import { Injectable } from "@nestjs/common";
import type { TTSProvider, TTSSynthesisInput, SynthesizedAudio } from "./tts-provider.js";
import { hashToSeed } from "../llm/seeded-random.js";

const CHARS_PER_SECOND_AT_NORMAL_RATE = 6; // Mock 階段的粗略估算，不代表真實語速

// P-4 MockTTSProvider：輸出韻律標記與佔位音檔參照，不呼叫任何真實語音服務——
// 讓語音管線的其他機制（韻律解析、非語言發聲、副語言分析）都能在沒有真實 TTS 供應商的情況下完整測試。
@Injectable()
export class MockTTSProvider implements TTSProvider {
  async synthesize(input: TTSSynthesisInput): Promise<SynthesizedAudio> {
    const seed = input.seed ?? hashToSeed(input.text);
    const { prosody, nonverbalCue, voiceSheet } = input;

    const spokenText = nonverbalCue.interjection ? `${nonverbalCue.interjection} ${input.text}` : input.text;
    const durationEstimateMs =
      nonverbalCue.pauseSeconds * 1000 + (spokenText.length / CHARS_PER_SECOND_AT_NORMAL_RATE / prosody.rateMultiplier) * 1000;

    const prosodyMarkup =
      `<voice timbre="${voiceSheet.baseTimbre}">` +
      `<break time="${nonverbalCue.pauseSeconds.toFixed(1)}s"/>` +
      `<prosody rate="${prosody.rateMultiplier.toFixed(2)}" pitch="${prosody.pitchShiftSemitones >= 0 ? "+" : ""}${prosody.pitchShiftSemitones.toFixed(1)}st" volume="${prosody.volumeMultiplier.toFixed(2)}" contour="${prosody.contour}">` +
      spokenText +
      `</prosody></voice>`;

    return {
      audioRef: `mock://tts/${seed}`,
      prosodyMarkup,
      durationEstimateMs: Math.round(durationEstimateMs),
    };
  }
}