import {
  createContext,
  useContext,
  useState,
  useCallback,
  useRef,
  type ReactNode,
} from 'react';
import type { ImportStatementResponse } from '@family-budget/shared';
import { importStatementStream, type SseEvent } from '../api/import';

export interface ImportProgress {
  active: boolean;
  stage: string;
  progress: number;
  message: string;
  result?: ImportStatementResponse;
  error?: string;
}

interface ImportContextValue {
  importState: ImportProgress;
  showModal: boolean;
  openModal: () => void;
  closeModal: () => void;
  startImport: (file: File) => void;
  clearImport: () => void;
}

const INITIAL: ImportProgress = {
  active: false,
  stage: '',
  progress: 0,
  message: '',
};

const ImportContext = createContext<ImportContextValue | null>(null);

export function ImportProvider({ children }: { children: ReactNode }) {
  const [importState, setImportState] = useState<ImportProgress>(INITIAL);
  const [showModal, setShowModal] = useState(false);
  const runningRef = useRef(false);

  const openModal = useCallback(() => setShowModal(true), []);
  const closeModal = useCallback(() => setShowModal(false), []);

  const startImport = useCallback((file: File) => {
    if (runningRef.current) return;
    runningRef.current = true;

    setImportState({
      active: true,
      stage: 'pdf',
      progress: 0,
      message: 'Загрузка файла...',
    });

    importStatementStream(file, (event: SseEvent) => {
      if (event.stage === 'done') {
        setImportState({
          active: false,
          stage: 'done',
          progress: 100,
          message: 'Импорт завершён',
          result: event.result,
        });
        runningRef.current = false;
      } else if (event.stage === 'error') {
        setImportState({
          active: false,
          stage: 'error',
          progress: 0,
          message: event.message,
          error: event.message,
        });
        runningRef.current = false;
      } else {
        setImportState({
          active: true,
          stage: event.stage,
          progress: event.progress,
          message: event.message,
        });
      }
    }).catch((err) => {
      setImportState({
        active: false,
        stage: 'error',
        progress: 0,
        message: err instanceof Error ? err.message : 'Ошибка импорта',
        error: err instanceof Error ? err.message : 'Ошибка импорта',
      });
      runningRef.current = false;
    });
  }, []);

  const clearImport = useCallback(() => {
    setImportState(INITIAL);
  }, []);

  return (
    <ImportContext.Provider value={{
      importState, showModal, openModal, closeModal, startImport, clearImport,
    }}>
      {children}
    </ImportContext.Provider>
  );
}

export function useImport(): ImportContextValue {
  const ctx = useContext(ImportContext);
  if (!ctx) throw new Error('useImport must be used within ImportProvider');
  return ctx;
}