strata-compile/runtime/worker/shared-worker.sts

/**
 * Strata Shared Worker
 * Manages cross-tab state, caching, and API deduplication
 */

interface TabConnection {
  port: MessagePort;
  tabId: string;
  connectedAt: number;
  lastActivity: number;
}

interface CacheEntry {
  data: any;
  timestamp: number;
  ttl: number;
  etag?: string;
}

interface InFlightRequest {
  promise: Promise<any>;
  subscribers: string[]; // tabIds waiting for this request
}

interface StoreState {
  [storeName: string]: {
    shared: Record<string, any>;
    tabs: Record<string, Record<string, any>>;
  };
}

class StrataSharedWorker {
  private tabs: Map<string, TabConnection> = new Map();
  private cache: Map<string, CacheEntry> = new Map();
  private inFlight: Map<string, InFlightRequest> = new Map();
  private stores: StoreState = {};
  private encryptionKey: Uint8Array | null = null;

  constructor() {
    self.onconnect = (e: MessageEvent) => this.handleConnect(e);
  }

  private generateTabId(): string {
    return 'tab_' + crypto.randomUUID().slice(0, 8);
  }

  private handleConnect(e: MessageEvent) {
    const port = e.ports[0];
    const tabId = this.generateTabId();

    const connection: TabConnection = {
      port,
      tabId,
      connectedAt: Date.now(),
      lastActivity: Date.now(),
    };

    this.tabs.set(tabId, connection);

    port.onmessage = (event) => this.handleMessage(tabId, event.data);
    port.start();

    // Send tabId to the new tab
    port.postMessage({
      type: 'connected',
      tabId,
      tabCount: this.tabs.size,
    });

    // Notify other tabs
    this.broadcast('tab:joined', { tabId, tabCount: this.tabs.size }, [tabId]);
  }

  private handleMessage(tabId: string, message: any) {
    const tab = this.tabs.get(tabId);
    if (tab) {
      tab.lastActivity = Date.now();
    }

    switch (message.type) {
      case 'fetch':
        this.handleFetch(tabId, message);
        break;
      case 'store:get':
        this.handleStoreGet(tabId, message);
        break;
      case 'store:set':
        this.handleStoreSet(tabId, message);
        break;
      case 'store:subscribe':
        this.handleStoreSubscribe(tabId, message);
        break;
      case 'broadcast':
        this.handleBroadcast(tabId, message);
        break;
      case 'cache:invalidate':
        this.handleCacheInvalidate(message);
        break;
      case 'disconnect':
        this.handleDisconnect(tabId);
        break;
      case 'setEncryptionKey':
        this.setEncryptionKey(message.key);
        break;
    }
  }

  private async handleFetch(tabId: string, message: any) {
    const { url, options, requestId } = message;
    const cacheKey = this.getCacheKey(url, options);

    // Check cache first
    const cached = this.cache.get(cacheKey);
    if (cached && !this.isCacheExpired(cached)) {
      this.sendToTab(tabId, {
        type: 'fetch:response',
        requestId,
        data: cached.data,
        fromCache: true,
      });
      return;
    }

    // Check if request is already in flight
    const inFlight = this.inFlight.get(cacheKey);
    if (inFlight) {
      // Add this tab to subscribers
      inFlight.subscribers.push(tabId);
      const data = await inFlight.promise;
      this.sendToTab(tabId, {
        type: 'fetch:response',
        requestId,
        data,
        deduplicated: true,
      });
      return;
    }

    // Make the request
    const fetchPromise = this.executeFetch(url, options);
    this.inFlight.set(cacheKey, {
      promise: fetchPromise,
      subscribers: [tabId],
    });

    try {
      const data = await fetchPromise;
      const inFlightEntry = this.inFlight.get(cacheKey);

      // Cache the response
      if (options?.cache !== 'none') {
        const ttl = this.parseTTL(options?.cache || 'smart');
        this.cache.set(cacheKey, {
          data,
          timestamp: Date.now(),
          ttl,
        });
      }

      // Send to all subscribers
      if (inFlightEntry) {
        for (const subTabId of inFlightEntry.subscribers) {
          this.sendToTab(subTabId, {
            type: 'fetch:response',
            requestId,
            data,
            fromCache: false,
          });
        }
      }
    } catch (error) {
      const inFlightEntry = this.inFlight.get(cacheKey);
      if (inFlightEntry) {
        for (const subTabId of inFlightEntry.subscribers) {
          this.sendToTab(subTabId, {
            type: 'fetch:error',
            requestId,
            error: error instanceof Error ? error.message : 'Unknown error',
          });
        }
      }
    } finally {
      this.inFlight.delete(cacheKey);
    }
  }

  private async executeFetch(url: string, options: any): Promise<any> {
    const response = await fetch(url, {
      method: options?.method || 'GET',
      headers: options?.headers,
      body: options?.body ? JSON.stringify(options.body) : undefined,
    });

    if (!response.ok) {
      throw new Error(`HTTP ${response.status}: ${response.statusText}`);
    }

    return response.json();
  }

  private getCacheKey(url: string, options: any): string {
    const method = options?.method || 'GET';
    const body = options?.body ? JSON.stringify(options.body) : '';
    return `${method}:${url}:${body}`;
  }

