"use client";

import * as React from "react";
import { Button } from "@/components/ui/button";
import { Badge } from "@/components/ui/badge";
import { Checkbox } from "@/components/ui/checkbox";
import { Separator } from "@/components/ui/separator";
import { ToggleGroup, ToggleGroupItem } from "@/components/ui/toggle-group";
import { toast } from "sonner";
import { Trash2, GripVertical } from "lucide-react";
import {
  DndContext,
  closestCenter,
  KeyboardSensor,
  PointerSensor,
  useSensor,
  useSensors,
  type DragEndEvent,
} from "@dnd-kit/core";
import {
  restrictToVerticalAxis,
  restrictToParentElement,
} from "@dnd-kit/modifiers";
import {
  arrayMove,
  SortableContext,
  sortableKeyboardCoordinates,
  verticalListSortingStrategy,
  useSortable,
} from "@dnd-kit/sortable";
import { CSS } from "@dnd-kit/utilities";
import {
  UserSelector,
  type UserSelectItem,
} from "@/components/common/user/user-selector";

// ----- Types -----
export type ApprovalRole = "0" | "1" | "2" | "3" | "4" | "7" | "9";

export interface ApprovalLineItem {
  id: string;
  epId?: string;
  userId?: string;
  emailAddress?: string;
  name?: string;
  deptName?: string;
  role: ApprovalRole;
  seq: string; // 0-based; 동일 seq는 병렬 그룹 의미
  opinion?: string;
}

export interface ApprovalLineSelectorProps {
  value: ApprovalLineItem[];
  onChange: (next: ApprovalLineItem[]) => void;
  placeholder?: string;
  maxSelections?: number;
  domainFilter?: any; // 프로젝트 전역 타입에 맞춰 느슨히 둠
  className?: string;
}

// 역할 텍스트 매핑
const getRoleText = (role: string) => {
  const map: Record<string, string> = {
    "0": "기안",
    "1": "결재",
    "2": "합의",
    "3": "후결",
    "4": "병렬합의",
    "7": "병렬결재",
    "9": "통보",
  };
  return map[role] || role;
};

// 고유 ID 생성
const generateUniqueId = () => `apln-${Date.now()}-${Math.random().toString(36).slice(2, 11)}`;

// Sortable Group Card (seq 단위)
interface SortableApprovalGroupProps {
  group: ApprovalLineItem[];
  index: number;
  onRemoveGroup: () => void;
  canRemove: boolean;
  selected: boolean;
  onSelect: () => void;
  onChangeRole: (role: ApprovalRole) => void;
}

function SortableApprovalGroup({
  group,
  index,
  onRemoveGroup,
  canRemove,
  selected,
  onSelect,
  onChangeRole,
}: SortableApprovalGroupProps) {
  const seq = group[0].seq;
  const role = group[0].role;

  const { attributes, listeners, setNodeRef, transform, transition, isDragging } =
    useSortable({ id: group[0].id });

  const style = {
    transform: CSS.Transform.toString(transform),
    transition,
    opacity: isDragging ? 0.5 : 1,
  } as React.CSSProperties;

  const isParallel = role === "7" || role === "4";

  return (
    <div
      ref={setNodeRef}
      style={style}
      className={`flex items-center gap-3 p-3 border rounded-lg bg-white shadow-sm ${selected ? "ring-2 ring-primary" : ""}`}
    >
      {/* Drag handle */}
      <div
        {...attributes}
        {...listeners}
        className="cursor-grab hover:cursor-grabbing text-gray-400 hover:text-gray-600"
      >
        <GripVertical className="w-5 h-5" />
      </div>

      {/* Group select (skip for drafter) */}
      {index !== 0 ? (
        <Checkbox checked={selected} onCheckedChange={onSelect} onClick={(e) => e.stopPropagation()} />
      ) : (
        <div className="w-4 h-4" />
      )}

      {/* seq index */}
      <Badge variant="outline">{parseInt(seq) + 1}</Badge>

      {/* Group details */}
      <div className="flex-1 grid grid-cols-3 gap-3">
        {/* Users in group */}
        <div className="flex flex-col justify-center gap-1">
          {group.map((u) => (
            <div key={u.id} className="text-sm">
              {u.name || "Knox 이름 없음"}
              {u.deptName ? ` / ${u.deptName}` : ""}
            </div>
          ))}
        </div>

        {/* Role UI */}
        <div className="flex items-center">
          {seq === "0" ? (
            <Badge variant="secondary" className="w-full justify-center">기안</Badge>
          ) : isParallel ? (
            <Badge variant="secondary" className="w-full justify-center">{getRoleText(role)}</Badge>
          ) : (
            <ToggleGroup
              type="single"
              value={role}
              onValueChange={(val) => val && onChangeRole(val as ApprovalRole)}
            >
              <ToggleGroupItem value="1">결재</ToggleGroupItem>
              <ToggleGroupItem value="2">합의</ToggleGroupItem>
              <ToggleGroupItem value="9">통보</ToggleGroupItem>
            </ToggleGroup>
          )}
        </div>

