#!/usr/bin/env ruby

require "colorize"
require "fileutils"
require "json"
require "open-uri"

# Print to STDOUT to clear line
CLEAR = "\r\e[K"

if %w[-v --version].include? ARGV.first
  puts "Gistribute #{File.read(File.expand_path("../../VERSION", __FILE__)).strip}"
  exit 0
end

print "Downloading data..."

# The user can pass in either just the ID or the entire URL to the Gist.
id = ARGV.first[/(^|\/)([[:xdigit:]]+)/, 2]

begin
  gist = JSON.parse(URI.open("https://api.github.com/gists/#{id}").read)
rescue OpenURI::HTTPError => msg
  print <<~EOS.red
    #{CLEAR}There was an error downloading the requested Gist.
    The error is as follows:
  EOS
  puts msg

  puts "The ID that was queried is:".red
  puts id

  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",
#
#   "owner" => nil, # IF ANONYMOUS
#   "owner" => {    # 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.
#   }
# }

# Regular expression word wrap to keep lines less than 80 characters. Then
# check to see if it's empty- if not, put newlines on each side so that it
# will be padded when displayed in the output.
desc = gist["description"].gsub(/(.{1,79})(\s+|\Z)/, "\\1\n").strip
desc = "\n#{desc}\n" unless desc.empty?

puts <<~EOS
  #{CLEAR}Finished downloading Gist from: #{gist["html_url"]}
  Gist uploaded by #{
    gist["owner"] ? "user #{gist["owner"]["login"]}" : "an anonymous user"
  }.
  #{desc}
  Beginning install...
EOS

gist["files"].each do |filename, data|
  metadata = filename.split("||").map &:strip

  # | as path separator in the Gist's file name, as Gist doesn't allow the
  # usage of /.
  path = metadata.last.gsub(/[~|]/, "|" => "/", "~" => Dir.home)
  # Default description is the name of the file.
  description = metadata.size == 1 ? File.basename(path) : metadata.first

  puts " #{"*".green} Installing #{description}..."

  # Handle directories that don't exist.
  FileUtils.mkdir_p File.dirname(path)

  File.write(path, data["content"])
end