const express = require('express');
const mongoose = require('mongoose');
const cors = require('cors');
const dotenv = require('dotenv');
const autocadRoutes = require('./routes/autocadRoutes');
const fs = require('fs');
const path = require('path');

// Load environment variables
dotenv.config();

// Initialize express app
const app = express();

// Middleware
app.use(cors());
app.use(express.json({ limit: '10mb' })); // Increase payload limit

// Set timeout for requests
app.use((req, res, next) => {
  res.setTimeout(30000, () => {
    console.error('Request timeout');
    res.status(408).send('Request Timeout');
  });
  next();
});

// Error handling middleware
app.use((err, req, res, next) => {
  console.error('Server error:', err);
  res.status(500).send('Internal Server Error');
});

// Serve static files from the public directory
app.use(express.static('public'));

// Create storage directory if it doesn't exist
const dataDir = path.join(__dirname, 'data');
if (!fs.existsSync(dataDir)) {
  fs.mkdirSync(dataDir);
}

// Initialize event storage by categories
global.autocadEvents = {
  all: [],
  blockEvents: {
    added: [],
    erased: [],
    stretched: [],
    rotated: [],
    scaled: [],
    moved: [],
    attributesChanged: [],
    modified: []
  },
  entityEvents: {
    added: [],
    erased: [],
    stretched: [],
    modified: []
  }
};

// Add a store of SSE clients for real-time updates
const sseClients = [];

// Performance monitoring
let eventCount = 0;
let lastSaveTime = Date.now();
const MAX_EVENTS_IN_MEMORY = 10000; // Limit total events in memory

// Middleware to handle SSE connections
app.get('/api/sse', (req, res) => {
  // Set headers for SSE
  res.writeHead(200, {
    'Content-Type': 'text/event-stream',
    'Cache-Control': 'no-cache',
    'Connection': 'keep-alive'
  });
  
  // Send initial connection established message
  res.write('event: connected\n');
  res.write('data: Connection established\n\n');
  
  // Add this client to the list
  const clientId = Date.now();
  const newClient = {
    id: clientId,
    res
  };
  sseClients.push(newClient);
  
  // Handle client disconnect
  req.on('close', () => {
    console.log(`SSE Client ${clientId} disconnected`);
    const index = sseClients.findIndex(client => client.id === clientId);
    if (index !== -1) {
      sseClients.splice(index, 1);
    }
  });
});

// Function to notify all SSE clients of a new event
function notifyClientsOfNewEvent(event) {
  const failedClients = [];
  
  sseClients.forEach((client, index) => {
    try {
      client.res.write(`event: new-event\n`);
      client.res.write(`data: ${JSON.stringify(event)}\n\n`);
    } catch (error) {
      console.error(`Error sending to client ${client.id}:`, error);
      failedClients.push(index);
    }
  });
  
  // Remove failed clients (in reverse order to avoid index issues)
  failedClients.reverse().forEach(index => {
    console.log(`Removing failed SSE client ${sseClients[index].id}`);
    sseClients.splice(index, 1);
  });
}

// Routes
app.use('/api', autocadRoutes);

// Add connection test endpoint
app.post('/api/connection-test', (req, res) => {
  console.log('Connection test received');
  res.status(200).json({ success: true, message: 'Connection successful', serverTime: new Date().toISOString() });
});

// Add custom event handling middleware
app.post('/api/events', (req, res) => {
  try {
    const eventData = req.body;
    
    // Handle connection test events specially
    if (eventData.EventType === 'ConnectionTest') {
      console.log('AutoCAD connection test received');
      return res.status(200).json({ 
        success: true, 
        message: 'Connection test successful',
        serverTime: new Date().toISOString(),
        eventsCount: global.autocadEvents.all.length
      });
    }
    
    // Add timestamp if not provided
    if (!eventData.timestamp) {
      eventData.timestamp = new Date().toISOString();
    }
    
    // Store in global all events array
    global.autocadEvents.all.push(eventData);
    eventCount++;
    
    // Limit memory usage by removing old events if we exceed MAX_EVENTS_IN_MEMORY
    if (global.autocadEvents.all.length > MAX_EVENTS_IN_MEMORY) {
      const excess = global.autocadEvents.all.length - MAX_EVENTS_IN_MEMORY;
      
      // Remove oldest events
      const removed = global.autocadEvents.all.splice(0, excess);
      console.log(`Memory limit reached: Removed ${removed.length} old events`);
      
