"use client";

import { useCallback, useMemo, useState } from "react";
import {
  Plus,
  Pencil,
  Trash2,
  Loader2,
  Save,
  X,
  ExternalLink,
  Megaphone,
} from "lucide-react";
import {
  apiAdminListAnnouncements,
  apiAdminCreateAnnouncement,
  apiAdminUpdateAnnouncement,
  apiAdminDeleteAnnouncement,
  type Announcement,
  type AnnouncementColor,
  type AnnouncementInput,
} from "@/lib/api";
import { formatRelative } from "@/lib/format";
import { toast } from "@/lib/toast";
import ConfirmDialog from "@/components/ConfirmDialog";
import {
  AdminEmpty,
  AdminField,
  AdminIconButton,
  AdminPageHeader,
  AdminSegmented,
  AdminStatusChip,
} from "@/components/admin";

const COLORS: { value: AnnouncementColor; label: string }[] = [
  { value: "blue", label: "蓝色" },
  { value: "green", label: "绿色" },
  { value: "orange", label: "橙色" },
  { value: "red", label: "红色" },
  { value: "purple", label: "紫色" },
  { value: "gray", label: "灰色" },
];

type FormState = AnnouncementInput & { id: number | null };
type PublishKey = "published" | "draft";
type StatusFilter = "all" | "published" | "draft";

const EMPTY_FORM: FormState = {
  id: null,
  title: "",
  content: "",
  tag: "公告",
  tag_color: "blue",
  published: true,
};

/** 粗略去掉 Markdown，取一行摘要 */
function plainSummary(md: string, max = 96): string {
  const text = md
    .replace(/```[\s\S]*?```/g, " ")
    .replace(/!\[[^\]]*\]\([^)]+\)/g, " ")
    .replace(/\[([^\]]+)\]\([^)]+\)/g, "$1")
    .replace(/[#>*_`~\-|=]/g, "")
    .replace(/\s+/g, " ")
    .trim();
  return text.length > max ? `${text.slice(0, max)}…` : text;
}

function AnnouncementForm({
  form,
  setForm,
  saving,
  onSave,
  onCancel,
}: {
  form: FormState;
  setForm: (f: FormState) => void;
  saving: boolean;
  onSave: () => void;
  onCancel: () => void;
}) {
  return (
    <div className="panel p-5">
      <p className="font-semibold text-[15px] mb-4" style={{ color: "var(--ink)" }}>
        {form.id == null ? "新建公告" : "编辑公告"}
      </p>

      <AdminField
        id="anno-title"
        className="mb-4"
        label="标题"
        maxLength={200}
        value={form.title}
        onChange={(title) => setForm({ ...form, title })}
        placeholder="请输入公告标题"
      />

      <div className="flex items-end gap-4 mb-4 flex-wrap">
        <div className="w-36">
          <AdminField
            id="anno-tag"
            label="标签"
            maxLength={32}
            value={form.tag}
            onChange={(tag) => setForm({ ...form, tag })}
            placeholder="公告"
          />
        </div>
        <div>
          <p className="field-label">标签颜色</p>
          <div className="flex items-center gap-2">
            {COLORS.map((c) => (
              <button
                key={c.value}
                type="button"
                data-tip={c.label}
                aria-label={c.label}
                aria-pressed={form.tag_color === c.value}
                className={`j13-anno-dot is-${c.value}`}
                onClick={() => setForm({ ...form, tag_color: c.value })}
              />
            ))}
          </div>
        </div>
      </div>

      <p className="field-label">发布状态</p>
      <div className="mb-4">
        <AdminSegmented<PublishKey>
          role="group"
          ariaLabel="发布状态"
          value={form.published ? "published" : "draft"}
          onChange={(key) => setForm({ ...form, published: key === "published" })}
          options={[
            { key: "published", label: "立即发布" },
            { key: "draft", label: "存为草稿" },
          ]}
        />
      </div>

