/**
 * @file  client.c
 * @brief Unified OPC UA client for discovery and server interaction.
 *
 * Supports three operations selected via CLI:
 *   find-servers   — queries a server's FindServers service
 *   get-endpoints  — queries a server's GetEndpoints service
 *   read-time      — connects to a server and reads the current time
 *
 * Encryption is optional: when certificate, privateKey, and trustStore are
 * provided, the client uses the configured security policy; otherwise it
 * connects without encryption.
 */

#include "common.h"
#include "config.h"

#include <open62541/client_config_default.h>
#include <open62541/client_highlevel.h>
#include <open62541/plugin/log_stdout.h>

#include <stdlib.h>
#include <string.h>

/* ========================================================================
 * Operation Dispatch
 * ======================================================================== */

typedef enum
{
  OP_FIND_SERVERS,
  OP_GET_ENDPOINTS,
  OP_READ_TIME,
  OP_INVALID
} Operation;

static Operation
parseOperation (const char *name)
{
  if (strcmp (name, "find-servers") == 0)
    return OP_FIND_SERVERS;
  if (strcmp (name, "get-endpoints") == 0)
    return OP_GET_ENDPOINTS;
  if (strcmp (name, "read-time") == 0)
    return OP_READ_TIME;
  return OP_INVALID;
}

/* ========================================================================
 * Operations
 * ======================================================================== */

/**
 * Calls the FindServers service and prints all discovered servers.
 *
 * @return EXIT_SUCCESS on success, EXIT_FAILURE otherwise.
 */
static int
opFindServers (UA_Client *client, const char *url)
{
  size_t arraySize = 0;
  UA_ApplicationDescription *array = NULL;

  UA_StatusCode retval = UA_Client_findServers (client, url, 0, NULL, 0, NULL,
                                                &arraySize, &array);
  if (retval != UA_STATUSCODE_GOOD)
    {
      UA_LOG_ERROR (UA_Log_Stdout, UA_LOGCATEGORY_CLIENT,
                    "FindServers failed: %s", UA_StatusCode_name (retval));
      return EXIT_FAILURE;
    }

  for (size_t i = 0; i < arraySize; i++)
    printApplicationDescription (&array[i], i);

  UA_Array_delete (array, arraySize,
                   &UA_TYPES[UA_TYPES_APPLICATIONDESCRIPTION]);
  return EXIT_SUCCESS;
}

/**
 * Calls the GetEndpoints service and prints all endpoints.
 *
 * @return EXIT_SUCCESS on success, EXIT_FAILURE otherwise.
 */
static int
opGetEndpoints (UA_Client *client, const char *url)
{
  size_t arraySize = 0;
  UA_EndpointDescription *array = NULL;

  UA_StatusCode retval
      = UA_Client_getEndpoints (client, url, &arraySize, &array);
  if (retval != UA_STATUSCODE_GOOD)
    {
      UA_LOG_ERROR (UA_Log_Stdout, UA_LOGCATEGORY_CLIENT,
                    "GetEndpoints failed: %s", UA_StatusCode_name (retval));
      return EXIT_FAILURE;
    }

  for (size_t i = 0; i < arraySize; i++)
    printEndpoint (&array[i], i);

  UA_Array_delete (array, arraySize, &UA_TYPES[UA_TYPES_ENDPOINTDESCRIPTION]);
  return EXIT_SUCCESS;
}

/**
 * Connects to a server and reads the current time node.
 *
 * Authentication (anonymous, username/password, or X509 certificate) is
 * configured in the client config before this function is called.
 *
 * @return EXIT_SUCCESS on success, EXIT_FAILURE otherwise.
 */
static int
opReadTime (UA_Client *client, const char *url)
{
  UA_StatusCode retval = UA_Client_connect (client, url);

  if (retval != UA_STATUSCODE_GOOD)
    {
      UA_LOG_ERROR (UA_Log_Stdout, UA_LOGCATEGORY_CLIENT,
                    "Could not connect: %s", UA_StatusCode_name (retval));
      return EXIT_FAILURE;
    }

