#!/bin/bash

# Check if the correct number of arguments is provided
if [ $# -ne 1 ]; then
    echo "Usage: $0 <top-level-directory>"
    exit 1
fi

# Get the top-level directory from the argument
TOP_DIR="$1"

# Define a temporary file to store the list of files
FILE_LIST="file_list.txt"

# Remove the temporary file if it exists
rm -f "$FILE_LIST"

# Find all segment directories and sort them numerically
dirs=$(find "$TOP_DIR" -maxdepth 1 -type d -name 'segment_*' | sort -V)

# Loop over the directories
for dir in $dirs; do
    segment_name=$(basename "$dir")
    segment_num=$(echo "$segment_name" | sed 's/segment_//')

    output_file="$dir/output_$segment_num.mp4"

    if [ -f "$output_file" ]; then
        echo "file '$output_file'" >> "$FILE_LIST"

    else
        echo "No output_$segment_num.mp4 found in $dir"
    fi
done

# Run ffmpeg to concatenate the videos
ffmpeg -f concat -safe 0 -i "$FILE_LIST" -c copy output_combined.mp4

# Remove the temporary file
rm "$FILE_LIST"