"use client";

import { useEffect, useState } from "react";
import type { MothershipAddressCandidate } from "@/lib/frontend/types";
import { PrimaryButton } from "@/components/ui/primary-button";

export interface AddressDisambiguationModalProps {
  open: boolean;
  pickupCandidates: MothershipAddressCandidate[];
  deliveryCandidates: MothershipAddressCandidate[];
  onConfirm: (pickup: MothershipAddressCandidate, delivery: MothershipAddressCandidate) => void;
  onCancel: () => void;
}

function isCandidateSelectable(item: MothershipAddressCandidate): boolean {
  return item.selectable !== false;
}

function pickDefaultId(
  candidates: MothershipAddressCandidate[],
): string | null {
  if (candidates.length === 0) {
    return null;
  }
  const selectable = candidates.filter(isCandidateSelectable);
  if (selectable.length === 1) {
    return selectable[0]!.option_id;
  }
  return null;
}

function findSelectableById(
  candidates: MothershipAddressCandidate[],
  id: string | null,
): MothershipAddressCandidate | null {
  if (!id) {
    return null;
  }
  const hit = candidates.find((c) => c.option_id === id);
  if (!hit || !isCandidateSelectable(hit)) {
    return null;
  }
  return hit;
}

function CandidateGroup({
  title,
  candidates,
  selectedId,
  onSelect,
}: {
  title: string;
  candidates: MothershipAddressCandidate[];
  selectedId: string | null;
  onSelect: (id: string) => void;
}) {
  if (candidates.length === 0) {
    return null;
  }

  const multi = candidates.length > 1;

  return (
    <fieldset className="space-y-2">
      <legend className="text-sm font-medium text-text-primary">{title}</legend>
      <p className="text-xs text-text-secondary">
        {multi
          ? "MotherShip 提供多个精确坐标，请选择与实际位置一致的一项"
          : "请确认以下 MotherShip 解析结果是否与实际位置一致"}
      </p>
      <ul className="space-y-2">
        {candidates.map((item) => {
          const disabled = !isCandidateSelectable(item);
          return (
            <li key={item.option_id}>
              <label
                className={`flex items-start gap-3 rounded-md border border-border p-3 ${
                  disabled
                    ? "cursor-not-allowed bg-surface-muted opacity-70"
                    : "cursor-pointer hover:bg-surface-muted"
                }`}
              >
                <input
                  type="radio"
                  name={title}
                  className="mt-1"
                  disabled={disabled}
                  checked={!disabled && selectedId === item.option_id}
                  onChange={() => onSelect(item.option_id)}
                />
                <span className="text-sm text-text-primary">
                  <span className="block">{item.display_label}</span>
                  {item.unavailable_reason ? (
                    <span className="mt-1 block text-xs text-error">
                      {item.unavailable_reason}
                    </span>
                  ) : null}
                </span>
              </label>
            </li>
          );
        })}
      </ul>
    </fieldset>
  );
}

export function AddressDisambiguationModal({
  open,
  pickupCandidates,
  deliveryCandidates,
  onConfirm,
  onCancel,
}: AddressDisambiguationModalProps) {
  const [pickupId, setPickupId] = useState<string | null>(null);
  const [deliveryId, setDeliveryId] = useState<string | null>(null);

  useEffect(() => {
    if (!open) {
      return;
    }
    setPickupId(pickDefaultId(pickupCandidates));
    setDeliveryId(pickDefaultId(deliveryCandidates));
  }, [open, pickupCandidates, deliveryCandidates]);

  if (!open) {
    return null;
  }

  const pickup = findSelectableById(pickupCandidates, pickupId);
  const delivery = findSelectableById(deliveryCandidates, deliveryId);
  const canConfirm = pickup != null && delivery != null;

  const handleConfirm = () => {
    if (!pickup || !delivery) {
      return;
    }
    onConfirm(pickup, delivery);
  };

  const hasMultiple =
    pickupCandidates.length > 1 || deliveryCandidates.length > 1;

  return (
    <div
      className="fixed inset-0 z-50 flex items-center justify-center bg-black/40 p-4"
      role="dialog"
      aria-modal="true"
      aria-labelledby="ms-address-title"
    >
      <div className="max-h-[90vh] w-full max-w-lg overflow-y-auto rounded-lg border border-border bg-surface p-6 shadow-card">
        <h2
          id="ms-address-title"
          className="text-lg font-semibold text-text-primary"
        >
          确认 MotherShip 精确地址
        </h2>
        <p className="mt-2 text-sm text-text-secondary">
          {hasMultiple
            ? "系统检测到 MotherShip 对您的地址有多个精确坐标。错误选择会导致报价不准，请逐项确认后再获取报价。"
            : "请确认 MotherShip 解析的提货/派送地址是否准确，确认无误后再获取报价。"}
        </p>

        <div className="mt-6 space-y-6">
          <CandidateGroup
            title="提货地址"
            candidates={pickupCandidates}
            selectedId={pickupId}
            onSelect={setPickupId}
          />
          <CandidateGroup
            title="派送地址"
            candidates={deliveryCandidates}
            selectedId={deliveryId}
            onSelect={setDeliveryId}
          />
        </div>

        <div className="mt-6 flex flex-wrap gap-3">
          <PrimaryButton disabled={!canConfirm} onClick={handleConfirm}>
            确认并获取报价
          </PrimaryButton>
          <button
            type="button"
            className="rounded-md border border-border px-4 py-2 text-sm text-text-secondary hover:bg-surface-muted"
            onClick={onCancel}
          >
            返回修改
          </button>
        </div>
      </div>
    </div>
  );
}