const healthText = document.querySelector("#healthText");
const refreshBtn = document.querySelector("#refreshBtn");
const recordForm = document.querySelector("#recordForm");
const recordQuery = document.querySelector("#recordQuery");
const recordMeta = document.querySelector("#recordMeta");
const recordRows = document.querySelector("#recordRows");
const dateSortBtn = document.querySelector("#dateSortBtn");
const timeSortBtn = document.querySelector("#timeSortBtn");
const inlineAccount = document.querySelector("#inlineAccount");
const correctionToolbar = document.querySelector("#correctionToolbar");
const correctionStatus = document.querySelector("#correctionStatus");
const copyCorrectedBtn = document.querySelector("#copyCorrectedBtn");
const correctionDialog = document.querySelector("#correctionDialog");
const correctionForm = document.querySelector("#correctionForm");
const correctionOriginal = document.querySelector("#correctionOriginal");
const correctionPreview = document.querySelector("#correctionPreview");
const correctionError = document.querySelector("#correctionError");
const correctionDate = document.querySelector("#correctionDate");
const correctionTime = document.querySelector("#correctionTime");
const correctionStudent = document.querySelector("#correctionStudent");
const correctionTeacher = document.querySelector("#correctionTeacher");
const correctionSubject = document.querySelector("#correctionSubject");
const closeCorrectionBtn = document.querySelector("#closeCorrectionBtn");
const cancelCorrectionBtn = document.querySelector("#cancelCorrectionBtn");

const WEEKDAYS = ["星期日", "星期一", "星期二", "星期三", "星期四", "星期五", "星期六"];
const COPY_LINE_BREAK = "\r\n";
const SORT_DIRECTIONS = { asc: 1, desc: -1 };
let currentRecords = [];
let recordSort = { date: "asc", time: "asc" };
let currentRecordOrder = [];
let correctedRecords = new Map();
let activeCorrectionKey = "";

function fmtHours(value) {
  return Number(value || 0).toLocaleString("zh-CN", { maximumFractionDigits: 2 });
}

function fmtTime(seconds) {
  if (!seconds) return "未知";
  return new Date(seconds * 1000).toLocaleString("zh-CN", { hour12: false });
}

function escapeHtml(value) {
  return String(value ?? "")
    .replaceAll("&", "&")
    .replaceAll("<", "&lt;")
    .replaceAll(">", "&gt;")
    .replaceAll('"', "&quot;")
    .replaceAll("'", "&#039;");
}

function metric(label, value) {
  return `<div class="metric"><span>${escapeHtml(label)}</span><strong>${escapeHtml(value)}</strong></div>`;
}

function makeRecordKey(row, index) {
  return JSON.stringify([index, row.date, row.time, row.student, row.duration, row.teacher, row.subject]);
}

function buildRecordLine(row) {
  return `${row.date}-${row.weekday}-${row.time}-${row.student}-${row.duration}-${row.teacher}-${row.subject}`;
}

function groupRecordsByTeacher(records) {
  const groups = new Map();
  records.forEach((row) => {
    const teacher = row.teacher || "未标注老师";
    if (!groups.has(teacher)) {
      groups.set(teacher, { teacher, count: 0, totalHours: 0, records: [] });
    }
    const group = groups.get(teacher);
    group.count += 1;
    group.totalHours += Number(row.duration_hours || 0);
    group.records.push(row);
  });
  return Array.from(groups.values()).sort((a, b) => {
    if (b.totalHours !== a.totalHours) return b.totalHours - a.totalHours;
    return a.teacher.localeCompare(b.teacher, "zh-CN");
  });
}

function getDisplayRecord(row) {
  return correctedRecords.get(row._recordKey) || row;
}

function normalizeDateForSort(value) {
  const text = String(value || "");
  const match = text.match(/^(\d{4})\.(\d{1,2})\.(\d{1,2})$/);
  if (!match) return text;
  return `${match[1]}.${match[2].padStart(2, "0")}.${match[3].padStart(2, "0")}`;
}

function compareDatesForSort(a, b) {
  return normalizeDateForSort(a).localeCompare(normalizeDateForSort(b), "zh-CN", { numeric: true });
}

