/*
  This file is part of TALER
  Copyright (C) 2018-2020 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 bank-lib/testing_api_cmd_history.c
 * @brief command to check the /history API from the bank.
 * @author Marcello Stanisci
 */
#include "platform.h"
#include "taler_json_lib.h"
#include <gnunet/gnunet_curl_lib.h>
#include "taler_exchange_service.h"
#include "taler_testing_lib.h"
#include "taler_testing_bank_lib.h"
#include "taler_fakebank_lib.h"
#include "taler_bank_service.h"
#include "taler_fakebank_lib.h"


/**
 * State for a "history" CMD.
 */
struct HistoryState
{
  /**
   * Base URL of the account offering the "history" operation.
   */
  char *account_url;

  /**
   * Reference to command defining the
   * first row number we want in the result.
   */
  const char *start_row_reference;

  /**
   * How many rows we want in the result, _at most_,
   * and ascending/descending.
   */
  long long num_results;

  /**
   * Handle to a pending "history" operation.
   */
  struct TALER_BANK_CreditHistoryHandle *hh;

  /**
   * Expected number of results (= rows).
   */
  uint64_t results_obtained;

  /**
   * Set to GNUNET_YES if the callback detects something
   * unexpected.
   */
  int failed;

};


/**
 * Item in the transaction history, as reconstructed from the
 * command history.
 */
struct History
{

  /**
   * Wire details.
   */
  struct TALER_BANK_CreditDetails details;

  /**
   * Serial ID of the wire transfer.
   */
  uint64_t row_id;

  /**
   * URL to free.
   */
  char *url;
};


/**
 * Offer internal data to other commands.
 *
 * @param cls closure.
 * @param ret[out] set to the wanted data.
 * @param trait name of the trait.
 * @param index index number of the traits to be returned.
 *
 * @return #GNUNET_OK on success
 */
static int
history_traits (void *cls,
                const void **ret,
                const char *trait,
                unsigned int index)
{
  (void) cls;
  (void) ret;
  (void) trait;
  (void) index;
  /* Must define this function because some callbacks
   * look for certain traits on _all_ the commands. */
  return GNUNET_SYSERR;
}


/**
 * Free history @a h of length @a h_len.
 *
 * @param h history array to free.
 * @param h_len number of entries in @a h.
 */
static void
free_history (struct History *h,
              uint64_t h_len)
{
  for (uint64_t off = 0; off<h_len; off++)
    GNUNET_free (h[off].url);
  GNUNET_free_non_null (h);
}


/**
 * Log which history we expected.  Called when an error occurs.
 *
 * @param h what we expected.
 * @param h_len number of entries in @a h.
 * @param off position of the missmatch.
 */
static void
print_expected (struct History *h,
                uint64_t h_len,
                unsigned int off)
{
  GNUNET_log (GNUNET_ERROR_TYPE_ERROR,
              "Transaction history missmatch at position %u/%llu\n",
              off,
              (unsigned long long) h_len);
  GNUNET_log (GNUNET_ERROR_TYPE_ERROR,
              "Expected history:\n");
  for (uint64_t i = 0; i<h_len; i++)
  {
    GNUNET_log (GNUNET_ERROR_TYPE_ERROR,
                "H(%llu): %s (serial: %llu, subject: %s,"
                " counterpart: %s)\n",
                (unsigned long long) i,
                TALER_amount2s (&h[i].details.amount),
                (unsigned long long) h[i].row_id,
                TALER_B2S (&h[i].details.reserve_pub),
                h[i].details.account_url);
  }
}


/**
 * Tell if the current item is beyond the allowed limit.
 *
 * @param total current number of items in the built history list.
 *        Note, this is the list we build locally and compare with
 *        what the server returned.
 * @param hs the history CMD state.
 * @param pos current item to be evaluated or not (if the list
 *        has already enough elements).
 * @return GNUNET_OK / GNUNET_NO.
 */
static int
build_history_hit_limit (uint64_t total,
                         const struct HistoryState *hs,
                         const struct TALER_TESTING_Command *pos)
{
  return total >= hs->num_results;
}


