require 'json'

module Checkstyle
  class FileReviewer

    HEADERS = { 'Authorization' => "token #{ENV['GITHUB_TOKEN']}" }

    RUBOCOP_QUOTES = [
      "> - Robo, excuse me, Robo. Any special message for all the kids watching at home?\n> - Stay out of trouble.",
      '> Four... three... two... one... I am now authorized to use physical force!',
      '> Thank you for your co-operation. Good night.',
      '> Serve the public trust. Protect the innocent. Uphold the law.',
      '> Your move, creep.',
      '> Come quietly or there will be trouble.',
      '> You are under arrest.',
      "> Dead or alive, you're coming with me!",
      '> Oooh, guns guns guns!',
      '> Excuse me, I have to go. Somewhere there is a crime happening.'
    ]

    attr_reader :file_path, :repository, :violations

    def initialize(repository, file_path, violations)
      @file_path = file_path
      @violations = violations
      @repository = repository
    end

    def review
      log "Reviewing file #{file_path}"

      violations.each { |violation| comment_violation(violation) }
    end

    private

    def line_for_violation(patch, violation)
      violating_line = violation['location']['line']
      meta, *patch_lines = patch.split("\n")

      start = meta.match(/\+(\d+)/)[1].to_i
      patch_index = 0

      patch_lines.each_with_index do |content, patch_position|
        next if content.first == '-'

        line_number = start + patch_index
        return { number: line_number, patch_position: patch_position + 1, content: content } if line_number == violating_line

        patch_index += 1
      end

      {}
    end

    def comment_violation(violation)
      commit_sha = violating_commit_sha(violation)
      commit = get("#{commit_url(commit_sha)}?v=3", cache: true).data

      file_object = commit.files.find { |f| f.filename == file_path }
      line = line_for_violation(file_object.patch, violation)

      comment_on_line(file_object, line[:number], line[:patch_position], violation, commit)
    end

    # Gets SHA of the commit where line was last changed
    def violating_commit_sha(violation)
      line = violation['location']['line']
      `git log --format="%H" -1 -L #{line},#{line}:#{file_path} | head -n 1`.strip
    end

    def commit_url(sha)
      "https://api.github.com/repos/#{repository}/commits/#{sha}"
    end

    def already_commented?(file, line_number, violation, commit)
      comments = get(commit.comments_url).data
      comments.any? do |comment|
        comment.body.scan(comment_signature(file, line_number, violation)).any?
      end
    end

    def comment_on_line(file, line_number, patch_position, violation, commit)
      if already_commented?(file, line_number, violation, commit)
        log "\tI already commented on this"
        return
      end

      body = {
        body: line_comment(file, line_number, violation),
        path: file.filename,
        position: patch_position
      }
      LHC.post(commit.comments_url, headers: HEADERS, body: body.to_json)
      log "\tfile change commented on Github"
    rescue LHC::Error
      log "\tencountered problems while trying to post comment file change on Github"
    end

    def comment_signature(file, line_number, violation)
      "*#{file.filename}:#{line_number} #{violation['cop_name']}*"
    end

    def get(url, options = {})
      LHC.get(url, options.reverse_merge(headers: HEADERS))
    end

    def line_comment(file, line_number, violation)
      return line_comment_with_quote(file, line_number, violation) if rand > 0.6

      plain_line_comment(file, line_number, violation)
    end

    def line_comment_with_quote(file, line_number, violation)
      "#{plain_line_comment(file, line_number, violation)}\n\n#{RUBOCOP_QUOTES.sample}"
    end

    def plain_line_comment(file, line_number, violation)
      "**[#{violation['severity']}]** #{violation['message']}\n#{comment_signature(file, line_number, violation)}"
    end

    def log(text)
      puts "[CHECKSTYLE][Review file] #{text}"
    end
  end
end