      <AdminField
        id="anno-content"
        label="正文（支持 Markdown）"
        as="textarea"
        minHeight="260px"
        value={form.content}
        onChange={(content) => setForm({ ...form, content })}
        placeholder="请输入公告正文，支持 Markdown 语法…"
      />

      <div className="flex items-center gap-2.5 mt-4">
        <button type="button" onClick={onSave} disabled={saving} className="btn btn-primary flex-1 justify-center">
          {saving ? (
            <>
              <Loader2 size={15} className="animate-spin" /> 保存中…
            </>
          ) : (
            <>
              <Save size={15} /> {form.id == null ? "发布公告" : "保存修改"}
            </>
          )}
        </button>
        <button
          type="button"
          onClick={onCancel}
          disabled={saving}
          className="btn btn-line"
          aria-label="取消编辑"
        >
          <X size={15} /> 取消
        </button>
      </div>
    </div>
  );
}

function AnnouncementPreview({ a }: { a: Announcement }) {
  return (
    <div className="panel p-5">
      <div className="flex items-center gap-2 flex-wrap mb-3">
        <span className={`j13-anno-tag is-${a.tag_color}`}>{a.tag}</span>
        <AdminStatusChip tone={a.published ? "ok" : "warn"}>
          {a.published ? "已发布" : "草稿"}
        </AdminStatusChip>
        <span className="meta text-[11.5px] tabular-nums">{formatRelative(a.updated_at || a.created_at)}</span>
      </div>
      <h2 className="text-[17px] font-semibold leading-snug" style={{ color: "var(--ink)" }}>
        {a.title}
      </h2>
      <p className="mt-3 text-[13.5px] leading-relaxed whitespace-pre-wrap" style={{ color: "var(--ink-2)" }}>
        {a.content}
      </p>
      {a.published ? (
        <a
          href={`/announcement/${a.id}`}
          className="btn btn-line btn-sm mt-4 inline-flex"
          target="_blank"
          rel="noreferrer"
        >
          <ExternalLink size={14} /> 查看前台页
        </a>
      ) : null}
    </div>
  );
}

export default function AnnouncementAdmin({
  initial,
  initError,
}: {
  initial: Announcement[];
  initError: string;
}) {
  const [list, setList] = useState(initial);
  const [loadError, setLoadError] = useState(initError);
  const [form, setForm] = useState<FormState | null>(null);
  const [selectedId, setSelectedId] = useState<number | null>(initial[0]?.id ?? null);
  const [statusFilter, setStatusFilter] = useState<StatusFilter>("all");
  const [saving, setSaving] = useState(false);
  const [deletingId, setDeletingId] = useState<number | null>(null);
  const [deleteTarget, setDeleteTarget] = useState<Announcement | null>(null);

  const publishedCount = useMemo(() => list.filter((a) => a.published).length, [list]);
  const draftCount = useMemo(() => list.filter((a) => !a.published).length, [list]);

  const filtered = useMemo(() => {
    if (statusFilter === "published") return list.filter((a) => a.published);
    if (statusFilter === "draft") return list.filter((a) => !a.published);
    return list;
  }, [list, statusFilter]);

  const selected = useMemo(
    () => (selectedId == null ? null : list.find((a) => a.id === selectedId) ?? null),
    [list, selectedId]
  );

  const load = useCallback(async () => {
    try {
      const res = await apiAdminListAnnouncements();
      setList(res.announcements);
      setLoadError("");
    } catch (e) {
      setLoadError(e instanceof Error ? e.message : "加载公告失败");
    }
  }, []);

  const startCreate = () => {
    setForm({ ...EMPTY_FORM });
    setSelectedId(null);
  };

  const startEdit = (a: Announcement) => {
    setSelectedId(a.id);
    setForm({
      id: a.id,
      title: a.title,
      content: a.content,
      tag: a.tag,
      tag_color: a.tag_color,
      published: a.published,
    });
  };

