import express from 'express';
import { WebSocketServer } from 'ws';
import cors from 'cors';
import { createServer } from 'http';
import fs from 'fs';
import path from 'path';
import { fileURLToPath } from 'url';
import {
  loadFullState, saveFullState, recordItemHistory,
  saveItems, saveFurnaces, saveAlerts, saveState,
  getHistory, getHistorySummary, closeDb, flushPendingSave,
} from './db.js';

const __filename = fileURLToPath(import.meta.url);
const __dirname = path.dirname(__filename);

const app = express();
const PORT = process.env.PORT || 3001;
const HOST = process.env.HOST || '0.0.0.0';

app.use(cors());
app.use(express.json({ limit: '5mb' }));

// ========== State ==========
const webClients = new Set();
const bridgeClients = new Set();

// Load persisted state from SQLite on startup
console.log('💾 Loading persisted state from database...');
const persisted = loadFullState();

let inventoryState = persisted.inventoryState;
let activityState = persisted.activityState;
let alertsState = persisted.alertsState;
let smeltingPaused = persisted.smeltingPaused;
let disabledRecipes = persisted.disabledRecipes;
let smeltableRecipes = persisted.smeltableRecipes;
let craftableRecipes = persisted.craftableRecipes;
let craftTurtleOk = persisted.craftTurtleOk;
let lastUpdate = persisted.lastUpdate;

if (lastUpdate > 0) {
  const ago = Math.round((Date.now() - lastUpdate) / 1000);
  console.log(`💾 Restored state from ${ago}s ago (${inventoryState.itemList.length} items)`);
} else {
  console.log('💾 No previous state found, starting fresh');
}

// Pending commands for bridge HTTP polling (fallback)
let pendingCommands = [];

// ========== Helpers ==========

function broadcastToClients(data) {
  const message = JSON.stringify(data);
  webClients.forEach((client) => {
    if (client.readyState === 1) {
      client.send(message);
    }
  });
}

function pushCommandToBridge(command) {
  let sent = false;
  for (const bridge of bridgeClients) {
    if (bridge.readyState === 1) {
      bridge.send(JSON.stringify(command));
      sent = true;
    }
  }
  if (!sent) {
    // Fallback: queue for HTTP polling
    pendingCommands.push({ ...command, timestamp: Date.now() });
    console.log(`[Bridge] Queued command via HTTP poll (no WS bridge)`);
  }
}

// ========== HTTP Server ==========
const server = createServer(app);

// ========== Texture Proxy / Cache ==========
const TEXTURE_CACHE_DIR = process.env.TEXTURE_CACHE_DIR || path.join('/data', 'texture-cache');
const NEGATIVE_CACHE_TTL = 7 * 24 * 60 * 60 * 1000; // 7 days for 404s

// Upstream CDN mapping
const TEXTURE_UPSTREAMS = {
  minecraft: 'https://cdn.jsdelivr.net/gh/InventivetalentDev/minecraft-assets@1.21.4/assets/minecraft/textures',
  computercraft: 'https://raw.githubusercontent.com/cc-tweaked/CC-Tweaked/mc-1.20.x/projects/common/src/main/resources/assets/computercraft/textures',
  create: 'https://raw.githubusercontent.com/Creators-of-Create/Create/mc1.20.1/dev/src/main/resources/assets/create/textures',
};

// Ensure cache directory exists
fs.mkdirSync(TEXTURE_CACHE_DIR, { recursive: true });

app.get('/api/texture/:namespace/*', async (req, res) => {
  const { namespace } = req.params;
  const texturePath = req.params[0]; // e.g. "item/diamond.png"

  const upstream = TEXTURE_UPSTREAMS[namespace];
  if (!upstream) {
    return res.status(404).send('Unknown namespace');
  }

  // Sanitize path to prevent directory traversal
  const safePath = path.normalize(texturePath).replace(/^(\.\.(\/|\\|$))+/, '');
  if (safePath.includes('..')) {
    return res.status(400).send('Invalid path');
  }

  const cacheFile = path.join(TEXTURE_CACHE_DIR, namespace, safePath);
  const cacheDir = path.dirname(cacheFile);
  const missFile = cacheFile + '.miss';

  // Check positive cache
  try {
    if (fs.existsSync(cacheFile)) {
      res.set('Content-Type', 'image/png');
      res.set('Cache-Control', 'public, max-age=604800'); // 7 days
      res.set('X-Texture-Cache', 'HIT');
      return res.sendFile(cacheFile);
    }
  } catch (_) { /* proceed to fetch */ }

