"use client";

import { ArrowDown, ArrowUp, Loader2, Plus, Save, Trash2 } from "lucide-react";
import { useState } from "react";
import { AdminField, AdminSection } from "@/components/admin";
import { apiUpdateSiteSettings, type PublicSettings } from "@/lib/api";
import {
  BRAND_LIMITS,
  footerURLAllowed,
  isExternalFooterURL,
  type FooterLink,
} from "@/lib/brand";
import { toast } from "@/lib/toast";

function clone(links: FooterLink[]): FooterLink[] {
  return links.map((l) => ({ ...l }));
}

export default function FooterLinksPanel({
  initial,
  onSaved,
}: {
  initial: PublicSettings;
  onSaved?: (next: PublicSettings) => void;
}) {
  const [links, setLinks] = useState<FooterLink[]>(() => clone(initial.footer_links));
  const [saved, setSaved] = useState<FooterLink[]>(() => clone(initial.footer_links));
  const [saving, setSaving] = useState(false);

  const dirty = JSON.stringify(links) !== JSON.stringify(saved);

  const update = (i: number, patch: Partial<FooterLink>) => {
    setLinks((prev) => prev.map((item, idx) => (idx === i ? { ...item, ...patch } : item)));
  };

  const save = async () => {
    if (saving || !dirty) return;
    for (const item of links) {
      if (!item.label.trim()) {
        toast("链接文案不能为空");
        return;
      }
      if (!footerURLAllowed(item.url)) {
        toast(`地址无效：${item.url || "（空）"}`);
        return;
      }
    }
    setSaving(true);
    try {
      const payload = links.map((item) => ({
        label: item.label.trim(),
        url: item.url.trim(),
        new_tab: item.new_tab,
      }));
      const res = await apiUpdateSiteSettings({ footer_links: payload });
      setLinks(clone(res.footer_links));
      setSaved(clone(res.footer_links));
      onSaved?.(res);
      toast("页脚链接已保存", "ok");
    } catch (e) {
      toast(e instanceof Error ? e.message : "保存失败");
    } finally {
      setSaving(false);
    }
  };

  const move = (i: number, dir: -1 | 1) => {
    setLinks((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;
    });
  };

  return (
    <div className="admin-settings-grid">
      <AdminSection
        title="页脚与合规"
        description="用于 ICP 备案、用户协议等。最多 8 条。外链默认新标签打开。"
        extra={
          <button type="button" className="btn btn-primary btn-sm" disabled={!dirty || saving} onClick={() => void save()}>
            {saving ? <Loader2 size={14} className="animate-spin" /> : <Save size={14} />}
            保存
          </button>
        }
      >
        <div className="flex flex-col gap-4">
          {links.map((item, i) => (
            <div key={i} className="rounded-xl p-3 flex flex-col gap-3" style={{ boxShadow: "inset 0 0 0 1px var(--line)" }}>
              <div className="flex items-center justify-between gap-2">
                <span className="meta text-[12px]">第 {i + 1} 条</span>
                <div className="flex items-center gap-1">
                  <button type="button" className="admin-icon-btn" aria-label="上移" disabled={i === 0} onClick={() => move(i, -1)}>
                    <ArrowUp size={14} />
                  </button>
                  <button
                    type="button"
                    className="admin-icon-btn"
                    aria-label="下移"
                    disabled={i === links.length - 1}
                    onClick={() => move(i, 1)}
                  >
                    <ArrowDown size={14} />
                  </button>
                  <button
                    type="button"
                    className="admin-icon-btn"
                    aria-label="删除"
                    onClick={() => setLinks((prev) => prev.filter((_, idx) => idx !== i))}
                  >
                    <Trash2 size={14} />
                  </button>
                </div>
              </div>
              <AdminField
                id={`footer-label-${i}`}
                label="文案"
                maxLength={BRAND_LIMITS.footerLabel}
                value={item.label}
                onChange={(v) => update(i, { label: v })}
                placeholder="京 ICP 备xxxxxxxx号"
              />
              <AdminField
                id={`footer-url-${i}`}
                label="地址"
                maxLength={BRAND_LIMITS.footerURL}
                value={item.url}
                onChange={(v) => {
                  const wasExt = isExternalFooterURL(item.url);
                  const nowExt = isExternalFooterURL(v);
                  update(i, { url: v, new_tab: !wasExt && nowExt ? true : item.new_tab });
                }}
                placeholder="https://beian.miit.gov.cn/ 或 /about"
              />
              <label className="flex items-center gap-2 text-[13px]" style={{ color: "var(--ink-2)" }}>
                <input
                  type="checkbox"
                  checked={item.new_tab}
                  onChange={(e) => update(i, { new_tab: e.target.checked })}
                />
                新标签打开
              </label>
            </div>
          ))}
          <button
            type="button"
            className="btn btn-line btn-sm self-start"
            disabled={links.length >= BRAND_LIMITS.footerLinks}
            onClick={() => setLinks((prev) => [...prev, { label: "", url: "", new_tab: false }])}
          >
            <Plus size={14} /> 新增链接
          </button>
        </div>
      </AdminSection>
      <AdminSection title="页脚预览" description="保存前仅在此处预览，前台页脚不会跟着变">
        <div className="rounded-xl px-4 py-3 flex flex-wrap items-center gap-x-4 gap-y-2" style={{ background: "var(--panel-2)" }}>
          <span className="meta text-[12px] whitespace-nowrap">© {new Date().getFullYear()} {initial.site_name}</span>
          {links.filter((l) => l.label.trim() && l.url.trim()).map((item) => (
            <span key={`${item.label}-${item.url}`} className="text-[12px]" style={{ color: "var(--ink-2)" }}>
              {item.label.trim()}
              {item.new_tab ? " ↗" : ""}
            </span>
          ))}
          <span className="meta text-[12px] ml-auto">性能指标</span>
        </div>
        <p className="meta text-[12px] mt-3">外链保存后带 target=_blank 与 rel=noopener。站内路径留在本页。</p>
      </AdminSection>
    </div>
  );
}