require 'json'
require 'tempfile'
require 'open3'
require 'bundler/inline'
require 'optparse'

gemfile do
  source 'https://rubygems.org'
  gem 'octokit'
end

class ScanPr
  def initialize
    @config_file = nil
    @github_token = ENV["GITHUB_TOKEN"]

    validate_token
  end

  def run(args)
    parse_options(args)
    repo_nwo, pr_number = extract_repo_and_pr(args)

    pr = fetch_pull_request(repo_nwo, pr_number)
    event_file = create_event_file(pr)

    execute_dependency_review(repo_nwo, event_file)
  ensure
    event_file&.unlink
  end

  private

  def validate_token
    if !@github_token || @github_token.empty?
      puts "Please set the GITHUB_TOKEN environment variable"
      exit -1
    end
  end

  def parse_options(args)
    op = OptionParser.new do |opts|
      usage = <<EOF
Run Dependency Review on a repository.

\e[1mUsage:\e[22m
  scripts/scan_pr [options] <pr_url>

\e[1mExample:\e[22m
  scripts/scan_pr https://github.com/actions/dependency-review-action/pull/294

EOF

      opts.banner = usage

      opts.on('-c', '--config-file <FILE>', 'Use an external configuration file') do |cf|
        @config_file = cf
      end

      opts.on("-h", "--help", "Prints this help") do
        puts opts
        exit
      end
    end

    op.parse!(args)
    @option_parser = op
  end

  def extract_repo_and_pr(args)
    # make sure we have a NWO somewhere in the parameters
    arg = /(?<repo_nwo>[\w\-]+\/[\w\-]+)\/pull\/(?<pr_number>\d+)/.match(args.join(" "))

    if arg.nil?
      puts @option_parser
      exit -1
    end

    [arg[:repo_nwo], arg[:pr_number]]
  end

  def fetch_pull_request(repo_nwo, pr_number)
    octo = Octokit::Client.new(access_token: @github_token)
    octo.pull_request(repo_nwo, pr_number)
  end

  def create_event_file(pr)
    event_file = Tempfile.new
    event_file.write("{ \"pull_request\": #{pr.to_h.to_json}}")
    event_file.close
    event_file
  end

  def execute_dependency_review(repo_nwo, event_file)
    action_inputs = {
      "repo-token": @github_token,
      "config-file": @config_file
    }

    dev_cmd_env = {
      "GITHUB_REPOSITORY" => repo_nwo,
      "GITHUB_EVENT_NAME" => "pull_request",
      "GITHUB_EVENT_PATH" => event_file.path,
      "GITHUB_STEP_SUMMARY" => "/dev/null"
    }

    # bash does not like variable names with dashes like the ones Actions
    # uses (e.g. INPUT_REPO-TOKEN). Passing them through `env` instead of
    # manually setting them does the job.
    action_inputs_env_str = action_inputs.map { |name, value| "\"INPUT_#{name.upcase}=#{value}\"" }.join(" ")
    dev_cmd = "./node_modules/.bin/nodemon --exec \"env #{action_inputs_env_str} node -r esbuild-register\" src/main.ts"

    Open3.popen2e(dev_cmd_env, dev_cmd) do |stdin, out|
      while line = out.gets
        puts line.gsub(@github_token, "<REDACTED>")
      end
    end
  end
end