import React, { useState, useEffect, useRef, useCallback } from 'react';
import type { GlobalBlockFolder, GlobalBlock } from '../services/api';
import {
  getGlobalFolders,
  createGlobalFolder,
  renameGlobalFolder,
  deleteGlobalFolder,
  getGlobalBlocks,
  createGlobalBlock,
  renameGlobalBlock,
  deleteGlobalBlock,
} from '../services/api';

interface BlockLibraryTreeProps {
  token: string;
  onBlockDragStart: (blockId: string, blockData: string) => void;
}

interface FolderNode {
  folder: GlobalBlockFolder;
  children: FolderNode[];
  blocks: GlobalBlock[];
  expanded: boolean;
}

const BlockLibraryTree: React.FC<BlockLibraryTreeProps> = ({ token, onBlockDragStart }) => {
  const [folders, setFolders] = useState<GlobalBlockFolder[]>([]);
  const [blocks, setBlocks] = useState<GlobalBlock[]>([]);
  const [expandedIds, setExpandedIds] = useState<Set<string>>(new Set());
  const [renamingId, setRenamingId] = useState<string | null>(null);
  const [renameValue, setRenameValue] = useState('');
  const [contextMenu, setContextMenu] = useState<{
    x: number;
    y: number;
    type: 'folder' | 'block' | 'root';
    id: string | null;
    parentId: string | null;
  } | null>(null);
  const [loading, setLoading] = useState(true);
  const fileInputRef = useRef<HTMLInputElement>(null);
  const [dragOverFolderId, setDragOverFolderId] = useState<string | null>(null);

  const loadData = useCallback(async () => {
    try {
      const [allFolders, allBlocks] = await Promise.all([
        getGlobalFolders(token),
        getGlobalBlocks(token),
      ]);
      setFolders(allFolders);
      setBlocks(allBlocks);
    } catch (err) {
      // Silently handle — user will see empty tree
    } finally {
      setLoading(false);
    }
  }, [token]);

  useEffect(() => {
    loadData();
  }, [loadData]);

  // Build tree structure from flat lists
  const buildTree = useCallback((): FolderNode[] => {
    const folderMap = new Map<string, FolderNode>();
    for (const f of folders) {
      folderMap.set(f.id, { folder: f, children: [], blocks: [], expanded: expandedIds.has(f.id) });
    }
    const roots: FolderNode[] = [];
    for (const f of folders) {
      const node = folderMap.get(f.id)!;
      if (f.parent_id && folderMap.has(f.parent_id)) {
        folderMap.get(f.parent_id)!.children.push(node);
      } else {
        roots.push(node);
      }
    }
    // Attach blocks to folders
    for (const b of blocks) {
      if (b.folder_id && folderMap.has(b.folder_id)) {
        folderMap.get(b.folder_id)!.blocks.push(b);
      }
    }
    // Sort children and blocks by name
    const sortRecursive = (nodes: FolderNode[]) => {
      nodes.sort((a, b) => a.folder.name.localeCompare(b.folder.name));
      for (const n of nodes) {
        n.blocks.sort((a, b) => a.name.localeCompare(b.name));
        sortRecursive(n.children);
      }
    };
    sortRecursive(roots);
    return roots;
  }, [folders, blocks, expandedIds]);

  const rootBlocks = blocks.filter(b => !b.folder_id).sort((a, b) => a.name.localeCompare(b.name));
  const tree = buildTree();

  const toggleExpand = (folderId: string) => {
    setExpandedIds(prev => {
      const next = new Set(prev);
      if (next.has(folderId)) next.delete(folderId);
      else next.add(folderId);
      return next;
    });
  };

  const handleCreateFolder = async (parentId: string | null) => {
    const name = window.prompt('Ordner-Name:', 'Neuer Ordner');
    if (!name) return;
    try {
      const created = await createGlobalFolder(token, name, parentId);
      setFolders(prev => [...prev, created]);
      if (parentId) {
        setExpandedIds(prev => new Set(prev).add(parentId));
      }
    } catch {
      window.alert('Fehler beim Erstellen des Ordners');
    }
  };