/**
 * This function constructs the list of history elements that
 * interest the account number of the caller.  It has two main
 * loops: the first to figure out how many history elements have
 * to be allocated, and the second to actually populate every
 * element.
 *
 * @param is interpreter state (supposedly having the
 *        current CMD pointing at a "history" CMD).
 * @param[out] rh history array to initialize.
 *
 * @return number of entries in @a rh.
 */
static uint64_t
build_history (struct TALER_TESTING_Interpreter *is,
               struct History **rh)
{
  struct HistoryState *hs = is->commands[is->ip].cls;
  uint64_t total;
  struct History *h;
  const struct TALER_TESTING_Command *add_incoming_cmd;
  int inc;
  unsigned int start;
  unsigned int end;

  /**
   * @var turns GNUNET_YES whenever either no 'start' value was
   *      given for the history query, or the given value is found
   *      in the list of all the CMDs.
   */int ok;
  const uint64_t *row_id_start = NULL;

  if (NULL != hs->start_row_reference)
  {
    TALER_LOG_INFO
      ("`%s': start row given via reference `%s'\n",
      TALER_TESTING_interpreter_get_current_label  (is),
      hs->start_row_reference);
    add_incoming_cmd = TALER_TESTING_interpreter_lookup_command
                         (is, hs->start_row_reference);
    GNUNET_assert (NULL != add_incoming_cmd);
    GNUNET_assert (GNUNET_OK == TALER_TESTING_get_trait_uint64
                     (add_incoming_cmd, 0, &row_id_start));
  }

  GNUNET_assert (0 != hs->num_results);
  if (0 == is->ip)
  {
    TALER_LOG_DEBUG ("Checking history at first CMD..\n");
    *rh = NULL;
    return 0;
  }

  /* AKA 'delta'.  */
  if (hs->num_results > 0)
  {
    inc = 1;  /* _inc_rement */
    start = 0;
    end = is->ip - 1;
  }
  else
  {
    inc = -1;
    start = is->ip - 1;
    end = 0;
  }

  total = 0;
  ok = GNUNET_NO;

  if (NULL == row_id_start)
    ok = GNUNET_YES;

  /* This loop counts how many commands _later than "start"_ belong
   * to the history of the caller.  This is stored in the @var total
   * variable.  */
  for (unsigned int off = start; off != end + inc; off += inc)
  {
    const struct TALER_TESTING_Command *pos = &is->commands[off];
    const uint64_t *row_id;
    const char *credit_account;
    const char *debit_account;

    /**
     * The following command allows us to skip over those CMDs
     * that do not offer a "row_id" trait.  Such skipped CMDs are
     * not interesting for building a history.
     */if (GNUNET_OK != TALER_TESTING_get_trait_uint64 (pos,
                                                     0,
                                                     &row_id))
      continue;

    /* Seek "/history" starting row.  */
    if (NULL != row_id_start)
    {
      if (*row_id_start == *row_id)
      {
        /* Doesn't count, start is excluded from output. */
        total = 0;
        ok = GNUNET_YES;
        continue;
      }
    }

    /* when 'start' was _not_ given, then ok == GNUNET_YES */
    if (GNUNET_NO == ok)
      continue; /* skip until we find the marker */

    TALER_LOG_DEBUG ("Found first row\n");

    if (build_history_hit_limit (total,
                                 hs,
                                 pos))
    {
      TALER_LOG_DEBUG ("Hit history limit\n");
      break;
    }


    GNUNET_assert
      (GNUNET_OK == TALER_TESTING_GET_TRAIT_CREDIT_ACCOUNT
        (pos, &credit_account));

    GNUNET_assert
      (GNUNET_OK == TALER_TESTING_GET_TRAIT_DEBIT_ACCOUNT
        (pos, &debit_account));

    TALER_LOG_INFO ("Potential history element:"
                    " %s->%s; my account: %s\n",
                    debit_account,
                    credit_account,
                    hs->account_url);

    if (0 == strcasecmp (hs->account_url,
                         credit_account))
    {
      TALER_LOG_INFO ("+1 my history\n");
      total++; /* found matching record */
    }
  }

