import { useMutation } from "@tanstack/react-query";
import {
  AlertCircle,
  CheckCircle2,
  Download,
  FileText,
  Loader2,
  Upload,
} from "lucide-react";
import * as React from "react";
import { Button } from "../../../components/ui/button";
import {
  Dialog,
  DialogContent,
  DialogDescription,
  DialogFooter,
  DialogHeader,
  DialogTitle,
  DialogTrigger,
} from "../../../components/ui/dialog";
import { ScrollArea } from "../../../components/ui/scroll-area";
import {
  type BulkUserItem,
  type BulkUserResult,
  bulkCreateUsers,
} from "../../../lib/adminApi";
import { t } from "../../../lib/i18n";
import { parseUserCSV } from "../utils/csvParser";

interface UserBulkUploadModalProps {
  onSuccess?: () => void;
}

export function UserBulkUploadModal({ onSuccess }: UserBulkUploadModalProps) {
  const [open, setOpen] = React.useState(false);
  const [file, setFile] = React.useState<File | null>(null);
  const [parsing, setParsing] = React.useState(false);
  const [previewData, setPreviewData] = React.useState<BulkUserItem[]>([]);
  const [results, setResults] = React.useState<BulkUserResult[] | null>(null);
  const fileInputRef = React.useRef<HTMLInputElement>(null);

  const mutation = useMutation({
    mutationFn: bulkCreateUsers,
    onSuccess: (data) => {
      setResults(data.results);
      onSuccess?.();
    },
  });

  const handleFileChange = (e: React.ChangeEvent<HTMLInputElement>) => {
    const selectedFile = e.target.files?.[0];
    if (selectedFile) {
      setFile(selectedFile);
      parseCSV(selectedFile);
    }
  };

  const parseCSV = (file: File) => {
    setParsing(true);
    const reader = new FileReader();
    reader.onload = (e) => {
      const text = e.target?.result as string;
      const data = parseUserCSV(text);
      setPreviewData(data);
      setParsing(false);
    };
    reader.readAsText(file);
  };

  const handleUpload = () => {
    if (previewData.length > 0) {
      mutation.mutate(previewData);
    }
  };

  const downloadTemplate = () => {
    const headers =
      "email,name,phone,role,tenant,department,position,jobTitle,employee_id";
    const example =
      "user1@example.com,홍길동,010-1234-5678,user,tenant-slug,개발팀,수석,프론트엔드,EMP001";
    const blob = new Blob([`${headers}\n${example}`], {
      type: "text/csv;charset=utf-8;",
    });
    const url = URL.createObjectURL(blob);
    const a = document.createElement("a");
    a.href = url;
    a.download = "user_bulk_template.csv";
    a.click();
    URL.revokeObjectURL(url);
  };

  const reset = () => {
    setFile(null);
    setPreviewData([]);
    setResults(null);
    if (fileInputRef.current) fileInputRef.current.value = "";
  };

  const successCount = results?.filter((r) => r.success).length ?? 0;
  const failCount = results ? results.length - successCount : 0;

  return (
    <Dialog
      open={open}
      onOpenChange={(val) => {
        setOpen(val);
        if (!val) reset();
      }}
    >
      <DialogTrigger asChild>
        <Button
          variant="outline"
          className="gap-2"
          data-testid="bulk-import-btn"
        >
          <Upload size={16} />
          {t("ui.admin.users.list.bulk_import", "일괄 등록 (CSV)")}
        </Button>
      </DialogTrigger>
      <DialogContent className="max-w-2xl">
        <DialogHeader>
          <DialogTitle data-testid="bulk-upload-title">
            {t("ui.admin.users.bulk.title", "사용자 일괄 등록")}
          </DialogTitle>
          <DialogDescription>
            {t(
              "msg.admin.users.bulk.description",
              "CSV 파일을 업로드하여 여러 사용자를 한 번에 등록합니다.",
            )}
          </DialogDescription>
        </DialogHeader>

        {!results ? (
          <div className="space-y-4 py-4">
            <div className="flex justify-between items-center">
              <Button
                variant="ghost"
                size="sm"
                onClick={downloadTemplate}
                className="gap-2"
              >
                <Download size={14} />
                {t("ui.admin.users.bulk.download_template", "템플릿 다운로드")}
              </Button>
              <input
                type="file"
                accept=".csv"
                className="hidden"
                ref={fileInputRef}
                onChange={handleFileChange}
              />
              <Button
                onClick={() => fileInputRef.current?.click()}
                variant="secondary"
              >
                {file
                  ? t("ui.common.change_file", "파일 변경")
                  : t("ui.common.select_file", "파일 선택")}
              </Button>
            </div>

