import { useCallback, useMemo } from 'react';
import { useNavigate } from 'react-router-dom';
import type { DragEvent } from 'react';
import { useStatusToast } from '../../../lib/context/StatusToastContext';
import { DEFAULT_FOLDER_NAME, hasFiles } from '../../../app/workspaceUtils';
import {
  createFolder,
  deleteFolder,
  moveFolder as moveFolderRequest,
  renameFolder as renameFolderRequest,
} from '../../../lib/api/apiClient';
import type { FolderId } from '../../../types/identifiers';
import type { MessageOptions, FolderNode } from '../../../types/documents';

type FolderKey = FolderId | 'root';

interface LoadFolderOptions {
  preserveSearch?: boolean;
}

interface SelectFolderOptions {
  replace?: boolean;
  immediate?: boolean;
}

interface FolderClickHandlers {
  onSelect: (folderId: FolderKey, options?: SelectFolderOptions) => Promise<void>;
  onDrop: (event: DragEvent<HTMLElement>, folderId: FolderKey) => Promise<void>;
  onDragOver: (event: DragEvent<HTMLElement>, folderId: FolderKey) => void;
  onDragLeave: (event: DragEvent<HTMLElement>) => void;
}

import useNotifyApiError from '../../../hooks/useNotifyApiError';

interface UseFolderTreeActionsOptions {
  folderNodes: Map<FolderKey, FolderNode>;
  setFolderNodes: (updater: (prev: Map<FolderKey, FolderNode>) => Map<FolderKey, FolderNode>) => void;
  selectedFolder: FolderKey;
  setSelectedFolder: (folderId: FolderKey) => void;
  handleFileDrop: (dataTransfer: DataTransfer, folderId: FolderKey) => Promise<void> | void;
  moveDocumentsToFolder: (docIds: FolderId[], folderId: FolderKey) => Promise<void>;
  draggedDocumentIds: FolderId[];
  draggedFolderId: FolderKey | null;
  setDraggedDocumentIds: (ids: FolderId[]) => void;
  setDraggedFolderId: (id: FolderKey | null) => void;
  isInvalidFolderDrop: (sourceFolderId: FolderKey, targetFolderId: FolderKey) => boolean;
  setCreatingFolder: (value: boolean) => void;
}

const useFolderTreeActions = ({
  folderNodes,
  setFolderNodes,
  selectedFolder,
  setSelectedFolder,
  handleFileDrop,
  moveDocumentsToFolder,
  draggedDocumentIds,
  draggedFolderId,
  setDraggedDocumentIds,
  setDraggedFolderId,
  isInvalidFolderDrop,
  setCreatingFolder,
}: UseFolderTreeActionsOptions) => {
  const { showToast } = useStatusToast();
  const notifyApiError = useNotifyApiError();
  const navigate = useNavigate();

  const moveFolder = useCallback(
    async (folderId: FolderKey, targetFolderId: FolderKey | null) => {
      const node = folderNodes.get(folderId);
      if (!node) {
        showToast('Folder metadata unavailable. Try refreshing.', 'error');
        return;
      }

      const previousParentKey = node.parentId ?? 'root';
      const targetKey = targetFolderId && targetFolderId !== 'root' ? targetFolderId : 'root';

      if (previousParentKey === targetKey) {
        return;
      }

      const parent_id = targetKey === 'root' ? null : targetKey;

      try {
        await moveFolderRequest(folderId, parent_id);

        setFolderNodes((prev) => {
          const next = new Map(prev);
          const currentNode = next.get(folderId);
          if (!currentNode) {
            return prev;
          }

          next.set(folderId, { ...currentNode, parentId: parent_id ?? null });

          const previousParent = next.get(previousParentKey);
          if (previousParent) {
            const remainingChildren = (previousParent.children || []).filter(
              (childId) => childId !== folderId,
            );
            next.set(previousParentKey, {
              ...previousParent,
              children: remainingChildren,
              hasChildren: remainingChildren.length > 0,
            });
          }

          if (!next.has(targetKey)) {
            next.set(targetKey, {
              id: targetKey,
              name: targetKey === 'root' ? DEFAULT_FOLDER_NAME : 'Folder',
              parentId: targetKey === 'root' ? null : null,
              children: [],
              expanded: targetKey === 'root',
              loaded: false,
              hasChildren: false,
            });
          }

          const targetNode = next.get(targetKey);
          if (targetNode && !targetNode.children.includes(folderId)) {
            next.set(targetKey, {
              ...targetNode,
              children: [...targetNode.children, folderId],
              hasChildren: true,
            });
          }

          return next;
        });

        if (selectedFolder === folderId) {
          setSelectedFolder(folderId);
        }

