/**
 * Text Encoding Factory
 *
 * Creates encoder/decoder instances with automatic polyfill selection
 *
 * @module text-encoding@1.0.0
 */

import { TextDecoderPolyfill } from './TextDecoderPolyfill';
import { TextEncoderPolyfill } from './TextEncoderPolyfill';
import type {
  ITextDecoder,
  ITextEncoder,
  ITextEncodingFactory,
  TextDecoderOptions,
} from './interfaces';

export class TextEncodingFactory implements ITextEncodingFactory {
  private static instance: TextEncodingFactory;

  /**
   * Get factory singleton instance
   */
  static getInstance(): TextEncodingFactory {
    if (!TextEncodingFactory.instance) {
      TextEncodingFactory.instance = new TextEncodingFactory();
    }
    return TextEncodingFactory.instance;
  }

  /**
   * Create a new TextEncoder instance
   * Uses native implementation if available, otherwise polyfill
   */
  createEncoder(): ITextEncoder {
    // @ts-expect-error - Check for native TextEncoder
    if (typeof TextEncoder !== 'undefined') {
      try {
        // @ts-expect-error - Try to use native
        return new TextEncoder();
      } catch (e) {
        // Fall back to polyfill if native fails
        console.warn('[TextEncodingFactory] Native TextEncoder failed, using polyfill:', e);
      }
    }

    return new TextEncoderPolyfill();
  }

  /**
   * Create a new TextDecoder instance
   * Uses native implementation if available, otherwise polyfill
   */
  createDecoder(label: string = 'utf-8', options?: TextDecoderOptions): ITextDecoder {
    // @ts-expect-error - Check for native TextDecoder
    if (typeof TextDecoder !== 'undefined') {
      try {
        // @ts-expect-error - Try to use native
        return new TextDecoder(label, options);
      } catch (e) {
        // Fall back to polyfill if native fails
        console.warn('[TextEncodingFactory] Native TextDecoder failed, using polyfill:', e);
      }
    }

    return new TextDecoderPolyfill(label, options);
  }

  /**
   * Check if native TextEncoder/TextDecoder are available
   */
  isNativelySupported(): boolean {
    // @ts-expect-error - Check global scope
    if (typeof TextEncoder === 'undefined' || typeof TextDecoder === 'undefined') {
      return false;
    }

    // Try to instantiate to make sure they work
    try {
      // @ts-expect-error
      const encoder = new TextEncoder();
      // @ts-expect-error
      const decoder = new TextDecoder();

      // Basic functionality test
      const testString = 'test';
      const encoded = encoder.encode(testString);
      const decoded = decoder.decode(encoded);

      return decoded === testString;
    } catch (_e) {
      return false;
    }
  }
}

/**
 * Convenience function to create an encoder
 */
export function createTextEncoder(): ITextEncoder {
  return TextEncodingFactory.getInstance().createEncoder();
}

/**
 * Convenience function to create a decoder
 */
export function createTextDecoder(label?: string, options?: TextDecoderOptions): ITextDecoder {
  return TextEncodingFactory.getInstance().createDecoder(label, options);
}

/**
 * Install polyfills globally if not present
 * This makes TextEncoder/TextDecoder available everywhere
 */
export function installTextEncodingPolyfills(): void {
  // @ts-expect-error
  if (typeof global !== 'undefined') {
    // @ts-expect-error
    if (typeof global.TextEncoder === 'undefined') {
      // @ts-expect-error
      global.TextEncoder = TextEncoderPolyfill;
      console.info('[TextEncodingFactory] Installed TextEncoder polyfill globally');
    }

    // @ts-expect-error
    if (typeof global.TextDecoder === 'undefined') {
      // @ts-expect-error
      global.TextDecoder = TextDecoderPolyfill;
      console.info('[TextEncodingFactory] Installed TextDecoder polyfill globally');
    }
  }
}