module GitHelper
  class GitHubPullRequest
    attr_accessor :local_repo, :local_branch, :local_code, :cli, :base_branch, :new_pr_title

    def initialize(options)
      @local_repo = options[:local_project]
      @local_branch = options[:local_branch]
      @local_code = options[:local_code]
      @cli = options[:cli]
    end

    def create(options)
      @base_branch = options[:base_branch]
      @new_pr_title = options[:new_title]

      begin
        new_pr_body

        puts "Creating pull request: #{new_pr_title}"
        pr = octokit_client.create_pull_request(local_repo, base_branch, local_branch, new_pr_title, new_pr_body)
        puts "Pull request successfully created: #{pr.html_url}"
      rescue Octokit::UnprocessableEntity => e
        puts 'Could not create pull request:'
        if e.message.include?('pull request already exists')
          puts '  A pull request already exists for this branch'
        elsif e.message.include?('No commits between')
          puts '  No commits have been pushed to GitHub'
        else
          puts e.message
        end
      rescue Exception => e
        puts 'Could not create pull request:'
        puts e.message
      end
    end

    def merge
      begin
        pr_id
        merge_method

        puts "Merging pull request: #{pr_id}"
        merge = octokit_client.merge_pull_request(local_repo, pr_id, existing_pr.title, { merge_method: merge_method })
        puts "Pull request successfully merged: #{merge.sha}"
      rescue Octokit::UnprocessableEntity => e
        puts 'Could not merge pull request:'
        puts e.message
      rescue Octokit::NotFound => e
        puts 'Could not merge pull request:'
        puts "  Could not a locate a pull request to merge with ID #{pr_id}"
      rescue Octokit::MethodNotAllowed => e
        puts 'Could not merge pull request:'
        if e.message.include?('405 - Required status check')
          puts '  A required status check has not passed'
        elsif e.message.include?('405 - Base branch was modified')
          puts '  The base branch has been modified'
        elsif e.message.include?('405 - Pull Request is not mergeable')
          puts '  The pull request is not mergeable'
        elsif e.message.include?('405 - Rebase merges are not allowed on this repository')
          puts '  Rebase merges are not allowed on this repository'
        elsif e.message.include?('405 - Merge commits are not allowed on this repository')
          puts '  Merge commits are not allowed on this repository'
        elsif e.message.include?('405 - Squash commits are not allowed on this repository')
          puts '  Squash merges are not allowed on this repository'
        else
          puts e.message
        end
      rescue Exception => e
        puts 'Could not merge pull request:'
        puts e.message
      end
    end

    private def new_pr_body
      @new_pr_body ||= template_name_to_apply ? local_code.read_template(template_name_to_apply) : ''
    end

    private def template_name_to_apply
      return @template_name_to_apply if @template_name_to_apply
      @template_name_to_apply = nil

      unless pr_template_options.empty?
        if pr_template_options.count == 1
          apply_single_template = cli.apply_template?(pr_template_options.first, 'pull')
          @template_name_to_apply = pr_template_options.first if apply_single_template
        else
          response = cli.template_to_apply(pr_template_options, 'pull')
          @template_name_to_apply = response unless response == 'None'
        end
      end

      @template_name_to_apply
    end

    private def pr_template_options
      @pr_template_options ||= local_code.template_options({
                                 template_directory: '.github',
                                 nested_directory_name: 'PULL_REQUEST_TEMPLATE',
                                 non_nested_file_name: 'pull_request_template'
                               })
    end

    private def pr_id
      @pr_id ||= cli.code_request_id('Pull')
    end

    private def merge_method
      @merge_method ||= merge_options.length == 1 ? merge_options.first : cli.merge_method(merge_options)
    end

    private def merge_options
      return @merge_options if @merge_options
      merge_options = []
      merge_options << 'merge' if existing_project.allow_merge_commit
      merge_options << 'squash' if existing_project.allow_squash_merge
      merge_options << 'rebase' if existing_project.allow_rebase_merge
      @merge_options = merge_options
    end

    private def existing_project
      @existing_project ||= octokit_client.repository(local_repo)
    end

    private def existing_pr
      @existing_pr ||= octokit_client.pull_request(local_repo, pr_id)
    end

    private def octokit_client
      @octokit_client ||= GitHelper::OctokitClient.new.client
    end
  end
end