"use client";

import React, { useState, useEffect, useMemo } from "react";
import { Delete, Trash2, Plus, ArrowLeft } from "lucide-react";
import {
  Dialog,
  DialogPortal,
  DialogOverlay,
  DialogTitle,
} from "@/components/ui/dialog";
import * as DialogPrimitive from "@radix-ui/react-dialog";
import { VisuallyHidden } from "@radix-ui/react-visually-hidden";
import {
  PackageUnitModal,
  PACKAGE_UNITS,
} from "./PackageUnitModal";
import type { CardPackageConfig, PackageEntry } from "../types";

type InputStep =
  | "quantity"          // 기본: 직접 수량 입력 (포장 OFF)
  | "package_count"     // 포장: 포장 수량 (N개)
  | "quantity_per_unit" // 포장: 개당 수량 (M EA)
  | "summary";          // 포장: 결과 확인 + 추가/완료

interface NumberInputModalProps {
  open: boolean;
  onOpenChange: (open: boolean) => void;
  unit?: string;
  initialValue?: number;
  initialPackageUnit?: string;
  min?: number;
  maxValue?: number;
  /** @deprecated packageConfig 사용 */
  showPackageUnit?: boolean;
  packageConfig?: CardPackageConfig;
  onConfirm: (value: number, packageUnit?: string, packageEntries?: PackageEntry[]) => void;
}

export function NumberInputModal({
  open,
  onOpenChange,
  unit = "EA",
  initialValue = 0,
  initialPackageUnit,
  min = 0,
  maxValue = 999999,
  showPackageUnit,
  packageConfig,
  onConfirm,
}: NumberInputModalProps) {
  const [displayValue, setDisplayValue] = useState("");
  const [step, setStep] = useState<InputStep>("quantity");
  const [isPackageModalOpen, setIsPackageModalOpen] = useState(false);

  // 포장 2단계 플로우용 상태
  const [selectedUnit, setSelectedUnit] = useState<{ id: string; label: string } | null>(null);
  const [packageCount, setPackageCount] = useState(0);
  const [entries, setEntries] = useState<PackageEntry[]>([]);

  const isPackageEnabled = packageConfig?.enabled ?? showPackageUnit ?? true;
  const showSummary = packageConfig?.showSummaryMessage !== false;

  const entriesTotal = useMemo(
    () => entries.reduce((sum, e) => sum + e.totalQuantity, 0),
    [entries]
  );
  const remainingQuantity = Math.max(0, maxValue - entriesTotal);

  useEffect(() => {
    if (open) {
      setDisplayValue(initialValue > 0 ? String(initialValue) : "");
      setStep("quantity");
      setSelectedUnit(null);
      setPackageCount(0);
      setEntries([]);
    }
  }, [open, initialValue]);

  // --- 키패드 핸들러 ---

  const currentMax = step === "quantity"
    ? maxValue
    : step === "package_count"
      ? 9999
      : step === "quantity_per_unit"
        ? Math.max(1, remainingQuantity)
        : maxValue;

  const handleNumberClick = (num: string) => {
    const newStr = displayValue + num;
    const numericValue = parseInt(newStr, 10);
    setDisplayValue(numericValue > currentMax ? String(currentMax) : newStr);
  };

  const handleBackspace = () =>
    setDisplayValue((prev) => prev.slice(0, -1));
  const handleClear = () => setDisplayValue("");
  const handleMax = () => setDisplayValue(String(currentMax));

  // --- 확인 버튼: step에 따라 다르게 동작 ---

  const handleConfirm = () => {
    const numericValue = parseInt(displayValue, 10) || 0;

    if (step === "quantity") {
      const finalValue = Math.max(min, Math.min(maxValue, numericValue));
      onConfirm(finalValue, undefined, undefined);
      onOpenChange(false);
      return;
    }

    if (step === "package_count") {
      if (numericValue <= 0) return;
      setPackageCount(numericValue);
      setDisplayValue("");
      setStep("quantity_per_unit");
      return;
    }

    if (step === "quantity_per_unit") {
      if (numericValue <= 0 || !selectedUnit) return;
      const total = Math.min(packageCount * numericValue, remainingQuantity);
      const newEntry: PackageEntry = {
        unitId: selectedUnit.id,
        unitLabel: selectedUnit.label,
        packageCount,
        quantityPerUnit: numericValue,
        totalQuantity: total,
      };
      setEntries((prev) => [...prev, newEntry]);
      setDisplayValue("");
      setStep("summary");
      return;
    }
  };

