# frozen_string_literal: true

require 'net/http'
require 'json'

module SmartTodo
  module Events
    # An event that check if a GitHub Pull Request or Issue is closed.
    # This event will make an API call to the GitHub API.
    #
    # If the Pull Request or Issue is on a private repository, exporting a token
    # with the `repos` scope in the +SMART_TODO_GITHUB_TOKEN+ environment variable
    # is required.
    class IssueClose
      TOKEN_ENV = 'SMART_TODO_GITHUB_TOKEN'

      # @param organization [String]
      # @param repo [String]
      # @param pr_number [String, Integer]
      def initialize(organization, repo, pr_number, type:)
        @url = "/repos/#{organization}/#{repo}/#{type}/#{pr_number}"
        @organization = organization
        @repo = repo
        @pr_number = pr_number
      end

      # @return [String, false]
      def met?
        response = client.get(@url, default_headers)

        if response.code_type < Net::HTTPClientError
          error_message
        elsif pull_request_closed?(response.body)
          message
        else
          false
        end
      end

      # Error message send to Slack in case the Pull Request or Issue couldn't be found.
      #
      # @return [String]
      def error_message
        <<~EOM
          I can't retrieve the information from the PR or Issue *#{@pr_number}* in the
          *#{@organization}/#{@repo}* repository.

          If the repository is a private one, make sure to export the `#{TOKEN_ENV}`
          environment variable with a correct GitHub token.
        EOM
      end

      # @return [String]
      def message
        <<~EOM
          The Pull Request or Issue https://github.com/#{@organization}/#{@repo}/pull/#{@pr_number}
          is now closed, your TODO is ready to be addressed.
        EOM
      end

      private

      # @return [Net::HTTP] an instance of Net::HTTP
      def client
        @client ||= Net::HTTP.new('api.github.com', Net::HTTP.https_default_port).tap do |client|
          client.use_ssl = true
        end
      end

      # @param pull_request [String] the Pull Request or Issue
      #   detail sent back from the GitHub API
      #
      # @return [true, false]
      def pull_request_closed?(pull_request)
        JSON.parse(pull_request)['state'] == 'closed'
      end

      # @return [Hash]
      def default_headers
        { 'Accept' => 'application/vnd.github.v3+json' }.tap do |headers|
          headers['Authorization'] = "token #{ENV[TOKEN_ENV]}" if ENV[TOKEN_ENV]
        end
      end
    end
  end
end