'use client';

import { ChevronDown, X } from 'lucide-react';
import { Command, CommandEmpty, CommandGroup, CommandInput, CommandItem, CommandList } from '@/components/ui/command';
import { Popover, PopoverContent, PopoverTrigger } from '@/components/ui/popover';
import { cn } from '@/lib/utils';

export interface CountryOption {
  id: string;
  code: string;
  label: string;
  maxDigits: number;
  /** Path to the country flag asset inside the public directory. */
  flagSrc: string;
}

export const FLAG_WIDTH = 24;
export const FLAG_HEIGHT = 18;

export const phoneCountries: CountryOption[] = [
  { id: 'RU', code: '+7', label: 'Россия', maxDigits: 10, flagSrc: '/flags/ru.svg' },
  { id: 'BY', code: '+375', label: 'Беларусь', maxDigits: 9, flagSrc: '/flags/by.svg' },
  { id: 'KZ', code: '+7', label: 'Казахстан', maxDigits: 10, flagSrc: '/flags/kz.svg' }
];

function FlagIcon({ src, className }: { src: string; className?: string }) {
  return (
    <span
      aria-hidden="true"
      className={cn('inline-block shrink-0 overflow-hidden rounded-[3px] bg-center bg-no-repeat shadow-[inset_0_0_0_1px_rgba(0,0,0,0.08)]', className)}
      style={{
        width: `${FLAG_WIDTH}px`,
        height: `${FLAG_HEIGHT}px`,
        backgroundImage: `url('${src}')`,
        backgroundSize: 'cover'
      }}
    />
  );
}

export function formatPhoneNumber(digits: string, country: CountryOption) {
  const clean = digits.replace(/\D/g, '').slice(0, country.maxDigits);
  if (country.code === '+375') {
    const part1 = clean.slice(0, 2);
    const part2 = clean.slice(2, 5);
    const part3 = clean.slice(5, 7);
    const part4 = clean.slice(7, 9);
    if (clean.length <= 2) return part1 ? `(${part1}` : '';
    if (clean.length <= 5) return `(${part1}) ${part2}`;
    if (clean.length <= 7) return `(${part1}) ${part2}-${part3}`;
    return `(${part1}) ${part2}-${part3}-${part4}`;
  }

  const part1 = clean.slice(0, 3);
  const part2 = clean.slice(3, 6);
  const part3 = clean.slice(6, 8);
  const part4 = clean.slice(8, 10);
  if (clean.length <= 3) return part1 ? `(${part1}` : '';
  if (clean.length <= 6) return `(${part1}) ${part2}`;
  if (clean.length <= 8) return `(${part1}) ${part2}-${part3}`;
  return `(${part1}) ${part2}-${part3}-${part4}`;
}

export function toE164(country: CountryOption, digits: string) {
  return `${country.code}${digits.replace(/\D/g, '').slice(0, country.maxDigits)}`;
}

export function parseE164Phone(e164: string): { country: CountryOption; digits: string } {
  if (!e164) {
    return { country: phoneCountries[0], digits: '' };
  }
  const sorted = [...phoneCountries].sort((a, b) => b.code.length - a.code.length);
  for (const country of sorted) {
    if (e164.startsWith(country.code)) {
      return { country, digits: e164.slice(country.code.length).replace(/\D/g, '') };
    }
  }
  return { country: phoneCountries[0], digits: e164.replace(/\D/g, '') };
}

const phoneThemes = {
  dark: {
    shell: 'border-[#555762] bg-transparent text-white focus-within:border-[#7b7f8f] focus-within:ring-white/10',
    trigger: 'text-white hover:bg-[#2a2c36]',
    chevron: 'text-[#8f92a0]',
    input: 'text-white placeholder:text-[#8f92a0]',
    clear: 'text-[#8f92a0] hover:bg-[#2a2c36] hover:text-white'
  },
  light: {
    shell: 'border-[#eceef4] bg-white text-[#111827] focus-within:border-[#c7cad6] focus-within:ring-[#eceef4]',
    trigger: 'text-[#111827] hover:bg-[#f4f5f8]',
    chevron: 'text-[#667085]',
    input: 'text-[#111827] placeholder:text-[#667085]',
    clear: 'text-[#667085] hover:bg-[#f4f5f8] hover:text-[#111827]'
  }
} as const;

export function PhoneInput({
  country,
  value,
  onCountryChange,
  onValueChange,
  className,
  variant = 'dark',
  required = true
}: {
  country: CountryOption;
  value: string;
  onCountryChange: (country: CountryOption) => void;
  onValueChange: (digits: string) => void;
  className?: string;
  variant?: keyof typeof phoneThemes;
  required?: boolean;
}) {
  const maskedValue = formatPhoneNumber(value, country);
  const theme = phoneThemes[variant];

  return (
    <div
      className={cn(
        'flex h-[58px] w-full items-center rounded-2xl border transition focus-within:ring-4',
        variant === 'light' ? 'h-11' : '',
        theme.shell,
        className
      )}
    >
      <Popover>
        <PopoverTrigger asChild>
          <button type="button" className={cn('flex h-full shrink-0 items-center gap-2 rounded-l-2xl px-4 outline-none', theme.trigger)} aria-label="Выбрать страну">
            <FlagIcon src={country.flagSrc} />
            <span className="text-base font-semibold">{country.code}</span>
            <ChevronDown className={cn('h-4 w-4', theme.chevron)} />
          </button>
        </PopoverTrigger>
        <PopoverContent className="w-80 p-1">
          <Command>
            <CommandInput placeholder="Страна или код" />
            <CommandList>
              <CommandEmpty>Страна не найдена</CommandEmpty>
              <CommandGroup>
                {phoneCountries.map((item) => (
                  <CommandItem
                    key={item.id}
                    value={`${item.label} ${item.code}`}
                    onSelect={() => {
                      onCountryChange(item);
                      onValueChange(value.replace(/\D/g, '').slice(0, item.maxDigits));
                    }}
                  >
                    <FlagIcon src={item.flagSrc} />
                    <span className="flex-1">{item.label}</span>
                    <span className="font-semibold text-[#667085]">{item.code}</span>
                  </CommandItem>
                ))}
              </CommandGroup>
            </CommandList>
          </Command>
        </PopoverContent>
      </Popover>

      <input
        className={cn('h-full min-w-0 flex-1 bg-transparent px-1 text-lg outline-none', variant === 'light' ? 'text-base' : '', theme.input)}
        inputMode="tel"
        placeholder={country.code === '+375' ? '(29) 123-45-67' : '(999) 123-45-67'}
        value={maskedValue}
        onChange={(event) => onValueChange(event.target.value.replace(/\D/g, '').slice(0, country.maxDigits))}
        required={required}
      />

      {value ? (
        <button type="button" className={cn('mr-3 flex h-8 w-8 shrink-0 items-center justify-center rounded-full', theme.clear)} onClick={() => onValueChange('')} aria-label="Очистить телефон">
          <X className="h-4 w-4" />
        </button>
      ) : null}
    </div>
  );
}