      // Also remove from specific event arrays
      for (const category of Object.keys(global.autocadEvents.blockEvents)) {
        if (global.autocadEvents.blockEvents[category].length > MAX_EVENTS_IN_MEMORY / 10) {
          const categoryExcess = global.autocadEvents.blockEvents[category].length - (MAX_EVENTS_IN_MEMORY / 10);
          global.autocadEvents.blockEvents[category].splice(0, categoryExcess);
        }
      }
      
      for (const category of Object.keys(global.autocadEvents.entityEvents)) {
        if (global.autocadEvents.entityEvents[category].length > MAX_EVENTS_IN_MEMORY / 10) {
          const categoryExcess = global.autocadEvents.entityEvents[category].length - (MAX_EVENTS_IN_MEMORY / 10);
          global.autocadEvents.entityEvents[category].splice(0, categoryExcess);
        }
      }
    }
    
    // Categorize by event type
    const eventType = eventData.EventType;
    
    // Handle block-specific events
    if (eventType.startsWith('Block')) {
      switch (eventType) {
        case 'BlockAdded':
          global.autocadEvents.blockEvents.added.push(eventData);
          break;
        case 'BlockErased':
          global.autocadEvents.blockEvents.erased.push(eventData);
          break;
        case 'BlockStretched':
          global.autocadEvents.blockEvents.stretched.push(eventData);
          break;
        case 'BlockRotated':
          global.autocadEvents.blockEvents.rotated.push(eventData);
          break;
        case 'BlockScaled':
          global.autocadEvents.blockEvents.scaled.push(eventData);
          break;
        case 'BlockMoved':
          global.autocadEvents.blockEvents.moved.push(eventData);
          break;
        case 'BlockAttributesChanged':
          global.autocadEvents.blockEvents.attributesChanged.push(eventData);
          break;
        case 'BlockModified':
          global.autocadEvents.blockEvents.modified.push(eventData);
          break;
      }
    } else {
      // Handle non-block entity events
      switch (eventType) {
        case 'Added':
          global.autocadEvents.entityEvents.added.push(eventData);
          break;
        case 'Erased':
          global.autocadEvents.entityEvents.erased.push(eventData);
          break;
        case 'Stretched':
          global.autocadEvents.entityEvents.stretched.push(eventData);
          break;
        case 'Modified':
          global.autocadEvents.entityEvents.modified.push(eventData);
          break;
      }
    }
    
    // Notify all connected clients of the new event
    notifyClientsOfNewEvent(eventData);
    
    // Periodically save events to disk (every 20 events or 5 minutes)
    const currentTime = Date.now();
    if (eventCount % 20 === 0 || (currentTime - lastSaveTime) > 300000) {
      saveEventsToDisk();
      lastSaveTime = currentTime;
    }
    
    // Enhanced logging based on event type
    if (eventType.startsWith('Block')) {
      // Basic log message with event type and block name
      console.log(`Received ${eventType} event for ${eventData.BlockName}`);
      
      // Use the formatting function for detailed output
      if (process.env.VERBOSE_LOGGING === 'true') {
        console.log(formatBlockData(eventData));
      }
      
      // Add specific position change logging
      if (eventType === 'BlockMoved' && eventData.OldPosition && eventData.NewPosition) {
        console.log(`POSITION CHANGE: From (${eventData.OldPosition.X.toFixed(2)}, ${eventData.OldPosition.Y.toFixed(2)}, ${eventData.OldPosition.Z.toFixed(2)}) to (${eventData.NewPosition.X.toFixed(2)}, ${eventData.NewPosition.Y.toFixed(2)}, ${eventData.NewPosition.Z.toFixed(2)})`);
      }
    } else {
      // Standard logging for non-block events
      console.log(`Received ${eventType} event for ${eventData.ObjectType}`);
    }
    
    res.status(200).json({ success: true, message: 'Event received' });
  } catch (error) {
    console.error('Error processing event:', error);
    res.status(500).json({ success: false, message: 'Error processing event' });
  }
});

// Add endpoints to get events by type
app.get('/api/events', (req, res) => {
  res.json(global.autocadEvents.all);
});

app.get('/api/events/blocks', (req, res) => {
  res.json(global.autocadEvents.blockEvents);
});

app.get('/api/events/blocks/:type', (req, res) => {
  const eventType = req.params.type;
  if (global.autocadEvents.blockEvents[eventType]) {
    res.json(global.autocadEvents.blockEvents[eventType]);
  } else {
    res.status(404).json({ message: 'Event type not found' });
  }
});

app.get('/api/events/entities', (req, res) => {
  res.json(global.autocadEvents.entityEvents);
});

app.get('/api/events/entities/:type', (req, res) => {
  const eventType = req.params.type;
  if (global.autocadEvents.entityEvents[eventType]) {
    res.json(global.autocadEvents.entityEvents[eventType]);
  } else {
    res.status(404).json({ message: 'Event type not found' });
  }
});