            {file && (
              <div className="rounded-lg border p-4 bg-muted/20">
                <div className="flex items-center gap-3 mb-2">
                  <FileText className="text-primary" />
                  <span className="font-medium">{file.name}</span>
                  <span className="text-xs text-muted-foreground">
                    ({(file.size / 1024).toFixed(1)} KB)
                  </span>
                </div>
                {parsing ? (
                  <div className="flex items-center gap-2 text-sm text-muted-foreground">
                    <Loader2 size={14} className="animate-spin" />
                    {t("msg.common.parsing", "파싱 중...")}
                  </div>
                ) : (
                  <div className="text-sm text-muted-foreground">
                    {t(
                      "msg.admin.users.bulk.parsed_count",
                      "{{count}}명의 사용자가 감지되었습니다.",
                      { count: previewData.length },
                    )}
                  </div>
                )}
              </div>
            )}

            {previewData.length > 0 && (
              <ScrollArea className="h-[200px] rounded-md border">
                <table className="w-full text-sm">
                  <thead className="bg-muted sticky top-0">
                    <tr>
                      <th className="p-2 text-left">Email</th>
                      <th className="p-2 text-left">Name</th>
                      <th className="p-2 text-left">Tenant</th>
                    </tr>
                  </thead>
                  <tbody>
                    {previewData.slice(0, 10).map((u) => (
                      <tr key={u.email} className="border-t">
                        <td className="p-2">{u.email}</td>
                        <td className="p-2">{u.name}</td>
                        <td className="p-2">{u.tenantSlug || "-"}</td>
                      </tr>
                    ))}
                    {previewData.length > 10 && (
                      <tr>
                        <td
                          colSpan={3}
                          className="p-2 text-center text-muted-foreground italic"
                        >
                          ... and {previewData.length - 10} more users
                        </td>
                      </tr>
                    )}
                  </tbody>
                </table>
              </ScrollArea>
            )}
          </div>
        ) : (
          <div className="space-y-4 py-4">
            <div className="flex items-center gap-4 p-4 rounded-lg bg-muted/30 border">
              <div className="flex-1 text-center">
                <div className="text-2xl font-bold text-green-600">
                  {successCount}
                </div>
                <div className="text-xs text-muted-foreground uppercase">
                  {t("ui.common.success", "성공")}
                </div>
              </div>
              <div className="w-px h-10 bg-border" />
              <div className="flex-1 text-center">
                <div className="text-2xl font-bold text-destructive">
                  {failCount}
                </div>
                <div className="text-xs text-muted-foreground uppercase">
                  {t("ui.common.fail", "실패")}
                </div>
              </div>
            </div>

            <ScrollArea className="h-[250px] rounded-md border">
              <div className="p-2 space-y-2">
                {results.map((r) => (
                  <div
                    key={r.email}
                    className="flex items-start gap-3 p-2 rounded border bg-card text-sm"
                  >
                    {r.success ? (
                      <CheckCircle2
                        size={16}
                        className="text-green-500 mt-0.5"
                      />
                    ) : (
                      <AlertCircle
                        size={16}
                        className="text-destructive mt-0.5"
                      />
                    )}
                    <div className="flex-1 min-w-0">
                      <div className="font-medium truncate">{r.email}</div>
                      {!r.success && (
                        <div className="text-xs text-destructive">
                          {r.message}
                        </div>
                      )}
                    </div>
                  </div>
                ))}
              </div>
            </ScrollArea>
          </div>
        )}

        <DialogFooter>
          {!results ? (
            <Button
              onClick={handleUpload}
              disabled={previewData.length === 0 || mutation.isPending}
              className="w-full sm:w-auto"
              data-testid="bulk-start-btn"
            >
              {mutation.isPending && (
                <Loader2 size={16} className="mr-2 animate-spin" />
              )}
              {t("ui.admin.users.bulk.start_upload", "등록 시작")}
            </Button>
          ) : (
            <Button
              onClick={() => setOpen(false)}
              className="w-full sm:w-auto"
              data-testid="bulk-close-dialog-btn"
            >
              {t("ui.common.close", "닫기")}
            </Button>
          )}
        </DialogFooter>
      </DialogContent>
    </Dialog>
  );
}