"use client";

import { useState, useEffect, useCallback, useMemo, useRef } from "react";
import {
  Dialog,
  DialogContent,
  DialogHeader,
  DialogTitle,
  DialogDescription,
  DialogFooter,
} from "@/components/ui/dialog";
import { Button } from "@/components/ui/button";
import { useUnsavedChangesGuard, UnsavedChangesDialog } from "@/components/common/UnsavedChangesGuard";
import { Checkbox } from "@/components/ui/checkbox";
import { Input } from "@/components/ui/input";
import { ScrollArea } from "@/components/ui/scroll-area";
import { Loader2, Search, ChevronRight, ChevronDown, FolderOpen, FileText } from "lucide-react";
import { menuApi } from "@/lib/api/menu";
import { MenuItem } from "@/types/menu";
import { cn } from "@/lib/utils";

interface MenuSelectModalProps {
  isOpen: boolean;
  onClose: () => void;
  onConfirm: (menuObjids: number[]) => void;
  selectedMenuObjids?: number[];
}

interface MenuTreeNode {
  objid: string;
  menuNameKor: string;
  menuUrl: string;
  level: number;
  children: MenuTreeNode[];
  parentObjId: string;
}

export function MenuSelectModal({ isOpen, onClose, onConfirm, selectedMenuObjids = [] }: MenuSelectModalProps) {
  const [menus, setMenus] = useState<MenuItem[]>([]);
  const [isLoading, setIsLoading] = useState(false);
  const [searchText, setSearchText] = useState("");
  const [selectedIds, setSelectedIds] = useState<Set<number>>(new Set(selectedMenuObjids));
  const [expandedIds, setExpandedIds] = useState<Set<string>>(new Set());
  const initialSelectionRef = useRef<string>("");

  const hasChanges = useCallback(() => {
    const currentSelection = JSON.stringify(Array.from(selectedIds).sort());
    return currentSelection !== initialSelectionRef.current;
  }, [selectedIds]);

  const guard = useUnsavedChangesGuard({
    hasChanges,
    onClose,
    description: "변경된 선택 내용이 저장되지 않습니다. 정말 닫으시겠습니까?",
  });

  useEffect(() => {
    if (isOpen) {
      setSelectedIds(new Set(selectedMenuObjids));
      initialSelectionRef.current = JSON.stringify(Array.from(new Set(selectedMenuObjids)).sort());
    }
  }, [isOpen, selectedMenuObjids]);

  useEffect(() => {
    if (isOpen) {
      fetchMenus();
    }
  }, [isOpen]);

  const fetchMenus = async () => {
    setIsLoading(true);
    try {
      const response = await menuApi.getUserMenus();
      if (response.success && response.data) {
        setMenus(response.data);
        const initialExpanded = new Set<string>();
        response.data.forEach((menu) => {
          const level = menu.lev || menu.LEV || 1;
          if (level <= 2) {
            initialExpanded.add(menu.objid || menu.OBJID || "");
          }
        });
        setExpandedIds(initialExpanded);
      }
    } catch (error) {
      console.error("메뉴 로드 오류:", error);
    } finally {
      setIsLoading(false);
    }
  };

  const menuTree = useMemo(() => {
    const menuMap = new Map<string, MenuTreeNode>();
    const rootMenus: MenuTreeNode[] = [];

    menus.forEach((menu) => {
      const objid = menu.objid || menu.OBJID || "";
      const parentObjId = menu.parentObjId || menu.PARENT_OBJ_ID || "";
      const menuNameKor = menu.menuNameKor || menu.MENU_NAME_KOR || menu.translated_name || menu.TRANSLATED_NAME || "";
      const menuUrl = menu.menuUrl || menu.MENU_URL || "";
      const level = menu.lev || menu.LEV || 1;

      menuMap.set(objid, { objid, menuNameKor, menuUrl, level, children: [], parentObjId });
    });

    menus.forEach((menu) => {
      const objid = menu.objid || menu.OBJID || "";
      const parentObjId = menu.parentObjId || menu.PARENT_OBJ_ID || "";
      const node = menuMap.get(objid);
      if (!node) return;

      const parent = menuMap.get(parentObjId);
      if (parent) {
        parent.children.push(node);
      } else {
        rootMenus.push(node);
      }
    });

    const sortChildren = (nodes: MenuTreeNode[]) => {
      nodes.sort((a, b) => a.menuNameKor.localeCompare(b.menuNameKor, "ko"));
      nodes.forEach((node) => sortChildren(node.children));
    };
    sortChildren(rootMenus);

    return rootMenus;
  }, [menus]);

  const filteredTree = useMemo(() => {
    if (!searchText.trim()) return menuTree;

    const searchLower = searchText.toLowerCase();

