"use client";

/**
 * 계산기 위젯 컴포넌트
 * - 기본 사칙연산 지원
 * - 실시간 계산
 * - 대시보드 위젯으로 사용 가능
 */

import React, { useState, useEffect } from "react";
import { Button } from "@/components/ui/button";
import { DashboardElement } from "@/components/admin/dashboard/types";

interface CalculatorWidgetProps {
  element?: DashboardElement;
  className?: string;
}

export default function CalculatorWidget({ element, className = "" }: CalculatorWidgetProps) {
  const [display, setDisplay] = useState<string>("0");
  const [previousValue, setPreviousValue] = useState<number | null>(null);
  const [operation, setOperation] = useState<string | null>(null);
  const [waitingForOperand, setWaitingForOperand] = useState<boolean>(false);

  // 숫자 입력 처리
  const handleNumber = (num: string) => {
    if (waitingForOperand) {
      setDisplay(num);
      setWaitingForOperand(false);
    } else {
      setDisplay(display === "0" ? num : display + num);
    }
  };

  // 소수점 입력
  const handleDecimal = () => {
    if (waitingForOperand) {
      setDisplay("0.");
      setWaitingForOperand(false);
    } else if (display.indexOf(".") === -1) {
      setDisplay(display + ".");
    }
  };

  // 연산자 입력
  const handleOperation = (nextOperation: string) => {
    const inputValue = parseFloat(display);

    if (previousValue === null) {
      setPreviousValue(inputValue);
    } else if (operation) {
      const currentValue = previousValue || 0;
      const newValue = calculate(currentValue, inputValue, operation);

      setDisplay(String(newValue));
      setPreviousValue(newValue);
    }

    setWaitingForOperand(true);
    setOperation(nextOperation);
  };

  // 계산 수행
  const calculate = (firstValue: number, secondValue: number, operation: string): number => {
    switch (operation) {
      case "+":
        return firstValue + secondValue;
      case "-":
        return firstValue - secondValue;
      case "×":
        return firstValue * secondValue;
      case "÷":
        return secondValue !== 0 ? firstValue / secondValue : 0;
      default:
        return secondValue;
    }
  };

  // 등호 처리
  const handleEquals = () => {
    const inputValue = parseFloat(display);

    if (previousValue !== null && operation) {
      const newValue = calculate(previousValue, inputValue, operation);
      setDisplay(String(newValue));
      setPreviousValue(null);
      setOperation(null);
      setWaitingForOperand(true);
    }
  };

  // 초기화
  const handleClear = () => {
    setDisplay("0");
    setPreviousValue(null);
    setOperation(null);
    setWaitingForOperand(false);
  };

  // 백스페이스
  const handleBackspace = () => {
    if (!waitingForOperand) {
      const newDisplay = display.slice(0, -1);
      setDisplay(newDisplay || "0");
    }
  };

  // 부호 변경
  const handleSign = () => {
    const value = parseFloat(display);
    setDisplay(String(value * -1));
  };

  // 퍼센트
  const handlePercent = () => {
    const value = parseFloat(display);
    setDisplay(String(value / 100));
  };

  // 키보드 입력 처리
  useEffect(() => {
    const handleKeyDown = (event: KeyboardEvent) => {
      const key = event.key;

      // 숫자 키 (0-9)
      if (/^[0-9]$/.test(key)) {
        event.preventDefault();
        handleNumber(key);
      }
      // 연산자 키
      else if (key === "+" || key === "-" || key === "*" || key === "/") {
        event.preventDefault();
        handleOperation(key);
      }
      // 소수점
      else if (key === ".") {
        event.preventDefault();
        handleDecimal();
      }
      // Enter 또는 = (계산)
      else if (key === "Enter" || key === "=") {
        event.preventDefault();
        handleEquals();
      }
      // Escape 또는 c (초기화)
      else if (key === "Escape" || key.toLowerCase() === "c") {
        event.preventDefault();
        handleClear();
      }
      // Backspace (지우기)
      else if (key === "Backspace") {
        event.preventDefault();
        handleBackspace();
      }
      // % (퍼센트)
      else if (key === "%") {
        event.preventDefault();
        handlePercent();
      }
    };

    // 이벤트 리스너 등록
    window.addEventListener("keydown", handleKeyDown);

    // 클린업
    return () => {
      window.removeEventListener("keydown", handleKeyDown);
    };
  }, [display, previousValue, operation, waitingForOperand]);

  return (
    <div className={`bg-background h-full w-full p-2 sm:p-3 ${className}`}>
      <div className="flex h-full flex-col gap-1.5 sm:gap-2">
        {/* 제목 */}
        <h3 className="text-foreground text-center text-sm font-semibold sm:text-base">
          {element?.customTitle || "계산기"}
        </h3>

