/*
  This file is part of TALER
  Copyright (C) 2023 Taler Systems SA

  TALER is free software; you can redistribute it and/or modify
  it under the terms of the GNU General Public License as
  published by the Free Software Foundation; either version 3, or
  (at your option) any later version.

  TALER is distributed in the hope that it will be useful, but
  WITHOUT ANY WARRANTY; without even the implied warranty of
  MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
  GNU General Public License for more details.

  You should have received a copy of the GNU General Public
  License along with TALER; see the file COPYING.  If not, see
  <http://www.gnu.org/licenses/>
*/

/**
 * @file testing/testing_api_cmd_testserver.c
 * @brief Implement a CMD to run an Testserver service for faking the legitimation service
 * @author Priscilla HUANG
 */
#include "platform.h"
#include "taler/taler_json_lib.h"
#include <gnunet/gnunet_curl_lib.h>
#include "taler/taler_testing_lib.h"
#include "taler/taler_mhd_lib.h"
#include "taler_merchant_testing_lib.h"
#include "taler_merchant_service.h"
#include <taler/taler_exchange_service.h>

/**
 * State for the testserver CMD.
 */
struct TestserverState
{

  /**
   * Handle to the "testserver" service.
   */
  struct MHD_Daemon *mhd;

  /**
   * Port to listen on.
   */
  uint16_t port;

  /**
   * Array where we remember all of the requests this
   * server answered.
   */
  struct RequestCtx **rcs;

  /**
   * Length of the @a rcs array
   */
  unsigned int rcs_length;
};


struct RequestCtx
{
  /**
   * URL where we are redirect.
   */
  char *url;

  /**
   * http method of the webhook.
   */
  char *http_method;

  /**
   * header of the webhook.
   */
  char *header;

  /**
   * body of the webhook.
   */
  void *body;

  /**
   * size of the body
   */
  size_t body_size;

  /**
   * Set to true when we are done with the request.
   */
  bool done;
};


/**
 * A client has requested the given url using the given method
 * (#MHD_HTTP_METHOD_GET, #MHD_HTTP_METHOD_PUT,
 * #MHD_HTTP_METHOD_DELETE, #MHD_HTTP_METHOD_POST, etc).  The callback
 * must call MHD callbacks to provide content to give back to the
 * client and return an HTTP status code (i.e. #MHD_HTTP_OK,
 * #MHD_HTTP_NOT_FOUND, etc.).
 *
 * @param cls argument given together with the function
 *        pointer when the handler was registered with MHD
 * @param connection the connection being handled
 * @param url the requested url
 * @param method the HTTP method used (#MHD_HTTP_METHOD_GET,
 *        #MHD_HTTP_METHOD_PUT, etc.)
 * @param version the HTTP version string (i.e.
 *        MHD_HTTP_VERSION_1_1)
 * @param upload_data the data being uploaded (excluding HEADERS,
 *        for a POST that fits into memory and that is encoded
 *        with a supported encoding, the POST data will NOT be
 *        given in upload_data and is instead available as
 *        part of MHD_get_connection_values(); very large POST
 *        data *will* be made available incrementally in
 *        @a upload_data)
 * @param[in,out] upload_data_size set initially to the size of the
 *        @a upload_data provided; the method must update this
 *        value to the number of bytes NOT processed;
 * @param[in,out] con_cls pointer that the callback can set to some
 *        address and that will be preserved by MHD for future
 *        calls for this request; since the access handler may
 *        be called many times (i.e., for a PUT/POST operation
 *        with plenty of upload data) this allows the application
 *        to easily associate some request-specific state.
 *        If necessary, this state can be cleaned up in the
 *        global MHD_RequestCompletedCallback (which
 *        can be set with the #MHD_OPTION_NOTIFY_COMPLETED).
 *        Initially, `*con_cls` will be NULL.
 * @return #MHD_YES if the connection was handled successfully,
 *         #MHD_NO if the socket must be closed due to a serious
 *         error while handling the request
 */
static MHD_RESULT
handler_cb (void *cls,
            struct MHD_Connection *connection,
            const char *url,
            const char *method,
            const char *version,
            const char *upload_data,
            size_t *upload_data_size,
            void **con_cls)
{
  struct TestserverState *ts = cls;
  struct RequestCtx *rc = *con_cls;

  (void) version;
  if (NULL == rc)
  {
    const char *hdr;

    rc = GNUNET_new (struct RequestCtx);
    *con_cls = rc;
    rc->http_method = GNUNET_strdup (method);
    hdr = MHD_lookup_connection_value (connection,
                                       MHD_HEADER_KIND,
                                       "Taler-test-header");
    if (NULL != hdr)
      rc->header = GNUNET_strdup (hdr);
    if (NULL != url)
      rc->url = GNUNET_strdup (url);
    GNUNET_array_append (ts->rcs,
                         ts->rcs_length,
                         rc);
    fprintf (stderr,
             "Webhook called server at `%s' with header `%s'\n",
             url,
             hdr);
    return MHD_YES;
  }
  if (0 == strcasecmp (method,
                       MHD_HTTP_METHOD_GET))
  {
    json_t *reply;

