#include <evapp/util.h>

bool response_cacheable(evapp_ctx *ctx,
                        enum cacheable_t type,
                        size_t lifetime) {
  char header[64]; // XXX: long enough?
  struct tm tm;
  time_t t;
  struct evhttp_request *request = evapp_request(ctx);
  switch (type) {
    case CACHE_PUBLIC:
      t = time(NULL) + lifetime;
      gmtime_r(&t, &tm);
      /* Add the expires in the future. Let evhttp stamp the date */
      if (strftime(header, sizeof(header),
                   "%a, %d %b %Y %H:%M:%S GMT", &tm) != 0) {
        evhttp_add_header(request->output_headers,
                          "Expires", header);
      }
      snprintf(header, sizeof(header),
               "public, max-age=%zu", lifetime);
      evhttp_add_header(request->output_headers,
                         "Cache-Control", header);
      break;
    case CACHE_PRIVATE:
      /* Disallow HTTP/1.0 caching by setting 
       * the expires == date.  Not setting it in the past
       * due to a firefox bug
       */
      t = time(NULL);
      gmtime_r(&t, &tm);
      if (strftime(header, sizeof(header),
                   "%a, %d %b %Y %H:%M:%S GMT", &tm) != 0) {
        evhttp_add_header(request->output_headers,
                          "Expires", header);
        evhttp_add_header(request->output_headers,
                          "Date", header);
       }
       snprintf(header, sizeof(header),
                "private, max-age=%zu", lifetime);
       evhttp_add_header(request->output_headers,
                          "Cache-Control", header);
      break;
    case CACHE_NONE:
      t = time(NULL);
      gmtime_r(&t, &tm);
      if (strftime(header, sizeof(header),
                   "%a, %d %b %Y %H:%M:%S GMT", &tm) != 0) {
        evhttp_add_header(request->output_headers,
                          "Expires", header);
        evhttp_add_header(request->output_headers,
                          "Date", header);
       }
       evhttp_add_header(request->output_headers,
                          "Cache-Control", "no-cache");
      break;
    default:
      return false;
      break;
  }
  return true;
}