/* 全页面悬浮问答：复用后端 AI 接口，不在前端保存密钥。 */
"use strict";
(() => {
  const byId = id => document.getElementById(id);
  const trigger = byId("floating-ai-trigger");
  const panel = byId("floating-ai-panel");
  const input = byId("floating-ai-question");
  const messages = byId("floating-ai-messages");
  let busy = false;
  // 超过 6 像素才视为拖动，轻点仍打开聊天；鼠标和触屏共用 Pointer Events。
  let drag = null;
  let suppressClick = false;
  const margin = 12;
  const clamp = (value, min, max) => Math.min(Math.max(value, min), Math.max(min, max));
  function viewport() {
    const view = window.visualViewport;
    return {left: view ? view.offsetLeft : 0, top: view ? view.offsetTop : 0,
      width: view ? view.width : document.documentElement.clientWidth,
      height: view ? view.height : window.innerHeight};
  }
  function placeTrigger(left, top) {
    const view = viewport(), box = trigger.getBoundingClientRect();
    trigger.style.right = "auto"; trigger.style.bottom = "auto";
    trigger.style.left = `${clamp(left, view.left + margin, view.left + view.width - box.width - margin)}px`;
    trigger.style.top = `${clamp(top, view.top + margin, view.top + view.height - box.height - margin)}px`;
    placePanel();
  }
  function placePanel() {
    if (panel.hidden) return;
    const view = viewport(), anchor = trigger.getBoundingClientRect();
    const leftEdge = view.left + margin, topEdge = view.top + margin;
    const rightEdge = view.left + view.width - margin, bottomEdge = view.top + view.height - margin;
    const gap = 10;
    panel.style.right = "auto"; panel.style.bottom = "auto";
    panel.style.maxWidth = `${Math.max(0, view.width - margin * 2)}px`;
    const width = panel.getBoundingClientRect().width;
    let left, top;
    // 宽屏优先放在头像旁边，窄屏在头像上方或下方展开。
    if (anchor.left - gap - width >= leftEdge || anchor.right + gap + width <= rightEdge) {
      left = anchor.left - gap - width >= leftEdge ? anchor.left - gap - width : anchor.right + gap;
      panel.style.maxHeight = `${Math.max(0, view.height - margin * 2)}px`;
      top = clamp(anchor.bottom - panel.getBoundingClientRect().height, topEdge, bottomEdge - panel.getBoundingClientRect().height);
    } else {
      const above = anchor.top - gap - topEdge, below = bottomEdge - anchor.bottom - gap;
      const useAbove = above >= below;
      panel.style.maxHeight = `${Math.max(0, useAbove ? above : below)}px`;
      top = useAbove ? anchor.top - gap - panel.getBoundingClientRect().height : anchor.bottom + gap;
      left = clamp(anchor.right - width, leftEdge, rightEdge - width);
    }
    panel.style.left = `${left}px`; panel.style.top = `${top}px`;
  }
  trigger.addEventListener("pointerdown", event => {
    if (!event.isPrimary || event.button !== 0) return;
    const box = trigger.getBoundingClientRect();
    suppressClick = false;
    drag = {id: event.pointerId, x: event.clientX, y: event.clientY, left: box.left, top: box.top, moved: false};
    trigger.setPointerCapture(event.pointerId);
  });
  trigger.addEventListener("pointermove", event => {
    if (!drag || drag.id !== event.pointerId) return;
    const dx = event.clientX - drag.x, dy = event.clientY - drag.y;
    if (!drag.moved && Math.hypot(dx, dy) < 6) return;
    drag.moved = true;
    trigger.classList.add("dragging");
    placeTrigger(drag.left + dx, drag.top + dy);
  });
  function endDrag(event) {
    if (!drag || drag.id !== event.pointerId) return;
    suppressClick = drag.moved;
    drag = null;
    trigger.classList.remove("dragging");
    if (trigger.hasPointerCapture(event.pointerId)) trigger.releasePointerCapture(event.pointerId);
  }
  trigger.addEventListener("pointerup", endDrag);
  trigger.addEventListener("pointercancel", endDrag);
  trigger.addEventListener("lostpointercapture", endDrag);
  trigger.addEventListener("dragstart", event => event.preventDefault());
  function fitViewport() {
    const box = trigger.getBoundingClientRect();
    placeTrigger(box.left, box.top);
  }
  window.addEventListener("resize", fitViewport);
  if (window.visualViewport) {
    window.visualViewport.addEventListener("resize", fitViewport);
    window.visualViewport.addEventListener("scroll", fitViewport);
  }
  // 回答变长、输入框调整高度时，聊天框也跟随头像保持在可视区域。
  if (typeof ResizeObserver !== "undefined") new ResizeObserver(placePanel).observe(panel);

  function setOpen(open, returnFocus = true) {
    panel.hidden = !open;
    if (open) placePanel();
    trigger.setAttribute("aria-expanded", String(open));
