'use client';

import { useState, useEffect } from 'react';
import { PAYMENT_TYPE_META } from '@/lib/pay-utils';

export interface MethodLimitInfo {
  available: boolean;
  remaining: number | null;
  /** 单笔限额，0 = 使用全局 maxAmount */
  singleMax?: number;
  /** 手续费率百分比，0 = 无手续费 */
  feeRate?: number;
}

interface PaymentFormProps {
  userId: number;
  userName?: string;
  userBalance?: number;
  enabledPaymentTypes: string[];
  methodLimits?: Record<string, MethodLimitInfo>;
  minAmount: number;
  maxAmount: number;
  onSubmit: (amount: number, paymentType: string) => Promise<void>;
  loading?: boolean;
  dark?: boolean;
}

const QUICK_AMOUNTS = [10, 20, 50, 100, 200, 500, 1000, 2000];
const AMOUNT_TEXT_PATTERN = /^\d*(\.\d{0,2})?$/;

function hasValidCentPrecision(num: number): boolean {
  return Math.abs(Math.round(num * 100) - num * 100) < 1e-8;
}

export default function PaymentForm({
  userId,
  userName,
  userBalance,
  enabledPaymentTypes,
  methodLimits,
  minAmount,
  maxAmount,
  onSubmit,
  loading,
  dark = false,
}: PaymentFormProps) {
  const [amount, setAmount] = useState<number | ''>('');
  const [paymentType, setPaymentType] = useState(enabledPaymentTypes[0] || 'alipay');
  const [customAmount, setCustomAmount] = useState('');

  // Reset paymentType when enabledPaymentTypes changes (e.g. after config loads)
  useEffect(() => {
    if (!enabledPaymentTypes.includes(paymentType)) {
      setPaymentType(enabledPaymentTypes[0] || 'stripe');
    }
  }, [enabledPaymentTypes, paymentType]);

  const handleQuickAmount = (val: number) => {
    setAmount(val);
    setCustomAmount(String(val));
  };

  const handleCustomAmountChange = (val: string) => {
    if (!AMOUNT_TEXT_PATTERN.test(val)) {
      return;
    }

    setCustomAmount(val);

    if (val === '') {
      setAmount('');
      return;
    }

    const num = parseFloat(val);
    if (!isNaN(num) && num > 0 && hasValidCentPrecision(num)) {
      setAmount(num);
    } else {
      setAmount('');
    }
  };

  const selectedAmount = amount || 0;
  const isMethodAvailable = !methodLimits || (methodLimits[paymentType]?.available !== false);
  const methodSingleMax = methodLimits?.[paymentType]?.singleMax;
  const effectiveMax = (methodSingleMax !== undefined && methodSingleMax > 0) ? methodSingleMax : maxAmount;
  const feeRate = methodLimits?.[paymentType]?.feeRate ?? 0;
  const feeAmount = feeRate > 0 && selectedAmount > 0
    ? Math.ceil(selectedAmount * feeRate / 100 * 100) / 100
    : 0;
  const payAmount = feeRate > 0 && selectedAmount > 0
    ? Math.round((selectedAmount + feeAmount) * 100) / 100
    : selectedAmount;
  const isValid = selectedAmount >= minAmount && selectedAmount <= effectiveMax && hasValidCentPrecision(selectedAmount) && isMethodAvailable;

  const handleSubmit = async (e: React.FormEvent) => {
    e.preventDefault();
    if (!isValid || loading) return;
    await onSubmit(selectedAmount, paymentType);
  };

  const renderPaymentIcon = (type: string) => {
    if (type === 'alipay') {
      return (
        <span className="flex h-8 w-8 items-center justify-center rounded-md bg-[#00AEEF] text-xl font-bold leading-none text-white">
          支
        </span>
      );
    }
    if (type === 'wxpay') {
      return (
        <span className="flex h-8 w-8 items-center justify-center rounded-full bg-[#2BB741] text-white">
          <svg viewBox="0 0 24 24" className="h-5 w-5" fill="currentColor">
            <path d="M10 3C6.13 3 3 5.58 3 8.75c0 1.7.84 3.23 2.17 4.29l-.5 2.21 2.4-1.32c.61.17 1.25.27 1.93.27.22 0 .43-.01.64-.03C9.41 13.72 9 12.88 9 12c0-3.31 3.13-6 7-6 .26 0 .51.01.76.03C15.96 3.98 13.19 3 10 3z" />
            <path d="M16 8c-3.31 0-6 2.24-6 5s2.69 5 6 5c.67 0 1.31-.1 1.9-.28l2.1 1.15-.55-2.44C20.77 15.52 22 13.86 22 12c0-2.21-2.69-4-6-4z" />
          </svg>
        </span>
      );
    }
    if (type === 'stripe') {
      return (
        <span className="flex h-8 w-8 items-center justify-center rounded-lg bg-[#635bff] text-white">
          <svg
            viewBox="0 0 24 24"
            className="h-5 w-5"
            fill="none"
            stroke="currentColor"
            strokeWidth="1.8"
            strokeLinecap="round"
            strokeLinejoin="round"
          >
            <rect x="2" y="5" width="20" height="14" rx="2" />
            <path d="M2 10h20" />
          </svg>
        </span>
      );
    }
    return null;
  };

