/**
 * TTS Provider Factory
 *
 * Creates and registers TTS providers based on speech configuration.
 * Reads enabled flags and URLs from config and instantiates the appropriate
 * provider for each tier.
 *
 * Each tier maps to a specific TTS engine:
 * - default: Kokoro-FastAPI (CPU, always available)
 * - premium: Chatterbox (GPU, voice cloning)
 * - fallback: Piper via OpenedAI Speech (ultra-lightweight CPU)
 *
 * Issue #391
 */

import { Logger } from "@nestjs/common";
import { ChatterboxTTSProvider } from "./chatterbox-tts.provider";
import { KokoroTtsProvider } from "./kokoro-tts.provider";
import { PiperTtsProvider } from "./piper-tts.provider";
import type { ITTSProvider } from "../interfaces/tts-provider.interface";
import type { SpeechTier, AudioFormat } from "../interfaces/speech-types";
import type { SpeechConfig } from "../speech.config";

// ==========================================
// Factory function
// ==========================================

const logger = new Logger("TTSProviderFactory");

/**
 * Create and register TTS providers based on the speech configuration.
 *
 * Only creates providers for tiers that are enabled in the config.
 * Returns a Map keyed by SpeechTier for use with the TTS_PROVIDERS injection token.
 *
 * @param config - Speech configuration with TTS tier settings
 * @returns Map of enabled TTS providers keyed by tier
 */
export function createTTSProviders(config: SpeechConfig): Map<SpeechTier, ITTSProvider> {
  const providers = new Map<SpeechTier, ITTSProvider>();

  // Default tier: Kokoro
  if (config.tts.default.enabled) {
    const provider = new KokoroTtsProvider(
      config.tts.default.url,
      config.tts.default.voice,
      config.tts.default.format as AudioFormat
    );
    providers.set("default", provider);
    logger.log(`Registered default TTS provider: kokoro at ${config.tts.default.url}`);
  }

  // Premium tier: Chatterbox
  if (config.tts.premium.enabled) {
    const provider = new ChatterboxTTSProvider(config.tts.premium.url);
    providers.set("premium", provider);
    logger.log(`Registered premium TTS provider: chatterbox at ${config.tts.premium.url}`);
  }

  // Fallback tier: Piper
  if (config.tts.fallback.enabled) {
    const provider = new PiperTtsProvider(config.tts.fallback.url);
    providers.set("fallback", provider);
    logger.log(`Registered fallback TTS provider: piper at ${config.tts.fallback.url}`);
  }

  if (providers.size === 0) {
    logger.warn("No TTS providers are enabled. TTS synthesis will not be available.");
  } else {
    const tierNames = Array.from(providers.keys()).join(", ");
    logger.log(`TTS providers ready: ${tierNames} (${String(providers.size)} total)`);
  }

  return providers;
}