require "open-uri"
require "json"
require "base64"

module OrganizationAudit
  class Repo
    HOST = "https://api.github.com"

    def initialize(data, token=nil)
      @data = data
      @token = token
    end

    def gem?
      !!gemspec_file
    end

    def gemspec_content
      content(gemspec_file) if gem?
    end

    def url
      api_url.sub("api.", "").sub("/repos", "")
    end

    def to_s
      "#{url} -- #{last_commiter}"
    end

    def name
      api_url.split("/").last
    end

    def self.all(options)
      user = if options[:organization]
        "orgs/#{options[:organization]}"
      elsif options[:user]
        "users/#{options[:user]}"
      else
        "user"
      end
      url = File.join(HOST, user, "repos")

      token = options[:token]
      download_all_pages(url, headers(token)).map { |data| Repo.new(data, token) }
    end

    def content(file)
      @content ||= {}
      @content[file] ||= begin
        if private?
          download_content_via_api(file)
        else
          download_content_via_raw(file)
        end
      end
    rescue OpenURI::HTTPError => e
      raise "Error downloading #{file} from #{url} (#{e})" unless e.message.start_with?("404")
    end

    def private?
      @data["private"]
    end

    def last_commiter
      response = call_api("commits/#{branch}")
      committer = response["commit"]["committer"]
      "#{committer["name"]} <#{committer["email"]}>"
    end

    def clone_url
      if private?
        url.sub("https://", "git@").sub("/", ":") + ".git"
      else
        url + ".git"
      end
    end

    def file_list
      @file_list ||= call_api("contents?branch=#{branch}").
        select { |f| f["type"] == "file" }.
        map { |file| file["path"] }
    end

    private

    def gemspec_file
      file_list.grep(/\.gemspec$/).first
    end

    def self.download_all_pages(url, headers)
      results = []
      page = 1
      loop do
        response = decorate_errors do
          open("#{url}?page=#{page}", headers).read
        end
        result = JSON.parse(response)
        if result.size == 0
          break
        else
          results.concat(result)
          page += 1
        end
      end
      results
    end

    def branch
      @data["default_branch"] || @data["master_branch"] || "master"
    end

    def api_url
      @data["url"]
    end

    def raw_url
      url.sub("://", "://raw.")
    end

    # increases api rate limit
    def download_content_via_api(file)
      content = call_api("contents/#{file}?branch=#{branch}")["content"]
      Base64.decode64(content)
    end

    def call_api(path)
      content = self.class.decorate_errors do
        open(File.join(api_url, path), self.class.headers(@token)).read
      end
      JSON.load(content)
    end

    def self.decorate_errors
      yield
    rescue OpenURI::HTTPError => e
      e.message << " -- body: " << e.io.read
      raise e
    end

    # unlimited
    def download_content_via_raw(file)
      open(File.join(raw_url, branch, file)).read
    end

    def self.headers(token)
      token ? {"Authorization" => "token #{token}"} : {}
    end
  end
end