function parseStartMinutes(value) {
  const match = String(value || "").match(/^(\d{1,2}):(\d{2})/);
  if (!match) return null;
  return Number(match[1]) * 60 + Number(match[2]);
}

function compareStartTimesForSort(a, b) {
  const minutesA = parseStartMinutes(a);
  const minutesB = parseStartMinutes(b);
  if (minutesA !== null && minutesB !== null) return minutesA - minutesB;
  if (minutesA !== null) return -1;
  if (minutesB !== null) return 1;
  return String(a || "").localeCompare(String(b || ""), "zh-CN", { numeric: true });
}

function compareRecordsForDisplay(a, b) {
  const displayA = getDisplayRecord(a);
  const displayB = getDisplayRecord(b);
  const dateCompare = compareDatesForSort(displayA.date, displayB.date);
  if (dateCompare !== 0) return dateCompare * SORT_DIRECTIONS[recordSort.date];

  const timeCompare = compareStartTimesForSort(displayA.time, displayB.time);
  if (timeCompare !== 0) return timeCompare * SORT_DIRECTIONS[recordSort.time];

  return (a._recordIndex || 0) - (b._recordIndex || 0);
}

function sortRecordsForDisplay(records) {
  return [...records].sort(compareRecordsForDisplay);
}

function sortDirectionLabel(direction) {
  return direction === "asc" ? "升序排列" : "降序排列";
}

function sortDirectionName(direction) {
  return sortDirectionLabel(direction);
}

function nextSortDirectionName(direction) {
  return direction === "asc" ? "降序排列" : "升序排列";
}

function updateRecordSortButtons() {
  dateSortBtn.textContent = `日期 ${sortDirectionLabel(recordSort.date)}`;
  dateSortBtn.setAttribute(
    "aria-label",
    `日期排序：${sortDirectionName(recordSort.date)}，点击切换为${nextSortDirectionName(recordSort.date)}`,
  );
  timeSortBtn.textContent = `时间 ${sortDirectionLabel(recordSort.time)}`;
  timeSortBtn.setAttribute(
    "aria-label",
    `时间排序：${sortDirectionName(recordSort.time)}，点击切换为${nextSortDirectionName(recordSort.time)}`,
  );
}

function resetRecordSort() {
  recordSort = { date: "asc", time: "asc" };
  updateRecordSortButtons();
}

function renderCurrentRecords() {
  if (!currentRecords.length) return;
  recordRows.innerHTML = renderGroupedRecords(currentRecords);
}

function toggleRecordSort(field) {
  recordSort = { ...recordSort, [field]: recordSort[field] === "asc" ? "desc" : "asc" };
  updateRecordSortButtons();
  renderCurrentRecords();
}

function renderRecordRow(row) {
  const key = row._recordKey;
  const corrected = correctedRecords.get(key);
  const displayRow = getDisplayRecord(row);
  const correctedClass = corrected ? " corrected-row" : "";
  const actionLabel = corrected ? "编辑" : "纠错";
  const badge = corrected ? '<span class="correction-badge">已修改</span>' : "";
  return `<tr class="record-row${correctedClass}">
    <td>${escapeHtml(displayRow.date)} ${escapeHtml(displayRow.weekday)}</td>
    <td>${escapeHtml(displayRow.time)}</td>
    <td>${escapeHtml(displayRow.student)}</td>
    <td>${escapeHtml(displayRow.teacher)}</td>
    <td>${escapeHtml(displayRow.subject)}</td>
    <td class="num">${escapeHtml(displayRow.duration)}</td>
    <td class="record-action-cell">
      <div class="record-actions">
        <button class="small-button correction-edit" type="button" data-record-key="${escapeHtml(key)}">${actionLabel}</button>
        ${badge}
      </div>
    </td>
  </tr>`;
}