  return (
    <form onSubmit={handleSubmit} className="space-y-6">
      {/* User Info */}
      <div
        className={[
          'rounded-xl border p-4',
          dark ? 'border-slate-700 bg-slate-800/80' : 'border-slate-200 bg-slate-50',
        ].join(' ')}
      >
        <div className={['text-xs uppercase tracking-wide', dark ? 'text-slate-400' : 'text-slate-500'].join(' ')}>
          充值账户
        </div>
        <div className={['mt-1 text-base font-medium', dark ? 'text-slate-100' : 'text-slate-900'].join(' ')}>
          {userName || `用户 #${userId}`}
        </div>
        {userBalance !== undefined && (
          <div className={['mt-1 text-sm', dark ? 'text-slate-400' : 'text-slate-500'].join(' ')}>
            当前余额: <span className="font-medium text-green-600">{userBalance.toFixed(2)}</span>
          </div>
        )}
      </div>

      {/* Quick Amount Selection */}
      <div>
        <label className={['mb-2 block text-sm font-medium', dark ? 'text-slate-200' : 'text-slate-700'].join(' ')}>
          充值金额
        </label>
        <div className="grid grid-cols-3 gap-2">
          {QUICK_AMOUNTS.filter((val) => val >= minAmount && val <= effectiveMax).map((val) => (
            <button
              key={val}
              type="button"
              onClick={() => handleQuickAmount(val)}
              className={`rounded-lg border-2 px-4 py-3 text-center font-medium transition-colors ${
                amount === val
                  ? 'border-blue-500 bg-blue-50 text-blue-700'
                  : dark
                    ? 'border-slate-700 bg-slate-900 text-slate-200 hover:border-slate-500'
                    : 'border-gray-200 bg-white text-gray-700 hover:border-gray-300'
              }`}
            >
              ¥{val}
            </button>
          ))}
        </div>
      </div>

      {/* Custom Amount */}
      <div>
        <label className={['mb-2 block text-sm font-medium', dark ? 'text-slate-200' : 'text-slate-700'].join(' ')}>
          自定义金额
        </label>
        <div className="relative">
          <span
            className={['absolute left-3 top-1/2 -translate-y-1/2', dark ? 'text-slate-500' : 'text-gray-400'].join(
              ' ',
            )}
          >
            ¥
          </span>
          <input
            type="text"
            inputMode="decimal"
            step="0.01"
            min={minAmount}
            max={effectiveMax}
            value={customAmount}
            onChange={(e) => handleCustomAmountChange(e.target.value)}
            placeholder={`${minAmount} - ${effectiveMax}`}
            className={[
              'w-full rounded-lg border py-3 pl-8 pr-4 focus:border-blue-500 focus:outline-none focus:ring-1 focus:ring-blue-500',
              dark ? 'border-slate-700 bg-slate-900 text-slate-100' : 'border-gray-300 bg-white text-gray-900',
            ].join(' ')}
          />
        </div>
      </div>

      {customAmount !== '' && !isValid && (() => {
        const num = parseFloat(customAmount);
        let msg = '金额需在范围内，且最多支持 2 位小数（精确到分）';
        if (!isNaN(num)) {
          if (num < minAmount) msg = `单笔最低充值 ¥${minAmount}`;
          else if (num > effectiveMax) msg = `单笔最高充值 ¥${effectiveMax}`;
        }
        return (
          <div className={['text-xs', dark ? 'text-amber-300' : 'text-amber-700'].join(' ')}>
            {msg}
          </div>
        );
      })()}

