import { create } from 'zustand';
import { v4 as uuidv4 } from 'uuid';
import { FileNode, getFiles, saveFile, deleteFile } from '../lib/db';
import { arrayMove } from '@dnd-kit/sortable';

interface FileStore {
  files: FileNode[];
  activeFileId: string | null;
  selectedIds: string[];
  
  loadFiles: () => Promise<void>;
  setActiveFile: (id: string | null, skipHistory?: boolean) => void;
  navigationHistory: string[];
  historyIndex: number;
  goBack: () => void;
  goForward: () => void;
  toggleSelect: (id: string, multi: boolean) => void;
  clearSelection: () => void;
  
  createNode: (name: string, type: 'file' | 'folder', parentId: string | null) => Promise<string>;
  renameNode: (id: string, newName: string) => Promise<void>;
  deleteNode: (id: string) => Promise<void>;
  duplicateNode: (id: string) => Promise<void>;
  updateFileContent: (id: string, content: string) => Promise<void>;
  moveNode: (id: string, newParentId: string | null) => Promise<void>;
  reorderNodes: (activeId: string, overId: string, newParentId: string | null) => Promise<void>;
  setNodeIcon: (id: string, icon: string) => Promise<void>;
  setNodeColor: (id: string, color: string) => Promise<void>;
  setComment: (fileId: string, lineId: string, comment: string) => Promise<void>;
  copySelectedContents: () => string;
  copyNodeContents: (id: string) => string;
}

export const useFileStore = create<FileStore>((set, get) => ({
  files: [],
  activeFileId: null,
  selectedIds: [],
  navigationHistory: [],
  historyIndex: -1,

  loadFiles: async () => {
    const data = await getFiles();
    // Sort all files by orderIndex initially
    const sorted = [...data].sort((a, b) => a.orderIndex - b.orderIndex);
    set({ files: sorted });
  },

  setActiveFile: (id, skipHistory = false) => {
    const { navigationHistory, historyIndex } = get();
    if (id && !skipHistory) {
      const newHistory = navigationHistory.slice(0, historyIndex + 1);
      // Only push if it's different from current
      if (newHistory[newHistory.length - 1] !== id) {
        newHistory.push(id);
        // Limit history to 50 items
        if (newHistory.length > 50) newHistory.shift();
        set({ 
          activeFileId: id, 
          selectedIds: [id],
          navigationHistory: newHistory,
          historyIndex: newHistory.length - 1
        });
        return;
      }
    }
    set({ activeFileId: id, selectedIds: id ? [id] : [] });
  },

  goBack: () => {
    const { navigationHistory, historyIndex, setActiveFile } = get();
    if (historyIndex > 0) {
      const newIndex = historyIndex - 1;
      set({ historyIndex: newIndex });
      setActiveFile(navigationHistory[newIndex], true);
    }
  },

  goForward: () => {
    const { navigationHistory, historyIndex, setActiveFile } = get();
    if (historyIndex < navigationHistory.length - 1) {
      const newIndex = historyIndex + 1;
      set({ historyIndex: newIndex });
      setActiveFile(navigationHistory[newIndex], true);
    }
  },

  toggleSelect: (id, multi) => {
    const { selectedIds } = get();
    if (multi) {
      set({ selectedIds: selectedIds.includes(id) 
        ? selectedIds.filter(i => i !== id) 
        : [...selectedIds, id] 
      });
    } else {
      set({ selectedIds: [id], activeFileId: id });
    }
  },

  clearSelection: () => set({ selectedIds: [] }),

  createNode: async (name, type, parentId) => {
    const { files } = get();
    // Find max orderIndex in current parent
    const peerIndices = files.filter(f => f.parentId === parentId).map(f => f.orderIndex);
    const nextIndex = peerIndices.length > 0 ? Math.max(...peerIndices) + 1 : 0;

    const newNode: FileNode = {
      id: uuidv4(),
      name,
      type,
      parentId,
      content: type === 'file' ? '' : undefined,
      orderIndex: nextIndex
    };
    await saveFile(newNode);
    set(state => ({ files: [...state.files, newNode] }));
    return newNode.id;
  },

  renameNode: async (id, newName) => {
    const { files } = get();
    const node = files.find(f => f.id === id);
    if (!node) return;
    const updated = { ...node, name: newName };
    await saveFile(updated);
    set(state => ({ files: state.files.map(f => f.id === id ? updated : f) }));
  },

  deleteNode: async (id) => {
    const { files, activeFileId, selectedIds } = get();
    
    // Recursive delete logic
    const toDelete = new Set<string>();
    const findChildren = (nodeId: string) => {
      toDelete.add(nodeId);
      files.forEach(f => {
        if (f.parentId === nodeId) findChildren(f.id);
      });
    };
    findChildren(id);

    // DB delete
    for (const delId of toDelete) {
      await deleteFile(delId);
    }
    
    set(state => ({
      files: state.files.filter(f => !toDelete.has(f.id)),
      activeFileId: activeFileId && toDelete.has(activeFileId) ? null : state.activeFileId,
      selectedIds: selectedIds.filter(sid => !toDelete.has(sid)),
    }));
  },

  duplicateNode: async (id) => {
    const { files, createNode } = get();
    const node = files.find(f => f.id === id);
    if (!node) return;
    await createNode(`${node.name} (copy)`, node.type, node.parentId);
  },