function renderGroupedRecords(records) {
  currentRecordOrder = [];
  return groupRecordsByTeacher(records)
    .map(
      (group) => `<tr class="teacher-group">
        <td colspan="7">
          <div class="teacher-group-title">
            <strong>${escapeHtml(group.teacher)}</strong>
            <span>${group.count} 条记录 · ${fmtHours(group.totalHours)} 小时</span>
          </div>
        </td>
      </tr>${sortRecordsForDisplay(group.records)
        .map((row) => {
          currentRecordOrder.push(row._recordKey);
          return renderRecordRow(row);
        })
        .join("")}`,
    )
    .join("");
}

function statusClass(status) {
  if (status === "欠费") return "debt";
  if (status === "预警") return "warning";
  if (status === "正常") return "normal";
  return "closed";
}

function renderPayments(payments) {
  if (!payments.length) return "暂无缴费记录";
  return payments.map((item) => `${item.date}：${fmtHours(item.hours)} 小时`).join("，");
}

function renderInlineAccount(account) {
  inlineAccount.hidden = false;
  inlineAccount.innerHTML = `<div class="inline-account-head">
      <div>
        <h3>${escapeHtml(account.student)} 课时账户</h3>
        <p>${escapeHtml(account.student_id)}</p>
      </div>
      <span class="status ${statusClass(account.account_status)}">${escapeHtml(account.account_status)}</span>
    </div>
    <div class="inline-account-grid">
      ${metric("剩余课时", fmtHours(account.remaining))}
      ${metric("缴费次数", account.payments_count)}
      ${metric("缴费记录", renderPayments(account.payments))}
      ${metric("备注", account.note || "无")}
    </div>`;
}

async function loadInlineAccount(student) {
  inlineAccount.hidden = false;
  inlineAccount.innerHTML = `<div class="inline-account-loading">正在读取 ${escapeHtml(student)} 的课时账户</div>`;
  try {
    const account = await fetchJson(`/api/student-account/${encodeURIComponent(student)}`);
    renderInlineAccount(account);
  } catch (error) {
    inlineAccount.innerHTML = `<div class="inline-account-loading">课时账户读取失败：${escapeHtml(error.message)}</div>`;
  }
}

function clearInlineAccount() {
  inlineAccount.hidden = true;
  inlineAccount.innerHTML = "";
}

function updateCorrectionToolbar(message = "", isError = false) {
  const count = correctedRecords.size;
  correctionToolbar.hidden = count === 0;
  copyCorrectedBtn.disabled = count === 0;
  copyCorrectedBtn.textContent = `复制已修改记录 ${count} 条`;
  correctionStatus.textContent = message || `已修改 ${count} 条记录`;
  correctionStatus.classList.toggle("is-error", isError);
}

function resetCorrections() {
  correctedRecords = new Map();
  currentRecordOrder = [];
  activeCorrectionKey = "";
  updateCorrectionToolbar();
}

function parseCorrectionDate(value) {
  const match = value.trim().match(/^(\d{4})\.(\d{2})\.(\d{2})$/);
  if (!match) {
    throw new Error("日期格式应为 YYYY.MM.DD，例如 2026.06.10");
  }
  const year = Number(match[1]);
  const month = Number(match[2]);
  const day = Number(match[3]);
  const parsed = new Date(year, month - 1, day);
  if (parsed.getFullYear() !== year || parsed.getMonth() !== month - 1 || parsed.getDate() !== day) {
    throw new Error("日期不存在，请检查年月日");
  }
  return {
    date: `${year}.${String(month).padStart(2, "0")}.${String(day).padStart(2, "0")}`,
    weekday: WEEKDAYS[parsed.getDay()],
  };
}

function parseCorrectionTime(value) {
  const match = value.trim().match(/^([01]?\d|2[0-3]):([0-5]\d)-([01]?\d|2[0-3]):([0-5]\d)$/);
  if (!match) {
    throw new Error("时间格式应为 HH:MM-HH:MM，例如 08:00-10:00");
  }
  const startHour = Number(match[1]);
  const startMinute = Number(match[2]);
  const endHour = Number(match[3]);
  const endMinute = Number(match[4]);
  const startTotal = startHour * 60 + startMinute;
  const endTotal = endHour * 60 + endMinute;
  if (endTotal <= startTotal) {
    throw new Error("结束时间必须晚于开始时间");
  }
  const totalMinutes = endTotal - startTotal;
  const hours = Math.floor(totalMinutes / 60);
  const minutes = totalMinutes % 60;
  return {
    time: `${String(startHour).padStart(2, "0")}:${String(startMinute).padStart(2, "0")}-${String(endHour).padStart(2, "0")}:${String(endMinute).padStart(2, "0")}`,
    duration: `${hours}小时${minutes}分`,
    duration_hours: Math.round((totalMinutes / 60) * 100) / 100,
  };
}