      {/* Payment Type — only show when multiple types available */}
      {enabledPaymentTypes.length > 1 && (
        <div>
          <label className={['mb-2 block text-sm font-medium', dark ? 'text-slate-200' : 'text-gray-700'].join(' ')}>
            支付方式
          </label>
          <div className="flex gap-3">
            {enabledPaymentTypes.map((type) => {
              const meta = PAYMENT_TYPE_META[type];
              const isSelected = paymentType === type;
              const limitInfo = methodLimits?.[type];
              const isUnavailable = limitInfo !== undefined && !limitInfo.available;

              return (
                <button
                  key={type}
                  type="button"
                  disabled={isUnavailable}
                  onClick={() => !isUnavailable && setPaymentType(type)}
                  title={isUnavailable ? '今日充值额度已满，请使用其他支付方式' : undefined}
                  className={[
                    'relative flex h-[58px] flex-1 flex-col items-center justify-center rounded-lg border px-3 transition-all',
                    isUnavailable
                      ? dark
                        ? 'cursor-not-allowed border-slate-700 bg-slate-800/50 opacity-50'
                        : 'cursor-not-allowed border-gray-200 bg-gray-50 opacity-50'
                      : isSelected
                        ? `${meta?.selectedBorder || 'border-blue-500'} ${meta?.selectedBg || 'bg-blue-50'} text-slate-900 shadow-sm`
                        : dark
                          ? 'border-slate-700 bg-slate-900 text-slate-200 hover:border-slate-500'
                          : 'border-gray-300 bg-white text-slate-700 hover:border-gray-400',
                  ].join(' ')}
                >
                  <span className="flex items-center gap-2">
                    {renderPaymentIcon(type)}
                    <span className="flex flex-col items-start leading-none">
                      <span className="text-xl font-semibold tracking-tight">{meta?.label || type}</span>
                      {isUnavailable ? (
                        <span className="text-[10px] tracking-wide text-red-400">今日额度已满</span>
                      ) : meta?.sublabel ? (
                        <span
                          className={`text-[10px] tracking-wide ${dark && !isSelected ? 'text-slate-400' : 'text-slate-600'}`}
                        >
                          {meta.sublabel}
                        </span>
                      ) : null}
                    </span>
                  </span>
                </button>
              );
            })}
          </div>

          {/* 当前选中渠道额度不足时的提示 */}
          {(() => {
            const limitInfo = methodLimits?.[paymentType];
            if (!limitInfo || limitInfo.available) return null;
            return (
              <p className={['mt-2 text-xs', dark ? 'text-amber-300' : 'text-amber-600'].join(' ')}>
                所选支付方式今日额度已满，请切换到其他支付方式
              </p>
            );
          })()}
        </div>
      )}

      {/* Fee Detail */}
      {feeRate > 0 && selectedAmount > 0 && (
        <div
          className={[
            'rounded-xl border px-4 py-3 text-sm',
            dark ? 'border-slate-700 bg-slate-800/60 text-slate-300' : 'border-slate-200 bg-slate-50 text-slate-600',
          ].join(' ')}
        >
          <div className="flex items-center justify-between">
            <span>充值金额</span>
            <span>¥{selectedAmount.toFixed(2)}</span>
          </div>
          <div className="flex items-center justify-between mt-1">
            <span>手续费（{feeRate}%）</span>
            <span>¥{feeAmount.toFixed(2)}</span>
          </div>
          <div className={[
            'flex items-center justify-between mt-1.5 pt-1.5 border-t font-medium',
            dark ? 'border-slate-700 text-slate-100' : 'border-slate-200 text-slate-900',
          ].join(' ')}>
            <span>实付金额</span>
            <span>¥{payAmount.toFixed(2)}</span>
          </div>
        </div>
      )}

      {/* Submit */}
      <button
        type="submit"
        disabled={!isValid || loading}
        className={`w-full rounded-lg py-3 text-center font-medium text-white transition-colors ${
          isValid && !loading
            ? paymentType === 'stripe'
              ? 'bg-[#635bff] hover:bg-[#5851db] active:bg-[#4b44c7]'
              : 'bg-blue-600 hover:bg-blue-700 active:bg-blue-800'
            : dark
              ? 'cursor-not-allowed bg-slate-700 text-slate-300'
              : 'cursor-not-allowed bg-gray-300'
        }`}
      >
        {loading ? '处理中...' : `立即充值 ¥${(feeRate > 0 && selectedAmount > 0 ? payAmount : selectedAmount || 0).toFixed(2)}`}
      </button>
    </form>
  );
}