    reply = GNUNET_JSON_PACK (
      GNUNET_JSON_pack_string (
        "status",
        "success"));
    return TALER_MHD_reply_json_steal (connection,
                                       reply,
                                       MHD_HTTP_OK);
  }
  if (0 != strcasecmp (method,
                       MHD_HTTP_METHOD_POST))
  {
    GNUNET_break (0);
    return MHD_NO;
  }
  if (0 != *upload_data_size)
  {
    void *body;

    body = GNUNET_malloc (rc->body_size + *upload_data_size);
    GNUNET_memcpy (body,
                   rc->body,
                   rc->body_size);
    GNUNET_free (rc->body);
    GNUNET_memcpy (body + rc->body_size,
                   upload_data,
                   *upload_data_size);
    rc->body = body;
    rc->body_size += *upload_data_size;
    *upload_data_size = 0;
    return MHD_YES;
  }

  {
    json_t *reply;

    reply = GNUNET_JSON_PACK (
      GNUNET_JSON_pack_string ("something",
                               "good"));
    return TALER_MHD_reply_json_steal (connection,
                                       reply,
                                       MHD_HTTP_OK);
  }
}


static void
cleanup (void *cls,
         struct MHD_Connection *connection,
         void **con_cls,
         enum MHD_RequestTerminationCode toe)
{
  struct RequestCtx *rc = *con_cls;

  (void) cls;
  (void) connection;
  (void) toe;
  if (NULL == rc)
    return;
  rc->done = true;
}


/**
 * Run the command.
 *
 * @param cls closure.
 * @param cmd the command to execute.
 * @param is the interpreter state.
 */
static void
testserver_run (void *cls,
                const struct TALER_TESTING_Command *cmd,
                struct TALER_TESTING_Interpreter *is)
{
  struct TestserverState *ser = cls;

  (void) cmd;
  ser->mhd = MHD_start_daemon (MHD_USE_AUTO_INTERNAL_THREAD,
                               ser->port,
                               NULL, NULL,
                               &handler_cb, ser,
                               MHD_OPTION_NOTIFY_COMPLETED, &cleanup, NULL,
                               NULL);
  if (NULL == ser->mhd)
  {
    GNUNET_break (0);
    TALER_TESTING_interpreter_fail (is);
    return;
  }
  TALER_TESTING_interpreter_next (is);
}


/**
 * Cleanup the state from a "testserver" CMD, and possibly cancel a operation
 * thereof.
 *
 * @param cls closure.
 * @param cmd the command which is being cleaned up.
 */
static void
testserver_cleanup (void *cls,
                    const struct TALER_TESTING_Command *cmd)
{
  struct TestserverState *ser = cls;

  (void) cmd;
  if (NULL != ser->mhd)
  {
    MHD_stop_daemon (ser->mhd);
    ser->mhd = NULL;
  }
  for (unsigned int i = 0; i<ser->rcs_length; i++)
  {
    struct RequestCtx *rc = ser->rcs[i];

    GNUNET_assert (rc->done);
    GNUNET_free (rc->url);
    GNUNET_free (rc->http_method);
    GNUNET_free (rc->header);
    GNUNET_free (rc->body);
    GNUNET_free (rc);
  }
  GNUNET_array_grow (ser->rcs,
                     ser->rcs_length,
                     0);
  GNUNET_free (ser);
}


static enum GNUNET_GenericReturnValue
traits_testserver (void *cls,
                   const void **ret,
                   const char *trait,
                   unsigned int index)
{
  struct TestserverState *ser = cls;

  if (index >= ser->rcs_length)
    return GNUNET_NO;

  {
    const struct RequestCtx *rc = ser->rcs[index];
    struct TALER_TESTING_Trait traits[] = {
      TALER_TESTING_make_trait_urls (index,
                                     rc->url),
      TALER_TESTING_make_trait_http_methods (index,
                                             rc->http_method),
      TALER_TESTING_make_trait_http_header (index,
                                            rc->header),
      TALER_TESTING_make_trait_http_body (index,
                                          rc->body),
      TALER_TESTING_make_trait_http_body_size (index,
                                               &rc->body_size),
      TALER_TESTING_trait_end (),
    };

    if (! rc->done)
      return GNUNET_NO;
    return TALER_TESTING_get_trait (traits,
                                    ret,
                                    trait,
                                    index);
  }
}


/**
 * This function is used to start the web server.
 *
 * @param label command label
 * @param port is the port of the web server
 */
struct TALER_TESTING_Command
TALER_TESTING_cmd_testserver (const char *label,
                              uint16_t port)
{
  struct TestserverState *ser;

  ser = GNUNET_new (struct TestserverState);
  ser->port = port;
  {
    struct TALER_TESTING_Command cmd = {
      .cls = ser,
      .label = label,
      .run = &testserver_run,
      .cleanup = &testserver_cleanup,
      .traits = &traits_testserver
    };

    return cmd;
  }
}


/* end of testing_api_cmd_checkserver.c */