        showToast('Folder moved.', 'success');
      } catch (error) {
        const message = error.response?.data?.error || 'Failed to move folder.';
        notifyApiError(error, message);
      }
    },
    [
      folderNodes,
      notifyApiError,
      selectedFolder,
      setFolderNodes,
      setSelectedFolder,
      showToast,
    ],
  );

  const loadFolder = useCallback(
    async (folderId: FolderKey | null, { preserveSearch: _preserveSearch = false }: LoadFolderOptions = {}) => {
      const targetId = folderId || 'root';
      setSelectedFolder(targetId);
      // Data fetching is now reactive in the parent component based on selectedFolder
    },
    [setSelectedFolder],
  );

  const selectFolder = useCallback(
    async (folderId: FolderKey | null, { replace = false, immediate = false }: SelectFolderOptions = {}) => {
      const targetId = folderId && folderId !== 'root' ? folderId : 'root';

      if (!navigate || immediate) {
        await loadFolder(targetId);
        return;
      }

      const path = targetId === 'root' ? '/documents' : `/documents/folder/${targetId}`;
      navigate(path, { replace });
    },
    [
      loadFolder,
      navigate,
    ],
  );

  const handleFolderRename = useCallback(
    async (folderId: FolderKey, nextName: string) => {
      const trimmed = nextName?.trim?.() || '';
      if (!trimmed) {
        showToast('Folder name cannot be empty.', 'error');
        return false;
      }
      try {
        await renameFolderRequest(folderId, trimmed);

        setFolderNodes((prev) => {
          const next = new Map(prev);
          const node = next.get(folderId);
          if (node) {
            next.set(folderId, { ...node, name: trimmed });
          }
          return next;
        });

        showToast('Folder renamed.', 'success');
        return true;
      } catch (error) {
        const message = error.response?.data?.error || 'Failed to rename folder.';
        notifyApiError(error, message);
        return false;
      }
    },
    [
      notifyApiError,
      setFolderNodes,
      showToast,
    ],
  );

  const handleFolderCreate = useCallback(
    async (name: string, parentId?: FolderKey | null) => {
      if (!name.trim()) {
        showToast('Folder name cannot be empty.', 'error');
        return false;
      }

      const targetParentId = parentId !== undefined
        ? (parentId === 'root' ? null : parentId)
        : (selectedFolder === 'root' ? null : selectedFolder);

      const payload = {
        name: name.trim(),
        parent_id: targetParentId,
      };
      setCreatingFolder(true);
      let succeeded = false;
      try {
        const data = await createFolder(payload);
        const folderData = (data as { folder?: { id?: FolderKey; name?: string; parent_id?: FolderKey | null; children?: FolderKey[] } }).folder;
        if (!folderData?.id) {
          throw new Error('Folder creation failed.');
        }
        showToast('Folder created.', 'success');
        setFolderNodes((prev) => {
          const next = new Map(prev);
          const parentId = folderData.parent_id ?? payload.parent_id ?? 'root';
          const parentNode = next.get(parentId);
          if (parentNode) {
            next.set(parentId, {
              ...parentNode,
              children: parentNode.children.concat([folderData.id]),
              loaded: true,
              hasChildren: true,
            });
          }
          next.set(folderData.id, {
            id: folderData.id,
            name: folderData.name ?? payload.name,
            parentId: parentId,
            children: folderData.children || [],
            expanded: false,
            loaded: false,
            hasChildren: Array.isArray(folderData.children) ? folderData.children.length > 0 : false,
          });
          return next;
        });

        await selectFolder(folderData.id, { immediate: true });
        succeeded = true;
        return true;
      } catch (error) {
        const message = error.response?.data?.error || 'Failed to create folder.';
        notifyApiError(error, message);
        return false;
      } finally {
        setCreatingFolder(false);
        if (!succeeded) {
          showToast('Folder creation failed.', 'error');
        }
      }
    },
    [
      notifyApiError,
      selectFolder,
      selectedFolder,
      setCreatingFolder,
      setFolderNodes,
      showToast,
    ],
  );

  const handleFolderDelete = useCallback(
    async (folderId: FolderKey, { showMessage = true }: MessageOptions = {}) => {
      if (!folderId || folderId === 'root') {
        if (showMessage) {
          showToast('The root folder cannot be removed.', 'error');
        }
        return false;
      }

      try {
        await deleteFolder(folderId);

        setFolderNodes((prev) => {
          const next = new Map(prev);
          const node = next.get(folderId);
          next.delete(folderId);
          if (node) {
            const parentId = node.parentId || 'root';
            const parentNode = next.get(parentId);
            if (parentNode) {
              const remaining = parentNode.children.filter((id) => id !== folderId);
              next.set(parentId, {
                ...parentNode,
                children: remaining,
                hasChildren: remaining.length > 0,
              });
            }
          }
          return next;
        });

