import React, { useRef, useState, useLayoutEffect, useCallback } from 'react';
import { Tree, type NodeApi } from 'react-arborist';
import {
  IconFile,
  IconFolder,
  IconFolderOpen,
  IconUpload,
} from '@tabler/icons-react';
import { Text, Box } from '@mantine/core';
import useResizeObserver from '@react-hook/resize-observer';
import { useFileOperations } from '../../hooks/useFileOperations';
import type { FileNode } from '@/types/models';

interface Size {
  width: number;
  height: number;
}

interface FileTreeProps {
  files: FileNode[];
  handleFileSelect: (filePath: string | null) => Promise<void>;
  showHiddenFiles: boolean;
  loadFileList: () => Promise<void>;
}

const useSize = (target: React.RefObject<HTMLElement>): Size | undefined => {
  const [size, setSize] = useState<Size>();

  useLayoutEffect(() => {
    if (target.current) {
      setSize(target.current.getBoundingClientRect());
    }
  }, [target]);

  useResizeObserver(target, (entry) => setSize(entry.contentRect));
  return size;
};

const FileIcon = ({ node }: { node: NodeApi<FileNode> }) => {
  if (node.isLeaf) {
    return <IconFile size={16} />;
  }
  return node.isOpen ? (
    <IconFolderOpen size={16} color="var(--mantine-color-yellow-filled)" />
  ) : (
    <IconFolder size={16} color="var(--mantine-color-yellow-filled)" />
  );
};

// Enhanced Node component with drag handle
function Node({
  node,
  style,
  dragHandle,
  onNodeClick,
}: {
  node: NodeApi<FileNode>;
  style: React.CSSProperties;
  dragHandle?: React.Ref<HTMLDivElement>;
  onNodeClick?: (node: NodeApi<FileNode>) => void;
}) {
  const handleClick = () => {
    if (node.isInternal) {
      node.toggle();
    } else if (typeof onNodeClick === 'function') {
      onNodeClick(node);
    }
  };

  return (
    <div
      ref={dragHandle} // This enables dragging for the node
      style={{
        ...style,
        paddingLeft: `${node.level * 20}px`,
        display: 'flex',
        alignItems: 'center',
        cursor: 'pointer',
        whiteSpace: 'nowrap',
        overflow: 'hidden',
        // Add visual feedback when being dragged
        opacity: node.state?.isDragging ? 0.5 : 1,
        // Highlight when this node will receive the drop
        backgroundColor: node.state?.willReceiveDrop
          ? 'rgba(0, 123, 255, 0.2)'
          : 'transparent',
        borderRadius: '4px',
      }}
      onClick={handleClick}
      title={node.data.name}
    >
      <FileIcon node={node} />
      <span
        style={{
          marginLeft: '8px',
          fontSize: '14px',
          overflow: 'hidden',
          textOverflow: 'ellipsis',
          flexGrow: 1,
        }}
      >
        {node.data.name}
      </span>
    </div>
  );
}

// Utility function to recursively find file paths by IDs
const findFilePathsById = (files: FileNode[], ids: string[]): string[] => {
  const paths: string[] = [];

  const searchFiles = (nodes: FileNode[]) => {
    for (const node of nodes) {
      if (ids.includes(node.id)) {
        paths.push(node.path);
      }
      if (node.children) {
        searchFiles(node.children);
      }
    }
  };

  searchFiles(files);
  return paths;
};

// Utility function to find parent path by ID
const findParentPathById = (
  files: FileNode[],
  parentId: string | null
): string => {
  if (!parentId) return '';

  const searchFiles = (nodes: FileNode[]): string | null => {
    for (const node of nodes) {
      if (node.id === parentId) {
        return node.path;
      }
      if (node.children) {
        const result = searchFiles(node.children);
        if (result) return result;
      }
    }
    return null;
  };

  return searchFiles(files) || '';
};

export const FileTree: React.FC<FileTreeProps> = ({
  files,
  handleFileSelect,
  showHiddenFiles,
  loadFileList,
}) => {
  const target = useRef<HTMLDivElement>(null);
  const size = useSize(target);
  const { handleMove, handleUpload } = useFileOperations();

  // State for drag and drop overlay
  const [isDragOver, setIsDragOver] = useState(false);

  const filteredFiles = files.filter((file) => {
    if (file.name.startsWith('.') && !showHiddenFiles) {
      return false;
    }
    return true;
  });