  GNUNET_assert (GNUNET_YES == ok);

  if (0 == total)
  {
    TALER_LOG_DEBUG ("Checking history at first CMD.. (2)\n");
    *rh = NULL;
    return 0;
  }


  GNUNET_assert (total < UINT_MAX);
  h = GNUNET_new_array ((unsigned int) total,
                        struct History);
  total = 0;
  ok = GNUNET_NO;
  if (NULL == row_id_start)
    ok = GNUNET_YES;

  /**
   * This loop _only_ populates the array of history elements.
   */
  for (unsigned int off = start; off != end + inc; off += inc)
  {
    const struct TALER_TESTING_Command *pos = &is->commands[off];
    const uint64_t *row_id;
    char *bank_hostname;
    const char *credit_account;
    const char *debit_account;

    if (GNUNET_OK != TALER_TESTING_GET_TRAIT_ROW_ID
          (pos, &row_id))
      continue;

    if (NULL != row_id_start)
    {

      if (*row_id_start == *row_id)
      {
        /**
         * Warning: this zeroing is superfluous, as
         * total doesn't get incremented if 'start'
         * was given and couldn't be found.
         */total = 0;
        ok = GNUNET_YES;
        continue;
      }
    }

    TALER_LOG_INFO ("Found first row (2)\n");

    if (GNUNET_NO == ok)
    {
      TALER_LOG_INFO ("Skip on `%s'\n",
                      pos->label);
      continue; /* skip until we find the marker */
    }

    if (build_history_hit_limit (total,
                                 hs,
                                 pos))
    {
      TALER_LOG_INFO ("Hit history limit (2)\n");
      break;
    }

    GNUNET_assert
      (GNUNET_OK == TALER_TESTING_GET_TRAIT_CREDIT_ACCOUNT
        (pos, &credit_account));

    GNUNET_assert
      (GNUNET_OK == TALER_TESTING_GET_TRAIT_DEBIT_ACCOUNT
        (pos, &debit_account));

    TALER_LOG_INFO ("Potential history bit:"
                    " %s->%s; my account: %s\n",
                    debit_account,
                    credit_account,
                    hs->account_url);

    /**
     * Discard transactions where the audited account played
     * _both_ the credit and the debit roles, but _only if_
     * the audit goes on both directions..  This needs more
     * explaination!
     */if (0 == strcasecmp (hs->account_url,
                         credit_account))
    {
      GNUNET_break (0);
      continue;
    }

    bank_hostname = strchr (hs->account_url, ':');
    GNUNET_assert (NULL != bank_hostname);
    bank_hostname += 3;

    /* Next two blocks only put the 'direction' and 'banking'
     * information.  */

    /* Asked for credit, and account got the credit.  */
    if (0 == strcasecmp (hs->account_url,
                         credit_account))
    {
      h[total].url = GNUNET_strdup (debit_account);
      h[total].details.account_url = h[total].url;
    }

    /* This block _completes_ the information of the current item,
     * with amount / subject / exchange URL.  */
    if (0 == strcasecmp (hs->account_url,
                         credit_account))
    {
      const struct TALER_Amount *amount;
      const struct TALER_ReservePublicKeyP *reserve_pub;
      const char *account_url;

      GNUNET_assert (GNUNET_OK ==
                     TALER_TESTING_get_trait_amount_obj
                       (pos, 0, &amount));
      GNUNET_assert (GNUNET_OK ==
                     TALER_TESTING_get_trait_reserve_pub
                       (pos, 0, &reserve_pub));
      GNUNET_assert (GNUNET_OK ==
                     TALER_TESTING_get_trait_url
                       (pos, 1,
                       &account_url));
      h[total].details.amount = *amount;
      h[total].row_id = *row_id;
      h[total].details.reserve_pub = *reserve_pub;
      h[total].details.account_url = account_url;
      TALER_LOG_INFO ("+1-bit of my history\n");
      total++;
    }
  }
  *rh = h;
  return total;
}


