Assuming all files are in the same folder, you can run the command like this: ./gh_repo_stats.rb --after 2012-11-01T13:00:00Z --before 2012-11-01T16:12:14Z --event PushEvent --count 42

gh_repo_stats.rb

#!/usr/bin/env ruby
# encoding: utf-8

require_relative 'github_archive'
require 'optparse'

# gh_repo_stats --after 2012-11-01T13:00:00Z --before 2012-11-02T03:12:14-03:00 --event PushEvent --count 42

options = {}
OptionParser.new do |opts|
  opts.banner = "Usage: github_archive.rb [options]"

  opts.on("-a", "--after DATETIME", "Start searching from this time") do |after|
    options[:from] = after
  end

  opts.on("-b", "--before DATETIME", "Stop searching at this time") do |before|
    options[:to] = before
  end

  opts.on("-e", "--event EVENT", "Filter by event name") do |event_name|
    options[:event] = event_name
  end

  opts.on("-c", "--count COUNT", "Restrict the number of entries") do |count|
    options[:count] = count.to_i
  end
end.parse!

puts GithubArchive::Displayer.new(
     event: options[:event],
     count: options[:count],
     uri: GithubArchive::URI.new(from: options[:from], to: options[:to])).display

github_archive.rb

# encoding: utf-8

require 'zlib'
require 'open-uri'
require 'yajl'

module GithubArchive
  class URI
    URL = "http://data.githubarchive.org/"

    attr_reader :from, :to

    def initialize(options)
      @from = DateTime.parse(options[:from]).to_time.utc
      @to = DateTime.parse(options[:to]).to_time.utc
    end

    def build_uri
      uris = []
      hour = from
      while hour < to
        uris << "#{URL}#{hour.year}-#{hour.month}-#{hour.strftime("%d")}-#{hour.hour}.json.gz"
        hour += 3600
      end
      uris
    end
  end

  class Displayer
    attr_reader :event, :count, :uri
    attr_accessor :json

    def initialize(options)
      @event = options[:event]
      @count = options[:count]
      @uri   = options[:uri]
      @json  = ''
    end

    def display
      parse.collect {|e| e.join(" - ") }.join(" events\n")
    end


    private
    def parse
      download_all
      puts "Parsing"
      event_counts = Hash.new(0)
      Yajl::Parser.new.parse @json do |activity|
        if activity["type"] =~ /#{event}/
          url = repository_owner_and_name(activity["repository"]["url"])
          event_counts[url] += 1
        end
      end
      event_counts.sort_by {|repo, event_count| event_count }.reverse[0..count]
    end

    def download_all
      uri.build_uri.each do |uri|
        puts "Downloading and unzipping #{uri}"
        json << Zlib::GzipReader.new(open uri).read
      end
    end

    def repository_owner_and_name(url)
      url.split('/')[-2..-1].join('/')
    end
  end
end

github_archive_spec.rb

# encoding: utf-8

require_relative 'github_archive'

describe GithubArchive::Displayer do
  describe "#display" do
    it "downloads the archive, untars it and returns JSON" do
      displayer = GithubArchive::Displayer.new(
           event: "PushEvent",
           count: 42,
           uri: GithubArchive::URI.new(from: "2012-11-01T13:00:00Z", to: "2012-11-01T15:12:14Z"))

      displayer.should_receive(:download_all)
      displayer.json = File.open('fixtures/github_archive.json').read

      expect(displayer.display).to match("antage/formtastic-plus-bootstrap - 2 events")
    end
  end
end

describe GithubArchive::URI do
  context "when from and to are different in days" do
    subject :archive do
      GithubArchive::URI.new from: "2012-11-01",
                        to:   "2012-11-02"
    end

    it "builds up the correct URI" do
      archive.build_uri.should include('http://data.githubarchive.org/2012-11-01-0.json.gz')
      archive.build_uri.should include('http://data.githubarchive.org/2012-11-01-23.json.gz')
    end
  end

  context "when time in from and to aren't equal" do
    subject :archive do
      GithubArchive::URI.new(from: "2012-11-01T13:00:00Z", to: "2012-11-01T16:12:14-03:00")
    end

    it "builds up the correct string given parameters" do
      archive.build_uri.should include('http://data.githubarchive.org/2012-11-01-15.json.gz')
    end
  end

  context "when day in from and to aren't equal" do
    subject :archive do
      GithubArchive::URI.new(from: "2012-11-01T13:00:00Z", to: "2012-11-03T16:12:14-03:00")
    end

    it "builds up the correct string given parameters" do
      archive.build_uri.should include('http://data.githubarchive.org/2012-11-03-13.json.gz')
    end
  end
end