  const handleRenameFolder = async (id: string, name: string) => {
    if (!name.trim()) return;
    try {
      await renameGlobalFolder(token, id, name);
      setFolders(prev => prev.map(f => f.id === id ? { ...f, name } : f));
    } catch {
      window.alert('Fehler beim Umbenennen des Ordners');
    }
  };

  const handleDeleteFolder = async (id: string) => {
    if (!window.confirm('Ordner und alle Inhalte löschen?')) return;
    try {
      await deleteGlobalFolder(token, id);
      setFolders(prev => prev.filter(f => f.id !== id && f.parent_id !== id));
      // Blocks in deleted folder get folder_id = NULL (SET NULL in schema)
      setBlocks(prev => prev.map(b => b.folder_id === id ? { ...b, folder_id: null } : b));
    } catch {
      window.alert('Fehler beim Löschen des Ordners');
    }
  };

  const handleRenameBlock = async (id: string, name: string) => {
    if (!name.trim()) return;
    try {
      await renameGlobalBlock(token, id, name);
      setBlocks(prev => prev.map(b => b.id === id ? { ...b, name } : b));
    } catch {
      window.alert('Fehler beim Umbenennen des Blocks');
    }
  };

  const handleDeleteBlock = async (id: string) => {
    if (!window.confirm('Block löschen?')) return;
    try {
      await deleteGlobalBlock(token, id);
      setBlocks(prev => prev.filter(b => b.id !== id));
    } catch {
      window.alert('Fehler beim Löschen des Blocks');
    }
  };

  const handleBlockDragStart = (e: React.DragEvent, block: GlobalBlock) => {
    e.dataTransfer.setData('text/global-block-id', block.id);
    e.dataTransfer.setData('text/global-block-data', block.block_data);
    e.dataTransfer.effectAllowed = 'copy';
    onBlockDragStart(block.id, block.block_data);
  };

  const handleFolderDragOver = (e: React.DragEvent, folderId: string) => {
    e.preventDefault();
    e.stopPropagation();
    setDragOverFolderId(folderId);
  };

  const handleFolderDrop = async (e: React.DragEvent, folderId: string) => {
    e.preventDefault();
    e.stopPropagation();
    setDragOverFolderId(null);
    // Drop an SVG file into folder
    const files = e.dataTransfer.files;
    if (files && files.length > 0) {
      const file = files[0];
      if (file.type === 'image/svg+xml' || file.name.endsWith('.svg')) {
        const reader = new FileReader();
        reader.onload = async (ev) => {
          const svgContent = ev.target?.result as string;
          try {
            const created = await createGlobalBlock(token, {
              name: file.name.replace(/\.svg$/i, ''),
              folder_id: folderId,
              block_data: JSON.stringify({ type: 'svg', svg: svgContent }),
              svg_data: svgContent,
            });
            setBlocks(prev => [...prev, created]);
          } catch {
            window.alert('Fehler beim Speichern des SVG-Blocks');
          }
        };
        reader.readAsText(file);
      }
    }
    // Drop a canvas element (text/global-block-data means it's already a global block, skip)
    const canvasElementData = e.dataTransfer.getData('text/canvas-element');
    if (canvasElementData) {
      try {
        const elementData = JSON.parse(canvasElementData);
        const created = await createGlobalBlock(token, {
          name: `Element ${Date.now()}`,
          folder_id: folderId,
          block_data: JSON.stringify(elementData),
        });
        setBlocks(prev => [...prev, created]);
      } catch {
        window.alert('Fehler beim Speichern des Elements als Block');
      }
    }
  };

  const handleSvgImport = (e: React.ChangeEvent<HTMLInputElement>) => {
    const file = e.target.files?.[0];
    if (!file) return;
    const reader = new FileReader();
    reader.onload = async (ev) => {
      const svgContent = ev.target?.result as string;
      try {
        const created = await createGlobalBlock(token, {
          name: file.name.replace(/\.svg$/i, ''),
          block_data: JSON.stringify({ type: 'svg', svg: svgContent }),
          svg_data: svgContent,
        });
        setBlocks(prev => [...prev, created]);
      } catch {
        window.alert('Fehler beim Importieren des SVG');
      }
    };
    reader.readAsText(file);
    e.target.value = '';
  };