  // Check negative cache (cached 404s)
  try {
    if (fs.existsSync(missFile)) {
      const stat = fs.statSync(missFile);
      const age = Date.now() - stat.mtimeMs;
      if (age < NEGATIVE_CACHE_TTL) {
        res.set('X-Texture-Cache', 'MISS-HIT');
        return res.status(404).send('Not found (cached)');
      }
      // Expired negative cache, remove it
      fs.unlinkSync(missFile);
    }
  } catch (_) { /* proceed to fetch */ }

  // Fetch from upstream
  const upstreamUrl = `${upstream}/${safePath}`;
  try {
    const response = await fetch(upstreamUrl);

    if (!response.ok) {
      // Cache the 404 so we don't keep hitting upstream
      try {
        fs.mkdirSync(cacheDir, { recursive: true });
        fs.writeFileSync(missFile, `${response.status}`);
      } catch (_) { /* ignore cache write errors */ }
      res.set('X-Texture-Cache', 'UPSTREAM-MISS');
      return res.status(404).send('Not found');
    }

    // Save to disk cache
    const buffer = Buffer.from(await response.arrayBuffer());
    try {
      fs.mkdirSync(cacheDir, { recursive: true });
      fs.writeFileSync(cacheFile, buffer);
      // Remove any stale negative cache
      if (fs.existsSync(missFile)) fs.unlinkSync(missFile);
    } catch (_) { /* ignore cache write errors */ }

    res.set('Content-Type', response.headers.get('content-type') || 'image/png');
    res.set('Cache-Control', 'public, max-age=604800');
    res.set('X-Texture-Cache', 'UPSTREAM-HIT');
    return res.send(buffer);
  } catch (err) {
    console.error(`[Texture Proxy] Error fetching ${upstreamUrl}:`, err.message);
    return res.status(502).send('Upstream error');
  }
});

// Clear negative texture cache (.miss files) — call after updating texture mappings
app.delete('/api/texture-cache/negative', (req, res) => {
  let cleared = 0;
  function walk(dir) {
    try {
      for (const entry of fs.readdirSync(dir, { withFileTypes: true })) {
        const full = path.join(dir, entry.name);
        if (entry.isDirectory()) walk(full);
        else if (entry.name.endsWith('.miss')) { fs.unlinkSync(full); cleared++; }
      }
    } catch (_) { /* ignore */ }
  }
  walk(TEXTURE_CACHE_DIR);
  console.log(`[Texture Cache] Cleared ${cleared} negative cache entries`);
  res.json({ cleared });
});

// Health check
app.get('/api/health', (req, res) => {
  res.json({
    status: 'ok',
    lastUpdate,
    uptime: process.uptime(),
    bridgeConnected: bridgeClients.size > 0,
    webClients: webClients.size,
  });
});

// Get current inventory state
app.get('/api/inventory', (req, res) => {
  res.json({
    inventory: inventoryState,
    activity: activityState,
    alerts: alertsState,
    smeltingPaused,
    disabledRecipes,
    smeltable: smeltableRecipes,
    craftable: craftableRecipes,
    craftTurtleOk,
    lastUpdate,
    bridgeConnected: bridgeClients.size > 0,
  });
});

// Get just the item list
app.get('/api/items', (req, res) => {
  res.json({ items: inventoryState.itemList || [] });
});

// Get furnace status
app.get('/api/furnaces', (req, res) => {
  res.json({
    furnaceCount: inventoryState.furnaceCount,
    furnaceStatus: inventoryState.furnaceStatus,
    smeltingPaused,
  });
});

// Get alerts
app.get('/api/alerts', (req, res) => {
  res.json({ alerts: alertsState });
});

// Get item count history
app.get('/api/history/:itemName', (req, res) => {
  const limit = parseInt(req.query.limit) || 100;
  const history = getHistory(req.params.itemName, Math.min(limit, 1000));
  res.json({ item: req.params.itemName, history });
});

// Get aggregate storage history (total items over time)
app.get('/api/history-summary', (req, res) => {
  const summary = getHistorySummary();
  res.json({ history: summary });
});

// Get recipes (smeltable + craftable)
app.get('/api/recipes', (req, res) => {
  res.json({
    smeltable: smeltableRecipes,
    craftable: craftableRecipes,
    disabledRecipes,
    smeltingPaused,
  });
});