  const selectRow = (a: Announcement) => {
    setSelectedId(a.id);
    if (form && form.id !== a.id) setForm(null);
  };

  async function save() {
    if (!form) return;
    const payload: AnnouncementInput = {
      title: form.title.trim(),
      content: form.content.trim(),
      tag: form.tag.trim() || "公告",
      tag_color: form.tag_color,
      published: form.published,
    };
    if (!payload.title || !payload.content) {
      toast("标题和内容不能为空");
      return;
    }
    setSaving(true);
    try {
      if (form.id == null) {
        const res = await apiAdminCreateAnnouncement(payload);
        toast(payload.published ? "公告已发布" : "草稿已保存", "ok");
        setForm(null);
        setSelectedId(res.announcement?.id ?? null);
      } else {
        await apiAdminUpdateAnnouncement(form.id, payload);
        toast("公告已更新", "ok");
        setForm(null);
        setSelectedId(form.id);
      }
      await load();
    } catch (e) {
      toast(e instanceof Error ? e.message : "保存失败");
    } finally {
      setSaving(false);
    }
  }

  async function remove(a: Announcement) {
    setDeletingId(a.id);
    try {
      await apiAdminDeleteAnnouncement(a.id);
      setList((l) => {
        const next = l.filter((x) => x.id !== a.id);
        if (selectedId === a.id) setSelectedId(next[0]?.id ?? null);
        return next;
      });
      if (form?.id === a.id) setForm(null);
      toast("公告已删除", "ok");
    } catch (e) {
      toast(e instanceof Error ? e.message : "删除失败");
    } finally {
      setDeletingId(null);
      setDeleteTarget(null);
    }
  }

  return (
    <div>
      <AdminPageHeader
        icon={Megaphone}
        title="站点公告管理"
        description="发布、编辑与下线右栏站点公告，支持自定义标签与标签颜色"
        actions={
          form?.id == null && form != null ? undefined : (
            <button type="button" onClick={startCreate} className="btn btn-primary">
              <Plus size={15} /> 新建公告
            </button>
          )
        }
      />

      <div className="mb-4">
        <AdminSegmented<StatusFilter>
          ariaLabel="公告状态筛选"
          size="sm"
          value={statusFilter}
          onChange={setStatusFilter}
          options={[
            { key: "all", label: "全部", count: list.length },
            { key: "published", label: "已发布", count: publishedCount },
            { key: "draft", label: "草稿", count: draftCount },
          ]}
        />
      </div>

      <div className="grid grid-cols-1 lg:grid-cols-2 gap-6 items-start">
        {/* 左侧列表 */}
        <div className="panel overflow-hidden min-w-0">
          <div
            className="px-4 sm:px-5 py-3 flex items-center justify-between"
            style={{ borderBottom: "1px solid var(--line)" }}
          >
            <span className="font-medium text-[14px]" style={{ color: "var(--ink)" }}>
              公告列表
            </span>
            <span className="meta text-[12px] tabular-nums">共 {filtered.length} 条</span>
          </div>

