/* =====================================================================
 * 评论模块（comment.js）
 * 评论列表（按 parent_id 分组展示回复）+ 发表评论 / 回复表单。
 * 仅好友或博主可评论。
 * ===================================================================== */

import { state } from "./state.js";
import { $, escapeHtml, formatDate, showToast } from "./utils.js";
import { api } from "./api.js";
import { openLoginModal } from "./auth.js";
import { applyFriend } from "./friend.js";

export async function renderComments(el, articleId) {
  let comments = [];
  try {
    comments = await api(`/api/comment/list?article_id=${articleId}`);
  } catch (err) { /* 好友文章对游客不可见评论，忽略 */ }
  el.innerHTML = `<p class="muted">共 ${comments.length} 条评论</p>`;

  const list = document.createElement("div");
  list.className = "comment-list";
  if (!comments.length) list.innerHTML = '<p class="empty">暂无评论，来抢沙发吧</p>';

  // 按 parent_id 分组：顶层评论在前，回复跟随其父评论
  const byId = new Map(comments.map((c) => [c.id, c]));
  const topLevel = comments.filter((c) => c.parent_id == null);
  const repliesByParent = {};
  comments.filter((c) => c.parent_id != null).forEach((r) => {
    (repliesByParent[r.parent_id] = repliesByParent[r.parent_id] || []).push(r);
  });

  topLevel.forEach((c) => {
    list.appendChild(buildCommentItem(el, articleId, c, byId, false));
    (repliesByParent[c.id] || []).forEach((r) => {
      list.appendChild(buildCommentItem(el, articleId, r, byId, true));
    });
  });
  el.appendChild(list);

  // 评论 / 回复表单（仅好友或博主）
  const canComment = state.user && (state.user.role === "friend" || state.user.role === "blogger");
  if (canComment) {
    el.appendChild(buildCommentForm(el, articleId, null));
  } else {
    const hint = document.createElement("p");
    hint.className = "muted comment-hint";
    if (state.user) {
      hint.innerHTML = `仅好友或博主可以评论 <button class="btn btn-outline btn-sm" id="hint-apply">申请好友</button>`;
      $("#hint-apply", hint).addEventListener("click", applyFriend);
    } else {
      hint.innerHTML = `登录并成为好友后可以评论 <button class="btn btn-outline btn-sm" id="hint-login">去登录</button>`;
      $("#hint-login", hint).addEventListener("click", openLoginModal);
    }
    el.appendChild(hint);
  }
}

function buildCommentItem(el, articleId, comment, byId, isReply) {
  const item = document.createElement("div");
  item.className = isReply ? "comment-item comment-reply" : "comment-item";
  const parent = comment.parent_id && byId.has(comment.parent_id) ? byId.get(comment.parent_id) : null;
  const parentLabel = parent ? `<span class="muted">回复 @${escapeHtml(parent.username || "匿名")}</span>` : "";
  // 评论者头像：有头像显示图片，没有则显示空占位
  const avatarHtml = comment.avatar
    ? `<img class="comment-avatar" src="${escapeHtml(comment.avatar)}" alt="">`
    : '<span class="comment-avatar comment-avatar-empty"></span>';
  item.innerHTML = `
    <div class="comment-head">
      <div class="comment-author">
        ${avatarHtml}
        <strong>${escapeHtml(comment.username || "匿名")}</strong>
        ${parentLabel}
      </div>
      <span class="muted">${formatDate(comment.created_time)}</span>
    </div>
    <p>${escapeHtml(comment.content)}</p>`;

  // 顶层评论显示“回复”按钮（仅好友/博主）
  const canReply = state.user && (state.user.role === "friend" || state.user.role === "blogger");
  if (canReply && !isReply) {
    const replyBtn = document.createElement("button");
    replyBtn.className = "btn btn-text btn-sm comment-reply-btn";
    replyBtn.textContent = "回复";
    replyBtn.addEventListener("click", () => {
      let box = item.querySelector(".comment-reply-box");
      if (box) { box.remove(); return; }
      box = document.createElement("div");
      box.className = "comment-reply-box";
      box.appendChild(buildCommentForm(el, articleId, comment));
      item.appendChild(box);
    });
    item.appendChild(replyBtn);
  }
  return item;
}

function buildCommentForm(el, articleId, parent) {
  const form = document.createElement("div");
  form.className = "comment-form";
  const placeholder = parent
    ? `回复 @${parent.username || "匿名"}…`
    : "写下你的评论…";
  const btnText = parent ? "回复" : "发表评论";
  form.innerHTML = `
    <textarea class="comment-input" rows="2" maxlength="2000" placeholder="${escapeHtml(placeholder)}"></textarea>
    <button class="btn btn-primary" type="button">${btnText}</button>`;
  const textarea = $(".comment-input", form);
  const btn = $("button", form);
  btn.addEventListener("click", async () => {
    const content = textarea.value.trim();
    if (!content) { showToast("评论内容不能为空", "error"); return; }
    if (content.length > 2000) { showToast("评论内容不能超过 2000 字", "error"); return; }
    btn.disabled = true; btn.textContent = "发送中…";
    try {
      const body = parent
        ? { article_id: articleId, content, parent_id: parent.id }
        : { article_id: articleId, content };
      await api("/api/comment/add", { method: "POST", body });
      showToast("评论成功", "success");
      await renderComments(el, articleId);
    } catch (err) {
      showToast(err.message, "error");
    }
  });
  return form;
}