# frozen_string_literal: true

require_relative 'base_command_builder'
require_relative '../resource/context'

module Gitlab
  module Triage
    module CommandBuilders
      class CommentBodyBuilder < BaseCommandBuilder
        SUPPORTED_PLACEHOLDERS = {
          created_at: "{{created_at}}",
          updated_at: "{{updated_at}}",
          closed_at: "{{closed_at}}",
          merged_at: "{{merged_at}}",
          state: "{{state}}",
          author: "@{{author.username}}",
          assignee: "@{{assignee.username}}",
          assignees: "@{{assignees.username}}",
          closed_by: "@{{closed_by.username}}",
          merged_by: "@{{merged_by.username}}",
          milestone: %(%"{{milestone.title}}"),
          labels: %(~"{{labels}}"),
          upvotes: "{{upvotes}}",
          downvotes: "{{downvotes}}"
        }.freeze
        PLACEHOLDER_REGEX = /{{([\w\.]+)}}/

        attr_reader :resource, :net

        def initialize(items, resource: nil, net: {})
          super(items)
          @resource = resource
          @net = net
        end

        private

        def separator
          "\n\n"
        end

        def format_item(item)
          return item unless resource

          replace_placeholders(eval_interpolation(item))
        end

        def eval_interpolation(item)
          quoted_comment = "%Q{#{item}}"

          Resource::Context.new(resource, net).eval(quoted_comment)
        end

        def replace_placeholders(item)
          SUPPORTED_PLACEHOLDERS.inject(item) do |comment, (placeholder, formatted_text)|
            next comment unless comment.include?("{{#{placeholder}}}")

            methods = formatted_text.match(/.*#{PLACEHOLDER_REGEX}.*/)[1].split('.')
            fields = resource_fields(resource, methods)

            final_fields = fields.map { |field| formatted_text.sub(PLACEHOLDER_REGEX, field.to_s) }

            if final_fields.any?
              comment.gsub("{{#{placeholder}}}", final_fields.join(', '))
            else
              comment
            end
          end
        end

        def resource_fields(resource, methods)
          method = methods.shift

          return Array(resource) unless method && resource
          return [] unless resource.key?(method)

          sub_resources = resource[method]
          Array.wrap(sub_resources).flat_map { |res| resource_fields(res, methods.dup) }
        end
      end
    end
  end
end