  // --- 포장 단위 선택 콜백 ---

  const handlePackageUnitSelect = (unitId: string) => {
    const matched = PACKAGE_UNITS.find((u) => u.value === unitId);
    const matchedCustom = packageConfig?.customUnits?.find((cu) => cu.id === unitId);
    const label = matched?.label ?? matchedCustom?.label ?? unitId;

    setSelectedUnit({ id: unitId, label });
    setDisplayValue("");
    setStep("package_count");
  };

  // --- summary 액션 ---

  const handleAddMore = () => {
    setIsPackageModalOpen(true);
  };

  const handleRemoveEntry = (index: number) => {
    setEntries((prev) => prev.filter((_, i) => i !== index));
  };

  const handleComplete = () => {
    if (entries.length === 0) return;
    const total = entries.reduce((sum, e) => sum + e.totalQuantity, 0);
    const lastUnit = entries[entries.length - 1].unitId;
    onConfirm(total, lastUnit, entries);
    onOpenChange(false);
  };

  const handleBack = () => {
    if (step === "package_count") {
      setStep("quantity");
      setSelectedUnit(null);
      setDisplayValue("");
    } else if (step === "quantity_per_unit") {
      setStep("package_count");
      setDisplayValue(String(packageCount));
    } else if (step === "summary") {
      if (entries.length > 0) {
        const last = entries[entries.length - 1];
        setEntries((prev) => prev.slice(0, -1));
        setSelectedUnit({ id: last.unitId, label: last.unitLabel });
        setPackageCount(last.packageCount);
        setDisplayValue(String(last.quantityPerUnit));
        setStep("quantity_per_unit");
      } else {
        setStep("quantity");
        setDisplayValue("");
      }
    }
  };

  // --- 안내 메시지 ---

  const guideMessage = useMemo(() => {
    switch (step) {
      case "quantity":
        return "수량을 입력하세요";
      case "package_count":
        return `${selectedUnit?.label || "포장"}을(를) 몇 개 사용하시나요?`;
      case "quantity_per_unit":
        return `${selectedUnit?.label || "포장"} 1개에 몇 ${unit} 넣으시나요?`;
      case "summary":
        return "";
      default:
        return "";
    }
  }, [step, selectedUnit, unit]);

  // --- 헤더 정보 ---

  const headerLabel = useMemo(() => {
    if (step === "summary") {
      return `등록: ${entriesTotal.toLocaleString()} ${unit} / 남은: ${remainingQuantity.toLocaleString()} ${unit}`;
    }
    if (entries.length > 0) {
      return `남은 ${remainingQuantity.toLocaleString()} ${unit}`;
    }
    return `최대 ${maxValue.toLocaleString()} ${unit}`;
  }, [step, entriesTotal, remainingQuantity, maxValue, unit, entries.length]);

  const displayText = displayValue
    ? parseInt(displayValue, 10).toLocaleString()
    : "";

  const isBackVisible = step !== "quantity";