          {loadError ? (
            <p className="alert-error m-4">{loadError}</p>
          ) : filtered.length === 0 ? (
            <AdminEmpty
              icon={<Megaphone size={22} />}
              title={list.length === 0 ? "还没有公告" : "该状态下暂无公告"}
              description={list.length === 0 ? "发布第一条站点公告，会出现在首页右栏" : "试试切换筛选条件"}
            />
          ) : (
            filtered.map((a, idx) => {
              const active = selectedId === a.id || form?.id === a.id;
              const summary = plainSummary(a.content);
              return (
                <div
                  key={a.id}
                  role="button"
                  tabIndex={0}
                  onClick={() => selectRow(a)}
                  onKeyDown={(e) => {
                    if (e.key === "Enter" || e.key === " ") {
                      e.preventDefault();
                      selectRow(a);
                    }
                  }}
                  className="px-4 sm:px-5 py-3.5 cursor-pointer outline-none focus-visible:ring-2 focus-visible:ring-[var(--accent)]"
                  style={{
                    borderTop: idx === 0 ? undefined : "1px solid var(--line)",
                    background: active ? "var(--accent-soft)" : undefined,
                  }}
                >
                  <div className="flex items-start gap-2 min-w-0">
                    <div className="min-w-0 flex-1">
                      <div className="flex items-center gap-1.5 flex-wrap">
                        <p
                          className="text-[14px] font-medium truncate max-w-full"
                          style={{ color: "var(--ink)" }}
                          data-tip={a.title}
                        >
                          {a.title}
                        </p>
                        <AdminStatusChip tone={a.published ? "ok" : "warn"}>
                          {a.published ? "已发布" : "草稿"}
                        </AdminStatusChip>
                        <span className="meta text-[11px] tabular-nums shrink-0">
                          {formatRelative(a.updated_at || a.created_at)}
                        </span>
                        <span
                          className="inline-flex items-center gap-0.5 shrink-0"
                          onClick={(e) => e.stopPropagation()}
                          onKeyDown={(e) => e.stopPropagation()}
                        >
                          {a.published ? (
                            <AdminIconButton
                              href={`/announcement/${a.id}`}
                              tip="查看"
                              ariaLabel="查看公告"
                            >
                              <ExternalLink size={14} />
                            </AdminIconButton>
                          ) : null}
                          <AdminIconButton tip="编辑" ariaLabel="编辑公告" onClick={() => startEdit(a)}>
                            <Pencil size={14} />
                          </AdminIconButton>
                          <AdminIconButton
                            tip="删除"
                            ariaLabel="删除公告"
                            tone="danger"
                            disabled={deletingId === a.id}
                            onClick={() => setDeleteTarget(a)}
                          >
                            {deletingId === a.id ? (
                              <Loader2 size={14} className="animate-spin" />
                            ) : (
                              <Trash2 size={14} />
                            )}
                          </AdminIconButton>
                        </span>
                      </div>
                      {summary ? (
                        <p className="meta text-[12.5px] mt-1 line-clamp-1">{summary}</p>
                      ) : null}
                    </div>
                  </div>
                </div>
              );
            })
          )}

          {list.length === 0 && !loadError ? (
            <div className="px-4 sm:px-5 pb-5 -mt-4 flex justify-center">
              <button type="button" onClick={startCreate} className="btn btn-primary">
                <Plus size={15} /> 新建第一条公告
              </button>
            </div>
          ) : null}
        </div>

        {/* 右侧：表单 / 预览 / 占位 */}
        <div className="min-w-0 lg:sticky lg:top-4">
          {form ? (
            <AnnouncementForm
              form={form}
              setForm={setForm}
              saving={saving}
              onSave={() => void save()}
              onCancel={() => setForm(null)}
            />
          ) : selected ? (
            <AnnouncementPreview a={selected} />
          ) : (
            <div className="panel p-8">
              <AdminEmpty
                icon={<Megaphone size={22} />}
                title="选择或新建公告"
                description="在左侧点选一条查看预览，或新建公告"
              />
              <div className="flex justify-center -mt-4 pb-2">
                <button type="button" onClick={startCreate} className="btn btn-primary">
                  <Plus size={15} /> 新建公告
                </button>
              </div>
            </div>
          )}
        </div>
      </div>

      {/* 移动端编辑时：若只在右侧显示表单，列表仍在上方可见，符合双栏降级 */}
      <ConfirmDialog
        open={!!deleteTarget}
        title="删除公告"
        message={deleteTarget ? `确定删除公告「${deleteTarget.title}」吗？此操作不可撤销。` : ""}
        danger
        busy={deletingId != null}
        confirmLabel="删除"
        onCancel={() => deletingId == null && setDeleteTarget(null)}
        onConfirm={() => {
          if (deleteTarget) void remove(deleteTarget);
        }}
      />
    </div>
  );
}