import { Injectable, Logger, ServiceUnavailableException } from '@nestjs/common';
import { ConfigService } from '@nestjs/config';

const MAX_AUDIO_BYTES = 8 * 1024 * 1024;

@Injectable()
export class SttClientService {
  private readonly logger = new Logger(SttClientService.name);

  constructor(private readonly config: ConfigService) {}

  isEnabled(): boolean {
    return this.config.get<string>('STT_ENABLED') === 'true';
  }

  async downloadAndTranscribe(recordingUrl: string): Promise<string> {
    if (!this.isEnabled()) {
      throw new ServiceUnavailableException('سرویس تبدیل گفتار فعال نیست');
    }

    const timeoutMs = Number(
      this.config.get<string>('STT_TIMEOUT_MS') || 180000,
    );
    const audio = await this.downloadAudio(recordingUrl, timeoutMs);
    return this.transcribeAudio(audio, timeoutMs);
  }

  async transcribeAudio(
    audio: { buffer: ArrayBuffer; contentType: string; filename: string },
    timeoutMs?: number,
  ): Promise<string> {
    if (!this.isEnabled()) {
      throw new ServiceUnavailableException('سرویس تبدیل گفتار فعال نیست');
    }

    const baseUrl = this.config.get<string>('STT_URL')?.trim();
    if (!baseUrl) {
      throw new ServiceUnavailableException('آدرس سرویس STT تنظیم نشده');
    }

    const waitMs = timeoutMs ?? Number(
      this.config.get<string>('STT_TIMEOUT_MS') || 180000,
    );
    const token = this.config.get<string>('STT_INTERNAL_TOKEN')?.trim() || '';

    const form = new FormData();
    const blob = new Blob([new Uint8Array(audio.buffer)], {
      type: audio.contentType,
    });
    form.append('audio', blob, audio.filename);

    const headers: Record<string, string> = {};
    if (token) headers['X-STT-Token'] = token;

    const controller = new AbortController();
    const timer = setTimeout(() => controller.abort(), waitMs);
    try {
      const res = await fetch(`${baseUrl.replace(/\/$/, '')}/transcribe`, {
        method: 'POST',
        headers,
        body: form,
        signal: controller.signal,
      });
      if (!res.ok) {
        const text = await res.text().catch(() => '');
        throw new ServiceUnavailableException(
          `خطای STT (${res.status})${text ? `: ${text.slice(0, 200)}` : ''}`,
        );
      }
      const data = (await res.json()) as { text?: string };
      const text = String(data.text ?? '').trim();
      if (!text) {
        throw new ServiceUnavailableException('متن خالی از STT برگشت');
      }
      return text;
    } catch (err) {
      if (err instanceof ServiceUnavailableException) throw err;
      if (err instanceof Error && err.name === 'AbortError') {
        throw new ServiceUnavailableException('زمان تبدیل گفتار تمام شد');
      }
      this.logger.warn(
        `STT failed: ${err instanceof Error ? err.message : String(err)}`,
      );
      throw new ServiceUnavailableException('تبدیل گفتار ناموفق بود');
    } finally {
      clearTimeout(timer);
    }
  }

  private async downloadAudio(
    url: string,
    timeoutMs: number,
  ): Promise<{ buffer: ArrayBuffer; contentType: string; filename: string }> {
    const controller = new AbortController();
    const timer = setTimeout(() => controller.abort(), Math.min(timeoutMs, 60000));
    try {
      const res = await fetch(url, {
        method: 'GET',
        signal: controller.signal,
        headers: { 'User-Agent': 'MontactCRM-VoIP/1.0' },
        redirect: 'follow',
      });
      if (!res.ok) {
        throw new ServiceUnavailableException(
          `دانلود ضبط ناموفق بود (${res.status})`,
        );
      }
      const contentLength = Number(res.headers.get('content-length') || 0);
      if (contentLength > MAX_AUDIO_BYTES) {
        throw new ServiceUnavailableException('حجم فایل ضبط بیش از حد مجاز است');
      }
      const buffer = await res.arrayBuffer();
      if (buffer.byteLength > MAX_AUDIO_BYTES) {
        throw new ServiceUnavailableException('حجم فایل ضبط بیش از حد مجاز است');
      }
      if (!buffer.byteLength) {
        throw new ServiceUnavailableException('فایل ضبط خالی است');
      }
      const contentType =
        res.headers.get('content-type')?.split(';')[0]?.trim() ||
        'audio/wav';
      const pathPart = url.split('?')[0] ?? url;
      const baseName = pathPart.split('/').pop() || 'recording.wav';
      const filename = /\.\w+$/.test(baseName) ? baseName : `${baseName}.wav`;
      return { buffer, contentType, filename };
    } catch (err) {
      if (err instanceof ServiceUnavailableException) throw err;
      if (err instanceof Error && err.name === 'AbortError') {
        throw new ServiceUnavailableException('زمان دانلود ضبط تمام شد');
      }
      throw new ServiceUnavailableException('دانلود فایل ضبط ناموفق بود');
    } finally {
      clearTimeout(timer);
    }
  }
}