# MP3 Audio Hosting Feature

This document describes the MP3 audio hosting functionality added to the blog-backup project.

## Overview

The blog now supports uploading and hosting MP3 audio files for individual blog posts. This allows you to:
- Upload custom MP3 files to any blog post
- Attach audio commentary, interviews, or supplementary content
- Automatically estimate audio duration
- Play audio directly in the blog post with a custom audio player

## Features

### 1. Supabase Storage Integration
- **Bucket**: `podcast-audio` (shared with podcast feature)
- **File Size Limit**: 50MB per file
- **Supported Formats**: MP3, WAV, AIFF
- **Public Access**: Files are publicly readable via signed URLs

### 2. API Endpoints

#### `GET /api/audio?postId={id}`
Retrieves audio information for a blog post.

**Response:**
```json
{
  "hasAudio": true,
  "audioUrl": "https://...",
  "duration": 180
}
```

#### `POST /api/audio`
Uploads an audio file and associates it with a blog post.

**Request:**
- Content-Type: `multipart/form-data`
- Authorization: `Bearer {token}`
- Body: `file` (audio file), `postId` (string)

**Response:**
```json
{
  "success": true,
  "url": "https://...",
  "path": "upload-2026-02-25-123456789-1740523456789.mp3",
  "size": 5242880,
  "estimatedDuration": 327
}
```

#### `DELETE /api/audio`
Removes audio from a blog post and deletes the file from storage.

**Request:**
- Authorization: `Bearer {token}`
- Body: `{ "postId": "..." }`

### 3. Database Schema

The `blog_messages` table now includes:
- `audio_url` (text, nullable) - Public URL to the audio file
- `audio_duration` (integer, nullable) - Estimated duration in seconds

### 4. Components

#### `AudioPlayer`
Located in `src/components/AudioPlayer.tsx`

A custom audio player with:
- Play/pause controls
- Progress bar with seek functionality
- Volume control with mute toggle
- Time display (current / total)
- Dark mode support

**Usage:**
```tsx
import { AudioPlayer } from "@/components/AudioPlayer";

<AudioPlayer 
  url="https://..." 
  duration={180} // optional
/>
```

#### `CompactAudioPlayer`
A minimal version for inline use:
```tsx
import { CompactAudioPlayer } from "@/components/AudioPlayer";

<CompactAudioPlayer url="https://..." />
```

#### `AudioUpload`
Located in `src/components/AudioUpload.tsx`

Upload component for the admin interface with:
- Drag-and-drop file selection
- File type validation
- File size validation (50MB max)
- Upload progress indicator
- Current audio preview
- Remove/delete functionality

**Usage:**
```tsx
import { AudioUpload } from "@/components/AudioUpload";

<AudioUpload
  postId="123"
  existingAudioUrl={post.audio_url}
  onUploadSuccess={(url, duration) => {}}
  onDeleteSuccess={() => {}}
/>
```

### 5. Admin Interface

The admin dashboard (`/admin`) now includes:
- Audio indicator badge on posts with audio
- Audio upload section in the edit modal
- Preview player for uploaded audio
- Remove audio functionality

## Usage Guide

### Adding Audio to a Post

1. Go to `/admin` and log in
2. Find the post you want to add audio to
3. Click "Edit"
4. Scroll to the "Audio Attachment" section
5. Click to upload or drag and drop an MP3 file
6. Wait for upload to complete
7. Save changes

### Removing Audio from a Post

1. Go to `/admin` and log in
2. Edit the post with audio
3. In the "Audio Attachment" section, click "Remove"
4. Confirm deletion
5. Save changes

### Viewing Audio on the Blog

- Posts with audio display a 🎧 icon in the admin list
- On the public blog, audio appears at the top of the post
- The custom audio player provides full playback controls

## Technical Details

### File Naming
Uploaded files are named with the pattern:
```
upload-{date}-{postId}-{timestamp}.{ext}
```

Example: `upload-2026-02-25-123456789-1740523456789.mp3`

### Duration Estimation
Since extracting exact MP3 duration server-side requires additional libraries, we estimate duration based on file size:
- Assumption: 128 kbps bitrate (standard for MP3)
- Formula: `duration = (fileSize / (128 * 1024 / 8)) * 60`

The browser will display the actual duration once the audio file loads.

### Storage Costs
- Supabase free tier includes 1GB storage
- At 128kbps, 1GB = ~17.5 hours of audio
- Podcast audio and uploaded MP3s share the same bucket

## Future Enhancements

Potential improvements:
1. **Exact Duration Extraction**: Use `music-metadata` library for accurate duration
2. **Multiple Audio Files**: Support for multiple audio tracks per post
3. **Audio Transcription**: Auto-generate transcripts from audio
4. **Waveform Visualization**: Display audio waveforms
5. **Download Button**: Allow users to download audio files

## Troubleshooting

### Upload fails
- Check that file is under 50MB
- Verify file is a valid audio format (MP3, WAV, AIFF)
- Ensure you're logged in with a valid session

### Audio doesn't play
- Check browser console for errors
- Verify audio_url is accessible in the database
- Test the direct URL in a new tab

### Duration shows 0:00
- This is normal for the initial display
- The actual duration loads when the audio file is fetched
- Duration is estimated from file size for the initial display