Fix(Demerge_pdfs): Fix crash on empty hardcoded PDF, PyPDF2 deprecations, add multi-mode splitting & CLI (#527)

Demerge_pdfs/README.md

@@ -1,25 +1,82 @@
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-# Demerging_pdfs
+# Demerging PDFs
 
 ## 🛠️ Description
 
-Python program to convert a large pdf file to number of different sized pdf files without any change in the large file.
+A powerful, robust Python utility to split, demerge, and extract pages from large PDF documents without modifying the original source file.
 
-## ⚙️ Languages or Frameworks Used
-PyPDF2, it can be installed by typing `pip3 install PyPDF2` on your command line
+### ✨ Features
+- **Interactive Wizard Mode**: Step-by-step assistant that displays remaining page counts, prevents invalid page inputs, and lets you custom-name each output piece.
+- **Equal Chunk Splitting**: Automatically split a PDF into equal parts of *N* pages each (e.g. split a 100-page book every 10 pages).
+- **Page Ranges Extraction**: Extract specific page ranges and individual pages in one go (e.g. `1-5, 8, 12-20`).
+- **Burst Mode**: Split every page into its own individual PDF document.
+- **Command-Line Interface (CLI)**: Full support for automated scripts and terminal execution with flags (`-i`, `-m`, `-p`, `-r`, `-o`, `--prefix`).
+- **Modern Compatibility**: Supports `pypdf` as well as `PyPDF2` (v3.0+ and legacy).
+- **Safe Output Handling**: Direct outputs to any destination folder, creating directories on-the-fly and sanitizing filenames.
 
-## 🌟 How to run
-Running the script is really simple! Just open a terminal in the folder where this  script is located and run the following command:
+---
+
+## ⚙️ Requirements & Installation
+
+Install the required dependencies using pip:
+
+```sh
+pip install -r requirements.txt
+```
+*Alternatively:*
+```sh
+pip install pypdf
+```
+
+---
+
+## 🌟 How to Run
+
+### 1. Interactive Mode
+Run the script without arguments to launch the interactive CLI wizard:
 ```sh
-python demerging_pdf.py
+python demerging_pdfs.py
 ```
-<img width="599" alt="Screenshot 2021-12-18 at 6 52 30 PM" src="https://user-images.githubusercontent.com/95535468/147670937-b6832970-8ed1-4180-a13a-264a55db0dd7.png">
+You will be prompted for:
+1. The path to your PDF file
+2. The destination folder
+3. The splitting mode (Custom Chunks, Equal Pages, Page Ranges, or Burst)
 
-## 🤖 Author
-[Darpan Balar]
+---
 
+### 2. Command-Line (CLI) Modes
 
+#### A. Equal Size Split
+Split `document.pdf` into chunks of 10 pages each:
+```sh
+python demerging_pdfs.py -i document.pdf -m equal -p 10 -o ./output_folder
+```
+
+#### B. Specific Page Ranges
+Extract pages 1 through 5, page 8, and pages 12 through 20:
+```sh
+python demerging_pdfs.py -i document.pdf -m ranges -r "1-5, 8, 12-20" -o ./extracted_pages
+```
+
+#### C. Burst Mode (1 Page Per File)
+Extract every page into individual PDFs:
+```sh
+python demerging_pdfs.py -i document.pdf -m burst -o ./burst_pages
+```
+
+---
+
+## 🧪 Running Automated Tests
+
+Run the unit test suite to verify filename sanitization, range parsing, and splitting logic:
+```sh
+python -m unittest test_demerging_pdfs.py -v
+```
 
+---
 
+## 🤖 Author & Contributors
+- **Original Author**: [Darpan Balar]
+- **Improvements & Fixes**: Open Source Contributors