    if (open) {if (!busy) input.focus();} else if (returnFocus) trigger.focus();
  }
  function scrollBottom() {const area = messages.parentElement; area.scrollTop = area.scrollHeight;}
  function appendMessage(role, text, failed = false) {
    const article = document.createElement("article"); article.className = `floating-message ${role}${failed ? " failed" : ""}`;
    const label = document.createElement("span"); label.className = "floating-message-label"; label.textContent = role === "user" ? "你" : "沃林 AI 助手";
    const body = document.createElement("div"); body.className = "floating-message-body";
    if (role === "assistant" && !failed && typeof answerMarkup === "function") body.innerHTML = answerMarkup(text); else body.textContent = text;
    article.append(label, body); messages.append(article); scrollBottom(); return body;
  }
  function setBusy(value) {
    busy = value; input.readOnly = value;
    byId("floating-ai-send").disabled = value;
    byId("floating-ai-clear").disabled = value;
    byId("floating-ai-send").textContent = value ? "回答中…" : "发送 ↗";
    byId("floating-ai-progress").hidden = !value;
    trigger.classList.toggle("thinking", value);
  }
  async function submitQuestion() {
    if (busy) return;
    const question = input.value.trim();
    const error = byId("floating-ai-error"); error.hidden = true;
    if (!question || question.length > 1800) {error.textContent = "请输入 1 至 1800 个字符的问题。"; error.hidden = false; return;}
    byId("floating-ai-greeting").hidden = true;
    appendMessage("user", question); setBusy(true);
    try {
      const response = await fetch("/api/studentsManagement/ai/chat", {
        method:"POST", headers:{"Content-Type":"application/json"},
        body:JSON.stringify({question:question + "\n请简短回答，优先给出结论和必要数据，尽量控制在150字内；如果数据不足请说明，不要省略影响结论的条件。"}),
        signal:AbortSignal.timeout(150000),
      });
      let result;
      try {result = await response.json();} catch {throw new Error("AI 服务没有返回有效回答，请稍后重试。");}
      if (!response.ok) throw new Error(typeof result.detail === "string" ? result.detail : "AI 服务暂时不可用，请稍后重试。");
      if (typeof result.answer !== "string" || !result.answer.trim()) throw new Error("AI 返回了空回答，请稍后重试。");
      const body = appendMessage("assistant", result.answer);
      const sources = document.createElement("small"); sources.className = "floating-sources";
      sources.textContent = result.data ? "依据：本次数据库查询与需求资料" : "依据：本次参考资料 · 未查询数据库";
      body.append(sources);
      input.value = ""; byId("floating-ai-count").textContent = "0 / 1800";
    } catch (reason) {
      const message = reason.name === "TimeoutError" ? "等待回答超时，请稍后重试。" : reason instanceof TypeError ? "无法连接服务，请确认后端已启动。" : reason.message || "请求失败，请稍后重试。";
      appendMessage("assistant", message, true);
      error.textContent = "原问题已保留，可以重试。"; error.hidden = false;
    } finally {setBusy(false); scrollBottom(); if (!panel.hidden && panel.contains(document.activeElement)) input.focus();}
  }
  trigger.addEventListener("click", event => {
    if (suppressClick && event.detail !== 0) {suppressClick = false; return;}
    suppressClick = false;
    setOpen(panel.hidden);
  });
  byId("floating-ai-close").addEventListener("click", () => setOpen(false));
  panel.addEventListener("keydown", event => {if (event.key === "Escape") {event.preventDefault(); setOpen(false);}});
  byId("floating-ai-form").addEventListener("submit", event => {event.preventDefault(); submitQuestion();});
  input.addEventListener("input", () => byId("floating-ai-count").textContent = `${input.value.length} / 1800`);
  input.addEventListener("keydown", event => {if (event.key === "Enter" && !event.shiftKey && !event.ctrlKey && !event.metaKey && !event.isComposing) {event.preventDefault(); submitQuestion();}});
  byId("floating-ai-clear").addEventListener("click", () => {
    if (busy) return;
    messages.replaceChildren(); byId("floating-ai-greeting").hidden = false;
    byId("floating-ai-error").hidden = true; input.value = ""; byId("floating-ai-count").textContent = "0 / 1800"; input.focus();
  });
  byId("floating-ai-full").addEventListener("click", () => {
    // 跳转到现有完整助手，不重复发送，也不扩大数据库操作权限。
    if (input.value.trim()) {byId("ai-question").value = input.value.trim(); byId("ai-length").textContent = `${input.value.trim().length} / 2000`;}
    location.hash = "ai"; setOpen(false, false); byId("ai-question").focus();
  });
})();