changelog_generator

#!/usr/bin/env ruby
# frozen_string_literal: true

require "json"
require "ruby-progressbar"

require "./lib/decidim/github_manager/querier"

class EmptyTokenError < RuntimeError
  def full_message
    <<~HELP
      Decidim's changelog generator.

      ## Example

          bin/changelog_generator <GITHUB PERSONAL ACCESS TOKEN> <SHA>

      ## Params

      The <GITHUB PERSONAL ACCESS TOKEN> can be obtained from https://github.com/settings/tokens/new
      You'll need to create one with `public_repo` access.

      The <SHA> is the git commit SHA from which to consider the changes. It's
      usually the last commit that modified the `.decidim_version` file.

      ## Explanation

      This script will generate the sections needed for the changelog, using the
      labels of the merged PRs as a source of truth. It will add a section at the
      end, "Unsorted", with the list of PRs that couldn't be classified.

      It ignores any Crowdin PR.
    HELP
  end
end

class ChangeLogGenerator
  TYPES = {
    "Added" => {
      label: "type: feature",
      skip_modules: false
    },
    "Changed" => {
      label: "type: change",
      skip_modules: false
    },
    "Fixed" => {
      label: "type: fix",
      skip_modules: false
    },
    "Removed" => {
      label: "type: removal",
      skip_modules: false
    },
    "Developer improvements" => {
      label: "target: developer-experience",
      skip_modules: true
    },
    "Internal" => {
      label: "type: internal",
      skip_modules: false
    }
  }.freeze

  def initialize(github_token, since_sha)
    @github_token = github_token
    @since_sha = since_sha
    @output_file = []
    @handled_ids = []

    @progress_bar = ProgressBar.create(title: "PRs", total: list_of_commits.count)
  end

  def run
    raise EmptyTokenError if github_token.nil? || github_token == "--help"

    TYPES.each do |type_title, type_data|
      type_prs = prs.select do |_commit_title, data|
        next unless data

        data[:type].include?(type_data[:label])
      end

      output "### #{type_title}"
      output ""

      if type_prs.any?
        type_prs.each do |_pr_title, data|
          process_single_pr(data, type_data)
        end
      else
        output "Nothing."
      end

      output ""
    end

    process_unsorted_prs
    write_data_file!
  end

  private

  def write_data_file!
    File.write("temporary_changelog.md", @output_file.join("\n"))
    puts "Written file: temporary_changelog.md"
  end

  def process_single_pr(data, type_data)
    modules_list = data[:modules].map { |l| "**decidim-#{l.delete_prefix("module: ")}**" }
    id = data[:id]
    title = data[:title]

    @handled_ids << id

    if type_data[:skip_modules] || modules_list.empty?
      output "- #{title} #{pr_link(id)}"
    else
      output "- #{modules_list.join(", ")}: #{title} #{pr_link(id)}"
    end
  end

  def process_unsorted_prs
    return unless unsorted_prs.any?

    output "### Unsorted"
    output ""

    unsorted_prs.map do |title, data|
      pr_data = data || {}
      output "- #{title} #{pr_link(pr_data[:id])} || #{data}"
    end
  end

  def unsorted_prs
    @unsorted_prs ||= prs.reject do |_commit_title, data|
      pr_data = data || {}

      @handled_ids.include?(pr_data[:id])
    end
  end

  attr_reader :github_token, :since_sha

  def prs
    @prs ||= list_of_commits.inject({}) do |acc, commit|
      next acc if crowdin?(commit)

      acc.update(commit => get_pr_data(commit))
    end
  end

  def list_of_commits
    @list_of_commits ||= `git log #{since_sha}..HEAD --oneline`.split("\n").reverse
  end

  def crowdin?(commit)
    !commit.match(/New Crowdin updates/).nil?
  end

  def get_pr_id(commit)
    id = commit.scan(/#\d+/).last
    return unless id

    id.delete_prefix("#")
  end

  def get_pr_data(commit)
    @progress_bar.increment

    id = get_pr_id(commit)
    return nil unless id

    Decidim::GithubManager::Querier.new(
      token: github_token,
      issue_id: id
    ).call
  end

  def pr_link(id)
    # We need to do this so that it generates the expected Markdown format.
    # String interpolation messes with the format.
    "[#{"\\#" + id.to_s}](https://github.com/decidim/decidim/pull/#{id})" # rubocop:disable Style/StringConcatenation
  end

  def output(str)
    @output_file << str
  end
end

begin
  ChangeLogGenerator.new(ARGV[0], ARGV[1] || "HEAD~5").run
rescue EmptyTokenError => e
  puts e.full_message
  exit 1
end