#!/usr/bin/env -S ENABLE_SPRING=0 bin/rails runner -e test

# This is helper script to swap foreign key to loose foreign key
# using DB schema

require 'optparse'

$options = {
  cross_schema: false,
  dry_run: false,
  rspec: true
}

OptionParser.new do |opts|
  opts.banner = "Usage: #{$0} [options] <regexp filters...>"

  opts.on("-c", "--cross-schema", "Show only cross-schema foreign keys") do |v|
    $options[:cross_schema] = v
  end

  opts.on("-n", "--dry-run", "Do not execute any commands (dry run)") do |v|
    $options[:dry_run] = v
  end

  opts.on("-r", "--[no-]rspec", "Create or not a rspecs automatically") do |v|
    $options[:rspec] = v
  end

  opts.on("-h", "--help", "Prints this help") do
    puts opts
    exit
  end
end.parse!

unless system("git diff --quiet db/structure.sql")
  raise "The db/structure.sql is changed. Reset branch or commit changes."
end

unless system("git diff --quiet")
  raise "There are uncommitted changes. Commit to continue."
end

$files_affected = []

puts "Re-creating current test database"
ActiveRecord::Tasks::DatabaseTasks.drop_current
ActiveRecord::Tasks::DatabaseTasks.create_current
ActiveRecord::Tasks::DatabaseTasks.load_schema_current
ActiveRecord::Tasks::DatabaseTasks.migrate
ActiveRecord::Migration.check_pending!
ActiveRecord::Base.connection_pool.disconnect!
puts

def exec_cmd(*args, fail: nil)
  # output full command
  if $options[:dry_run]
    puts ">> #{args.shelljoin}"
    return true
  end

  # truncate up-to 60 chars or first line
  command = args.shelljoin
  truncated_command = command.truncate([command.lines.first.length+3, 120].min)

  puts ">> #{truncated_command}"
  return true if system(*args)

  raise fail if fail

  puts "--------------------------------------------------"
  puts "This command failed:"
  puts ">> #{command}"
  puts "--------------------------------------------------"
  false
end

def write_file(file_path, content)
  $files_affected << file_path
  File.write(file_path, content)
end

def print_files_affected
  puts "The following files have been generated/modified:"
  $files_affected.each do |filepath|
    puts filepath
  end
end

def has_lfk?(definition)
  Gitlab::Database::LooseForeignKeys.definitions.any? do |lfk_definition|
    lfk_definition.from_table == definition.from_table &&
      lfk_definition.to_table == definition.to_table &&
      lfk_definition.column == definition.column
  end
end

def foreign_key_matching?(definition, filters)
  filters.all? do |filter|
    definition.from_table.match?(filter) ||
      definition.to_table.match?(filter) ||
      definition.column.match?(filter)
  end
end

def columns(*args)
  puts("%5s | %7s | %40s | %20s | %30s | %15s " % args)
end

def add_definition_to_yaml(definition)
  content = YAML.load_file(Rails.root.join('config/gitlab_loose_foreign_keys.yml'))
  table_definitions = content[definition.from_table]

  # insert new entry in alphabetic order
  unless table_definitions
    table_definitions = []

    content[definition.from_table] = table_definitions
    content = content.sort.to_h
  end

  on_delete =
    case definition.on_delete
    when :cascade
      'async_delete'
    when :nullify
      'async_nullify'
    else
      raise "Unsupported on_delete behavior: #{definition.on_delete}"
    end

  yaml_definition = {
    "table" => definition.to_table,
    "column" => definition.column,
    "on_delete" => on_delete
  }

  # match and update by "table", "column"
  if existing = table_definitions.pluck("table", "column").index([definition.to_table, definition.column])
    puts "Updated existing definition from #{table_definitions[existing]} to #{yaml_definition}."
    table_definitions[existing] = yaml_definition
  else
    puts "Add new definition for #{yaml_definition}."
    table_definitions.append(yaml_definition)
  end

  # emulate existing formatting
  write_file(
    Rails.root.join('config/gitlab_loose_foreign_keys.yml'),
    content.to_yaml.gsub(/^([- ] )/, '  \1')
  )
end

def generate_migration(definition)
  timestamp = Time.now.utc.strftime("%Y%m%d%H%M%S")

  # db/post_migrate/20220111221516_remove_projects_ci_pending_builds_fk.rb

  migration_name = "db/post_migrate/#{timestamp}_remove_#{definition.to_table}_#{definition.from_table}_#{definition.column}_fk.rb"
  puts "Writing #{migration_name}"

  content = <<-EOF.strip_heredoc
    # frozen_string_literal: true

    class Remove#{definition.to_table.camelcase}#{definition.from_table.camelcase}#{definition.column.camelcase}Fk < Gitlab::Database::Migration[#{Gitlab::Database::Migration.current_version}]
      milestone '#{Gitlab.current_milestone}'
      disable_ddl_transaction!

