require "danger/plugin_support/plugin"

module Danger
  # Handles interacting with GitHub inside a Dangerfile. Provides a few functions which wrap `pr_json` and also
  # through a few standard functions to simplify your code.
  #
  # @example Warn when a PR is classed as work in progress
  #
  #          warn "PR is classed as Work in Progress" if github.pr_title.include? "[WIP]"
  #
  # @example Ensure that labels have been used on the PR
  #
  #          fail "Please add labels to this PR" if github.labels.empty?
  #
  # @example Check if a user is in a specific GitHub org, and message them if so
  #
  #          unless github.api.organization_member?('danger', github.pr_author)
  #            message "@#{pr_author} is not a contributor yet, would you like to join the Danger org?"
  #          end
  #
  # @example Ensure there is a summary for a PR
  #
  #          fail "Please provide a summary in the Pull Request description" if github.pr_body.length < 5
  #
  # @see  danger/danger
  # @tags core, github

  class DangerfileGitHubPlugin < Plugin
    def initialize(dangerfile)
      super(dangerfile)
      return nil unless dangerfile.env.request_source.class == Danger::RequestSources::GitHub

      @github = dangerfile.env.request_source
    end

    def self.instance_name
      "github"
    end

    # @!group PR Metadata
    # The title of the Pull Request.
    # @return [String]
    #
    def pr_title
      @github.pr_json[:title].to_s
    end

    # @!group PR Metadata
    # The body text of the Pull Request.
    # @return [String]
    #
    def pr_body
      pr_json[:body].to_s
    end

    # @!group PR Metadata
    # The username of the author of the Pull Request.
    # @return [String]
    #
    def pr_author
      pr_json[:user][:login].to_s
    end

    # @!group PR Metadata
    # The labels assigned to the Pull Request.
    # @return [String]
    #
    def pr_labels
      @github.issue_json[:labels].map { |l| l[:name] }
    end

    # @!group PR Commit Metadata
    # The branch to which the PR is going to be merged into.
    # @return [String]
    #
    def branch_for_base
      pr_json[:base][:ref]
    end

    # @!group PR Commit Metadata
    # The branch to which the PR is going to be merged from.
    # @return [String]
    #
    def branch_for_head
      pr_json[:head][:ref]
    end

    # @!group PR Commit Metadata
    # The base commit to which the PR is going to be merged as a parent.
    # @return String
    #
    def base_commit
      pr_json[:base][:sha]
    end

    # @!group PR Commit Metadata
    # The head commit to which the PR is requesting to be merged from.
    # @return [String]
    #
    def head_commit
      pr_json[:head][:sha]
    end

    # @!group GitHub Misca
    # The hash that represents the PR's JSON. For an example of what this looks like
    # see the [Danger Fixture'd one](https://raw.githubusercontent.com/danger/danger/master/spec/fixtures/pr_response.json).
    # @return [Hash]
    #
    def pr_json
      @github.pr_json
    end

    # @!group GitHub Misc
    # Provides access to the GitHub API client used inside Danger. Making
    # it easy to use the GitHub API inside a Dangerfile.
    # @return [Octokit::Client]
    def api
      @github.client
    end
  end
end