"use client";

import { ArrowDown, ArrowUp, BookOpen, ExternalLink, Home, Plus, Trash2, Trophy } from "lucide-react";
import { useEffect, useState } from "react";
import { AdminSettingsActions, AdminSettingsGroup, AdminSwitch } from "@/components/admin";
import { apiUpdateSiteSettings, type PublicSettings } from "@/lib/api";
import {
  HEADER_NAV_BUILTIN_KEYS,
  HEADER_NAV_BUILTIN_LABELS,
  HEADER_NAV_LIMITS,
  isHeaderNavExternal,
  type HeaderNavBuiltinKey,
  type HeaderNavItem,
} from "@/lib/headerNav";
import { footerURLAllowed } from "@/lib/brand";
import { toast } from "@/lib/toast";

const BUILTIN_ICONS: Record<HeaderNavBuiltinKey, React.ReactNode> = {
  home: <Home size={14} />,
  leaderboard: <Trophy size={14} />,
  library: <BookOpen size={14} />,
};

/** 内置项目标页说明（实际地址随伪静态风格变化，不允许改地址） */
const BUILTIN_HINTS: Record<HeaderNavBuiltinKey, string> = {
  home: "站点首页 /",
  leaderboard: "排行榜页（地址随伪静态风格变化）",
  library: "书库页（地址随伪静态风格变化）",
};

type BuiltinSwitches = Record<HeaderNavBuiltinKey, boolean>;

function clone(items: HeaderNavItem[]): HeaderNavItem[] {
  return items.map((item) => ({ ...item }));
}

function switchesOf(items: HeaderNavItem[]): BuiltinSwitches {
  const present = new Set(
    items.filter((it): it is Extract<HeaderNavItem, { type: "builtin" }> => it.type === "builtin").map((it) => it.key),
  );
  return {
    home: present.has("home"),
    leaderboard: present.has("leaderboard"),
    library: present.has("library"),
  };
}

/** 完整行列表：已启用项按配置顺序在前，未启用的内置项按默认顺序追加在后 */
function rowsOf(items: HeaderNavItem[]): HeaderNavItem[] {
  const present = new Set(
    items.filter((it): it is Extract<HeaderNavItem, { type: "builtin" }> => it.type === "builtin").map((it) => it.key),
  );
  const hidden = HEADER_NAV_BUILTIN_KEYS.filter((key) => !present.has(key)).map((key) => ({
    type: "builtin" as const,
    key,
  }));
  return [...clone(items), ...hidden];
}

/**
 * 桌面端 Header 品牌名右侧的主导航：排序、开关显隐内置项、增删自定义链接，整体替换保存。
 * 与移动端底栏面板同款交互：操作按钮居右，内置项开关隐藏（隐藏项保留排序位置）。
 */
export default function HeaderNavPanel({
  initial,
  onSaved,
  onDirtyChange,
}: {
  initial: PublicSettings;
  onSaved?: (next: PublicSettings) => void;
  onDirtyChange?: (dirty: boolean) => void;
}) {
  const [rows, setRows] = useState<HeaderNavItem[]>(() => rowsOf(initial.header_nav));
  const [on, setOn] = useState<BuiltinSwitches>(() => switchesOf(initial.header_nav));
  const [savedPayload, setSavedPayload] = useState<HeaderNavItem[]>(() => clone(initial.header_nav));
  const [saving, setSaving] = useState(false);
  const [error, setError] = useState("");
  // 新增自定义行挂载后自动聚焦名称输入框
  const [focusIdx, setFocusIdx] = useState<number | null>(null);

