Enhanced Transfer: File Preview System

[sanchxt]

Description

Generate and display file previews before accepting transfers for safety and convenience.

Requirements

• Receiver sees file previews before accepting transfer
• Preview generation on sender side (non-blocking)
• Multiple preview types based on file format
• Configurable preview generation (enable/disable per file type)
• Preview size limits (max bandwidth for preview transfer)

Preview Types

Images (jpg, png, gif, webp)

• Thumbnail: 256x256px
• Max size: 50KB
• Format: JPEG for transfer

Videos (mp4, mov, webm)

• First frame thumbnail: 256x256px
• Max size: 50KB
• Duration and resolution metadata

PDFs

• First page thumbnail: 512x512px
• Max size: 100KB
• Page count metadata

Text/Code Files

• First 1KB of content
• Syntax highlighting hint (file extension)
• Line count, encoding

Archives (zip, tar, gz)

• File listing (first 50 entries)
• Total files count
• Compressed/uncompressed sizes

Other Files

• File icon based on extension
• MIME type
• Size and modification date

Protocol Extension

New message types (0x07-0x08):

• PreviewRequest - Receiver requests preview for specific file
• PreviewData - Sender sends preview data

Configuration

[preview]
enabled = true
max_image_size = "50KB"
max_text_length = 1024
generate_pdf = true
generate_video = true
generate_archive_listing = true

Technical Details

• Use image crate for image thumbnails
• Use pdf or poppler for PDF rendering
• Use ffmpeg or gstreamer for video frames (optional)
• Use zip, tar crates for archive listings
• Async preview generation (don't block transfer)
• Cache generated previews during session

UI Display

• CLI: Text preview or "[Image: 1920x1080 JPEG]" placeholders
• TUI: Render thumbnails using Unicode blocks or kitty graphics protocol
• Web: Display actual images/thumbnails in browser

Acceptance Criteria

• Receiver sees meaningful preview for images, PDFs, videos, text
• Preview generation doesn't delay transfer initiation
• Previews are optional (can skip and accept blindly)
• Preview size limited to avoid bandwidth waste