// Add an endpoint to clear events
app.delete('/api/events', (req, res) => {
  global.autocadEvents = {
    all: [],
    blockEvents: {
      added: [],
      erased: [],
      stretched: [],
      rotated: [],
      scaled: [],
      moved: [],
      attributesChanged: [],
      modified: []
    },
    entityEvents: {
      added: [],
      erased: [],
      stretched: [],
      modified: []
    }
  };
  res.json({ success: true, message: 'All events cleared' });
});

// Function to save events to disk
function saveEventsToDisk() {
  try {
    const timestamp = new Date().toISOString().replace(/:/g, '-');
    const filePath = path.join(dataDir, `events_${timestamp}.json`);
    
    // Use a more memory-efficient approach for large event arrays
    if (global.autocadEvents.all.length > 1000) {
      // Write to file stream instead of creating a large string in memory
      const fileStream = fs.createWriteStream(filePath);
      fileStream.write('{\n');
      fileStream.write('"all": [\n');
      
      global.autocadEvents.all.forEach((event, index) => {
        const eventJson = JSON.stringify(event);
        fileStream.write(eventJson);
        if (index < global.autocadEvents.all.length - 1) {
          fileStream.write(',\n');
        } else {
          fileStream.write('\n');
        }
      });
      
      fileStream.write('],\n');
      fileStream.write('"blockEvents": ' + JSON.stringify(global.autocadEvents.blockEvents) + ',\n');
      fileStream.write('"entityEvents": ' + JSON.stringify(global.autocadEvents.entityEvents) + '\n');
      fileStream.write('}');
      fileStream.end();
      
      console.log(`Events saved to ${filePath} (stream method)`);
    } else {
      // For smaller datasets, use the simpler approach
      fs.writeFileSync(filePath, JSON.stringify(global.autocadEvents, null, 2));
      console.log(`Events saved to ${filePath}`);
    }
  } catch (error) {
    console.error('Error saving events to disk:', error);
  }
}

// Connect to MongoDB (optional - comment out if you don't want to use it)
// mongoose.connect(process.env.MONGODB_URI || 'mongodb://localhost:27017/autocad_tracker')
//   .then(() => console.log('Connected to MongoDB'))
//   .catch(err => console.error('Could not connect to MongoDB', err));

// Default route
app.get('/', (req, res) => {
  res.redirect('/index.html');
});

// Legacy route for backward compatibility
app.get('/attribute-history', (req, res) => {
  res.redirect('/index.html');
});

// Update the formatBlockData function for better color formatting
function formatBlockData(block) {
  let output = '';
  
  // Add basic block info
  output += `\n--- Block Details ---`;
  output += `\nName: ${block.BlockName}`;
  output += `\nObject ID: ${block.ObjectId}`;
  
  // Add position information
  if (block.NewPosition) {
    output += `\nPosition: (${block.NewPosition.X.toFixed(2)}, ${block.NewPosition.Y.toFixed(2)}, ${block.NewPosition.Z.toFixed(2)})`;
    
    // Add old position if available (for moved blocks)
    if (block.OldPosition) {
      output += `\nOld Position: (${block.OldPosition.X.toFixed(2)}, ${block.OldPosition.Y.toFixed(2)}, ${block.OldPosition.Z.toFixed(2)})`;
    }
  } else if (block.Position) {
    output += `\nPosition: (${block.Position.X.toFixed(2)}, ${block.Position.Y.toFixed(2)}, ${block.Position.Z.toFixed(2)})`;
  }
  
  // Add rotation information
  if (block.NewRotation !== undefined) {
    output += `\nRotation: ${(block.NewRotation * 180 / Math.PI).toFixed(2)} degrees`;
    
    // Add old rotation if available
    if (block.OldRotation !== undefined) {
      output += `\nOld Rotation: ${(block.OldRotation * 180 / Math.PI).toFixed(2)} degrees`;
    }
  }
  
  // Add scale information
  if (block.NewScale) {
    output += `\nScale: X=${block.NewScale.X.toFixed(3)}, Y=${block.NewScale.Y.toFixed(3)}, Z=${block.NewScale.Z.toFixed(3)}`;
    
    // Add old scale if available
    if (block.OldScale) {
      output += `\nOld Scale: X=${block.OldScale.X.toFixed(3)}, Y=${block.OldScale.Y.toFixed(3)}, Z=${block.OldScale.Z.toFixed(3)}`;
    }
  }
  