        if (selectedFolder === folderId) {
          const node = folderNodes.get(folderId);
          const parentId = node?.parentId || 'root';
          setSelectedFolder(parentId);
        }

        if (showMessage) {
          showToast('Folder deleted.', 'success');
        }
        return true;
      } catch (error) {
        const message = error.response?.data?.error || 'Failed to delete folder.';
        notifyApiError(error, message);
        if (showMessage) {
          showToast(message, 'error');
        }
        return false;
      }
    },
    [
      folderNodes,
      notifyApiError,
      selectedFolder,
      setFolderNodes,
      setSelectedFolder,
      showToast,
    ],
  );

  const folderClickHandlers: FolderClickHandlers = useMemo(
    () => ({
      onSelect: selectFolder,
      onDrop: async (event: DragEvent<HTMLElement>, folderId: FolderKey) => {
        event.preventDefault();
        event.stopPropagation();
        event.currentTarget.classList.remove('is-drop-target');

        let folderIds: FolderId[] = [];
        try {
          const rawFolderList = event.dataTransfer.getData('application/x-papercrate-folder-list');
          if (rawFolderList) {
            const parsed = JSON.parse(rawFolderList);
            if (Array.isArray(parsed)) {
              folderIds = parsed.filter(Boolean);
            }
          }
        } catch (error) {
          console.warn('[folders] Failed to parse folder list drag payload', error);
        }

        if (!folderIds.length) {
          let folderSourceId = draggedFolderId;
          if (!folderSourceId) {
            try {
              if (event.dataTransfer.types?.includes('application/x-papercrate-folder')) {
                folderSourceId = event.dataTransfer.getData('application/x-papercrate-folder');
              }
            } catch (error) {
              console.warn('[folders] Failed to read folder id from drag payload', error);
            }
          }

          if (folderSourceId) {
            folderIds = [folderSourceId];
          }
        }

        folderIds = Array.from(new Set(folderIds.filter(Boolean)));

        if (folderIds.length) {
          setDraggedFolderId(null);
          const invalidMove = folderIds.some((sourceId) => isInvalidFolderDrop(sourceId, folderId));
          if (invalidMove) {
            showToast(
              'Cannot move a folder into itself or one of its descendants.',
              'error',
            );
            return;
          }

          for (const sourceId of folderIds) {
            await moveFolder(sourceId, folderId);
          }
        }

        if (hasFiles(event)) {
          await handleFileDrop(event.dataTransfer, folderId);
          return;
        }

        let docIds: FolderId[] = [];
        try {
          const raw = event.dataTransfer.getData('application/x-papercrate-doc-list');
          if (raw) {
            const parsed = JSON.parse(raw);
            if (Array.isArray(parsed)) {
              docIds = parsed.filter(Boolean);
            }
          }
        } catch (error) {
          console.warn('[documents] Failed to parse document list drag payload', error);
        }

        if (!docIds.length) {
          try {
            const single = event.dataTransfer.getData('application/x-papercrate-doc');
            if (single) {
              docIds = [single];
            }
          } catch (error) {
            console.warn('[documents] Failed to read single document drag payload', error);
          }
        }

        if (!docIds.length && draggedDocumentIds.length) {
          docIds = draggedDocumentIds;
        }

        docIds = Array.from(new Set(docIds));

        if (!docIds.length || folderId === selectedFolder) {
          return;
        }

        setDraggedDocumentIds([]);
        await moveDocumentsToFolder(docIds, folderId);
      },
      onDragOver: (event: DragEvent<HTMLElement>, folderId: FolderKey) => {
        const folderDragActive = Boolean(draggedFolderId);
        if (folderDragActive && isInvalidFolderDrop(draggedFolderId, folderId)) {
          return;
        }

        if (hasFiles(event)) {
          event.preventDefault();
          event.dataTransfer.dropEffect = 'copy';
          event.currentTarget.classList.add('is-drop-target');
          return;
        }

        if (draggedDocumentIds.length || folderDragActive) {
          event.preventDefault();
          event.dataTransfer.dropEffect = 'move';
          event.currentTarget.classList.add('is-drop-target');
        }
      },
      onDragLeave: (event: DragEvent<HTMLElement>) => {
        event.currentTarget.classList.remove('is-drop-target');
      },
    }),
    [
      draggedDocumentIds,
      draggedFolderId,
      handleFileDrop,
      isInvalidFolderDrop,
      moveDocumentsToFolder,
      moveFolder,
      selectFolder,
      selectedFolder,
      setDraggedDocumentIds,
      setDraggedFolderId,
      showToast,
    ],
  );

  return {
    loadFolder,
    selectFolder,
    handleFolderRename,
    handleFolderCreate,
    handleFolderDelete,
    folderClickHandlers,
  };
};

export default useFolderTreeActions;