// ========== Command Endpoints ==========

// Order an item from storage
app.post('/api/order', (req, res) => {
  try {
    const { itemName, amount, dropperName } = req.body;
    if (!itemName || !amount) {
      return res.status(400).json({ error: 'Missing itemName or amount' });
    }
    
    const command = {
      type: 'command',
      action: 'order',
      itemName,
      amount: parseInt(amount),
      dropperName: dropperName || null,
    };
    
    pushCommandToBridge(command);
    console.log(`📦 Order: ${itemName} x${amount}`);
    res.json({ success: true, message: `Order sent: ${itemName} x${amount}` });
  } catch (error) {
    res.status(500).json({ error: error.message });
  }
});

// Request inventory scan
app.post('/api/scan', (req, res) => {
  try {
    pushCommandToBridge({ type: 'command', action: 'scan' });
    console.log('🔍 Scan requested');
    res.json({ success: true, message: 'Scan requested' });
  } catch (error) {
    res.status(500).json({ error: error.message });
  }
});

// Toggle smelting pause
app.post('/api/smelting/toggle', (req, res) => {
  try {
    pushCommandToBridge({ type: 'command', action: 'toggle_pause' });
    console.log('🔥 Smelting toggle requested');
    res.json({ success: true });
  } catch (error) {
    res.status(500).json({ error: error.message });
  }
});

// Toggle a specific recipe
app.post('/api/recipes/toggle', (req, res) => {
  try {
    const { recipe } = req.body;
    if (!recipe) return res.status(400).json({ error: 'Missing recipe name' });
    
    pushCommandToBridge({ type: 'command', action: 'toggle_recipe', recipe });
    console.log(`🔄 Recipe toggle: ${recipe}`);
    res.json({ success: true });
  } catch (error) {
    res.status(500).json({ error: error.message });
  }
});

// Enable/disable all recipes
app.post('/api/recipes/enable-all', (req, res) => {
  pushCommandToBridge({ type: 'command', action: 'enable_all' });
  res.json({ success: true });
});

app.post('/api/recipes/disable-all', (req, res) => {
  pushCommandToBridge({ type: 'command', action: 'disable_all' });
  res.json({ success: true });
});

// Sort barrel
app.post('/api/sort-barrel', (req, res) => {
  try {
    const { barrelName } = req.body;
    if (!barrelName) return res.status(400).json({ error: 'Missing barrelName' });
    
    pushCommandToBridge({ type: 'command', action: 'sort_barrel', barrelName });
    console.log(`📦 Sort barrel: ${barrelName}`);
    res.json({ success: true });
  } catch (error) {
    res.status(500).json({ error: error.message });
  }
});

// Craft item
app.post('/api/craft', (req, res) => {
  try {
    const { recipeIdx } = req.body;
    if (recipeIdx === undefined) return res.status(400).json({ error: 'Missing recipeIdx' });
    
    pushCommandToBridge({ type: 'command', action: 'craft', recipeIdx: parseInt(recipeIdx) });
    console.log(`🔨 Craft request: recipe #${recipeIdx}`);
    res.json({ success: true });
  } catch (error) {
    res.status(500).json({ error: error.message });
  }
});

// ========== Bridge Endpoints (for HTTP polling fallback) ==========

// Bridge sends inventory state
app.post('/api/bridge/state', (req, res) => {
  try {
    const data = req.body;
    updateStateFromBridge(data);
    res.json({ success: true });
  } catch (error) {
    console.error('❌ Error processing bridge state:', error);
    res.status(500).json({ error: error.message });
  }
});

// Bridge polls for pending commands
app.get('/api/bridge/commands', (req, res) => {
  try {
    const now = Date.now();
    // Clear old commands (>30s)
    pendingCommands = pendingCommands.filter(cmd => (now - cmd.timestamp) < 30000);
    
    const commands = [...pendingCommands];
    res.json({ commands });
  } catch (error) {
    res.status(500).json({ error: error.message });
  }
});

// Bridge acknowledges commands
app.post('/api/bridge/commands/ack', (req, res) => {
  try {
    const cleared = pendingCommands.length;
    pendingCommands = [];
    res.json({ success: true, cleared });
  } catch (error) {
    res.status(500).json({ error: error.message });
  }
});