  const handleContextMenu = (e: React.MouseEvent, type: 'folder' | 'block' | 'root', id: string | null, parentId: string | null) => {
    e.preventDefault();
    e.stopPropagation();
    setContextMenu({ x: e.clientX, y: e.clientY, type, id, parentId });
  };

  const closeContextMenu = () => setContextMenu(null);

  useEffect(() => {
    if (contextMenu) {
      const handleClick = () => closeContextMenu();
      window.addEventListener('click', handleClick);
      return () => window.removeEventListener('click', handleClick);
    }
  }, [contextMenu]);

  const startRename = (id: string, currentName: string) => {
    setRenamingId(id);
    setRenameValue(currentName);
  };

  const confirmRename = () => {
    if (!renamingId) return;
    const isFolder = folders.some(f => f.id === renamingId);
    if (isFolder) {
      handleRenameFolder(renamingId, renameValue);
    } else {
      handleRenameBlock(renamingId, renameValue);
    }
    setRenamingId(null);
    setRenameValue('');
  };

  const renderFolderNode = (node: FolderNode, depth: number): React.ReactNode => {
    const isRenaming = renamingId === node.folder.id;
    const isDragOver = dragOverFolderId === node.folder.id;
    return (
      <div key={node.folder.id}>
        <div
          className={`tree-item tree-item-folder${isDragOver ? ' drag-over' : ''}`}
          style={{ paddingLeft: `${depth * 16 + 8}px` }}
          onClick={() => toggleExpand(node.folder.id)}
          onContextMenu={(e) => handleContextMenu(e, 'folder', node.folder.id, node.folder.parent_id)}
          onDragOver={(e) => handleFolderDragOver(e, node.folder.id)}
          onDragLeave={() => setDragOverFolderId(null)}
          onDrop={(e) => handleFolderDrop(e, node.folder.id)}
        >
          <span className="tree-toggle">{node.children.length > 0 || node.blocks.length > 0 ? (node.expanded ? '▾' : '▸') : '·'}</span>
          <span className="tree-icon">📁</span>
          {isRenaming ? (
            <input
              type="text"
              className="tree-rename-input"
              value={renameValue}
              autoFocus
              onChange={(e) => setRenameValue(e.target.value)}
              onBlur={confirmRename}
              onKeyDown={(e) => {
                if (e.key === 'Enter') confirmRename();
                if (e.key === 'Escape') { setRenamingId(null); setRenameValue(''); }
              }}
              onClick={(e) => e.stopPropagation()}
            />
          ) : (
            <span
              className="tree-label"
              onDoubleClick={(e) => { e.stopPropagation(); startRename(node.folder.id, node.folder.name); }}
            >
              {node.folder.name}
            </span>
          )}
          <span className="tree-count">{node.blocks.length}</span>
        </div>
        {node.expanded && (
          <div className="tree-children">
            {node.children.map(child => renderFolderNode(child, depth + 1))}
            {node.blocks.map(block => {
              const isBlockRenaming = renamingId === block.id;
              return (
                <div
                  key={block.id}
                  className="tree-item tree-item-leaf draggable"
                  style={{ paddingLeft: `${(depth + 1) * 16 + 8}px` }}
                  draggable
                  onDragStart={(e) => handleBlockDragStart(e, block)}
                  onContextMenu={(e) => handleContextMenu(e, 'block', block.id, block.folder_id)}
                  title={block.name}
                >
                  <span className="tree-icon">📦</span>
                  {isBlockRenaming ? (
                    <input
                      type="text"
                      className="tree-rename-input"
                      value={renameValue}
                      autoFocus
                      onChange={(e) => setRenameValue(e.target.value)}
                      onBlur={confirmRename}
                      onKeyDown={(e) => {
                        if (e.key === 'Enter') confirmRename();
                        if (e.key === 'Escape') { setRenamingId(null); setRenameValue(''); }
                      }}
                      onClick={(e) => e.stopPropagation()}
                    />
                  ) : (
                    <span
                      className="tree-label"
                      onDoubleClick={(e) => { e.stopPropagation(); startRename(block.id, block.name); }}
                    >
                      {block.name}
                    </span>
                  )}
                </div>
              );
            })}
          </div>
        )}
      </div>
    );
  };

  if (loading) {
    return <div className="global-lib-loading">Globale Bibliothek lädt…</div>;
  }