  // Write queue for updating contents to prevent rapid IDB transaction crashes
  updateFileContent: (() => {
    let writeQueue = Promise.resolve();
    return async (id: string, content: string) => {
      writeQueue = writeQueue.then(async () => {
        const { files } = get();
        const node = files.find(f => f.id === id);
        if (!node) return;
        const updated = { ...node, content };
        await saveFile(updated);
        set(state => ({ files: state.files.map(f => f.id === id ? updated : f) }));
      }).catch(console.error);
      return writeQueue;
    };
  })(),

  moveNode: async (id, newParentId) => {
    const { files } = get();
    const node = files.find(f => f.id === id);
    if (!node) return;
    
    // Auto-calculate new index at end of target parent
    const peerIndices = files.filter(f => f.parentId === newParentId).map(f => f.orderIndex);
    const nextIndex = peerIndices.length > 0 ? Math.max(...peerIndices) + 1 : 0;

    const updated = { ...node, parentId: newParentId, orderIndex: nextIndex };
    await saveFile(updated);
    set(state => ({ files: state.files.map(f => f.id === id ? updated : f) }));
  },

  reorderNodes: async (activeId, overId, newParentId) => {
    const { files } = get();
    const activeNode = files.find(f => f.id === activeId);
    if (!activeNode) return;

    const peerNodes = files.filter(f => f.parentId === newParentId).sort((a,b) => a.orderIndex - b.orderIndex);
    const oldIndex = peerNodes.findIndex(n => n.id === activeId);
    const newIndex = peerNodes.findIndex(n => n.id === overId);

    if (oldIndex !== -1 && newIndex !== -1) {
      const newOrder = arrayMove(peerNodes, oldIndex, newIndex);
      // Batch update all peer indices
      const updates = newOrder.map((node, idx) => ({ ...node, orderIndex: idx, parentId: newParentId }));
      
      for (const updated of updates) {
        await saveFile(updated);
      }
      
      set(state => ({
        files: state.files.map(f => {
          const match = updates.find(u => u.id === f.id);
          return match || f;
        })
      }));
    } else if (activeNode.parentId !== newParentId) {
      // Different parent move
      await get().moveNode(activeId, newParentId);
    }
  },

  copySelectedContents: () => {
    const { files, selectedIds } = get();
    const contents: string[] = [];

    const addNodeContent = (id: string, depth = 0) => {
      const node = files.find(f => f.id === id);
      if (!node) return;

      if (node.type === 'folder') {
        files.filter(f => f.parentId === id)
             .sort((a,b) => a.orderIndex - b.orderIndex)
             .forEach(child => addNodeContent(child.id, depth + 1));
      } else {
        try {
          const parsed = JSON.parse(node.content || '{}');
          const extractText = (nodes: any[]): string => {
            return nodes?.map(n => {
              if (n.type === 'linebreak') return '\n';
              if (n.children) return extractText(n.children) + (n.type === 'paragraph' ? '\n' : '');
              return n.text || '';
            }).join('') || '';
          };
          const plainText = extractText(parsed.root?.children || []);
          const prefixed = plainText.split('\n').map(line => line.trim().length > 0 ? `— ${line.trim()}` : line).join('\n');
          if (prefixed) contents.push(prefixed);
        } catch {
          if (node.content && node.content.trim().length > 0) {
            const prefixed = node.content.split('\n').map(line => line.trim().length > 0 ? `— ${line.trim()}` : line).join('\n');
            contents.push(prefixed);
          }
        }
      }
    };

    selectedIds.forEach(id => addNodeContent(id));
    return contents.join('\n');
  },

  copyNodeContents: (id) => {
    const { files } = get();
    const contents: string[] = [];

    const addNodeContent = (nodeId: string, depth = 0) => {
      const node = files.find(f => f.id === nodeId);
      if (!node) return;

      if (node.type === 'folder') {
        files.filter(f => f.parentId === nodeId)
             .sort((a,b) => a.orderIndex - b.orderIndex)
             .forEach(child => addNodeContent(child.id, depth + 1));
      } else {
        try {
          const parsed = JSON.parse(node.content || '{}');
          const extractText = (nodes: any[]): string => {
            return nodes?.map(n => {
              if (n.type === 'linebreak') return '\n';
              if (n.children) return extractText(n.children) + (n.type === 'paragraph' ? '\n' : '');
              return n.text || '';
            }).join('') || '';
          };
          const plainText = extractText(parsed.root?.children || []);
          const prefixed = plainText.split('\n').map(line => line.trim().length > 0 ? `— ${line.trim()}` : line).join('\n');
          if (prefixed) contents.push(prefixed);
        } catch {
          if (node.content && node.content.trim().length > 0) {
            const prefixed = node.content.split('\n').map(line => line.trim().length > 0 ? `— ${line.trim()}` : line).join('\n');
            contents.push(prefixed);
          }
        }
      }
    };

    addNodeContent(id);
    return contents.join('\n');
  },

  setNodeIcon: async (id, icon) => {
    const { files } = get();
    const node = files.find(f => f.id === id);
    if (!node) return;
    const updated = { ...node, icon };
    await saveFile(updated);
    set(state => ({ files: state.files.map(f => f.id === id ? updated : f) }));
  },

  setNodeColor: async (id, color) => {
    const { files } = get();
    const node = files.find(f => f.id === id);
    if (!node) return;
    const updated = { ...node, color };
    await saveFile(updated);
    set(state => ({ files: state.files.map(f => f.id === id ? updated : f) }));
  },

  setComment: async (fileId, lineId, comment) => {
    const { files } = get();
    const node = files.find(f => f.id === fileId);
    if (!node) return;
    
    const newComments = { ...node.comments, [lineId]: comment };
    if (!comment) delete newComments[lineId];
    
    const updated = { ...node, comments: newComments };
    await saveFile(updated);
    set(state => ({ files: state.files.map(f => f.id === fileId ? updated : f) }));
  }
}));