class GdsApi::ContentStore::RedirectResolver

def self.call(*args)
  new(*args).call
end

def call
  redirect = redirect_for_path(request_path)
  raise UnresolvedRedirect, "Could not find a matching redirect" unless redirect
  destination_uri = URI.parse(
    resolve_destination(redirect, request_path, request_query),
  )
  url = if destination_uri.absolute?
          destination_uri.to_s
        else
          "#{Plek.new.website_root}#{destination_uri}"
        end
  [url, 301]
end

def initialize(content_item, request_path, request_query = "")
  @content_item = content_item
  @request_path = request_path
  @request_query = request_query.to_s
end

def prefix_destination(redirect, path, query)
  uri = URI.parse(redirect["destination"])
  start_char = redirect["path"].length
  suffix = path[start_char..]
  if uri.path == "" && suffix[0] != "/"
    uri.path = "/#{suffix}"
  else
    uri.path += suffix
  end
  uri.query = query if uri.query.nil? && !query.empty?
  uri.to_s
end

def redirect_for_path(path)
  redirects_by_segments.find do |r|
    next true if r["path"] == path
    route_prefix_match?(r["path"], path) if r["type"] == "prefix"
  end
end

def redirects_by_segments
  redirects = content_item["redirects"] || []
  redirects.sort_by { |r| r["path"].split("/").count * -1 }
end

def resolve_destination(redirect, path, query)
  return redirect["destination"] unless redirect["segments_mode"] == "preserve"
  if redirect["type"] == "prefix"
    prefix_destination(redirect, path, query)
  else
    redirect["destination"] + (query.empty? ? "" : "?#{query}")
  end
end

def route_prefix_match?(prefix_path, path_to_match)
  prefix_regex = %r{^#{Regexp.escape(prefix_path)}/}
  path_to_match.match prefix_regex
end