/**
 * Compute how many results we expect to be returned for
 * the current command at @a is.
 *
 * @param is the interpreter state to inspect.
 * @return number of results expected.
 */
static uint64_t
compute_result_count (struct TALER_TESTING_Interpreter *is)
{
  uint64_t total;
  struct History *h;

  total = build_history (is, &h);
  free_history (h, total);
  return total;
}


/**
 * Check that the "/history" response matches the
 * CMD whose offset in the list of CMDs is @a off.
 *
 * @param is the interpreter state.
 * @param off the offset (of the CMD list) where the command
 *        to check is.
 * @param dir the expected direction of the transaction.
 * @param details the expected transaction details.
 *
 * @return #GNUNET_OK if the transaction is what we expect.
 */
static int
check_result (struct TALER_TESTING_Interpreter *is,
              unsigned int off,
              const struct TALER_BANK_CreditDetails *details)
{
  uint64_t total;
  struct History *h;

  total = build_history (is, &h);
  if (off >= total)
  {
    GNUNET_log (GNUNET_ERROR_TYPE_ERROR,
                "Test says history has at most %u"
                " results, but got result #%u to check\n",
                (unsigned int) total,
                off);
    print_expected (h,
                    total,
                    off);
    return GNUNET_SYSERR;
  }
  if ( (0 != GNUNET_memcmp (&h[off].details.reserve_pub,
                            &details->reserve_pub)) ||
       (0 != TALER_amount_cmp (&h[off].details.amount,
                               &details->amount)) ||
       (0 != strcasecmp (h[off].details.account_url,
                         details->account_url)) )
  {
    GNUNET_break (0);
    print_expected (h,
                    total,
                    off);
    free_history (h,
                  total);
    return GNUNET_SYSERR;
  }
  free_history (h,
                total);
  return GNUNET_OK;
}


/**
 * This callback will (1) check that the HTTP response code
 * is acceptable and (2) that the history is consistent.  The
 * consistency is checked by going through all the past CMDs,
 * reconstructing then the expected history as of those, and
 * finally check it against what the bank returned.
 *
 * @param cls closure.
 * @param http_status HTTP response code, #MHD_HTTP_OK (200)
 *        for successful status request 0 if the bank's reply is
 *        bogus (fails to follow the protocol),
 *        #MHD_HTTP_NO_CONTENT if there are no more results; on
 *        success the last callback is always of this status
 *        (even if `abs(num_results)` were already returned).
 * @param ec taler status code.
 * @param dir direction of the transfer.
 * @param row_id monotonically increasing counter corresponding to
 *        the transaction.
 * @param details details about the wire transfer.
 * @param json detailed response from the HTTPD, or NULL if
 *        reply was not in JSON.
 * @return #GNUNET_OK to continue, #GNUNET_SYSERR to abort iteration
 */
static int
history_cb (void *cls,
            unsigned int http_status,
            enum TALER_ErrorCode ec,
            uint64_t row_id,
            const struct TALER_BANK_CreditDetails *details,
            const json_t *json)
{
  struct TALER_TESTING_Interpreter *is = cls;
  struct HistoryState *hs = is->commands[is->ip].cls;

  (void) row_id;
  if (MHD_HTTP_OK != http_status)
  {
    hs->hh = NULL;
    GNUNET_log (GNUNET_ERROR_TYPE_ERROR,
                "Unwanted response code from /history: %u\n",
                http_status);
    TALER_TESTING_interpreter_fail (is);
    return GNUNET_SYSERR;
  }
  if (NULL == details)
  {
    hs->hh = NULL;
    if ( (hs->results_obtained != compute_result_count (is)) ||
         (GNUNET_YES == hs->failed) )
    {
      uint64_t total;
      struct History *h;