// Bridge sends command result
app.post('/api/bridge/result', (req, res) => {
  try {
    const { action, success, message, error: err } = req.body;
    
    broadcastToClients({
      type: 'command_result',
      action,
      success,
      message,
      error: err,
    });
    
    console.log(`📩 Result: ${action} - ${success ? 'OK' : 'FAIL'}`);
    res.json({ success: true });
  } catch (error) {
    res.status(500).json({ error: error.message });
  }
});

// ========== State Update ==========

function updateStateFromBridge(data) {
  if (data.cache) {
    // Normalize itemList: Lua sends { name, total }, frontend expects { name, count }
    const rawItems = data.cache.itemList || [];
    const normalizedItems = Array.isArray(rawItems) ? rawItems.map(item => ({
      name: item.name || '',
      count: item.total !== undefined ? item.total : (item.count || 0),
      displayName: item.displayName || item.name || '',
    })) : [];

    // Normalize furnaceStatus: Lua sends array of { name, type, input, fuel, output, active }
    // Frontend expects object { furnaceName: { active, input, fuel, output } }
    const rawFurnaces = data.cache.furnaceStatus || [];
    let normalizedFurnaces = {};
    if (Array.isArray(rawFurnaces)) {
      rawFurnaces.forEach(f => {
        if (f && f.name) {
          normalizedFurnaces[f.name] = {
            active: f.active || false,
            type: f.type || 'minecraft:furnace',
            input: f.input || null,
            fuel: f.fuel || null,
            output: f.output || null,
          };
        }
      });
    } else if (typeof rawFurnaces === 'object') {
      normalizedFurnaces = rawFurnaces;
    }

    inventoryState = {
      itemList: normalizedItems,
      grandTotal: data.cache.grandTotal || 0,
      chestCount: data.cache.chestCount || 0,
      totalSlots: data.cache.totalSlots || 0,
      usedSlots: data.cache.usedSlots || 0,
      freeSlots: data.cache.freeSlots || 0,
      usedRatio: data.cache.usedRatio || 0,
      dropperOk: data.cache.dropperOk || false,
      barrelOk: data.cache.barrelOk || false,
      furnaceCount: data.cache.furnaceCount || 0,
      furnaceStatus: normalizedFurnaces,
      droppers: Array.isArray(data.cache.droppers) ? data.cache.droppers : [],
    };
  }

  if (data.activity !== undefined) activityState = data.activity || {};

  // Normalize alerts: Lua sends [{ label, current, min }] (only triggered ones)
  // Frontend expects [{ item, triggered, current, threshold }]
  if (data.alerts !== undefined) {
    const rawAlerts = data.alerts || [];
    alertsState = Array.isArray(rawAlerts) ? rawAlerts.map(a => ({
      item: a.name || a.item || a.label || '',
      triggered: true,
      current: a.current || 0,
      threshold: a.min || a.threshold || 0,
    })) : [];
  }

  if (data.smeltingPaused !== undefined) smeltingPaused = data.smeltingPaused;
  if (data.disabledRecipes !== undefined) disabledRecipes = data.disabledRecipes || {};
  if (data.smeltable !== undefined) smeltableRecipes = data.smeltable || {};

  // Normalize craftable: Lua sends { output, count, grid } (grid = flat array of 9)
  // Frontend expects { output, count, slots } (slots = object { slotIdx: itemName })
  if (data.craftable !== undefined) {
    const rawCraftable = data.craftable || [];
    craftableRecipes = Array.isArray(rawCraftable) ? rawCraftable.map(recipe => {
      const slots = {};
      if (recipe.grid && Array.isArray(recipe.grid)) {
        recipe.grid.forEach((item, idx) => {
          if (item) slots[idx + 1] = item;
        });
      } else if (recipe.slots) {
        Object.assign(slots, recipe.slots);
      }
      return {
        output: recipe.output || '',
        count: recipe.count || 1,
        slots,
      };
    }) : [];
  }

  if (data.craftTurtleOk !== undefined) craftTurtleOk = data.craftTurtleOk;
  
  lastUpdate = Date.now();

  // Broadcast to all web clients FIRST (non-blocking, instant)
  broadcastToClients({
    type: 'state_update',
    inventory: inventoryState,
    activity: activityState,
    alerts: alertsState,
    smeltingPaused,
    disabledRecipes,
    smeltable: smeltableRecipes,
    craftable: craftableRecipes,
    craftTurtleOk,
    lastUpdate,
    bridgeConnected: bridgeClients.size > 0,
  });