  return (
    <>
      <Dialog open={open} onOpenChange={onOpenChange}>
        <DialogPortal>
          <DialogOverlay />
          <DialogPrimitive.Content
            className="bg-background data-[state=open]:animate-in data-[state=closed]:animate-out data-[state=closed]:fade-out-0 data-[state=open]:fade-in-0 data-[state=closed]:zoom-out-95 data-[state=open]:zoom-in-95 fixed top-[50%] left-[50%] z-[1000] w-full max-w-[95vw] translate-x-[-50%] translate-y-[-50%] overflow-hidden border shadow-lg duration-200 sm:max-w-[360px] sm:rounded-lg"
          >
            <VisuallyHidden><DialogTitle>수량 입력</DialogTitle></VisuallyHidden>
            {/* 헤더 */}
            <div className="flex items-center justify-between bg-blue-500 px-4 py-3">
              <div className="flex items-center gap-2">
                {isBackVisible && (
                  <button
                    type="button"
                    onClick={handleBack}
                    className="flex items-center justify-center rounded-full bg-white/20 p-1.5 text-white hover:bg-white/30 active:bg-white/40"
                  >
                    <ArrowLeft className="h-4 w-4" />
                  </button>
                )}
                <span className="rounded-full bg-blue-400/50 px-3 py-1 text-sm font-medium text-white">
                  {headerLabel}
                </span>
              </div>
              {isPackageEnabled && step === "quantity" && (
                <button
                  type="button"
                  onClick={() => setIsPackageModalOpen(true)}
                  className="flex items-center gap-1 rounded-full bg-white/20 px-3 py-1.5 text-sm font-medium text-white hover:bg-white/30 active:bg-white/40"
                >
                  포장등록
                </button>
              )}
            </div>

            <div className="space-y-3 p-4">
              {/* summary 단계: 포장 내역 리스트 */}
              {step === "summary" ? (
                <div className="space-y-3">
                  {/* 안내 메시지 - 마지막 등록 결과 */}
                  {showSummary && entries.length > 0 && (
                    <div className="rounded-lg bg-blue-50 px-3 py-2 text-center text-sm font-medium text-blue-700">
                      {(() => {
                        const last = entries[entries.length - 1];
                        return `${last.packageCount}${last.unitLabel} x ${last.quantityPerUnit}${unit} = ${last.totalQuantity.toLocaleString()}${unit}`;
                      })()}
                    </div>
                  )}

                  {/* 포장 내역 리스트 */}
                  <div className="space-y-1.5">
                    <p className="text-xs font-medium text-gray-500">포장 내역</p>
                    {entries.map((entry, idx) => (
                      <div
                        key={idx}
                        className="flex items-center justify-between rounded-lg border border-gray-200 bg-gray-50 px-3 py-2"
                      >
                        <span className="text-sm text-gray-700">
                          {entry.packageCount}{entry.unitLabel} x {entry.quantityPerUnit}{unit} = {entry.totalQuantity.toLocaleString()}{unit}
                        </span>
                        <button
                          type="button"
                          onClick={() => handleRemoveEntry(idx)}
                          className="rounded-full p-1 text-gray-400 hover:bg-red-50 hover:text-red-500"
                        >
                          <Trash2 className="h-3.5 w-3.5" />
                        </button>
                      </div>
                    ))}
                  </div>

                  {/* 합계 */}
                  <div className="flex items-center justify-between rounded-lg bg-green-50 px-3 py-2">
                    <span className="text-sm font-medium text-green-700">합계</span>
                    <span className="text-lg font-bold text-green-700">
                      {entriesTotal.toLocaleString()} {unit}
                    </span>
                  </div>

                  {/* 남은 수량 */}
                  {remainingQuantity > 0 && (
                    <div className="flex items-center justify-between rounded-lg bg-amber-50 px-3 py-2">
                      <span className="text-sm font-medium text-amber-700">남은 수량</span>
                      <span className="text-sm font-bold text-amber-700">
                        {remainingQuantity.toLocaleString()} {unit}
                      </span>
                    </div>
                  )}

