import { NextRequest } from 'next/server';
import { auth, checkProjectAccess } from '@/lib/auth';
import { db } from '@/lib/db';
import { r2Client, R2_BUCKET_NAME } from '@/lib/r2';
import { PutObjectCommand } from '@aws-sdk/client-s3';
import { randomUUID } from 'crypto';
import { rateLimit } from '@/lib/rate-limit';
import { validateShareLinkAccess } from '@/lib/share-links';
import { getShareSessionFromRequest } from '@/lib/share-session';
import { apiErrors, successResponse, withCacheControl } from '@/lib/api-response';
import {
  deriveGuestUploadContext,
  enforceGuestUploadQuota,
  verifyGuestUploadToken,
} from '@/lib/guest-upload-token';

const MAX_FILE_SIZE = 10 * 1024 * 1024; // 10MB
const ALLOWED_TYPES = ['audio/webm', 'audio/ogg', 'audio/mp4', 'audio/mpeg', 'audio/wav'];

export async function POST(request: NextRequest) {
  try {
    // Check Content-Length header BEFORE loading the file
    const contentLength = request.headers.get('content-length');
    if (contentLength) {
      const fileSize = parseInt(contentLength, 10);
      if (isNaN(fileSize) || fileSize > MAX_FILE_SIZE) {
        return apiErrors.badRequest('File too large. Maximum size is 10MB.');
      }
    }

    // Rate limit
    const limited = await rateLimit(request, 'voice-upload');
    if (limited) return limited;

    const session = await auth();

    const formData = await request.formData();
    const file = formData.get('audio') as File | null;
    const videoId = formData.get('videoId');
    const uploadToken = formData.get('uploadToken');

    if (!file) {
      return apiErrors.badRequest('No audio file provided');
    }
    if (typeof videoId !== 'string' || !videoId.trim()) {
      return apiErrors.badRequest('videoId is required');
    }

    const safeVideoId = videoId.trim();
    const video = await db.video.findUnique({
      where: { id: safeVideoId },
      include: { project: true },
    });
    if (!video) {
      return apiErrors.notFound('Video');
    }

    const access = await checkProjectAccess(video.project, session?.user?.id);
    const shareSession = getShareSessionFromRequest(request, safeVideoId);
    const shareAccess = shareSession
      ? await validateShareLinkAccess({
        token: shareSession.token,
        projectId: video.projectId,
        videoId: safeVideoId,
        requiredPermission: 'COMMENT',
        passwordVerified: shareSession.passwordVerified,
      })
      : { hasAccess: false, canComment: false, canDownload: false, allowGuests: false, requiresPassword: false };
    const canCommentWithMembership = !!session?.user?.id && access.hasAccess;
    const canCommentWithShareLink = shareAccess.canComment && (session?.user?.id ? true : shareAccess.allowGuests);
    if (!canCommentWithMembership && !canCommentWithShareLink) {
      return apiErrors.forbidden('Access denied');
    }

    if (!session?.user?.id) {
      if (typeof uploadToken !== 'string' || !uploadToken.trim()) {
        return apiErrors.badRequest('uploadToken is required for guest uploads');
      }

      const expectedContext = deriveGuestUploadContext(request, shareSession?.token ?? null);
      if (!expectedContext) {
        return apiErrors.forbidden('Missing trusted client IP header');
      }

      const isValidUploadToken = verifyGuestUploadToken(uploadToken.trim(), {
        projectId: video.projectId,
        videoId: safeVideoId,
        intent: 'audio',
        context: expectedContext,
      });
      if (!isValidUploadToken) {
        return apiErrors.forbidden('Invalid upload token');
      }

      const quotaError = await enforceGuestUploadQuota(request, safeVideoId, 'audio', shareSession?.token ?? null);
      if (quotaError) return quotaError;
    }

    // Double-check file size (defense in depth - Content-Length can be spoofed)
    if (file.size > MAX_FILE_SIZE) {
      return apiErrors.badRequest('File too large. Maximum size is 10MB.');
    }

    // Check content type
    const contentType = file.type || 'audio/webm';
    if (!ALLOWED_TYPES.includes(contentType)) {
      return apiErrors.badRequest(`Unsupported audio format: ${contentType}`);
    }

    // Generate unique filename
    const ext = contentType.split('/')[1] || 'webm';
    const filename = `${randomUUID()}.${ext}`;
    const key = `voice/${filename}`;

    // Convert to buffer
    const arrayBuffer = await file.arrayBuffer();
    const buffer = Buffer.from(arrayBuffer);

    // Upload to R2
    await r2Client.send(
      new PutObjectCommand({
        Bucket: R2_BUCKET_NAME,
        Key: key,
        Body: buffer,
        ContentType: contentType,
      })
    );

    // Return the URL through our proxy endpoint
    const voiceUrl = `/api/upload/audio/${filename}`;

    const response = successResponse({ url: voiceUrl }, 201);
    return withCacheControl(response, 'private, no-store');
  } catch (error) {
    console.error('Error uploading audio:', error);
    return apiErrors.internalError('Failed to upload audio');
  }
}