import { BadGatewayException, Injectable, ServiceUnavailableException } from '@nestjs/common';
import { ConfigService } from '@nestjs/config';
import { GoogleAuth } from 'google-auth-library';
import { generateWaveformPeaksFromBuffer } from '../../common/utils/waveform.util';
import { ManagedStorageService } from '../../infrastructure/storage/managed-storage.service';
import { MediaProbeService } from '../../infrastructure/storage/media-probe.service';
import { TextToMusicDto } from './dto/text-to-music.dto';

@Injectable()
export class MediaService {
  constructor(
    private readonly configService: ConfigService,
    private readonly storageService: ManagedStorageService,
    private readonly mediaProbeService: MediaProbeService,
  ) {}

  async getMediaHealth() {
    const [storageHealth, ffmpeg, ffprobe] = await Promise.all([
      this.storageService.getHealth(),
      this.mediaProbeService.checkFfmpeg(),
      this.mediaProbeService.checkFfprobe(),
    ]);
    const storageProvider =
      this.configService.get<string>('storage.provider', { infer: true }) ?? 'local';
    const publicBaseUrl = this.configService.get<string>('publicBaseUrl', { infer: true }) ?? '';
    const warnings: string[] = [];
    const imageProcessingEnabled =
      this.configService.get<boolean>('imageProcessing.enabled', { infer: true }) ?? false;
    const videoProcessingEnabled =
      this.configService.get<boolean>('videoProcessing.enabled', { infer: true }) ?? false;
    const videoHlsGenerationEnabled =
      this.configService.get<boolean>('videoProcessing.generateHls', { infer: true }) ?? true;
    const videoThumbnailGenerationEnabled =
      this.configService.get<boolean>('videoProcessing.generateThumbnails', { infer: true }) ??
      true;
    const audioProcessingEnabled =
      this.configService.get<boolean>('audioProcessing.enabled', { infer: true }) ?? false;

    if (storageProvider === 'local') {
      warnings.push(
        'Local storage requires persistent volume mounted to /app/uploads in production',
      );
    }
    if (!publicBaseUrl) {
      warnings.push('PUBLIC_BASE_URL is not configured');
    }
    if ((imageProcessingEnabled || videoProcessingEnabled) && !ffmpeg.available) {
      warnings.push('ffmpeg is not available; image/video processing may fail');
    }
    if (!ffprobe.available) {
      warnings.push('ffprobe is not available; duration extraction may fail');
    }
    if (storageProvider === 's3' && !(storageHealth.isS3Configured ?? storageHealth.s3Configured)) {
      warnings.push('S3 provider selected but missing required env variables');
    }
    if (storageProvider === 's3' && !storageHealth.storagePublicBaseUrlConfigured) {
      warnings.push('STORAGE_PUBLIC_BASE_URL is not configured; media may be served from the storage endpoint instead of CDN');
    }
    const s3Health = storageHealth.s3 as Record<string, unknown> | undefined;
    if (storageProvider === 's3' && s3Health?.reachable === false) {
      warnings.push('S3 bucket is not reachable from the backend');
    }

    const storageWritable =
      storageProvider !== 'local' || storageHealth.uploadPathWritable !== false;
    const status = !storageWritable ? 'error' : warnings.length ? 'warning' : 'ok';

    return {
      status,
      storage: storageHealth,
      processing: {
        imageProcessingEnabled,
        videoProcessingEnabled,
        videoHlsGenerationEnabled,
        videoThumbnailGenerationEnabled,
        audioProcessingEnabled,
        ffmpegPath: ffmpeg.path,
        ffmpegAvailable: ffmpeg.available,
        ffmpegVersion: ffmpeg.version,
        ffprobePath: ffprobe.path,
        ffprobeAvailable: ffprobe.available,
        ffprobeVersion: ffprobe.version,
        ffmpeg,
        ffprobe,
      },
      serving: {
        rangeRequests: true,
        immutableCacheSeconds: 31536000,
        hlsManifestCacheSeconds: 300,
        s3ImmutableCacheControl: 'public, max-age=31536000, immutable',
        s3HlsManifestCacheControl: 'public, max-age=300',
      },
      staticServing: {
        uploadsPublicPath:
          storageHealth.uploadsPublicPath ?? storageHealth.publicPath ?? '/uploads',
        rangeRequestsExpected: true,
        cacheHeadersExpected: true,
        hlsMimeExpected: 'application/vnd.apple.mpegurl',
      },
      warnings,
    };
  }

