convert_pdf.sh

#!/bin/bash

# Check if an argument is provided
if [ -z "$1" ]; then
    echo "Error: You must provide the path to a PDF file as an argument."
    exit 1
fi

pdf_file="$1"

# Check if the file exists
if [ ! -f "$pdf_file" ]; then
    echo "Error: File '$pdf_file' not found."
    exit 1
fi

# Prepare output directory
dir="$(dirname "$pdf_file")"
base_name="$(basename -- "$pdf_file" .pdf)"
output_dir="$dir/images"
mkdir -p "$output_dir"

# Get number of pages
page_count=$(pdfinfo "$pdf_file" | awk '/Pages:/ {print $2}')

# Convert to PNG
if [ "$page_count" -gt 1 ]; then
    pdftoppm -png "$pdf_file" "$output_dir/$base_name"
else
    pdftoppm -png "$pdf_file" "$output_dir/$base_name"
    mv "$output_dir/${base_name}-1.png" "$output_dir/${base_name}.png"
fi

# Build output PDF name
output_pdf="${output_dir}/${base_name}_converted.pdf"

# Find PNGs safely (supporting spaces and Unicode), and store in an array
IFS=$'\n' read -d '' -r -a png_files < <(find "$output_dir" -maxdepth 1 -type f -name "${base_name}-*.png" -print | sort && printf '\0')

# If no multiple PNGs found, check for single-page file
if [ ${#png_files[@]} -eq 0 ]; then
    png_files=("$output_dir/${base_name}.png")
fi

# Check that at least one PNG file exists
if [ ! -f "${png_files[0]}" ]; then
    echo "Error: No PNG files found for conversion."
    exit 1
fi

# Combine into PDF using ImageMagick v7
if magick "${png_files[@]}" "$output_pdf"; then
    echo "Conversion complete: $output_pdf"
    mv "$output_pdf" "$dir/"
    rm -rf "$output_dir"
else
    echo "Error: Failed to create the output PDF."
    exit 1
fi