#!/usr/bin/env ruby

# ================================================================
# This scans mkdocs.yml and for each .md file updates the description string
# with line one of the .md file.
#
# Usage:
# * ./retitle mkdocs.yml > temp
# * diff mkdocs.yml temp # and review
# * mv temp mkdocs.yml   # to accept
# ================================================================

ARGF.each do |line|
  line.chomp!
  # >>    - "Miller in 10 minutes": "10min.md"<<
  if line =~ /(.*")([^"]*)(": ")(.*\.md)(")$/
    pre = $1
    old_tile = $2
    mid = $3
    md_file_name = $4
    post = $5

    if md_file_name == "index.md"
      new_title = "Introduction"
    else
      md_in_file_path = "./src/#{md_file_name}.in"
      new_title = File.open(md_in_file_path).readlines()[0].sub(/^# /, "").chomp
    end
    puts "#{pre}#{new_title}#{mid}#{md_file_name}#{post}"

  else
    puts line
  end
end