  // Add attribute information
  if (block.Attributes && Object.keys(block.Attributes).length > 0) {
    output += `\nAttributes:`;
    for (const [key, value] of Object.entries(block.Attributes)) {
      output += `\n  ${key}: ${value}`;
    }
  } else {
    output += `\nNo attributes`;
  }
  
  // Add attribute changes if available
  if (block.AttributeChanges && Object.keys(block.AttributeChanges).length > 0) {
    output += `\nAttribute Changes:`;
    for (const [key, change] of Object.entries(block.AttributeChanges)) {
      output += `\n  ${key}: "${change.OldValue}" -> "${change.NewValue}"`;
    }
  }
  
  return output;
}

// Add an endpoint to view detailed block information
app.get('/api/events/blocks/details/:id', (req, res) => {
  const blockId = req.params.id;
  
  // Search for the block in all categories
  const allBlocks = Object.values(global.autocadEvents.blockEvents)
    .flat()
    .filter(event => event.ObjectId === blockId);
  
  if (allBlocks.length === 0) {
    return res.status(404).json({ message: 'Block not found' });
  }
  
  // Get the latest block data
  const latestBlock = allBlocks[allBlocks.length - 1];
  
  // Format the block data
  const formattedData = {
    blockData: latestBlock,
    formatted: formatBlockData(latestBlock),
    history: allBlocks.map(block => ({
      timestamp: block.Timestamp,
      eventType: block.EventType
    }))
  };
  
  res.json(formattedData);
});

// Add an endpoint to get a list of all blocks with their latest attributes
app.get('/api/blocks', (req, res) => {
  // Get all block events
  const allBlockEvents = global.autocadEvents.all.filter(event => 
    event.EventType && event.EventType.startsWith('Block')
  );
  
  // Create a map to store the latest state of each block
  const blockMap = new Map();
  
  // Process events to get the latest state of each block
  allBlockEvents.forEach(event => {
    // Use object ID as the unique identifier
    const blockId = event.ObjectId;
    
    // Update the map with the latest event for each block
    blockMap.set(blockId, event);
  });
  
  // Convert map to array of blocks
  const blocks = Array.from(blockMap.values()).map(block => ({
    id: block.ObjectId,
    name: block.BlockName,
    position: block.NewPosition || block.Position,
    attributes: block.Attributes || {},
    lastEventType: block.EventType,
    timestamp: block.Timestamp
  }));
  
  res.json(blocks);
});

// Add an endpoint to get all attribute changes
app.get('/api/blocks/attribute-changes', (req, res) => {
  const attributeChanges = global.autocadEvents.blockEvents.attributesChanged;
  
  // Process attribute changes to make them more meaningful
  const processedChanges = attributeChanges.map(event => {
    // Extract basic information
    const { BlockName, ObjectId, Timestamp, Attributes, AttributeChanges } = event;
    
    // Process each changed attribute
    const changes = [];
    if (AttributeChanges) {
      for (const [tag, change] of Object.entries(AttributeChanges)) {
        changes.push({
          tag,
          oldValue: change.OldValue,
          newValue: change.NewValue,
          changeTime: Timestamp
        });
      }
    }
    
    return {
      blockName: BlockName,
      objectId: ObjectId,
      timestamp: Timestamp,
      currentAttributes: Attributes || {},
      changes
    };
  });
  
  res.json(processedChanges);
});

// Add an endpoint to get attribute change history for a specific block
app.get('/api/blocks/:id/attribute-history', (req, res) => {
  const blockId = req.params.id;
  
  // Find all attribute change events for this block
  const attributeChanges = global.autocadEvents.all
    .filter(event => 
      event.ObjectId === blockId && 
      (event.AttributeChanges || event.EventType === 'BlockAttributesChanged')
    )
    .sort((a, b) => new Date(a.Timestamp) - new Date(b.Timestamp));
  
  if (attributeChanges.length === 0) {
    return res.status(404).json({ message: 'No attribute changes found for this block' });
  }
  
  // Process the attribute history
  const history = [];
  const latestAttributes = {};
  
  attributeChanges.forEach(event => {
    const timestamp = event.Timestamp;
    
    // Track changes for each attribute
    if (event.AttributeChanges) {
      for (const [tag, change] of Object.entries(event.AttributeChanges)) {
        history.push({
          tag,
          oldValue: change.OldValue,
          newValue: change.NewValue,
          timestamp,
          blockName: event.BlockName
        });
        
        // Update latest attribute value
        latestAttributes[tag] = change.NewValue;
      }
    }
    