  // 提交负载 = 自定义链接 + 开关打开的内置项，按行顺序
  const payload: HeaderNavItem[] = rows.filter((item) => item.type === "custom" || on[item.key]);
  const dirty = JSON.stringify(payload) !== JSON.stringify(savedPayload);
  const atCap = payload.length >= HEADER_NAV_LIMITS.items;

  useEffect(() => {
    onDirtyChange?.(dirty);
  }, [dirty, onDirtyChange]);

  useEffect(() => {
    if (focusIdx !== null) setFocusIdx(null);
  }, [focusIdx]);

  const move = (i: number, dir: -1 | 1) => {
    setError("");
    setRows((prev) => {
      const j = i + dir;
      if (j < 0 || j >= prev.length) return prev;
      const next = [...prev];
      const [row] = next.splice(i, 1);
      next.splice(j, 0, row);
      return next;
    });
  };

  const removeAt = (i: number) => {
    setError("");
    setRows((prev) => prev.filter((_, idx) => idx !== i));
  };

  const addCustom = () => {
    if (atCap) return;
    setError("");
    setFocusIdx(rows.length);
    setRows((prev) => [...prev, { type: "custom", label: "", url: "", new_tab: false }]);
  };

  const updateCustom = (i: number, patch: Partial<Extract<HeaderNavItem, { type: "custom" }>>) => {
    setError("");
    setRows((prev) => prev.map((item, idx) => (idx === i && item.type === "custom" ? { ...item, ...patch } : item)));
  };

  const discard = () => {
    setRows(rowsOf(savedPayload));
    setOn(switchesOf(savedPayload));
    setError("");
  };

  const save = async () => {
    if (saving || !dirty) return;
    for (const item of payload) {
      if (item.type !== "custom") continue;
      if (!item.label.trim()) {
        setError("自定义菜单名称不能为空");
        toast("自定义菜单名称不能为空");
        return;
      }
      if (!footerURLAllowed(item.url)) {
        setError(`地址无效：${item.url || "（空）"}`);
        toast(`地址无效：${item.url || "（空）"}`);
        return;
      }
    }
    const body: HeaderNavItem[] = payload.map((item) =>
      item.type === "custom"
        ? { type: "custom", label: item.label.trim(), url: item.url.trim(), new_tab: item.new_tab }
        : { type: "builtin", key: item.key },
    );
    setSaving(true);
    try {
      const res = await apiUpdateSiteSettings({ header_nav: body });
      setSavedPayload(clone(res.header_nav));
      setRows(rowsOf(res.header_nav));
      setOn(switchesOf(res.header_nav));
      onSaved?.(res);
      toast("已保存，顶部导航已更新", "ok");
    } catch (e) {
      const msg = e instanceof Error ? e.message : "保存失败";
      setError(msg);
      toast(msg);
    } finally {
      setSaving(false);
    }
  };