        {/* Delete */}
        <div className="flex items-center justify-end">
          {canRemove && (
            <Button type="button" variant="ghost" size="sm" onClick={onRemoveGroup}>
              <Trash2 className="w-4 h-4" />
            </Button>
          )}
        </div>
      </div>
    </div>
  );
}

export function ApprovalLineSelector({
  value,
  onChange,
  placeholder = "결재자를 검색하세요...",
  maxSelections = 10,
  domainFilter,
  className,
}: ApprovalLineSelectorProps) {
  const aplns = value;
  const [selectedSeqs, setSelectedSeqs] = React.useState<string[]>([]);

  const toggleSelectGroup = (seq: string) => {
    setSelectedSeqs((prev) => (prev.includes(seq) ? prev.filter((s) => s !== seq) : [...prev, seq]));
  };
  const clearSelection = () => setSelectedSeqs([]);

  // drag sensors
  const sensors = useSensors(
    useSensor(PointerSensor, { activationConstraint: { distance: 8 } }),
    useSensor(KeyboardSensor, { coordinateGetter: sortableKeyboardCoordinates }),
  );

  // Utilities
  const reorderBySeq = (list: ApprovalLineItem[]): ApprovalLineItem[] => {
    const sorted = [...list].sort((a, b) => parseInt(a.seq) - parseInt(b.seq));
    const seqMap = new Map<string, string>();
    let nextSeq = 0;
    return sorted.map((apln) => {
      if (!seqMap.has(apln.seq)) {
        seqMap.set(apln.seq, nextSeq.toString());
        nextSeq += 1;
      }
      return { ...apln, seq: seqMap.get(apln.seq)! };
    });
  };

  const addApprovalUsers = (users: UserSelectItem[]) => {
    const newAplns = [...aplns];
    users.forEach((user) => {
      const exists = newAplns.findIndex((apln) => apln.userId === user.id.toString());
      if (exists === -1) {
        // 현재 존재하는 seq 중 최댓값 + 1을 다음 seq로 사용 (0은 상신자)
        const uniqueSeqs = Array.from(new Set(newAplns.map((a) => parseInt(a.seq))));
        const maxSeq = uniqueSeqs.length ? Math.max(...uniqueSeqs) : -1;
        const newSeq = (Math.max(1, maxSeq + 1)).toString();
        newAplns.push({
          id: generateUniqueId(),
          epId: (user as any).epId,
          userId: user.id.toString(),
          emailAddress: user.email,
          name: user.name,
          deptName: (user as any).deptName ?? undefined,
          role: "1",
          seq: newSeq,
          opinion: "",
        });
      }
    });
    onChange(newAplns);
  };

  const removeApprovalGroup = (seq: string) => {
    if (seq === "0") return; // 상신자 삭제 불가
    const remaining = aplns.filter((a) => a.seq !== seq);
    onChange(reorderBySeq(remaining));
  };

  const applyParallel = () => {
    if (selectedSeqs.length < 2) {
      toast.error("두 명 이상 선택해야 병렬 지정이 가능합니다.");
      return;
    }
    const current = aplns;
    const selectedAplns = current.filter((a) => selectedSeqs.includes(a.seq));
    const roles = Array.from(new Set(selectedAplns.map((a) => a.role)));
    if (roles.length !== 1) {
      toast.error("선택된 항목의 역할이 동일해야 합니다.");
      return;
    }
    const role = roles[0];
    let newRole: ApprovalRole;
    if (role === "1") newRole = "7";
    else if (role === "2") newRole = "4";
    else if (role === "9") newRole = "9";
    else {
      toast.error("결재, 합의 또는 통보만 병렬 지정 가능합니다.");
      return;
    }
    const minSeq = Math.min(...selectedAplns.map((a) => parseInt(a.seq)));
    const updated = current.map((a) =>
      selectedSeqs.includes(a.seq) ? { ...a, role: newRole, seq: minSeq.toString() } : a,
    );
    onChange(reorderBySeq(updated));
    clearSelection();
  };

  const applyAfter = () => {
    if (selectedSeqs.length !== 1) {
      toast.error("후결은 한 명만 지정할 수 있습니다.");
      return;
    }
    const targetSeq = selectedSeqs[0];
    const targetRole = aplns.find((a) => a.seq === targetSeq)?.role;
    if (targetRole === "7" || targetRole === "4") {
      toast.error("병렬 그룹은 후결로 전환할 수 없습니다.");
      return;
    }
    const updated = aplns.map((a) =>
      a.seq === targetSeq ? { ...a, role: (a.role === "3" ? "1" : "3") as ApprovalRole } : a,
    );
    onChange(reorderBySeq(updated));
    clearSelection();
  };

