# frozen_string_literal: true

require 'digest/md5'

REVIEW_ROULETTE_SECTION = <<MARKDOWN
## Reviewer roulette
MARKDOWN

CATEGORY_TABLE = <<MARKDOWN

Changes that require review have been detected!

Please refer to the table below for assigning reviewers and maintainers suggested by Danger in the specified category:

| Category | Reviewer | Maintainer |
| -------- | -------- | ---------- |
MARKDOWN

POST_TABLE_MESSAGE = <<MARKDOWN

To spread load more evenly across eligible reviewers, Danger has picked a candidate for each
review slot, based on their timezone. Feel free to
[override these selections](https://about.gitlab.com/handbook/engineering/projects/#gitlab)
if you think someone else would be better-suited
or use the [GitLab Review Workload Dashboard](https://gitlab-org.gitlab.io/gitlab-roulette/) to find other available reviewers.

To read more on how to use the reviewer roulette, please take a look at the
[Engineering workflow](https://about.gitlab.com/handbook/engineering/workflow/#basics)
and [code review guidelines](https://docs.gitlab.com/ee/development/code_review.html).
Please consider assigning a reviewer or maintainer who is a
[domain expert](https://about.gitlab.com/handbook/engineering/projects/#gitlab) in the area of the merge request.

Once you've decided who will review this merge request, assign them as a reviewer!
Danger does not automatically notify them for you.
MARKDOWN

NO_SUGGESTIONS = <<MARKDOWN

There are no reviewer and maintainer suggestions for the changes in this MR.
MARKDOWN

UNKNOWN_FILES_MESSAGE = <<MARKDOWN
### Uncategorized files

These files couldn't be categorized, so Danger was unable to suggest a reviewer.
Please consider creating a merge request to
[add support](https://gitlab.com/gitlab-org/gitlab/blob/master/tooling/danger/project_helper.rb)
for them.
MARKDOWN

def group_not_available_template(slack_channel, gitlab_group)
  <<~TEMPLATE
    No engineer is available for automated assignment, please reach out to `#{slack_channel}` slack channel or mention `#{gitlab_group}` for assistance.
  TEMPLATE
end

OPTIONAL_REVIEW_TEMPLATE = '%{role} review is optional for %{category}'
NOT_AVAILABLE_TEMPLATES = {
  default: 'No %{role} available',
  product_intelligence: group_not_available_template('#g_product_intelligence', '@gitlab-org/growth/product-intelligence/engineers'),
  integrations_be: group_not_available_template('#g_ecosystem_integrations', '@gitlab-org/ecosystem-stage/integrations'),
  integrations_fe: group_not_available_template('#g_ecosystem_integrations', '@gitlab-org/ecosystem-stage/integrations')
}.freeze

def note_for_spins_role(spins, role, category)
  template = NOT_AVAILABLE_TEMPLATES[category] || NOT_AVAILABLE_TEMPLATES[:default]

  spins.each do |spin|
    note = note_for_spin_role(spin, role)

    return note if note
  end

  template % { role: role }
end

def note_for_spin_role(spin, role)
  if spin.optional_role == role
    return OPTIONAL_REVIEW_TEMPLATE % { role: role.capitalize, category: helper.label_for_category(spin.category) }
  end

  spin.public_send(role)&.markdown_name(author: roulette.team_mr_author) # rubocop:disable GitlabSecurity/PublicSend
end

def markdown_row_for_spins(category, spins_array)
  maintainer_note = note_for_spins_role(spins_array, :maintainer, category)
  reviewer_note = note_for_spins_role(spins_array, :reviewer, category)

  "| #{helper.label_for_category(category)} | #{reviewer_note} | #{maintainer_note} |"
end

changes = project_helper.changes_by_category

# Ignore any files that are known but uncategorized. Prompt for any unknown files
changes.delete(:none)
# To reinstate roulette for documentation, remove this line.
changes.delete(:docs)
# No special review for changelog needed and changelog was never a label.
changes.delete(:changelog)
# No special review for feature flags needed.
changes.delete(:feature_flag)
categories = Set.new(changes.keys - [:unknown])

# Ensure to spin for database reviewer/maintainer when ~database is applied (e.g. to review SQL queries)
categories << :database if helper.mr_labels.include?('database')

# Ensure to spin for UX reviewer for community contributions when ~UX is applied (e.g. to review changes to the UI)
categories << :ux if (["UX", "Community contribution"] - helper.mr_labels).empty?

# Ensure to spin for Product Intelligence reviewer when ~"product intelligence::review pending" is applied
categories << :product_intelligence if helper.mr_labels.include?("product intelligence::review pending")

# Skip Product intelligence reviews for growth experiment MRs
categories.delete(:product_intelligence) unless helper.mr_labels.include?("growth experiment")

if changes.any?
  project = project_helper.project_name

  random_roulette_spins = roulette.spin(project, categories, timezone_experiment: false)

  rows = random_roulette_spins.map do |spin|
    markdown_row_for_spins(spin.category, [spin])
  end

  markdown(REVIEW_ROULETTE_SECTION)

  if rows.empty?
    markdown(NO_SUGGESTIONS)
  else
    markdown(CATEGORY_TABLE + rows.join("\n"))
    markdown(POST_TABLE_MESSAGE)
  end

  unknown = changes.fetch(:unknown, [])
  markdown(UNKNOWN_FILES_MESSAGE + helper.markdown_list(unknown)) unless unknown.empty?
end