# frozen_string_literal: true

module IcalEncoder
  SANITIZER = Rails::Html::FullSanitizer.new

  # Encodes a string for use in iCalendar text fields (SUMMARY, DESCRIPTION, LOCATION).
  # Strips HTML tags, decodes HTML entities, and escapes special characters per RFC 5545.
  def self.encode(text)
    return "" if text.blank?
    text = SANITIZER.sanitize(text)
    text = CGI.unescapeHTML(text)
    text
      .gsub("\\", "\\\\\\\\")
      .gsub(",", "\\,")
      .gsub(";", "\\;")
      .gsub("\r\n", "\\n")
      .gsub("\n", "\\n")
      .html_safe
  end

  # Encodes a URI for iCalendar URL properties (RFC 5545 §3.8.4.6).
  # URL values are URIs per RFC 3986, so comma and semicolon (valid sub-delimiters)
  # must not be TEXT-escaped. Entities are decoded first, then CR/LF stripped —
  # order matters: stripping CR/LF after decoding neutralizes entity-encoded
  # newlines (e.g. `
`) that would otherwise inject additional ICS
  # properties on the following line.
  def self.encode_uri(uri)
    return "" if uri.blank?

    CGI.unescapeHTML(uri.to_s).delete("\r\n").html_safe
  end
end