  async generateMusicFromText(userId: string, dto: TextToMusicDto) {
    const enabled = this.configService.get<boolean>('aiMusic.enabled', { infer: true });
    if (!enabled) {
      throw new ServiceUnavailableException('AI music generation is disabled');
    }

    const apiKey = this.configService.get<string>('aiMusic.apiKey', { infer: true }) ?? '';
    const projectId = this.configService.get<string>('aiMusic.projectId', { infer: true }) ?? '';
    const location = this.configService.get<string>('aiMusic.location', { infer: true }) ?? '';
    const model = this.configService.get<string>('aiMusic.model', { infer: true }) ?? 'lyria-002';
    if (!projectId || !location) {
      throw new ServiceUnavailableException('AI music settings are not configured');
    }

    let url = `https://${location}-aiplatform.googleapis.com/v1/projects/${projectId}/locations/${location}/publishers/google/models/${model}:predict`;
    let authorizationHeader: string | null = null;

    if (apiKey) {
      url = `${url}?key=${encodeURIComponent(apiKey)}`;
    } else {
      const auth = new GoogleAuth({
        scopes: ['https://www.googleapis.com/auth/cloud-platform'],
      });

      const client = await auth.getClient();
      const accessTokenRaw = await client.getAccessToken();
      const accessToken =
        typeof accessTokenRaw === 'string' ? accessTokenRaw : (accessTokenRaw?.token ?? '');

      if (!accessToken) {
        throw new ServiceUnavailableException('Failed to authenticate with Google Cloud');
      }
      authorizationHeader = `Bearer ${accessToken}`;
    }

    const requestBody: Record<string, unknown> = {
      instances: [{ prompt: dto.prompt }],
      parameters: {
        sampleCount: 1,
        durationSeconds: dto.durationSeconds ?? 12,
      },
    };

    if (typeof dto.seed === 'number') {
      (requestBody.parameters as Record<string, unknown>).seed = dto.seed;
    }

    const response = await fetch(url, {
      method: 'POST',
      headers: {
        ...(authorizationHeader ? { Authorization: authorizationHeader } : {}),
        'Content-Type': 'application/json',
      },
      body: JSON.stringify(requestBody),
    });

    const result = (await response.json()) as {
      error?: { message?: string };
      predictions?: Array<{
        bytesBase64Encoded?: string;
        mimeType?: string;
        audio?: { bytesBase64Encoded?: string; mimeType?: string };
      }>;
    };

    if (!response.ok) {
      throw new BadGatewayException(
        result?.error?.message ?? 'Google AI returned an unexpected error',
      );
    }

    const first = result?.predictions?.[0];
    const audioBase64 = first?.bytesBase64Encoded ?? first?.audio?.bytesBase64Encoded ?? '';
    const mimeType = first?.mimeType ?? first?.audio?.mimeType ?? 'audio/wav';

    if (!audioBase64) {
      throw new BadGatewayException('Google AI did not return audio content');
    }

    const extension = this.resolveAudioExtension(mimeType);
    const buffer = Buffer.from(audioBase64, 'base64');
    const audioUrl = await this.storageService.saveFile({
      folderSegments: ['ai-music'],
      extension: `.${extension}`,
      buffer,
      contentType: mimeType,
      fileNamePrefix: `ai-${userId}`,
    });

    return {
      prompt: dto.prompt,
      durationSeconds: dto.durationSeconds ?? 12,
      mimeType,
      sizeBytes: buffer.length,
      audioUrl,
      waveformPeaks: generateWaveformPeaksFromBuffer(buffer),
    };
  }

  private resolveAudioExtension(mimeType: string): string {
    if (mimeType.includes('mpeg') || mimeType.includes('mp3')) {
      return 'mp3';
    }
    if (mimeType.includes('ogg')) {
      return 'ogg';
    }
    if (mimeType.includes('aac')) {
      return 'aac';
    }
    if (mimeType.includes('wav')) {
      return 'wav';
    }
    return 'wav';
  }
}