  // Handler for node click
  const onNodeClick = (node: NodeApi<FileNode>) => {
    const fileNode = node.data;
    if (!node.isInternal) {
      void handleFileSelect(fileNode.path);
    }
  };

  // Handle file movement within the tree
  const handleTreeMove = useCallback(
    async ({
      dragIds,
      parentId,
      index,
    }: {
      dragIds: string[];
      parentId: string | null;
      index: number;
    }) => {
      try {
        // Map dragged file IDs to their corresponding paths
        const dragPaths = findFilePathsById(filteredFiles, dragIds);

        // Find the parent path where files will be moved
        const targetParentPath = findParentPathById(filteredFiles, parentId);

        // Move files to the new location
        const success = await handleMove(dragPaths, targetParentPath, index);
        if (success) {
          await loadFileList();
        }
      } catch (error) {
        console.error('Error moving files:', error);
      }
    },
    [handleMove, loadFileList, filteredFiles]
  );

  // External file drag and drop handlers
  const handleDragEnter = useCallback((e: React.DragEvent) => {
    // Check if drag contains files (not internal tree nodes)
    if (e.dataTransfer.types.includes('Files')) {
      e.preventDefault();
      e.stopPropagation();
      setIsDragOver(true);
    }
  }, []);

  const handleDragLeave = useCallback((e: React.DragEvent) => {
    // Only handle if it's an external file drag
    if (e.dataTransfer.types.includes('Files')) {
      e.preventDefault();
      e.stopPropagation();

      // Only hide overlay when leaving the container itself
      if (e.currentTarget === e.target) {
        setIsDragOver(false);
      }
    }
  }, []);

  const handleDragOver = useCallback((e: React.DragEvent) => {
    // Only handle external file drags
    if (e.dataTransfer.types.includes('Files')) {
      e.preventDefault();
      e.stopPropagation();
      // Set the drop effect to indicate this is a valid drop target
      e.dataTransfer.dropEffect = 'copy';
    }
  }, []);

  const handleDrop = useCallback(
    (e: React.DragEvent) => {
      const { files } = e.dataTransfer;
      // Only handle if it's an external file drop
      if (files && files.length > 0) {
        e.preventDefault();
        e.stopPropagation();
        setIsDragOver(false);

        const uploadFiles = async () => {
          try {
            const success = await handleUpload(files);
            if (success) {
              await loadFileList();
            }
          } catch (error) {
            console.error('Error uploading files:', error);
          }
        };

        void uploadFiles();
      }
    },
    [handleUpload, loadFileList]
  );

  return (
    <div
      ref={target}
      style={{
        height: 'calc(100vh - 140px)',
        marginTop: '20px',
        position: 'relative',
      }}
      onDragEnter={handleDragEnter}
      onDragLeave={handleDragLeave}
      onDragOver={handleDragOver}
      onDrop={handleDrop}
    >
      {/* Drag overlay */}
      {isDragOver && (
        <Box
          style={{
            position: 'absolute',
            top: 0,
            left: 0,
            right: 0,
            bottom: 0,
            backgroundColor: 'rgba(0, 123, 255, 0.1)',
            border: '2px dashed var(--mantine-color-blue-6)',
            borderRadius: '8px',
            display: 'flex',
            alignItems: 'center',
            justifyContent: 'center',
            flexDirection: 'column',
            zIndex: 1000,
            pointerEvents: 'none',
          }}
        >
          <IconUpload size={48} color="var(--mantine-color-blue-6)" />
          <Text size="lg" fw={500} c="blue" mt="md">
            Drop files here to upload
          </Text>
        </Box>
      )}

      {size && (
        <Tree
          data={filteredFiles}
          openByDefault={false}
          width={size.width}
          height={size.height}
          indent={24}
          rowHeight={28}
          idAccessor="id"
          onMove={handleTreeMove}
          disableDrag={() => false}
          disableDrop={() => false}
          onActivate={(node) => {
            const fileNode = node.data;
            if (!node.isInternal) {
              void handleFileSelect(fileNode.path);
            }
          }}
        >
          {(props) => <Node {...props} onNodeClick={onNodeClick} />}
        </Tree>
      )}
    </div>
  );
};

export default FileTree;