createTIL.py

''' Simple script to auto-generate the README.md file for a TIL project. 
	Apply as a git hook by running the following command in Linux: 
	cd .git/hooks/ && ln -s ../../createTIL.py pre-commit && cd -
'''
import os

HEADER = '''# TIL

> Today I Learned

A collection of concise write-ups on small things I learn across a variety of 
languages and technologies.

'''

FOOTER = '''## Usage

Steps to follow:

1. Create directories for specific topics. For example if you solve a problem on 
	*HackerRank* create a directory named `Competitive Programming` or if you 
	learned something new in JavaScript, create a directory for the same.

	Some recommended categories:

	- Data Structures & Algorithms
	- Meet-ups
	- C++/JavaScript/Python
	- HTML/CSS
	- Git/Version Control
	- Machine Learning

2. Inside those directories create a [`Markdown`](https://www.markdownguide.org/basic-syntax/) 
	file with your title for example `Variables-in-JavaScript.md`, 
	`Create_React_App.md` etc. Make sure that the markdown file has a title. 
	Spaces in titles are _not_ recommended since different services render 
	markdown differently.

3. Every Markdown TIL file should start with a `#` i.e h1 heading.

4. Run `python createTIL.py` to auto-generate the new README file for you 
	
	OR
	
	If you are using git, you can install this script as a pre-commit git hook so 
	that it is autogenerated on each commit. Use the following command:

	`cd .git/hooks/ && ln -s ../../createtil.py pre-commit && cd -`
 
5. Once satisfied push your changes.

## About

Original Idea/Work [thoughtbot/til](https://github.com/thoughtbot/til).

## Other TIL Collections

* [Today I Learned by Hashrocket](https://til.hashrocket.com)
* [jwworth/til](https://github.com/jwworth/til)
* [thoughtbot/til](https://github.com/thoughtbot/til)'''

def get_category_list ():
	''' Walk the current directory and get a list of all subdirectories at that
	level.  These are the "categories" in which there are TILs. '''
	dirs = [x for x in os.listdir ('.') if os.path.isdir (x) and '.git' not in x]
	return dirs

def get_title (til_file):
	''' Read the file until we hit the first line that starts with a #
	indicating a title in markdown.  We'll use that as the title for this
	entry. '''
	with open (til_file) as file:
		for line in file:
			line = line.strip ()
			if line.startswith ('#'):
				return line[1:].lstrip ()  # text after # and whitespace

def get_tils (category):
	''' For a given category, get the list of TIL titles. '''
	til_files = [x for x in os.listdir (category)]
	titles = []
	for filename in til_files:
		fullname = os.path.join (category, filename)
		if (os.path.isfile (fullname)) and fullname.endswith ('.md'):
			title = get_title (fullname)
			# changing path separator for Windows paths
			# https://mail.python.org/pipermail/tutor/2011-July/084788.html
			titles.append ((title, fullname.replace (os.path.sep, '/')))
	return titles

def get_category_dict (category_names):
	categories = {}
	count = 0
	for category in category_names:
		titles = get_tils (category)
		categories[category] = titles
		count += len (titles)
	return (count, categories)

def print_file (category_names, count, categories):
	''' Now we have all the information, print it out in markdown format. '''
	with open ('README.md', 'w') as file:
		file.write (HEADER)
		if count == 1:
			file.write ('_{0} TIL and counting..._'.format(count))
		else:
			file.write ('_{0} TILs and counting..._'.format(count))
		file.write ('''

## Categories
''')
		# print the list of categories with links
		for category in sorted (category_names):
			file.write ('* [{0}](#{1})\n'.format (category.capitalize (), category))

		if len (category_names) > 0:
			file.write ('''
---

''')
		# print the section for each category
		for category in sorted (category_names):
			file.write ('### {0}\n'.format (category.capitalize ()))
			file.write ('\n')
			tils = categories[category]
			for (title, filename) in sorted (tils):
				file.write ('- [{0}]({1})\n'.format (title, filename))
			file.write ('\n')

		if len (category_names) > 0:
			file.write ('''---

''')
		file.write (FOOTER)

def create_README ():
	''' Create a TIL README.md file with a nice index for using it directly
		from GitHub. '''
	category_names = get_category_list ()
	count, categories = get_category_dict (category_names)
	print_file (category_names, count, categories)

if __name__ == '__main__':
	create_README ()