/**
 * @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
 */

#include "common.h"
#include "config.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.
 *
 * @param username Username for session auth, or NULL for anonymous.
 * @param password Password for session auth (ignored when username is NULL).
 * @return EXIT_SUCCESS on success, EXIT_FAILURE otherwise.
 */
static int
opReadTime (UA_Client *client, const char *url, const char *username,
            const char *password)
{
  UA_StatusCode retval;
  if (username)
    retval = UA_Client_connectUsername (client, url, username, password);
  else
    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");
  const char *certPath = configRequire (&cfg, "certificate", "Client");
  const char *keyPath = configRequire (&cfg, "privateKey", "Client");
  const char *secModeStr = configRequire (&cfg, "securityMode", "Client");
  const char *secPolStr = configRequire (&cfg, "securityPolicy", "Client");

  if (!applicationUri || !certPath || !keyPath || !secModeStr || !secPolStr)
    {
      configFree (&cfg);
      return EXIT_FAILURE;
    }

  UA_MessageSecurityMode secMode = parseSecurityMode (secModeStr);
  if (secMode == UA_MESSAGESECURITYMODE_INVALID)
    {
      UA_LOG_FATAL (UA_Log_Stdout, UA_LOGCATEGORY_USERLAND,
                    "Unknown security mode: %s", secModeStr);
      configFree (&cfg);
      return EXIT_FAILURE;
    }

  const char *secPolUri = resolveSecurityPolicyUri (secPolStr);
  if (!secPolUri)
    {
      UA_LOG_FATAL (UA_Log_Stdout, UA_LOGCATEGORY_USERLAND,
                    "Unknown security policy: %s", secPolStr);
      configFree (&cfg);
      return EXIT_FAILURE;
    }

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

  const char *username = NULL, *password = NULL;

  if (op == OP_READ_TIME
      && parseAuthConfig (&cfg, "Client", NULL, &username, &password) != 0)
    {
      configFree (&cfg);
      return EXIT_FAILURE;
    }

  /* ---- Trust store ---- */

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

  char **trustPaths = NULL;
  size_t trustSize = 0;
  if (loadTrustStore (trustStore, &trustPaths, &trustSize) != 0)
    {
      configFree (&cfg);
      return EXIT_FAILURE;
    }

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

  UA_Client *client = UA_Client_new ();
  UA_StatusCode retval = createSecureClientConfig (
      UA_Client_getConfig (client), applicationUri, certPath, keyPath,
      trustPaths, trustSize, secMode, secPolUri);
  if (retval != UA_STATUSCODE_GOOD)
    {
      UA_Client_delete (client);
      freeTrustStore (trustPaths, 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, username, password);
      break;
    default:
      rc = EXIT_FAILURE;
      break;
    }

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

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

  return rc;
}