  private isCacheExpired(entry: CacheEntry): boolean {
    if (entry.ttl === -1) return false; // permanent
    return Date.now() - entry.timestamp > entry.ttl;
  }

  private parseTTL(cache: string): number {
    if (cache === 'permanent') return -1;
    if (cache === 'none') return 0;
    if (cache === 'smart') return 5 * 60 * 1000; // 5 minutes default

    const match = cache.match(/^(\d+)(s|m|h|d)$/);
    if (match) {
      const value = parseInt(match[1]);
      const unit = match[2];
      const multipliers: Record<string, number> = {
        s: 1000,
        m: 60 * 1000,
        h: 60 * 60 * 1000,
        d: 24 * 60 * 60 * 1000,
      };
      return value * multipliers[unit];
    }

    return 5 * 60 * 1000; // default 5 minutes
  }

  private handleStoreGet(tabId: string, message: any) {
    const { storeName, key, scope } = message;
    const store = this.stores[storeName];

    if (!store) {
      this.sendToTab(tabId, {
        type: 'store:value',
        storeName,
        key,
        value: undefined,
      });
      return;
    }

    let value;
    if (scope === 'tab') {
      value = store.tabs[tabId]?.[key];
    } else {
      value = store.shared[key];
    }

    // Decrypt if needed
    if (this.encryptionKey && value) {
      value = this.decrypt(value);
    }

    this.sendToTab(tabId, {
      type: 'store:value',
      storeName,
      key,
      value,
    });
  }

  private handleStoreSet(tabId: string, message: any) {
    const { storeName, key, value, scope, encrypt } = message;

    if (!this.stores[storeName]) {
      this.stores[storeName] = { shared: {}, tabs: {} };
    }

    let storedValue = value;
    if (encrypt && this.encryptionKey) {
      storedValue = this.encrypt(value);
    }

    if (scope === 'tab') {
      if (!this.stores[storeName].tabs[tabId]) {
        this.stores[storeName].tabs[tabId] = {};
      }
      this.stores[storeName].tabs[tabId][key] = storedValue;
    } else {
      this.stores[storeName].shared[key] = storedValue;

      // Notify all tabs about shared state change
      this.broadcast('store:changed', {
        storeName,
        key,
        value,
      });
    }
  }

  private handleStoreSubscribe(tabId: string, message: any) {
    // Store subscriptions are handled via broadcast
    // When store changes, all tabs receive updates
  }

  private handleBroadcast(fromTabId: string, message: any) {
    const { event, data, targetTabs } = message;
    this.broadcast(event, data, targetTabs ? undefined : [fromTabId]);
  }

  private handleCacheInvalidate(message: any) {
    const { pattern } = message;

    if (pattern === '*') {
      this.cache.clear();
    } else {
      for (const key of this.cache.keys()) {
        if (key.includes(pattern)) {
          this.cache.delete(key);
        }
      }
    }
  }

  private handleDisconnect(tabId: string) {
    this.tabs.delete(tabId);

    // Clean up tab-specific store data
    for (const storeName in this.stores) {
      delete this.stores[storeName].tabs[tabId];
    }

    // Notify remaining tabs
    this.broadcast('tab:left', { tabId, tabCount: this.tabs.size });
  }

  private broadcast(event: string, data: any, excludeTabs: string[] = []) {
    for (const [tabId, tab] of this.tabs) {
      if (!excludeTabs.includes(tabId)) {
        tab.port.postMessage({
          type: 'broadcast',
          event,
          data,
        });
      }
    }
  }

  private sendToTab(tabId: string, message: any) {
    const tab = this.tabs.get(tabId);
    if (tab) {
      tab.port.postMessage(message);
    }
  }

  private setEncryptionKey(keyArray: number[]) {
    this.encryptionKey = new Uint8Array(keyArray);
  }

  private encrypt(data: any): string {
    if (!this.encryptionKey) return JSON.stringify(data);

    const jsonStr = JSON.stringify(data);
    const encoder = new TextEncoder();
    const dataBytes = encoder.encode(jsonStr);

    // XOR encryption with key (simple, fast)
    // In production, use SubtleCrypto AES-GCM
    const encrypted = new Uint8Array(dataBytes.length);
    for (let i = 0; i < dataBytes.length; i++) {
      encrypted[i] = dataBytes[i] ^ this.encryptionKey[i % this.encryptionKey.length];
    }

    return btoa(String.fromCharCode(...encrypted));
  }

  private decrypt(encryptedStr: string): any {
    if (!this.encryptionKey) return JSON.parse(encryptedStr);

    const encrypted = new Uint8Array(
      atob(encryptedStr)
        .split('')
        .map((c) => c.charCodeAt(0))
    );

    const decrypted = new Uint8Array(encrypted.length);
    for (let i = 0; i < encrypted.length; i++) {
      decrypted[i] = encrypted[i] ^ this.encryptionKey[i % this.encryptionKey.length];
    }

    const decoder = new TextDecoder();
    return JSON.parse(decoder.decode(decrypted));
  }
}

// Initialize worker
new StrataSharedWorker();