# frozen_string_literal: true

require_relative 'utils'

class Danger::DangerWCC < Danger::Plugin
  class RubocopExceptions
    include Utils

    DISABLE_REGEX = /^(?:\+\s)?.*\#\s*rubocop\:disable\s+(\S+)/i
    ENABLE_REGEX = /^(?:\+\s)?\s*\#\s*rubocop\:enable\s+(\S+)/i
    COMMENT_LINE_REGEX = /^(?:\+\s)?\s*\#\s*(.+)$/i

    def initialize(plugin, options = {})
      @plugin = plugin
      @options = options
    end

    def perform
      find_new_exceptions.each do |e|
        message = build_message(e)
        severity = message_severity(e)
        issue(message,
          severity: severity, file: e[:file], line: e[:disabled_at])
      end
    end

    private

    def build_message(e)
      message = "Rubocop rule #{e[:rule]} disabled in"\
                  " #{plugin.github.html_link(e[:file])}"
      message +=
        if !e[:context_lines].empty?
          "  explanation:\n\t> " + e[:context_lines].join("\n\t> ")
        else
          "  \nPlease provide an explanation why this rule was disabled."
        end
      unless e[:reenabled]
        message += "\n\nThe rule was not reenabled!\n"\
          'Please add a `rubocop:enable` comment so the rule is disabled '\
          'for the minimal scope.'
      end
      message
    end

    def message_severity(e)
      if !e[:reenabled]
        'fail'
      elsif e[:context_lines].empty?
        'warn'
      else
        'message'
      end
    end

    def find_new_exceptions
      find_in_diff(DISABLE_REGEX) do |m, line, hunk, file, _diff|
        make_violation(File.read(file.b_path), hunk, line, m.captures[0])
          .merge!(file: file.b_path)
      end
    end

    def make_violation(file_contents, hunk, line, rule)
      reenable_line_offset = find_reenable(file_contents,
        line.line_number.right,
        rule)

      {
        rule: rule,
        disabled_at: line.line_number.right,
        reenabled: !reenable_line_offset.nil?,
        context_lines: find_context(hunk.lines.drop(hunk.lines.index(line)))
      }
    end

    def find_context(diff_lines)
      # search for all non-`rubocop:` comment lines immediately
      # preceding this disable which were added by this hunk
      diff_lines
        .drop_while { |l| rubocop_line?(l) }
        .take_while { |l| l.addition? && l.content =~ COMMENT_LINE_REGEX }
        .map { |l| l.content.match(COMMENT_LINE_REGEX).captures[0] }
    end

    def find_reenable(file_contents, line_number, rule)
      # search for the reenabling of this line
      length_to_end = file_contents.lines.length - line_number
      file_contents.lines[line_number, length_to_end]
        .find_index do |l|
          m = l.match(ENABLE_REGEX)
          !m.nil? && rule.casecmp(m.captures[0]) == 0
        end
    end

    def rubocop_line?(l)
      l.content =~ DISABLE_REGEX || l.content =~ ENABLE_REGEX
    end
  end
end