module Ops
  class LogPatternMatcher
    Match = Struct.new(:name, :severity, :line, keyword_init: true)

    def initialize(patterns: nil)
      @patterns = patterns || load_patterns
    end

    def scan(text)
      return [] if text.blank?

      matches = []
      text.each_line do |line|
        @patterns.each do |pattern|
          next unless line.match?(pattern[:regex])

          matches << Match.new(name: pattern[:name], severity: pattern[:severity], line: line.strip)
        end
      end
      matches
    end

    private

    def load_patterns
      path = Rails.root.join("config/ops_log_patterns.yml")
      raw = YAML.safe_load(File.read(path), permitted_classes: [], aliases: true) || {}
      Array(raw["patterns"]).map do |entry|
        {
          name: entry["name"].to_s,
          severity: entry["severity"].to_s,
          regex: Regexp.new(entry["regex"], Regexp::IGNORECASE)
        }
      end
    end
  end
end