brainy/src/utils/textEncoding.ts

/**
 * Unified Text Encoding Utilities
 *
 * This module provides a consistent way to handle text encoding/decoding across all environments
 * without relying on TextEncoder/TextDecoder polyfills or patches.
 */

/**
 * A simple text encoder that works in all environments
 * This avoids the need for TextEncoder polyfills and patches
 */
export class SimpleTextEncoder {
  /**
   * Encode a string to a Uint8Array
   * @param input - The string to encode
   * @returns A Uint8Array containing the encoded string
   */
  encode(input: string): Uint8Array {
    // Simple UTF-8 encoding implementation that works everywhere
    return new Uint8Array([...input].map((c) => c.charCodeAt(0)))
  }
}

/**
 * A simple text decoder that works in all environments
 * This avoids the need for TextDecoder polyfills and patches
 */
export class SimpleTextDecoder {
  /**
   * Decode a Uint8Array to a string
   * @param input - The Uint8Array to decode
   * @returns The decoded string
   */
  decode(input: Uint8Array): string {
    // Simple UTF-8 decoding implementation that works everywhere
    return String.fromCharCode.apply(null, [...input])
  }
}

// Create constructor functions that can be used as drop-in replacements
// for the native TextEncoder and TextDecoder

/**
 * Interface for UniversalTextEncoder instance
 */
interface IUniversalTextEncoder {
  encode: (input: string) => Uint8Array;
}

/**
 * A constructor function for TextEncoder that works in all environments
 */
export function UniversalTextEncoder(this: IUniversalTextEncoder) {
  if (!(this instanceof UniversalTextEncoder)) {
    return new (UniversalTextEncoder as any)()
  }

  try {
    // Try to use the native TextEncoder if available
    const nativeEncoder: TextEncoder = new TextEncoder()
    this.encode = nativeEncoder.encode.bind(nativeEncoder)
  } catch (e) {
    // Fall back to our simple implementation
    const simpleEncoder: SimpleTextEncoder = new SimpleTextEncoder()
    this.encode = simpleEncoder.encode.bind(simpleEncoder)
  }
}

/**
 * Interface for UniversalTextDecoder instance
 */
interface IUniversalTextDecoder {
  decode: (input: Uint8Array) => string;
}

/**
 * A constructor function for TextDecoder that works in all environments
 */
export function UniversalTextDecoder(this: IUniversalTextDecoder) {
  if (!(this instanceof UniversalTextDecoder)) {
    return new (UniversalTextDecoder as any)()
  }

  try {
    // Try to use the native TextDecoder if available
    const nativeDecoder: TextDecoder = new TextDecoder()
    this.decode = nativeDecoder.decode.bind(nativeDecoder)
  } catch (e) {
    // Fall back to our simple implementation
    const simpleDecoder: SimpleTextDecoder = new SimpleTextDecoder()
    this.decode = simpleDecoder.decode.bind(simpleDecoder)
  }
}

/**
 * Get a text encoder that works in the current environment
 * @returns A text encoder object with an encode method
 */
export function getTextEncoder(): IUniversalTextEncoder {
  return new (UniversalTextEncoder as any)()
}

/**
 * Get a text decoder that works in the current environment
 * @returns A text decoder object with a decode method
 */
export function getTextDecoder(): IUniversalTextDecoder {
  return new (UniversalTextDecoder as any)()
}

/**
 * Apply the TensorFlow.js platform patch if needed
 * This function patches the global object to provide a PlatformNode class
 * that uses our text encoding utilities instead of relying on TextEncoder/TextDecoder
 */
export function applyTensorFlowPatch(): void {
  // Only apply in Node.js environment
  if (
    typeof global !== 'undefined' &&
    typeof process !== 'undefined' &&
    process.versions &&
    process.versions.node
  ) {
    try {
      // Get encoders/decoders
      const encoder = getTextEncoder()
      const decoder = getTextDecoder()

      // Define a custom PlatformNode class
      class PlatformNode {
        util: any
        textEncoder: any
        textDecoder: any

        constructor() {
          // Create a util object with necessary methods and constructors
          this.util = {
            isFloat32Array: (arr: any) =>
              !!(
                arr instanceof Float32Array ||
                (arr &&
                  Object.prototype.toString.call(arr) ===
                    '[object Float32Array]')
              ),
            isTypedArray: (arr: any) =>
              !!(ArrayBuffer.isView(arr) && !(arr instanceof DataView)),
            // Add TextEncoder and TextDecoder as constructors
            TextEncoder: UniversalTextEncoder,
            TextDecoder: UniversalTextDecoder
          }

          // Initialize using the constructors from util
          this.textEncoder = new this.util.TextEncoder()
          this.textDecoder = new this.util.TextDecoder()
        }
      }

      // Assign the PlatformNode class to the global object
      ;(global as any).PlatformNode = PlatformNode

      // Also create an instance and assign it to global.platformNode (lowercase p)
      ;(global as any).platformNode = new PlatformNode()
    } catch (error) {
      console.warn('Failed to apply TensorFlow.js platform patch:', error)
    }
  }
}