function requireText(value, label) {
  const text = value.trim();
  if (!text) {
    throw new Error(`${label}不能为空`);
  }
  if (text.includes("-")) {
    throw new Error(`${label}不能包含 -`);
  }
  return text;
}

function findCurrentRecord(key) {
  return currentRecords.find((row) => row._recordKey === key);
}

function buildCorrectedRecord(original) {
  const datePart = parseCorrectionDate(correctionDate.value);
  const timePart = parseCorrectionTime(correctionTime.value);
  return {
    ...original,
    ...datePart,
    ...timePart,
    student: requireText(correctionStudent.value, "学生"),
    teacher: requireText(correctionTeacher.value, "老师"),
    subject: requireText(correctionSubject.value, "科目"),
  };
}

function setCorrectionError(message) {
  correctionError.textContent = message;
  correctionError.hidden = !message;
}

function updateCorrectionPreview() {
  const original = findCurrentRecord(activeCorrectionKey);
  if (!original) return;
  try {
    const corrected = buildCorrectedRecord(original);
    correctionPreview.textContent = buildRecordLine(corrected);
    setCorrectionError("");
  } catch (error) {
    correctionPreview.textContent = "请修正上方字段后保存";
    setCorrectionError(error.message);
  }
}

function openCorrectionDialog(key) {
  const original = findCurrentRecord(key);
  if (!original) return;
  const corrected = correctedRecords.get(key) || original;
  activeCorrectionKey = key;
  correctionOriginal.textContent = `原记录：${buildRecordLine(original)}`;
  correctionDate.value = corrected.date;
  correctionTime.value = corrected.time;
  correctionStudent.value = corrected.student;
  correctionTeacher.value = corrected.teacher;
  correctionSubject.value = corrected.subject;
  correctionDialog.hidden = false;
  updateCorrectionPreview();
  correctionDate.focus();
}

function closeCorrectionDialog() {
  correctionDialog.hidden = true;
  activeCorrectionKey = "";
  setCorrectionError("");
}

function saveCorrection() {
  const original = findCurrentRecord(activeCorrectionKey);
  if (!original) return;
  const corrected = buildCorrectedRecord(original);
  if (buildRecordLine(corrected) === buildRecordLine(original)) {
    correctedRecords.delete(activeCorrectionKey);
  } else {
    correctedRecords.set(activeCorrectionKey, corrected);
  }
  recordRows.innerHTML = renderGroupedRecords(currentRecords);
  closeCorrectionDialog();
  updateCorrectionToolbar(`已保存 ${correctedRecords.size} 条修改`);
}

async function copyTextToClipboard(text) {
  if (navigator.clipboard && navigator.clipboard.writeText) {
    try {
      await navigator.clipboard.writeText(text);
      return;
    } catch (_error) {
      // HTTP access on the VPS usually needs the fallback path below.
    }
  }
  const textarea = document.createElement("textarea");
  textarea.value = text;
  textarea.setAttribute("readonly", "");
  textarea.style.position = "fixed";
  textarea.style.left = "-9999px";
  textarea.style.top = "0";
  document.body.appendChild(textarea);
  textarea.focus();
  textarea.select();
  const copied = document.execCommand("copy");
  textarea.remove();
  if (!copied) {
    throw new Error("浏览器拒绝写入剪切板");
  }
}

async function copyCorrectedRecords() {
  const correctedInPageOrder = currentRecordOrder
    .map((key) => correctedRecords.get(key))
    .filter(Boolean);
  if (!correctedInPageOrder.length) return;
  const text = correctedInPageOrder.map(buildRecordLine).join(COPY_LINE_BREAK);
  try {
    await copyTextToClipboard(text);
    updateCorrectionToolbar(`已复制 ${correctedInPageOrder.length} 条修改`);
  } catch (error) {
    updateCorrectionToolbar(`复制失败：${error.message}`, true);
  }
}