      FOREIGN_KEY_NAME = "#{definition.name}"

      def up
        with_lock_retries do
          remove_foreign_key_if_exists(:#{definition.from_table}, :#{definition.to_table},
            name: FOREIGN_KEY_NAME, reverse_lock_order: true)
        end
      end

      def down
        add_concurrent_foreign_key(:#{definition.from_table}, :#{definition.to_table},
          name: FOREIGN_KEY_NAME, column: :#{definition.column},
          target_column: :#{definition.primary_key}, on_delete: :#{definition.on_delete})
      end
    end
  EOF

  write_file(migration_name, content)

  exec_cmd("bin/rails", "db:migrate", fail: "Failed to run db:migrate.")
end

def class_by_table_name
  @index_by_table_name ||= ActiveRecord::Base
    .descendants
    .reject(&:abstract_class)
    .map(&:base_class)
    .index_by(&:table_name)
end

def spec_from_clazz(clazz, definition)
  %w[spec/models ee/spec/models].each do |specs_path|
    path = File.join(specs_path, clazz.underscore + "_spec.rb")
    return path if File.exist?(path)
  end

  raise "Cannot find specs for #{clazz} (#{definition.from_table})"
end

def add_test_to_specs(definition)
  return unless $options[:rspec]

  clazz = class_by_table_name[definition.from_table]
  raise "Cannot map #{definition.from_table} to clazz" unless clazz

  spec_path = spec_from_clazz(clazz, definition)
  puts "Adding test to #{spec_path}..."

  spec_test = <<-EOF.strip_heredoc.indent(2)
    context 'with loose foreign key on #{definition.from_table}.#{definition.column}' do
      it_behaves_like 'cleanup by a loose foreign key' do
        let_it_be(:parent) { create(:#{definition.to_table.singularize}) }
        let_it_be(:model) { create(:#{definition.from_table.singularize}, #{definition.column.delete_suffix("_id").singularize}: parent) }
      end
    end
  EOF

  # append to end of file with empty line before
  lines = File.readlines(spec_path)
  insert_line = lines.count - 1
  lines.insert(insert_line, "\n", *spec_test.lines)
  write_file(spec_path, lines.join(""))
end

def update_no_cross_db_foreign_keys_spec(definition)
  from_column = "#{definition.from_table}.#{definition.column}"
  spec_path = "spec/lib/gitlab/database/no_cross_db_foreign_keys_spec.rb"

  puts "Updating #{spec_path}..."
  lines = File.readlines(spec_path)
  updated = lines.reject { |line| line.strip == from_column }

  if lines.count == updated.count
    puts "Nothing changed."
    return
  end

  write_file(spec_path, updated.join(""))
end

all_foreign_keys = ActiveRecord::Base.connection.tables.flat_map do |table|
  ActiveRecord::Base.connection.foreign_keys(table)
end

# Show only cross-schema foreign keys
if $options[:cross_schema]
  all_foreign_keys.select! do |definition|
    Gitlab::Database::GitlabSchema.table_schema!(definition.from_table) != Gitlab::Database::GitlabSchema.table_schema!(definition.to_table)
  end
end

if $options[:cross_schema]
  puts "Showing cross-schema foreign keys (#{all_foreign_keys.count}):"
else
  puts "Showing all foreign keys (#{all_foreign_keys.count}):"
  puts "Did you meant `#{$0} --cross-schema ...`?"
end

columns("ID", "HAS_LFK", "FROM", "TO", "COLUMN", "ON_DELETE")
all_foreign_keys.each_with_index do |definition, idx|
  columns(idx, has_lfk?(definition) ? 'Y' : 'N', definition.from_table, definition.to_table, definition.column, definition.on_delete)
end
puts

puts "To match FK write one or many filters to match against FROM/TO/COLUMN:"
puts "- #{$0} <filter(s)...>"
puts "- #{$0} ci_job_artifacts project_id"
puts "- #{$0} dast_site_profiles_pipelines"
puts

return if ARGV.empty?

puts "Loading all models..."
# Fix bug with loading `app/models/identity/uniqueness_scopes.rb`
require_relative Rails.root.join('app/models/identity.rb')

%w[app/models/**/*.rb ee/app/models/**/*.rb].each do |filter|
  Dir.glob(filter).each do |path|
    require_relative Rails.root.join(path)
  end
end
puts

puts "Generating Loose Foreign Key for given filters: #{ARGV}"

all_foreign_keys.each_with_index do |definition, idx|
  next unless foreign_key_matching?(definition, ARGV.map { |arg| Regexp.new(arg) })

  puts "Matched: #{idx} (#{definition.from_table}, #{definition.to_table}, #{definition.column})"

  add_definition_to_yaml(definition)
  generate_migration(definition)
  add_test_to_specs(definition)
  update_no_cross_db_foreign_keys_spec(definition)
end

print_files_affected

puts