    const filterNodes = (nodes: MenuTreeNode[]): MenuTreeNode[] => {
      return nodes
        .map((node) => {
          const filteredChildren = filterNodes(node.children);
          const matches = node.menuNameKor.toLowerCase().includes(searchLower);
          if (matches || filteredChildren.length > 0) {
            return { ...node, children: filteredChildren };
          }
          return null;
        })
        .filter((node): node is MenuTreeNode => node !== null);
    };

    return filterNodes(menuTree);
  }, [menuTree, searchText]);

  const toggleSelect = useCallback((objid: string) => {
    const numericId = Number(objid);
    setSelectedIds((prev) => {
      const next = new Set(prev);
      if (next.has(numericId)) {
        next.delete(numericId);
      } else {
        next.add(numericId);
      }
      return next;
    });
  }, []);

  const toggleExpand = useCallback((objid: string) => {
    setExpandedIds((prev) => {
      const next = new Set(prev);
      if (next.has(objid)) {
        next.delete(objid);
      } else {
        next.add(objid);
      }
      return next;
    });
  }, []);

  const handleConfirm = () => {
    onConfirm(Array.from(selectedIds));
    onClose();
  };

  const renderMenuNode = (node: MenuTreeNode, depth: number = 0) => {
    const hasChildren = node.children.length > 0;
    const isExpanded = expandedIds.has(node.objid);
    const isSelected = selectedIds.has(Number(node.objid));

    return (
      <div key={node.objid}>
        <div
          className={cn(
            "hover:bg-muted/50 flex cursor-pointer items-center gap-2 rounded-md px-2 py-1.5",
            isSelected && "bg-primary/10",
          )}
          style={{ paddingLeft: `${depth * 20 + 8}px` }}
          onClick={() => toggleSelect(node.objid)}
        >
          {hasChildren ? (
            <button
              type="button"
              onClick={(e) => {
                e.stopPropagation();
                toggleExpand(node.objid);
              }}
              className="hover:bg-muted rounded p-0.5"
            >
              {isExpanded ? (
                <ChevronDown className="text-muted-foreground h-4 w-4" />
              ) : (
                <ChevronRight className="text-muted-foreground h-4 w-4" />
              )}
            </button>
          ) : (
            <div className="w-5" />
          )}

          <Checkbox
            checked={isSelected}
            onCheckedChange={() => toggleSelect(node.objid)}
            onClick={(e) => e.stopPropagation()}
          />

          {hasChildren ? (
            <FolderOpen className="h-4 w-4 text-amber-500" />
          ) : (
            <FileText className="text-muted-foreground h-4 w-4" />
          )}

          <span className={cn("flex-1 truncate text-sm", isSelected && "text-primary font-medium")}>
            {node.menuNameKor}
          </span>
        </div>

        {hasChildren && isExpanded && <div>{node.children.map((child) => renderMenuNode(child, depth + 1))}</div>}
      </div>
    );
  };

  return (
    <>
      <Dialog open={isOpen} onOpenChange={guard.handleOpenChange}>
        <DialogContent className="flex max-h-[80vh] max-w-[600px] flex-col">
          <DialogHeader>
            <DialogTitle>사용 메뉴 선택</DialogTitle>
            <DialogDescription>
              이 리포트를 사용할 메뉴를 선택하세요. 선택한 메뉴에서 이 리포트를 사용할 수 있습니다.
            </DialogDescription>
          </DialogHeader>

          <div className="relative">
            <Search className="text-muted-foreground absolute top-1/2 left-3 h-4 w-4 -translate-y-1/2" />
            <Input
              placeholder="메뉴 검색..."
              value={searchText}
              onChange={(e) => setSearchText(e.target.value)}
              className="pl-10"
            />
          </div>

          <div className="text-muted-foreground text-sm">{selectedIds.size}개 메뉴 선택됨</div>

          <ScrollArea className="flex-1 rounded-md border">
            {isLoading ? (
              <div className="flex items-center justify-center py-8">
                <Loader2 className="text-muted-foreground h-6 w-6 animate-spin" />
                <span className="text-muted-foreground ml-2 text-sm">메뉴 로드 중...</span>
              </div>
            ) : filteredTree.length === 0 ? (
              <div className="text-muted-foreground flex items-center justify-center py-8 text-sm">
                {searchText ? "검색 결과가 없습니다." : "표시할 메뉴가 없습니다."}
              </div>
            ) : (
              <div className="p-2">{filteredTree.map((node) => renderMenuNode(node))}</div>
            )}
          </ScrollArea>

          <DialogFooter>
            <Button variant="outline" onClick={guard.tryClose}>
              취소
            </Button>
            <Button onClick={handleConfirm}>확인 ({selectedIds.size}개 선택)</Button>
          </DialogFooter>
        </DialogContent>
      </Dialog>

      <UnsavedChangesDialog guard={guard} />
    </>
  );
}