))}${item.Room ? ` · room ${esc(item.Room)}` : ""}</div>
          </div>`
        )
        .join("")
    : `<div class="empty">no scheduled conferences</div>`;

  $("#view").innerHTML = `
    <div class="view-inner">
      <div class="split-2">
        <section class="panel">
          <div class="panel-title"><span>school free days</span><span class="title-note">${school.length}</span></div>
          <div class="panel-body tight">${schoolRows}</div>
        </section>
        <section class="panel">
          <div class="panel-title"><span>teacher free days</span><span class="title-note">${teachers.length}</span></div>
          <div class="panel-body tight">${teacherRows}</div>
        </section>
        <section class="panel span-2">
          <div class="panel-title"><span>parent-teacher conferences</span><span class="title-note">${conf.length}</span></div>
          <div class="panel-body tight">${confRows}</div>
        </section>
      </div>
    </div>
  `;
}