#!/bin/bash
set -e

# Base directories
VIDEO_SOURCE_DIR="static/videos"
HLS_OUTPUT_DIR="static/videos/hls"
POSTER_OUTPUT_DIR="static/videos/posters"

# Create output directories if they don't exist
mkdir -p "$HLS_OUTPUT_DIR"
mkdir -p "$POSTER_OUTPUT_DIR"

# HLS Settings
SEGMENT_TIME=4  # Segment duration in seconds
KEYFRAME_INTERVAL=48  # Keyframe interval (2 seconds at 24fps)

# Resolutions for adaptive streaming
RESOLUTIONS=(
  "256:144"  # 144p
  "426:240"  # 240p
  "640:360"  # 360p
  "854:480"  # 480p
  "1280:720" # 720p
)

# Bitrates for each resolution (in kbps)
BITRATES=(
  "200k"     # 144p
  "400k"     # 240p
  "800k"     # 360p
  "1500k"    # 480p
  "2500k"    # 720p
)

# Function to generate HLS streams for a video
transcode_to_hls() {
  local input_file="$1"
  local video_id=$(basename "$input_file" .mp4)
  local output_dir="$HLS_OUTPUT_DIR/$video_id"
  
  echo "Transcoding $input_file to HLS format..."
  
  # Create output directory
  mkdir -p "$output_dir"
  
  # Generate variant playlists for each resolution
  for i in "${!RESOLUTIONS[@]}"; do
    local resolution=${RESOLUTIONS[$i]}
    local bitrate=${BITRATES[$i]}
    local width=$(echo $resolution | cut -d':' -f1)
    local height=$(echo $resolution | cut -d':' -f2)
    
    echo "  Creating $height stream ($bitrate)..."
    
    # Using better encoding settings for quality and efficiency
    ffmpeg -y -i "$input_file" \
      -vf "scale=$resolution:force_original_aspect_ratio=decrease,pad=$resolution:-1:-1:color=black" \
      -c:v libx264 -preset slower -crf 22 -maxrate $bitrate -bufsize $(echo $bitrate | sed 's/k/000/') \
      -g $KEYFRAME_INTERVAL -keyint_min $KEYFRAME_INTERVAL \
      -sc_threshold 0 -hls_time $SEGMENT_TIME \
      -hls_playlist_type vod \
      -hls_segment_filename "$output_dir/${video_id}_${height}p_%03d.ts" \
      -master_pl_name "master.m3u8" \
      -var_stream_map "v:0,name:${height}p" \
      -c:a aac -b:a 128k \
      "$output_dir/${video_id}_${height}p.m3u8"
  done
  
  # Create master playlist
  echo "#EXTM3U" > "$output_dir/master.m3u8"
  echo "#EXT-X-VERSION:3" >> "$output_dir/master.m3u8"
  
  for i in "${!RESOLUTIONS[@]}"; do
    local resolution=${RESOLUTIONS[$i]}
    local bitrate=${BITRATES[$i]}
    local width=$(echo $resolution | cut -d':' -f1)
    local height=$(echo $resolution | cut -d':' -f2)
    
    echo "#EXT-X-STREAM-INF:BANDWIDTH=$(echo $bitrate | sed 's/k/000/'),RESOLUTION=$resolution" >> "$output_dir/master.m3u8"
    echo "${video_id}_${height}p.m3u8" >> "$output_dir/master.m3u8"
  done
  
  # Create a symlink for index.m3u8
  ln -sf "master.m3u8" "$output_dir/index.m3u8"
  
  echo "  Transcoding complete for $video_id"
}

# Function to generate WebP thumbnails
generate_thumbnails() {
  local input_file="$1"
  local video_id=$(basename "$input_file" .mp4)
  
  echo "Generating thumbnails for $input_file..."
  
  # Generate thumbnail at 25% of the video duration
  ffmpeg -y -i "$input_file" -ss $(ffprobe -v error -show_entries format=duration -of default=noprint_wrappers=1:nokey=1 "$input_file" | awk '{print $1/4}') \
    -vframes 1 -vf "scale=640:-1" "$POSTER_OUTPUT_DIR/${video_id}.jpg"
  
  # Convert to WebP with better quality
  ffmpeg -y -i "$POSTER_OUTPUT_DIR/${video_id}.jpg" -vf "scale=640:-1" -quality 90 "$POSTER_OUTPUT_DIR/${video_id}.webp"
  
  # Copy thumbnails to HLS directory for reference
  cp "$POSTER_OUTPUT_DIR/${video_id}.webp" "$HLS_OUTPUT_DIR/$video_id/poster.webp"
  cp "$POSTER_OUTPUT_DIR/${video_id}.jpg" "$HLS_OUTPUT_DIR/$video_id/poster.jpg"
  
  echo "  Thumbnail generation complete for $video_id"
}

# Process each video
for video_file in $VIDEO_SOURCE_DIR/*.mp4; do
  if [ -f "$video_file" ]; then
    transcode_to_hls "$video_file"
    generate_thumbnails "$video_file"
  fi
done

echo "All videos have been transcoded to HLS format and thumbnails generated."
echo "HLS streams are available in $HLS_OUTPUT_DIR"
echo "Thumbnails are available in $POSTER_OUTPUT_DIR"