  return (
    <div className="global-lib-tree" onContextMenu={(e) => handleContextMenu(e, 'root', null, null)}>
      <div className="global-lib-header">
        <span className="global-lib-title">🌐 Globale Bibliothek</span>
        <button
          className="global-lib-add-btn"
          title="SVG in globale Bibliothek importieren"
          onClick={() => fileInputRef.current?.click()}
        >
          <svg viewBox="0 0 24 24" width="14" height="14" fill="none" stroke="currentColor" strokeWidth="2" strokeLinecap="round" strokeLinejoin="round"><path d="M21 15v4a2 2 0 0 1-2 2H5a2 2 0 0 1-2-2v-4"/><polyline points="17 8 12 3 7 8"/><line x1="12" y1="3" x2="12" y2="15"/></svg>
        </button>
        <input ref={fileInputRef} type="file" accept=".svg,image/svg+xml" style={{ display: 'none' }} onChange={handleSvgImport} />
      </div>
      <div className="tree tree-global" role="tree" aria-label="Globale Block-Bibliothek">
        {tree.map(node => renderFolderNode(node, 0))}
        {rootBlocks.map(block => {
          const isBlockRenaming = renamingId === block.id;
          return (
            <div
              key={block.id}
              className="tree-item tree-item-leaf draggable"
              draggable
              onDragStart={(e) => handleBlockDragStart(e, block)}
              onContextMenu={(e) => handleContextMenu(e, 'block', block.id, null)}
              title={block.name}
            >
              <span className="tree-icon">📦</span>
              {isBlockRenaming ? (
                <input
                  type="text"
                  className="tree-rename-input"
                  value={renameValue}
                  autoFocus
                  onChange={(e) => setRenameValue(e.target.value)}
                  onBlur={confirmRename}
                  onKeyDown={(e) => {
                    if (e.key === 'Enter') confirmRename();
                    if (e.key === 'Escape') { setRenamingId(null); setRenameValue(''); }
                  }}
                />
              ) : (
                <span
                  className="tree-label"
                  onDoubleClick={(e) => { e.stopPropagation(); startRename(block.id, block.name); }}
                >
                  {block.name}
                </span>
              )}
            </div>
          );
        })}
        {folders.length === 0 && blocks.length === 0 && (
          <div className="global-lib-empty">Globale Bibliothek ist leer — Rechtsklick für Ordner</div>
        )}
      </div>

      {contextMenu && (
        <div
          className="context-menu"
          style={{ position: 'fixed', left: contextMenu.x, top: contextMenu.y, zIndex: 10000 }}
          onClick={(e) => e.stopPropagation()}
        >
          {contextMenu.type === 'root' && (
            <>
              <button className="context-menu-item" onClick={() => { handleCreateFolder(null); closeContextMenu(); }}>
                📁 Neuer Ordner
              </button>
            </>
          )}
          {contextMenu.type === 'folder' && contextMenu.id && (
            <>
              <button className="context-menu-item" onClick={() => { handleCreateFolder(contextMenu.id); closeContextMenu(); }}>
                📁 Neuer Unterordner
              </button>
              <button className="context-menu-item" onClick={() => { if (contextMenu.id) startRename(contextMenu.id, folders.find(f => f.id === contextMenu.id)?.name ?? ''); closeContextMenu(); }}>
                ✏️ Umbenennen
              </button>
              <button className="context-menu-item danger" onClick={() => { if (contextMenu.id) handleDeleteFolder(contextMenu.id); closeContextMenu(); }}>
                🗑️ Löschen
              </button>
            </>
          )}
          {contextMenu.type === 'block' && contextMenu.id && (
            <>
              <button className="context-menu-item" onClick={() => { if (contextMenu.id) startRename(contextMenu.id, blocks.find(b => b.id === contextMenu.id)?.name ?? ''); closeContextMenu(); }}>
                ✏️ Umbenennen
              </button>
              <button className="context-menu-item danger" onClick={() => { if (contextMenu.id) handleDeleteBlock(contextMenu.id); closeContextMenu(); }}>
                🗑️ Löschen
              </button>
            </>
          )}
        </div>
      )}
    </div>
  );
};

export default BlockLibraryTree;