import { useEffect, useState } from "react";
import { ArrowLeft } from "lucide-react";
import { api } from "../api";
import type { Product } from "../types";
import { NUTRIMENT_LABELS } from "../types";

function Row({ label, value }: { label: string; value: React.ReactNode }) {
  if (value === null || value === undefined || value === "") return null;
  return (
    <div className="flex py-2 border-b last:border-0 text-sm">
      <div className="w-32 shrink-0 text-gray-400">{label}</div>
      <div className="text-gray-800">{value}</div>
    </div>
  );
}

export default function ProductView({ id, onBack }: { id: string; onBack: () => void }) {
  const [p, setP] = useState<Product | null>(null);
  const [error, setError] = useState("");

  useEffect(() => {
    api.product(id).then(setP).catch((e) => setError(e.message));
  }, [id]);

  if (error) {
    return (
      <div>
        <button onClick={onBack} className="text-sm text-gray-500 flex items-center gap-1 mb-4">
          <ArrowLeft className="w-4 h-4" /> 返回
        </button>
        <div className="rounded-xl bg-red-50 px-4 py-3 text-sm text-red-700">{error}</div>
      </div>
    );
  }
  if (!p) return <div className="text-gray-400 animate-pulse">加载中…</div>;

  const basisLabel: Record<string, string> = {
    per_100g: "每 100g",
    per_100ml: "每 100ml",
    per_serving: "每份",
  };
  const nutriEntries = Object.entries(p.nutriments || {}).filter(
    ([, v]) => v !== null && v !== undefined,
  );
  const latestMsrp = (p.msrp || [])[0];
  const msrpText = latestMsrp
    ? latestMsrp.currency === "CNY"
      ? `¥${latestMsrp.amount.toFixed(2)}`
      : `${latestMsrp.amount.toFixed(2)} ${latestMsrp.currency}`
    : null;

  return (
    <div>
      <button onClick={onBack} className="mb-4 inline-flex items-center gap-1 text-sm text-gray-500 hover:text-gray-700">
        <ArrowLeft className="w-4 h-4" /> 返回检索
      </button>

      <div className="card p-6 animate-fade-up">
        <div className="flex items-start justify-between gap-4">
          <h1 className="text-2xl font-semibold tracking-tight text-gray-900">{p.name}</h1>
          <span className="shrink-0 rounded-full border border-brand-100 bg-brand-50 px-2.5 py-1 text-xs font-medium text-brand-700">
            质量分 {Math.round(p.quality_score * 100)}
          </span>
        </div>

        <div className="mt-4">
          <Row label="品牌" value={p.brand} />
          <Row label="条码 (GTIN)" value={p.gtin} />
          {(() => {
            const others = (p.barcodes || []).filter(
              (b) => !b.is_primary && b.gtin !== p.gtin,
            );
            return others.length ? (
              <Row
                label="其他条码"
                value={
                  <div className="flex flex-wrap gap-1.5">
                    {others.map((b) => (
                      <span
                        key={b.gtin}
                        className="font-mono text-xs bg-gray-100 text-gray-600 rounded px-1.5 py-0.5"
                        title={`${b.gtin_type} · ${b.pack_level}`}
                      >
                        {b.gtin}
                      </span>
                    ))}
                  </div>
                }
              />
            ) : null;
          })()}
          <Row label="品类" value={p.category_path} />
          <Row
            label="净含量"
            value={
              p.net_content_value != null
                ? `${p.net_content_value} ${p.net_content_unit || ""}`
                : null
            }
          />
          <Row label="产地" value={p.country_of_origin} />
          <Row
            label="建议零售价"
            value={
              msrpText ? (
                <span className="inline-flex items-baseline gap-2">
                  <span className="font-medium text-gray-900">{msrpText}</span>
                  <span className="text-xs text-gray-400">厂商建议，仅供参考</span>
                </span>
              ) : null
            }
          />
          <Row label="Nutri-Score" value={p.nutri_score} />
          <Row label="配料" value={p.ingredients_text} />
          <Row
            label="过敏原"
            value={p.allergens && p.allergens.length ? p.allergens.join("、") : null}
          />
          <Row
            label="添加剂"
            value={p.additives && p.additives.length ? p.additives.join("、") : null}
          />
        </div>
      </div>

      {p.specs && p.specs.length > 0 && (
        <div className="card p-6 mt-4">
          <h2 className="font-medium text-gray-700 mb-2">规格参数</h2>
          <div className="grid grid-cols-1 sm:grid-cols-2 gap-2 text-sm">
            {p.specs.map((s) => (
              <div key={s.key} className="bg-gray-50 rounded px-3 py-2">
                <div className="text-gray-400 text-xs">{s.label}</div>
                <div className="text-gray-800">
                  {s.value}
                  {s.unit ? ` ${s.unit}` : ""}
                </div>
              </div>
            ))}
          </div>
        </div>
      )}

      {nutriEntries.length > 0 && (
        <div className="card p-6 mt-4">
          <h2 className="font-medium text-gray-700 mb-2">
            营养成分
            {p.nutrition_basis ? `（${basisLabel[p.nutrition_basis] || p.nutrition_basis}）` : ""}
          </h2>
          <div className="grid grid-cols-2 sm:grid-cols-3 gap-2 text-sm">
            {nutriEntries.map(([k, v]) => (
              <div key={k} className="bg-gray-50 rounded px-3 py-2">
                <div className="text-gray-400 text-xs">{NUTRIMENT_LABELS[k] || k}</div>
                <div className="text-gray-800">{String(v)}</div>
              </div>
            ))}
          </div>
        </div>
      )}
    </div>
  );
}