                  {/* 액션 버튼 */}
                  <div className="grid grid-cols-2 gap-2">
                    {remainingQuantity > 0 && (
                      <button
                        type="button"
                        className="flex h-12 items-center justify-center gap-1.5 rounded-2xl border border-blue-200 bg-blue-50 text-sm font-bold text-blue-600 active:bg-blue-100"
                        onClick={handleAddMore}
                      >
                        <Plus className="h-4 w-4" />
                        추가 포장
                      </button>
                    )}
                    <button
                      type="button"
                      className={`flex h-12 items-center justify-center rounded-2xl bg-green-500 text-base font-bold text-white active:bg-green-600 ${remainingQuantity <= 0 ? "col-span-2" : ""}`}
                      onClick={handleComplete}
                    >
                      완료
                    </button>
                  </div>
                </div>
              ) : (
                <>
                  {/* 숫자 표시 영역 */}
                  <div className="flex min-h-[72px] items-center justify-end rounded-xl border-2 border-gray-200 bg-gray-50 px-4 py-4">
                    {displayText ? (
                      <span className="text-4xl font-bold tracking-tight text-gray-900">
                        {displayText}
                      </span>
                    ) : (
                      <span className="text-2xl text-gray-300">0</span>
                    )}
                  </div>

                  {/* 단계별 안내 텍스트 */}
                  <p className="text-muted-foreground text-center text-sm">
                    {guideMessage}
                  </p>

                  {/* 키패드 4x4 */}
                  <div className="grid grid-cols-4 gap-2">
                    {["7", "8", "9"].map((n) => (
                      <button
                        key={n}
                        type="button"
                        className="h-14 rounded-2xl border border-gray-200 bg-gray-50 text-xl font-semibold text-gray-800 active:bg-gray-200"
                        onClick={() => handleNumberClick(n)}
                      >
                        {n}
                      </button>
                    ))}
                    <button
                      type="button"
                      className="flex h-14 items-center justify-center rounded-2xl bg-amber-100 text-amber-600 active:bg-amber-200"
                      onClick={handleBackspace}
                    >
                      <Delete className="h-5 w-5" />
                    </button>

                    {["4", "5", "6"].map((n) => (
                      <button
                        key={n}
                        type="button"
                        className="h-14 rounded-2xl border border-gray-200 bg-gray-50 text-xl font-semibold text-gray-800 active:bg-gray-200"
                        onClick={() => handleNumberClick(n)}
                      >
                        {n}
                      </button>
                    ))}
                    <button
                      type="button"
                      className="h-14 rounded-2xl bg-amber-100 text-base font-bold text-amber-600 active:bg-amber-200"
                      onClick={handleClear}
                    >
                      C
                    </button>

                    {["1", "2", "3"].map((n) => (
                      <button
                        key={n}
                        type="button"
                        className="h-14 rounded-2xl border border-gray-200 bg-gray-50 text-xl font-semibold text-gray-800 active:bg-gray-200"
                        onClick={() => handleNumberClick(n)}
                      >
                        {n}
                      </button>
                    ))}
                    <button
                      type="button"
                      className="h-14 rounded-2xl bg-blue-100 text-sm font-bold text-blue-600 active:bg-blue-200"
                      onClick={handleMax}
                    >
                      MAX
                    </button>

                    <button
                      type="button"
                      className="h-14 rounded-2xl border border-gray-200 bg-gray-50 text-xl font-semibold text-gray-800 active:bg-gray-200"
                      onClick={() => handleNumberClick("0")}
                    >
                      0
                    </button>
                    <button
                      type="button"
                      className="col-span-3 h-14 rounded-2xl bg-green-500 text-base font-bold text-white active:bg-green-600"
                      onClick={handleConfirm}
                    >
                      {step === "package_count" ? "다음" : "확인"}
                    </button>
                  </div>
                </>
              )}
            </div>

          </DialogPrimitive.Content>
        </DialogPortal>
      </Dialog>

      {/* 포장 단위 선택 모달 */}
      <PackageUnitModal
        open={isPackageModalOpen}
        onOpenChange={(isOpen) => {
          setIsPackageModalOpen(isOpen);
          if (!isOpen && step === "summary") {
            // summary에서 추가 포장 모달 닫힘 -> 단위 선택 안 한 경우 유지
          }
        }}
        onSelect={(unitId) => {
          handlePackageUnitSelect(unitId);
          setIsPackageModalOpen(false);
        }}
        enabledUnits={packageConfig?.enabledUnits}
        customUnits={packageConfig?.customUnits}
      />
    </>
  );
}
