"use client";

import { useEffect, useId, useRef, useState } from "react";
import { P1FieldLabel } from "@/components/priority1/feathery-card";
import {
  filterPhoneCountries,
  findPhoneCountry,
  type PhoneCountry,
} from "@/lib/priority1/phone-countries";

interface P1PhoneFieldProps {
  country: string;
  value: string;
  disabled?: boolean;
  error?: string;
  onCountryChange: (code: string) => void;
  onChange: (digits: string) => void;
}

function formatUsPhoneDisplay(digits: string): string {
  const d = digits.replace(/\D/g, "").slice(0, 10);
  if (d.length <= 3) return d;
  if (d.length <= 6) return `${d.slice(0, 3)} ${d.slice(3)}`;
  return `${d.slice(0, 3)} ${d.slice(3, 6)} ${d.slice(6)}`;
}

function formatPhoneDisplay(country: PhoneCountry, digits: string): string {
  if (country.code === "US" || country.dial === "+1") {
    return formatUsPhoneDisplay(digits);
  }
  return digits.replace(/\D/g, "").slice(0, 15);
}

function maxPhoneDigits(country: PhoneCountry): number {
  if (country.code === "US" || (country.dial === "+1" && country.code !== "DO")) {
    return 10;
  }
  return 15;
}

/** 电话 — 可搜索国家列表（A–Z）+ 自动显示区号前缀 */
export function P1PhoneField({
  country,
  value,
  disabled,
  error,
  onCountryChange,
  onChange,
}: P1PhoneFieldProps) {
  const listId = useId();
  const rootRef = useRef<HTMLDivElement>(null);
  const [open, setOpen] = useState(false);
  const [search, setSearch] = useState("");
  const selected = findPhoneCountry(country);
  const filtered = filterPhoneCountries(search);

  useEffect(() => {
    if (!open) return;
    const onDoc = (e: MouseEvent) => {
      if (!rootRef.current?.contains(e.target as Node)) setOpen(false);
    };
    document.addEventListener("mousedown", onDoc);
    return () => document.removeEventListener("mousedown", onDoc);
  }, [open]);

  const pickCountry = (c: PhoneCountry) => {
    onCountryChange(c.code);
    setOpen(false);
    setSearch("");
  };

  return (
    <div className="space-y-1" ref={rootRef}>
      <P1FieldLabel required htmlFor="p1-phone">
        电话
      </P1FieldLabel>
      <div
        className={`flex overflow-visible rounded-sm border bg-neutral-100 ${
          error ? "border-red-500" : "border-neutral-400"
        }`}
      >
        <div className="relative shrink-0">
          <button
            type="button"
            disabled={disabled}
            aria-expanded={open}
            aria-controls={listId}
            onClick={() => setOpen((v) => !v)}
            className="flex h-11 min-w-[7.5rem] items-center gap-1 border-r border-neutral-300 bg-white px-2 text-left text-sm focus:outline-none disabled:opacity-60"
          >
            <span className="truncate font-medium">{selected.dial}</span>
            <span className="text-neutral-400" aria-hidden>
              ▾
            </span>
          </button>
          {open ? (
            <div
              id={listId}
              className="absolute left-0 top-full z-30 mt-1 w-72 rounded-sm border border-neutral-300 bg-white shadow-lg"
            >
              <div className="border-b border-neutral-200 p-2">
                <input
                  type="search"
                  autoFocus
                  value={search}
                  placeholder="搜索国家或区号…"
                  onChange={(e) => setSearch(e.target.value)}
                  className="h-9 w-full rounded-sm border border-neutral-300 px-2 text-sm focus:border-neutral-600 focus:outline-none"
                />
              </div>
              <ul className="max-h-56 overflow-y-auto py-1" role="listbox">
                {filtered.map((c) => (
                  <li key={c.code}>
                    <button
                      type="button"
                      role="option"
                      aria-selected={c.code === selected.code}
                      onClick={() => pickCountry(c)}
                      className={`flex w-full items-center justify-between px-3 py-2 text-left text-sm hover:bg-neutral-100 ${
                        c.code === selected.code ? "bg-neutral-50 font-medium" : ""
                      }`}
                    >
                      <span className="truncate">{c.name}</span>
                      <span className="ml-2 shrink-0 text-neutral-500">{c.dial}</span>
                    </button>
                  </li>
                ))}
                {filtered.length === 0 ? (
                  <li className="px-3 py-2 text-sm text-neutral-500">无匹配国家</li>
                ) : null}
              </ul>
            </div>
          ) : null}
        </div>
        <div className="flex min-w-0 flex-1 items-center gap-1 px-2 text-sm text-neutral-600">
          <span className="shrink-0 font-medium">{selected.dial}</span>
          <input
            id="p1-phone"
            type="tel"
            disabled={disabled}
            value={formatPhoneDisplay(selected, value)}
            placeholder={selected.code === "US" ? "753 640 7420" : "电话号码"}
            onChange={(e) =>
              onChange(
                e.target.value.replace(/\D/g, "").slice(0, maxPhoneDigits(selected)),
              )
            }
            className="h-11 min-w-0 flex-1 bg-transparent focus:outline-none disabled:opacity-60"
          />
        </div>
      </div>
      {error ? <p className="text-xs text-red-600">{error}</p> : null}
    </div>
  );
}