async function fetchJson(url) {
  const response = await fetch(url, { cache: "no-store" });
  if (!response.ok) {
    let detail = `${response.status} ${response.statusText}`;
    try {
      const payload = await response.json();
      detail = payload.detail || detail;
    } catch (_error) {
      detail = response.statusText || detail;
    }
    throw new Error(detail);
  }
  return response.json();
}

async function loadHealth() {
  try {
    const data = await fetchJson("/api/health");
    healthText.textContent = `数据更新时间 ${fmtTime(data.classnotes.mtime)}`;
  } catch (error) {
    healthText.textContent = `读取失败：${error.message}`;
  }
}

async function queryRecords(query) {
  const q = query.trim();
  if (!q) return;
  recordRows.innerHTML = `<tr><td colspan="7" class="empty">正在查询</td></tr>`;
  recordMeta.innerHTML = "";
  currentRecords = [];
  resetCorrections();
  resetRecordSort();
  clearInlineAccount();
  try {
    const data = await fetchJson(`/api/records?q=${encodeURIComponent(q)}&limit=500`);
    const summary = data.summary;
    recordMeta.innerHTML = [
      metric("识别日期", data.query.date_range),
      metric("命中记录", `${summary.count} 条`),
      metric("总课时", `${fmtHours(summary.total_hours)} 小时`),
      metric("授课老师", `${Object.keys(summary.teachers || {}).length} 位`),
    ].join("");

    if (data.query.students.length === 1) {
      await loadInlineAccount(data.query.students[0]);
    }

    if (!data.records.length) {
      recordRows.innerHTML = `<tr><td colspan="7" class="empty">未找到符合条件的上课记录</td></tr>`;
      return;
    }

    currentRecords = data.records.map((row, index) => ({
      ...row,
      _recordIndex: index,
      _recordKey: makeRecordKey(row, index),
    }));
    recordRows.innerHTML = renderGroupedRecords(currentRecords);
  } catch (error) {
    recordRows.innerHTML = `<tr><td colspan="7" class="empty">查询失败：${escapeHtml(error.message)}</td></tr>`;
  }
}

recordForm.addEventListener("submit", (event) => {
  event.preventDefault();
  queryRecords(recordQuery.value);
});

refreshBtn.addEventListener("click", () => {
  loadHealth();
  if (recordQuery.value.trim()) queryRecords(recordQuery.value);
});

dateSortBtn.addEventListener("click", () => toggleRecordSort("date"));
timeSortBtn.addEventListener("click", () => toggleRecordSort("time"));

document.querySelectorAll("[data-query]").forEach((button) => {
  button.addEventListener("click", () => {
    recordQuery.value = button.dataset.query;
    queryRecords(recordQuery.value);
  });
});

recordRows.addEventListener("click", (event) => {
  const button = event.target.closest(".correction-edit");
  if (!button) return;
  openCorrectionDialog(button.dataset.recordKey);
});

[correctionDate, correctionTime, correctionStudent, correctionTeacher, correctionSubject].forEach((input) => {
  input.addEventListener("input", updateCorrectionPreview);
});

correctionForm.addEventListener("submit", (event) => {
  event.preventDefault();
  try {
    saveCorrection();
  } catch (error) {
    setCorrectionError(error.message);
    correctionPreview.textContent = "请修正上方字段后保存";
  }
});

closeCorrectionBtn.addEventListener("click", closeCorrectionDialog);
cancelCorrectionBtn.addEventListener("click", closeCorrectionDialog);
correctionDialog.addEventListener("click", (event) => {
  if (event.target === correctionDialog) closeCorrectionDialog();
});
document.addEventListener("keydown", (event) => {
  if (event.key === "Escape" && !correctionDialog.hidden) {
    closeCorrectionDialog();
  }
});

copyCorrectedBtn.addEventListener("click", copyCorrectedRecords);

updateRecordSortButtons();
loadHealth();