        {/* 디스플레이 */}
        <div className="bg-background border-border min-h-[60px] rounded-lg border-2 p-2 shadow-inner sm:min-h-[80px] sm:p-4">
          <div className="flex h-full flex-col justify-center text-right">
            <div className="mb-0.5 h-3 sm:mb-1 sm:h-4">
              {operation && previousValue !== null && (
                <div className="text-muted-foreground text-[10px] sm:text-xs">
                  {previousValue} {operation}
                </div>
              )}
            </div>
            <div className="text-foreground truncate text-lg font-bold sm:text-2xl">{display}</div>
          </div>
        </div>

        {/* 버튼 그리드 */}
        <div className="grid flex-1 grid-cols-4 gap-1 sm:gap-2">
          {/* 첫 번째 줄 */}
          <Button
            variant="outline"
            onClick={handleClear}
            className="text-destructive hover:bg-destructive/10 hover:text-destructive h-full text-xs font-semibold select-none sm:text-base"
          >
            AC
          </Button>
          <Button
            variant="outline"
            onClick={handleSign}
            className="text-foreground hover:bg-muted h-full text-xs font-semibold select-none sm:text-base"
          >
            +/-
          </Button>
          <Button
            variant="outline"
            onClick={handlePercent}
            className="text-foreground hover:bg-muted h-full text-xs font-semibold select-none sm:text-base"
          >
            %
          </Button>
          <Button
            variant="default"
            onClick={() => handleOperation("÷")}
            className="bg-primary hover:bg-primary/90 text-primary-foreground h-full text-xs font-semibold select-none sm:text-base"
          >
            ÷
          </Button>

          {/* 두 번째 줄 */}
          <Button
            variant="outline"
            onClick={() => handleNumber("7")}
            className="hover:bg-muted h-full text-sm font-semibold select-none sm:text-lg"
          >
            7
          </Button>
          <Button
            variant="outline"
            onClick={() => handleNumber("8")}
            className="hover:bg-muted h-full text-sm font-semibold select-none sm:text-lg"
          >
            8
          </Button>
          <Button
            variant="outline"
            onClick={() => handleNumber("9")}
            className="hover:bg-muted h-full text-sm font-semibold select-none sm:text-lg"
          >
            9
          </Button>
          <Button
            variant="default"
            onClick={() => handleOperation("×")}
            className="bg-primary hover:bg-primary/90 text-primary-foreground h-full text-xs font-semibold select-none sm:text-base"
          >
            ×
          </Button>

          {/* 세 번째 줄 */}
          <Button
            variant="outline"
            onClick={() => handleNumber("4")}
            className="hover:bg-muted h-full text-sm font-semibold select-none sm:text-lg"
          >
            4
          </Button>
          <Button
            variant="outline"
            onClick={() => handleNumber("5")}
            className="hover:bg-muted h-full text-sm font-semibold select-none sm:text-lg"
          >
            5
          </Button>
          <Button
            variant="outline"
            onClick={() => handleNumber("6")}
            className="hover:bg-muted h-full text-sm font-semibold select-none sm:text-lg"
          >
            6
          </Button>
          <Button
            variant="default"
            onClick={() => handleOperation("-")}
            className="bg-primary hover:bg-primary/90 text-primary-foreground h-full text-xs font-semibold select-none sm:text-base"
          >
            -
          </Button>

          {/* 네 번째 줄 */}
          <Button
            variant="outline"
            onClick={() => handleNumber("1")}
            className="hover:bg-muted h-full text-sm font-semibold select-none sm:text-lg"
          >
            1
          </Button>
          <Button
            variant="outline"
            onClick={() => handleNumber("2")}
            className="hover:bg-muted h-full text-sm font-semibold select-none sm:text-lg"
          >
            2
          </Button>
          <Button
            variant="outline"
            onClick={() => handleNumber("3")}
            className="hover:bg-muted h-full text-sm font-semibold select-none sm:text-lg"
          >
            3
          </Button>
          <Button
            variant="default"
            onClick={() => handleOperation("+")}
            className="bg-primary hover:bg-primary/90 text-primary-foreground h-full text-xs font-semibold select-none sm:text-base"
          >
            +
          </Button>

          {/* 다섯 번째 줄 */}
          <Button
            variant="outline"
            onClick={() => handleNumber("0")}
            className="hover:bg-muted col-span-2 h-full text-sm font-semibold select-none sm:text-lg"
          >
            0
          </Button>
          <Button
            variant="outline"
            onClick={handleDecimal}
            className="hover:bg-muted h-full text-sm font-semibold select-none sm:text-lg"
          >
            .
          </Button>
          <Button
            variant="default"
            onClick={handleEquals}
            className="bg-success hover:bg-success/90 text-primary-foreground h-full text-xs font-semibold select-none sm:text-base"
          >
            =
          </Button>
        </div>
      </div>
    </div>
  );
}