      GNUNET_break (0);
      total = build_history (is, &h);
      GNUNET_log (GNUNET_ERROR_TYPE_ERROR,
                  "Expected history of length %llu, got %llu;"
                  " HTTP status code: %u/%d, failed: %d\n",
                  (unsigned long long) total,
                  (unsigned long long) hs->results_obtained,
                  http_status,
                  (int) ec,
                  hs->failed);
      print_expected (h,
                      total,
                      UINT_MAX);
      free_history (h,
                    total);
      TALER_TESTING_interpreter_fail (is);
      return GNUNET_SYSERR;
    }
    TALER_TESTING_interpreter_next (is);
    return GNUNET_OK;
  }

  /* check current element */
  if (GNUNET_OK != check_result (is,
                                 hs->results_obtained,
                                 details))
  {
    char *acc;

    GNUNET_break (0);
    acc = json_dumps (json,
                      JSON_COMPACT);
    GNUNET_log (GNUNET_ERROR_TYPE_ERROR,
                "Result %u was `%s'\n",
                (unsigned int) hs->results_obtained++,
                acc);
    if (NULL != acc)
      free (acc);
    hs->failed = GNUNET_YES;
    return GNUNET_SYSERR;
  }
  hs->results_obtained++;
  return GNUNET_OK;
}


/**
 * Run the command.
 *
 * @param cls closure.
 * @param cmd the command to execute.
 * @param is the interpreter state.
 */
static void
history_run (void *cls,
             const struct TALER_TESTING_Command *cmd,
             struct TALER_TESTING_Interpreter *is)
{
  struct HistoryState *hs = cls;
  uint64_t row_id = (hs->num_results > 0) ? 0 : UINT64_MAX;
  const uint64_t *row_ptr;

  (void) cmd;
  /* Get row_id from trait. */
  if (NULL != hs->start_row_reference)
  {
    const struct TALER_TESTING_Command *history_cmd;

    history_cmd = TALER_TESTING_interpreter_lookup_command
                    (is, hs->start_row_reference);

    if (NULL == history_cmd)
      TALER_TESTING_FAIL (is);

    if (GNUNET_OK !=
        TALER_TESTING_get_trait_uint64 (history_cmd,
                                        0,
                                        &row_ptr))
      TALER_TESTING_FAIL (is);
    else
      row_id = *row_ptr;
    TALER_LOG_DEBUG ("row id (from trait) is %llu\n",
                     (unsigned long long) row_id);
  }

  hs->hh = TALER_BANK_credit_history (is->ctx,
                                      hs->account_url,
                                      NULL,
                                      row_id,
                                      hs->num_results,
                                      &history_cb,
                                      is);
  GNUNET_assert (NULL != hs->hh);
}


/**
 * Free the state from a "history" CMD, and possibly cancel
 * a pending operation thereof.
 *
 * @param cls closure.
 * @param cmd the command which is being cleaned up.
 */
static void
history_cleanup (void *cls,
                 const struct TALER_TESTING_Command *cmd)
{
  struct HistoryState *hs = cls;

  (void) cmd;
  if (NULL != hs->hh)
  {
    TALER_LOG_WARNING ("/history did not complete\n");
    TALER_BANK_credit_history_cancel (hs->hh);
  }
  GNUNET_free (hs->account_url);
  GNUNET_free (hs);
}


/**
 * Make a "history" CMD.
 *
 * @param label command label.
 * @param account_url base URL of the account offering the "history"
 *        operation.
 * @param start_row_reference reference to a command that can
 *        offer a row identifier, to be used as the starting row
 *        to accept in the result.
 * @param num_results how many rows we want in the result.
 * @return the command.
 */
struct TALER_TESTING_Command
TALER_TESTING_cmd_bank_credits (const char *label,
                                const char *account_url,
                                const char *start_row_reference,
                                long long num_results)
{
  struct HistoryState *hs;

  hs = GNUNET_new (struct HistoryState);
  hs->account_url = GNUNET_strdup (account_url);
  hs->start_row_reference = start_row_reference;
  hs->num_results = num_results;

  {
    struct TALER_TESTING_Command cmd = {
      .label = label,
      .cls = hs,
      .run = &history_run,
      .cleanup = &history_cleanup,
      .traits = &history_traits
    };

    return cmd;
  }
}


/* end of testing_api_cmd_credit_history.c */