  // Persist to SQLite (debounced — won't block the broadcast)
  saveFullState({
    inventoryState,
    activityState,
    alertsState,
    smeltingPaused,
    disabledRecipes,
    smeltableRecipes,
    craftableRecipes,
    craftTurtleOk,
  });

  // Record history snapshot (throttled to every 5 min internally)
  if (inventoryState.itemList?.length) {
    recordItemHistory(inventoryState.itemList);
  }
}

// ========== WebSocket Server ==========

const wss = new WebSocketServer({ server });

console.log(`🚀 Inventory Manager Web Server starting...`);
console.log(`📡 HTTP Server: http://localhost:${PORT}`);
console.log(`🔌 WebSocket Server: ws://localhost:${PORT}/ws`);

wss.on('connection', (ws, req) => {
  const url = req.url || '';
  
  // ---- Bridge WebSocket connection ----
  if (url.startsWith('/ws/bridge')) {
    console.log('🌉 CC:Tweaked bridge connected via WebSocket');
    bridgeClients.add(ws);
    
    ws.on('message', (raw) => {
      try {
        const data = JSON.parse(raw);
        
        if (data.type === 'ping') {
          ws.send(JSON.stringify({ type: 'pong' }));
          return;
        }
        
        if (data.type === 'state') {
          // Full state update from bridge
          updateStateFromBridge(data);
        } else if (data.type === 'command_result') {
          // Command result from bridge
          broadcastToClients({
            type: 'command_result',
            action: data.action,
            success: data.success,
            message: data.message,
            error: data.error,
          });
        }
      } catch (error) {
        console.error('❌ Bridge WS message error:', error.message);
      }
    });
    
    ws.on('close', () => {
      console.log('🌉 CC:Tweaked bridge disconnected');
      bridgeClients.delete(ws);
    });
    
    ws.on('error', (error) => {
      console.error('❌ Bridge WS error:', error);
      bridgeClients.delete(ws);
    });
    
    return;
  }
  
  // ---- Web client WebSocket connection ----
  console.log('🌐 New web client connected');
  webClients.add(ws);
  ws.isAlive = true;
  
  // Send current state to new client
  ws.send(JSON.stringify({
    type: 'initial_state',
    inventory: inventoryState,
    activity: activityState,
    alerts: alertsState,
    smeltingPaused,
    disabledRecipes,
    smeltable: smeltableRecipes,
    craftable: craftableRecipes,
    craftTurtleOk,
    lastUpdate,
    bridgeConnected: bridgeClients.size > 0,
  }));
  
  ws.on('pong', () => { ws.isAlive = true; });
  
  ws.on('message', (message) => {
    try {
      const data = JSON.parse(message);
      
      if (data.type === 'command') {
        // Forward command to bridge
        pushCommandToBridge(data);
      }
    } catch (error) {
      console.error('❌ Error processing web client message:', error);
    }
  });
  
  ws.on('close', () => {
    console.log('👋 Web client disconnected');
    webClients.delete(ws);
  });
  
  ws.on('error', (error) => {
    console.error('❌ WebSocket error:', error);
  });
});

// ========== WebSocket Keep-Alive ==========
// Ping all web clients every 25s to keep connections alive through reverse proxies
const WS_PING_INTERVAL = setInterval(() => {
  webClients.forEach((ws) => {
    if (!ws.isAlive) {
      webClients.delete(ws);
      return ws.terminate();
    }
    ws.isAlive = false;
    ws.ping();
  });
}, 25000);

wss.on('close', () => {
  clearInterval(WS_PING_INTERVAL);
});

// ========== Start Server ==========

server.listen(PORT, HOST, () => {
  console.log(`✅ Inventory Manager Web Server ready on ${HOST}:${PORT}`);
  console.log(`\nBridge HTTP endpoint: http://localhost:${PORT}/api/bridge/state`);
  console.log(`Bridge WebSocket: ws://localhost:${PORT}/ws/bridge`);
  console.log(`Web client WebSocket: ws://localhost:${PORT}/ws`);
});

// Graceful shutdown
function shutdown() {
  console.log('\n🛑 Shutting down server...');
  try {
    closeDb();
    console.log('💾 Database closed');
  } catch (err) {
    console.error('❌ Error closing database:', err.message);
  }
  process.exit(0);
}

process.on('SIGINT', shutdown);
process.on('SIGTERM', shutdown);