  UA_Variant value;
  UA_Variant_init (&value);

  const UA_NodeId nodeId = UA_NS0ID (SERVER_SERVERSTATUS_CURRENTTIME);
  retval = UA_Client_readValueAttribute (client, nodeId, &value);

  int rc = EXIT_SUCCESS;
  if (retval == UA_STATUSCODE_GOOD
      && UA_Variant_hasScalarType (&value, &UA_TYPES[UA_TYPES_DATETIME]))
    {
      UA_DateTime raw_date = *(UA_DateTime *)value.data;
      UA_DateTimeStruct dts = UA_DateTime_toStruct (raw_date);
      UA_LOG_INFO (UA_Log_Stdout, UA_LOGCATEGORY_APPLICATION,
                   "date is: %u-%u-%u %u:%u:%u.%03u", dts.day, dts.month,
                   dts.year, dts.hour, dts.min, dts.sec, dts.milliSec);
    }
  else
    {
      UA_LOG_ERROR (UA_Log_Stdout, UA_LOGCATEGORY_CLIENT,
                    "Could not read current time: %s",
                    UA_StatusCode_name (retval));
      rc = EXIT_FAILURE;
    }

  UA_Variant_clear (&value);
  UA_Client_disconnect (client);
  return rc;
}

/* ========================================================================
 * Main
 * ======================================================================== */

int
main (int argc, char **argv)
{
  if (argc < 4 || argc > 5)
    {
      UA_LOG_FATAL (UA_Log_Stdout, UA_LOGCATEGORY_USERLAND,
                    "Usage: %s <config-file> <operation> <endpoint-url> "
                    "[log-level]\n"
                    "Operations: find-servers, get-endpoints, read-time",
                    argv[0]);
      return EXIT_FAILURE;
    }

  Operation op = parseOperation (argv[2]);
  if (op == OP_INVALID)
    {
      UA_LOG_FATAL (UA_Log_Stdout, UA_LOGCATEGORY_USERLAND,
                    "Unknown operation: %s "
                    "(expected find-servers, get-endpoints, read-time)",
                    argv[2]);
      return EXIT_FAILURE;
    }

  const char *endpointUrl = argv[3];

  const char *logLevelStr = (argc == 5) ? argv[4] : "info";
  int logLevel = parseLogLevel (logLevelStr);
  if (logLevel < 0)
    {
      UA_LOG_FATAL (UA_Log_Stdout, UA_LOGCATEGORY_USERLAND,
                    "Unknown log level: %s "
                    "(expected trace, debug, info, warning, error, fatal)",
                    logLevelStr);
      return EXIT_FAILURE;
    }

  Config cfg;
  if (configLoad (argv[1], &cfg) != 0)
    return EXIT_FAILURE;

  /* ---- Common config keys ---- */

  const char *applicationUri
      = configRequire (&cfg, "applicationUri", "Client");
  if (!applicationUri)
    {
      configFree (&cfg);
      return EXIT_FAILURE;
    }

  SecurityConfig sec;
  if (parseSecurityConfig (&cfg, "Client", true, &sec) != 0)
    {
      configFree (&cfg);
      return EXIT_FAILURE;
    }

  /* ---- Auth config (read-time only) ---- */

  AuthConfig auth = { .mode = AUTH_ANONYMOUS };

  if (op == OP_READ_TIME && parseAuthConfig (&cfg, "Client", &auth) != 0)
    {
      freeTrustStore (sec.trustPaths, sec.trustSize);
      configFree (&cfg);
      return EXIT_FAILURE;
    }

  /* ---- Create client ---- */

  UA_Client *client = UA_Client_new ();

  UA_StatusCode retval;
  if (sec.certPath)
    retval = createSecureClientConfig (UA_Client_getConfig (client),
                                       applicationUri, &sec, &auth);
  else
    retval = createUnsecureClientConfig (UA_Client_getConfig (client),
                                         applicationUri, &auth);

  if (retval != UA_STATUSCODE_GOOD)
    {
      UA_Client_delete (client);
      freeTrustStore (sec.trustPaths, sec.trustSize);
      configFree (&cfg);
      return EXIT_FAILURE;
    }

  UA_Client_getConfig (client)->logging->context = (void *)(uintptr_t)logLevel;

  /* ---- Dispatch operation ---- */

  int rc;
  switch (op)
    {
    case OP_FIND_SERVERS:
      rc = opFindServers (client, endpointUrl);
      break;
    case OP_GET_ENDPOINTS:
      rc = opGetEndpoints (client, endpointUrl);
      break;
    case OP_READ_TIME:
      rc = opReadTime (client, endpointUrl);
      break;
    default:
      rc = EXIT_FAILURE;
      break;
    }

  /* ---- Cleanup ---- */

  UA_Client_delete (client);
  freeTrustStore (sec.trustPaths, sec.trustSize);
  configFree (&cfg);

  return rc;
}