  return (
    <AdminSettingsGroup
      id="settings-header-nav"
      title="顶部导航菜单"
      description="桌面端页眉品牌名右侧的菜单，顺序即前台展示顺序；移动端导航由底部菜单承担。全部隐藏后前台不显示导航。"
      footer={
        <AdminSettingsActions
          dirty={dirty}
          saving={saving}
          saveLabel="保存"
          error={error}
          onSave={() => void save()}
          onDiscard={discard}
        />
      }
    >
      <div className="flex flex-col gap-2">
        {rows.map((item, i) => {
          const enabled = item.type === "custom" || on[item.key];
          return (
            <div
              key={item.type === "builtin" ? `builtin-${item.key}` : `custom-${i}`}
              className="flex flex-wrap items-center gap-2 rounded-xl px-2 py-2"
              style={{
                border: "1px solid var(--line)",
                background: "var(--panel)",
                opacity: enabled ? 1 : 0.55,
              }}
            >
              {item.type === "builtin" ? (
                <>
                  <span
                    className="w-7 h-7 flex items-center justify-center rounded-full shrink-0"
                    style={{ color: "var(--ink-2)", background: "var(--panel-2)" }}
                    aria-hidden
                  >
                    {BUILTIN_ICONS[item.key]}
                  </span>
                  <span className="text-[13.5px] font-semibold shrink-0" style={{ color: "var(--ink)" }}>
                    {HEADER_NAV_BUILTIN_LABELS[item.key]}
                  </span>
                  <span className="meta text-[12px] truncate">{BUILTIN_HINTS[item.key]}</span>
                </>
              ) : (
                <>
                  <div className="admin-field-shell w-32 shrink-0">
                    <input
                      className="admin-field-input"
                      style={{ padding: "7px 10px" }}
                      maxLength={HEADER_NAV_LIMITS.label}
                      value={item.label}
                      onChange={(e) => updateCustom(i, { label: e.target.value })}
                      placeholder="菜单名称"
                      aria-label={`第 ${i + 1} 个自定义菜单名称`}
                      autoFocus={focusIdx === i}
                    />
                  </div>
                  <div className="admin-field-shell min-w-[10rem] flex-1">
                    <input
                      className="admin-field-input"
                      style={{ padding: "7px 10px" }}
                      maxLength={HEADER_NAV_LIMITS.url}
                      value={item.url}
                      onChange={(e) => {
                        const v = e.target.value;
                        const wasExt = isHeaderNavExternal(item.url);
                        const nowExt = isHeaderNavExternal(v);
                        updateCustom(i, { url: v, new_tab: !wasExt && nowExt ? true : item.new_tab });
                      }}
                      placeholder="https://… 或 /p/about"
                      aria-label={`第 ${i + 1} 个自定义菜单地址`}
                    />
                  </div>
                  <div className="shrink-0 w-[8.75rem]">
                    <div className="admin-footer-open-toggle" role="group" aria-label={`第 ${i + 1} 个菜单打开方式`}>
                      <button
                        type="button"
                        className={`admin-footer-open-opt${!item.new_tab ? " is-on" : ""}`}
                        aria-pressed={!item.new_tab}
                        onClick={() => updateCustom(i, { new_tab: false })}
                      >
                        本页
                      </button>
                      <button
                        type="button"
                        className={`admin-footer-open-opt${item.new_tab ? " is-on" : ""}`}
                        aria-pressed={item.new_tab}
                        onClick={() => updateCustom(i, { new_tab: true })}
                      >
                        <ExternalLink size={12} aria-hidden />
                        新标签
                      </button>
                    </div>
                  </div>
                </>
              )}
              <div className="flex items-center gap-1 shrink-0 ml-auto">
                <button
                  type="button"
                  className="admin-icon-btn"
                  aria-label="上移"
                  disabled={i === 0 || saving}
                  onClick={() => move(i, -1)}
                >
                  <ArrowUp size={14} />
                </button>
                <button
                  type="button"
                  className="admin-icon-btn"
                  aria-label="下移"
                  disabled={i === rows.length - 1 || saving}
                  onClick={() => move(i, 1)}
                >
                  <ArrowDown size={14} />
                </button>
                {item.type === "builtin" ? (
                  <AdminSwitch
                    checked={on[item.key]}
                    disabled={saving || (!on[item.key] && atCap)}
                    onChange={() => {
                      setError("");
                      setOn((prev) => ({ ...prev, [item.key]: !prev[item.key] }));
                    }}
                    label={`顶部导航显示${HEADER_NAV_BUILTIN_LABELS[item.key]}`}
                  />
                ) : (
                  <button
                    type="button"
                    className="admin-icon-btn is-danger"
                    aria-label="移除"
                    onClick={() => removeAt(i)}
                  >
                    <Trash2 size={14} />
                  </button>
                )}
              </div>
            </div>
          );
        })}

        <div className="flex flex-wrap items-center gap-2 pt-1">
          <button type="button" className="btn btn-line btn-sm" disabled={atCap} onClick={addCustom}>
            <Plus size={14} /> 新增自定义链接
            <span className="meta text-[12px] ml-1">
              {payload.length}/{HEADER_NAV_LIMITS.items}
            </span>
          </button>
        </div>

        <ul className="admin-url-style-notes meta mt-1 text-[12px]">
          <li>内置菜单（首页/排行榜/书库）用开关控制显隐，地址由系统按伪静态风格自动生成；隐藏项保留排序位置。</li>
          <li>自定义链接支持站内路径（如 /p/about、/announcements）或 http(s) 外链；名称最多 16 字。</li>
        </ul>
      </div>
    </AdminSettingsGroup>
  );
}