#!/usr/bin/env ruby

require "json"
require "open-uri"
require "colorize"
require "nutella"

print "Downloading data..."

begin
  # TODO: Let the user paste the entire Gist URL and parse out the ID.
  gist = JSON.parse open("https://api.github.com/gists/#{ARGV.first}").read
rescue OpenURI::HTTPError => msg
  puts <<-EOS.heredoc.red


    There was an error downloading the requested Gist.
    The error is as follows:
  EOS

  puts msg

  exit -1
end

# The JSON data contains a lot of information. The information that is
# relevant to this program is as follows:
#
# {
#   "html_url" => "Link to the Gist",
#   "description" => "The description for the Gist",
#
#   "user" => nil, # IF ANONYMOUS
#   "user" => {    # IF TIED TO A USER
#     "login" => "username"
#   },
#
#   "files" => {
#     "filename of first file" => {
#       "content" => "entire contents of the file"
#     }
#     # Repeat the above for every file in the Gist.
#   }
# }

user = gist["user"] ? "user #{gist["user"]["login"]}" : "an anonymous user"

puts <<-EOS.heredoc


  Finished downloading Gist from: #{gist["html_url"]}
  Gist uploaded by #{user}.

  Beginning install...
EOS

gist["files"].each do |filename, data|
  lines = data["content"].split "\n"

  # Parse out all metadata after %% on the first two lines, strip out
  # (lead|trail)ing whitespace while we're at it.
  metadata = lines[0..1].map { |line| line[/%%\s*(.*\S)\s*/, 1] }

  # Skip non-Gistribute files.
  next if metadata.first.nil?

  puts " #{"*".green} Installing #{metadata[1] || filename}..."

  # TODO: Handle ~ better. Also, handle EOF newlines.
  File.open(metadata.first.gsub(/~/, Dir.home), "w") do |f|
    # Remove all lines with metadata- lines that don't match will return nil,
    # so compact it and drop that many off the top of the file.
    f << lines[metadata.compact.size..-1].join("\n")
  end
end