  const ungroupParallel = () => {
    if (selectedSeqs.length === 0) {
      toast.error("해제할 결재선을 선택하세요.");
      return;
    }
    let newSeqCounter = 1; // 0은 상신자 유지
    const updated = aplns.map((a) => {
      if (selectedSeqs.includes(a.seq)) {
        let newRole: ApprovalRole = a.role;
        if (a.role === "7") newRole = "1";
        if (a.role === "4") newRole = "2";
        return { ...a, role: newRole, seq: "" };
      }
      return { ...a };
    });
    const reassigned = updated
      .sort((x, y) => parseInt(x.seq || "0") - parseInt(y.seq || "0"))
      .map((a) => {
        if (a.seq === "0") return a;
        const next = { ...a, seq: newSeqCounter.toString() };
        newSeqCounter += 1;
        return next;
      });
    onChange(reassigned);
    clearSelection();
  };

  const handleDragEnd = (event: DragEndEvent) => {
    const { active, over } = event;
    if (!over || active.id === over.id) return;
    const activeKey = active.id as string;
    const overKey = over.id as string;

    const idToSeq = new Map<string, string>();
    aplns.forEach((a) => idToSeq.set(a.id, a.seq));
    const activeSeq = idToSeq.get(activeKey);
    const overSeq = idToSeq.get(overKey);
    if (!activeSeq || !overSeq) return;
    if (activeSeq === "0" || overSeq === "0") return; // 상신자 이동 불가

    const seqOrder = Array.from(new Set(aplns.map((a) => a.seq)));
    const keyOrder = seqOrder.map((seq) => aplns.find((a) => a.seq === seq)!.id);
    const oldIndex = keyOrder.indexOf(activeKey);
    const newIndex = keyOrder.indexOf(overKey);
    const newKeyOrder = arrayMove(keyOrder, oldIndex, newIndex);

    const keyToNewSeq = new Map<string, string>();
    newKeyOrder.forEach((k, idx) => keyToNewSeq.set(k, idx.toString()));

    const updatedAplns: ApprovalLineItem[] = [];
    newKeyOrder.forEach((k) => {
      const oldSeq = idToSeq.get(k)!;
      const groupItems = aplns.filter((a) => a.seq === oldSeq);
      groupItems.forEach((item) => {
        updatedAplns.push({ ...item, seq: keyToNewSeq.get(k)! });
      });
    });
    onChange(updatedAplns);
  };

  // Render groups by seq
  const groups = React.useMemo(() => {
    const grouped = Object.values(
      aplns.reduce<Record<string, ApprovalLineItem[]>>((acc, apln) => {
        acc[apln.seq] = acc[apln.seq] ? [...acc[apln.seq], apln] : [apln];
        return acc;
      }, {}),
    ).sort((a, b) => parseInt(a[0].seq) - parseInt(b[0].seq));
    return grouped;
  }, [aplns]);

  return (
    <div className={className}>
      <h3 className="text-lg font-semibold">결재 경로</h3>

      {/* Controls */}
      <div className="flex justify-end gap-2 mb-2">
        <Button type="button" variant="outline" size="sm" onClick={applyParallel}>
          병렬
        </Button>
        <Button type="button" variant="outline" size="sm" onClick={applyAfter}>
          후결
        </Button>
        <Button type="button" variant="outline" size="sm" onClick={ungroupParallel}>
          해제
        </Button>
      </div>

      {/* User add */}
      <div className="p-4 border border-dashed border-gray-300 rounded-lg">
        <div className="mb-2">
          <label className="text-sm font-medium text-gray-700">결재자 추가</label>
          <p className="text-xs text-gray-500">사용자를 검색하여 결재 라인에 추가하세요</p>
        </div>
        <UserSelector
          selectedUsers={[]}
          onUsersChange={addApprovalUsers}
          placeholder={placeholder}
          domainFilter={domainFilter}
          maxSelections={maxSelections}
        />
      </div>

      {/* Groups */}
      <div className="mt-4">
        {aplns.length > 0 ? (
          <DndContext
            sensors={sensors}
            collisionDetection={closestCenter}
            modifiers={[restrictToVerticalAxis, restrictToParentElement]}
            onDragEnd={handleDragEnd}
          >
            <SortableContext items={groups.map((g) => g[0].id)} strategy={verticalListSortingStrategy}>
              <div className="space-y-3">
                {groups.map((group, idx) => (
                  <SortableApprovalGroup
                    key={group[0].id}
                    group={group}
                    index={idx}
                    onRemoveGroup={() => removeApprovalGroup(group[0].seq)}
                    canRemove={idx !== 0 && aplns.length > 1}
                    selected={selectedSeqs.includes(group[0].seq)}
                    onSelect={() => toggleSelectGroup(group[0].seq)}
                    onChangeRole={(role) => {
                      // 단일 그룹일 때만 역할 변경 허용
                      if (group.length > 1) return;
                      const gid = group[0].id;
                      const updated = aplns.map((a) => (a.id === gid ? { ...a, role } : a));
                      onChange(updated);
                    }}
                  />
                ))}
              </div>
            </SortableContext>
          </DndContext>
        ) : (
          <div className="text-center py-8 text-gray-500">
            <p>결재자를 추가해주세요</p>
          </div>
        )}
      </div>

      <Separator className="my-4" />
    </div>
  );
}

export default ApprovalLineSelector;