require 'gepub'
require 'erb'
require 'optparse'
require 'pathname'

# Parse epubs

options = {:subdir => "books"}
OptionParser.new do |opts|
  opts.banner = "Usage: index.rb [options]"

  opts.on("-d", "--dir DIR", "directory to index (subdir specified with '-s' will be indexed)") do |d|
    options[:dir] = d
  end

  opts.on("-s", "--subdir DIR", "subdirectory to search for books") do |s|
    options[:subdir] = s
  end
end.parse!

raise OptionParser::MissingArgument unless options[:dir]

books = Dir["#{options[:dir]}/#{options[:subdir]}/*.epub"].map do |f|
  [Pathname.new(f).relative_path_from(Pathname.new(options[:dir])), GEPUB::Book.parse(File.new f)]
end.to_h

# Collection of sort_by procs

author_surname_sort_by = proc { |filename, book|
  book.creator.content.split(" ")[-1]
}

title_sort_by = proc { |filename, book|
  book.title.content
}


# Sort books by one of the above

books = books.sort_by &title_sort_by

i = 0
book_ids = books.map { |filename, book| [filename, i += 1] }.to_h
i = nil

# Generate 'index.html' from template

bind = binding
bind.local_variable_set(:books, books)

html_template = File.read 'index.html.erb'

html_result = ERB.new(html_template).result(bind)
File.open "#{options[:dir]}/index.html", "w+" do |f|
  f << html_result
end


# Generate 'books.csv'

File.open "#{options[:dir]}/books.csv", "w+" do |f|
  f << "id\ttitle\tauthor\tfilename\n"
  books.each do |filename, book|
    f << "#{book_ids[filename]}\t"
    f << "#{book.title.content}\t"
    f << "#{book.creator.content}\t"
    f << "#{filename}\t"
    f << "\n"
  end
end