#include <signal.h>
#include <setjmp.h>
#include <assert.h>
#include <unistd.h>
#include <string.h>
#include <stdlib.h>

#include <gap/config.h>
#include <gap/system.h>
#include <gap/objects.h>
#include <gap/gap.h>
#include <gap/scanner.h>
#include <gap/sysfiles.h>
#include <gap/plist.h>
#include <gap/gasman.h>
#include <gap/string.h>
#include <gap/read.h>
#include <gap/code.h>
#include <gap/calls.h>
#include <gap/vars.h>
#include <gap/libgap.h>
#include <gap/libgap_internal.h>

// Path to the GAP root (for the library)
#ifndef SYS_DEFAULT_PATHS
#define SYS_DEFAULT_PATHS "/usr/share/gap"
#endif


// using namespace std;

/////////////////////////////////////////////////////////////////

void error_handler(char* msg)
{
  printf("Error handler: %s", msg);
}


/////////////////////////////////////////////////////////////////

void init()
{
  printf("Using gap library at %s\n", SYS_DEFAULT_PATHS);
  char* argv[13];
  argv[0] = "gap";
  argv[1] = "-l";
  argv[2] = SYS_DEFAULT_PATHS;
  char* memory_pool = "1000M";
  argv[3] = "-o";
  argv[4] = memory_pool;
  argv[5] = "-s";
  argv[6] = memory_pool;
  argv[7] = "-m";
  argv[8] = "64M";
  argv[9] = "-q";
  argv[10] = "-A";
  argv[11] = "-T";
  argv[12] = NULL;
  int argc=12;
  //  libgap_set_error_handler(&error_handler);
  //  libgap_initialize(argc, argv);

  libgap_initialize(argc, argv);
  libgap_start_interaction("");
  char * output_msg = libgap_get_output();
  if (strlen(output_msg) > 0)
    printf("libGAP initialization failed: %s\n", output_msg);
  char * error_msg = libgap_get_error();
  if (strlen(error_msg) > 0)
    printf("libGAP initialization failed: %s\n", error_msg);
  libgap_finish_interaction();
  libgap_set_error_handler(&error_handler);
}   




/////////////////////////////////////////////////////////////////

sigjmp_buf env;

#define signal_occurred   sigsetjmp(env,1)


void signal_handler(int sig) 
{
  printf("Caught signal %i\n", sig);
  siglongjmp(env, sig);
}


void install_signal_handler()
{
  struct sigaction sa;
  memset(&sa, 0, sizeof(sa));
  sa.sa_handler = signal_handler;
  sa.sa_flags |= SA_NODEFER;
  assert(0 == sigaction(SIGINT, &sa, NULL));
  assert(0 == sigaction(SIGILL, &sa, NULL));
  assert(0 == sigaction(SIGABRT, &sa, NULL));
  assert(0 == sigaction(SIGFPE, &sa, NULL));
  assert(0 == sigaction(SIGBUS, &sa, NULL));
  assert(0 == sigaction(SIGSEGV, &sa, NULL));
}


/////////////////////////////////////////////////////////////////


void check(char* input, char* expected)
{
  printf("--------------------\n");
  printf("Input: %s", input);

  libgap_enter();
  libgap_start_interaction(input);
  
  libGAP_ExecStatus status;
  status = libGAP_ReadEvalCommand(libGAP_BottomLVars, 0); /* 2nd parameter is "dualSemicolon" */
  libgap_exit();
  
  if (signal_occurred) {
    printf("signal caught\n");
    libgap_enter();
    libgap_finish_interaction();
    libgap_exit();
    return;
  }
  
  if (status != libGAP_STATUS_END) {
    printf("There was an error, no output.\n");
    libgap_finish_interaction();
    return;
  }

  assert(libGAP_Symbol == libGAP_S_SEMICOLON);
  libgap_enter();
  libGAP_GetSymbol();
  libgap_exit();
  if (libGAP_Symbol!=libGAP_S_EOF) {
    printf("Multiple statements; aborting!\n");
    libgap_finish_interaction();
    return;
  }

  if (libGAP_ReadEvalResult != NULL) {
    libgap_enter();
    libGAP_ViewObjHandler(libGAP_ReadEvalResult);
    libgap_exit();
  } else {
    printf("Command returned nothing\n");
    if (expected != NULL && strstr("Command returned nothing", expected) == NULL) {
      printf("Expected substring '%s' not found, aborting.\n", expected);
      exit(1);
    }
  }

  char* out = libgap_get_output();
  printf("Output follows...\n%s", out);

  if (expected != NULL && strstr(out, expected) == NULL) {
    printf("Expected substring '%s' not found, aborting.\n", expected);
    exit(1);
  }

  libgap_enter();
  libgap_finish_interaction();
  libgap_exit();
}



void eval(char* input) 
{
  return check(input, NULL);
}




int main(void)
{
  init();
  // install_signal_handler();

  eval("0;\n");

  eval("CyclicGroup(2);\n");

  eval("1 + CyclicGroup(2);\n");

  eval("1/0;\n");

  eval("a:=NormalSubgroups;\n");
  eval("b:=SymmetricGroup(4);\n");
  eval("a(b);\n");

  eval("SmallGroup(12,3);\n");
  eval("0;\n");

  eval("0;\n");
  eval("1+3;\n");
  eval("[1, 3, 5];\n");

  eval("if 4>3 then\nPrint(\"hi\n\");\n fi;\n");
  eval("0;\n");

  check("rec( a:=0, b:=1, c:=3 );\n",
        "rec( a := 0, b := 1, c := 3 )");

  check("0;\n", 
        "0");

  eval("rec( a=0, b:1, c;3 );\n");
  eval("0;\n");

  eval("rec( a=0, b:1, c;3 );\n");
  check("\"back to normal\";\n", 
        "\"back to normal\"");

  eval("Print(\"Printed Message\");\n");

  unlink("tmp_file.txt");
  eval("Print(\"Printed Message\");\n");
  eval("PrintTo(\"tmp_file.txt\", \"Printed Message\");\n");
  check("StringFile(\"tmp_file.txt\");\n", 
        "Printed Message");  

  eval("1/0;\n");
  
  return 0;
}