# frozen_string_literal: true

module URLFilters
  # Produces an absolute URL based on site.url and site.baseurl.
  #
  # input - the URL to make absolute.
  #
  # Returns the absolute URL as a String.
  def absolute_url(input)
    cache = (@context.registers[:cached_absolute_urls] ||= {})
    cache[input] ||= compute_absolute_url(input)
  end

  # Produces a URL relative to the domain root based on site.baseurl
  # unless it is already an absolute url with an authority (host).
  #
  # input - the URL to make relative to the domain root
  #
  # Returns a URL relative to the domain root as a String.
  def relative_url(input)
    cache = (@context.registers[:cached_relative_urls] ||= {})
    cache[input] ||= compute_relative_url(input)
  end

  # Strips trailing `/index.html` from URLs to create pretty permalinks
  #
  # input - the URL with a possible `/index.html`
  #
  # Returns a URL with the trailing `/index.html` removed
  def strip_index(input)
    return if input.nil? || input.to_s.empty?

    input.sub(%r[/index\.html?$], '/')
  end

  private

  def compute_absolute_url(input)
    return if input.nil?

    input = input.url if input.respond_to?(:url)
    return input if Addressable::URI.parse(input.to_s).absolute?

    site = @context.registers['content'].site
    return relative_url(input) if site.properties['url'].nil?

    Addressable::URI.parse(
      site.properties['url'].to_s + relative_url(input)
    ).normalize.to_s
  end

  def compute_relative_url(input)
    return if input.nil?

    input = input.url if input.respond_to?(:url)
    return input if Addressable::URI.parse(input.to_s).absolute?

    parts = [sanitized_baseurl, input]
    Addressable::URI.parse(
      parts.compact.map { |part| ensure_leading_slash(part.to_s) }.join
    ).normalize.to_s
  end

  def sanitized_baseurl
    site = @context.registers['content'].site
    site.properties['baseurl'].to_s.chomp('/')
  end

  def ensure_leading_slash(input)
    return input if input.nil? || input.empty? || input.start_with?('/')

    "/#{input}"
  end
end

Liquid::Template.register_filter(URLFilters)