    // Also get initial values from Attributes field if present
    if (event.Attributes && Object.keys(event.Attributes).length > 0) {
      for (const [tag, value] of Object.entries(event.Attributes)) {
        if (!latestAttributes[tag]) {
          latestAttributes[tag] = value;
        }
      }
    }
  });
  
  // Return formatted response
  res.json({
    blockId,
    blockName: attributeChanges[0].BlockName,
    latestAttributes,
    history
  });
});

// Add an endpoint to get position change history for a specific block
app.get('/api/blocks/:id/position-history', (req, res) => {
  const blockId = req.params.id;
  
  // Find all position change events for this block
  const positionChanges = global.autocadEvents.all
    .filter(event => 
      event.ObjectId === blockId && 
      (event.EventType === 'BlockMoved' || 
       event.EventType === 'BlockModified' ||
       event.EventType === 'BlockAdded') && 
      (event.NewPosition || event.Position)
    )
    .sort((a, b) => new Date(a.Timestamp) - new Date(b.Timestamp));
  
  if (positionChanges.length === 0) {
    return res.status(404).json({ message: 'No position changes found for this block' });
  }
  
  // Process the position history
  const history = positionChanges.map(event => {
    const entry = {
      timestamp: event.Timestamp,
      eventType: event.EventType,
      blockName: event.BlockName
    };
    
    // Add position data
    if (event.NewPosition) {
      entry.position = {
        x: event.NewPosition.X,
        y: event.NewPosition.Y,
        z: event.NewPosition.Z
      };
      
      // Add old position if available
      if (event.OldPosition) {
        entry.oldPosition = {
          x: event.OldPosition.X,
          y: event.OldPosition.Y,
          z: event.OldPosition.Z
        };
      }
    } else if (event.Position) {
      entry.position = {
        x: event.Position.X,
        y: event.Position.Y,
        z: event.Position.Z
      };
    }
    
    return entry;
  });
  
  // Get latest position
  const latestEvent = positionChanges[positionChanges.length - 1];
  const latestPosition = latestEvent.NewPosition || latestEvent.Position;
  
  // Return formatted response
  res.json({
    blockId,
    blockName: positionChanges[0].BlockName,
    latestPosition: {
      x: latestPosition.X,
      y: latestPosition.Y,
      z: latestPosition.Z
    },
    history
  });
});

// Add an endpoint to get server status and performance metrics
app.get('/api/status', (req, res) => {
  const status = {
    uptime: process.uptime(),
    memoryUsage: process.memoryUsage(),
    eventsCount: {
      total: global.autocadEvents.all.length,
      blocks: Object.keys(global.autocadEvents.blockEvents).reduce(
        (total, key) => total + global.autocadEvents.blockEvents[key].length, 0
      ),
      entities: Object.keys(global.autocadEvents.entityEvents).reduce(
        (total, key) => total + global.autocadEvents.entityEvents[key].length, 0
      )
    },
    sseClients: sseClients.length,
    lastSaveTime: new Date(lastSaveTime).toISOString()
  };
  
  res.json(status);
});

// Add an endpoint for checking server status (lightweight compared to SSE)
app.get('/api/server-status', (req, res) => {
  res.json({
    status: 'online',
    timestamp: new Date().toISOString(),
    uptime: process.uptime()
  });
});

// Start server
const PORT = process.env.PORT || 3000;
app.listen(PORT, () => {
  console.log(`Server is running on port ${PORT}`);
  console.log(`API endpoints available at:`);
  console.log(`  - GET /api/events: Get all events`);
  console.log(`  - GET /api/events/blocks: Get all block events`);
  console.log(`  - GET /api/events/blocks/:type: Get block events by type`);
  console.log(`  - GET /api/events/entities: Get all entity events`);
  console.log(`  - GET /api/events/entities/:type: Get entity events by type`);
  console.log(`  - DELETE /api/events: Clear all events`);
  console.log(`  - GET /api/events/blocks/details/:id: Get detailed block information`);
  console.log(`  - GET /api/blocks: Get a list of all blocks with their latest attributes`);
  console.log(`  - GET /api/blocks/attribute-changes: Get all attribute changes`);
  console.log(`  - GET /api/blocks/:id/attribute-history: Get attribute change history for a specific block`);
  console.log(`  - GET /api/blocks/:id/position-history: Get position change history for a specific block`);
  console.log(`  - GET /api/status: Get server status and performance metrics`);
  console.log(`  - GET /api/server-status: Get server status (lightweight)`);
  console.log(`  - Front-end interface available at: http://localhost:${PORT}`);
});