#include "crash-logger.hpp"

#include <cstdlib>
#include <cstdio>
#include <csignal>
#include <cstring>

#include <fcntl.h>

#include "compiler.hpp"
#include "consts.hpp"

// TODO: Double-check which includes are necessary

#ifdef WINDOWS
   // Check if this is necessary or lets me remove any windows includes
   // also check if it's needed in Linux
   #include <cstdint>

   #include <windows.h>
   #include <io.h>
   #include <sys/stat.h>

   #include "FileStackWalker.h"

   // The windows analogues to the unix open, close, and write functions
   // are _open, _close, and _write. These #defines let me use the same name in all cases.
   #define open _open
   #define close _close
   #define write _write

   #define STDERR_FILENO 2

   bool handleException(unsigned int expCode, EXCEPTION_POINTERS* pExp, HANDLE thread);
#else
   #include <unistd.h>
   #include <execinfo.h>
   #include <cxxabi.h>

   // CHeck if these are needed in Linux
   //#include <errno.h>
   //#include <cstring>

   void abortHandler(int signum);
   static inline void printStackTrace(int fd_out = STDERR_FILENO);
#endif

void printInfo(int fd_out);

CrashLogger::CrashLogger(int(*mainFunc)(int, char*[]), int argc, char* argv[]) {
   write(STDERR_FILENO, "Calling main\n", 13);

   #ifdef WINDOWS
      __try {
         mainFunc(argc, argv);
         // maybe do this and call a function inside CrashLogger
         // In that case, also pass GetCurrentThread() as a parameter to then pass to handleException
         // I could also move almost all of this into CrashLogger by creating a function in CrashLogger that takes a reference
         // to the effective main function and, for Windows, wraps it in all this error-handling stuff
      } __except (handleException(
            GetExceptionCode(),
            GetExceptionInformation(),
            GetCurrentThread())
            ? EXCEPTION_EXECUTE_HANDLER : EXCEPTION_EXECUTE_HANDLER) {
      }
   #else
      // Apparently, sigaction should be used instead for Linux
      // It gives more info. Check if I should bother switching

      signal(SIGABRT, abortHandler);
      signal(SIGSEGV, abortHandler);
      signal(SIGILL, abortHandler);
      signal(SIGFPE, abortHandler);

      write(STDERR_FILENO, "Handlers attached\n", 18);

      mainFunc(argc, argv);
   #endif
}

CrashLogger::~CrashLogger() {
}

#ifdef WINDOWS

bool handleException(unsigned int expCode, EXCEPTION_POINTERS* pExp, HANDLE thread) {
   int crash_log = open(CRASH_LOG_FILE, O_RDWR | O_CREAT | O_APPEND, _S_IREAD | _S_IWRITE);

   if (crash_log == -1) {
      // TODO: Figure out exactly what perror does and if I should use it
      perror("opening crash.log");  // TODO: Figure out exactly what perror does and if I should use it
   }

   printInfo(crash_log);

   FileStackWalker sw(crash_log == -1 ? STDERR_FILENO  : crash_log);

   if (pExp != NULL) {
      sw.ShowCallstack(thread, pExp->ContextRecord);
   } else {
      write(crash_log, "Could not get the stack trace\n", 30);
   }

   close(crash_log);

   if (expCode == EXCEPTION_ACCESS_VIOLATION) {
      write(STDERR_FILENO, "ACCESS VIOLATION\n", 17);
   }

   return true;
}

#else

void abortHandler(int signum) {
   int crash_log = open(CRASH_LOG_FILE, O_RDWR | O_CREAT | O_APPEND, S_IRUSR | S_IWUSR);

   if (crash_log == -1) {
      // TODO: Figure out exactly what perror does and if I should use it
      perror("opening crash.log"); 
   }

   printInfo(crash_log);

   printStackTrace(crash_log);

   close(crash_log);

   write(STDERR_FILENO, "The game has crashed. Check crash.log for more info\n", 52);

   exit(signum);
}

static inline void printStackTrace(int fd_out) {
   write(fd_out, "stack trace:\n", 13);

   // storage array for stack trace address data
   void* addrlist[64];

   // retrieve current stack addresses
   unsigned int addrlen = backtrace(addrlist, sizeof(addrlist) / sizeof(void*));

   if (addrlen == 0) {
      write(fd_out, "  \n", 3);
      return;
   }

   // create readable strings to each frame.
   char** symbollist = backtrace_symbols(addrlist, addrlen);

   size_t funcnamesize = 1024;
   char* funcname = (char*)malloc(sizeof(char) * funcnamesize);

   // iterate over the returned symbol lines
   // skip the first few, since those are printStackTrace, abortHandler,
   // and a couple others called after the crash
   for (unsigned int i = 0; i < addrlen; i++) {
      char* begin_name = NULL;
      char* begin_offset = NULL;

#ifdef MAC
      for (char *p = symbollist[i]; *p; p++) {
         if ((*p == '_') && (*(p-1) == ' ')) {
            begin_name = p-1;
         } else if (*p == '+') {
            begin_offset = p-1;
         }
      }

      write(fd_out, "  ", 2);
      if (begin_name && begin_offset && (begin_name < begin_offset)) {
         *begin_name++ = '\0';
         *begin_offset++ = '\0';

         // mangled name is now in [begin_name, begin_offset) and caller
         // offset in [begin_offset, end_offset). now apply
         // __cxa_demangle():
         int status;
         char* ret = abi::__cxa_demangle(begin_name, funcname, &funcnamesize, &status);

         if (status == 0)  {
            funcname = ret; // use possibly realloc()-ed string
            write(fd_out, symbollist[i], strlen(symbollist[i]));
            write(fd_out, " ", 1);
            write(fd_out, funcname, strlen(funcname));
            write(fd_out, " ", 1);
         } else {
            // demangling failed. Output function name as a C function with no arguments.
            write(fd_out, symbollist[i], strlen(symbollist[i]));
            write(fd_out, " ", 1);
            write(fd_out, begin_name, strlen(begin_name));
            write(fd_out, "() ", 3);
         }
         write(fd_out, begin_offset, strlen(begin_offset));
      } else {
         // couldn't parse the line? print the whole line.
         write(fd_out, symbollist[i], strlen(symbollist[i]));
      }
      write(fd_out, "\n", 1);
#else
      char* end_offset = NULL;

      for (char *p = symbollist[i]; *p; p++) {
         if (*p == '(') {
            begin_name = p;
         } else if (*p == '+') {
            begin_offset = p;
         } else if (*p == ')' && (begin_offset || begin_name)) {
            end_offset = p;
         }
      }

      write(fd_out, "  ", 2);
      if (begin_name && end_offset && (begin_name < end_offset)) {
         *begin_name++ = '\0';
         *end_offset++ = '\0';
         if (begin_offset) {
            *begin_offset++ = '\0';
         }

         // mangled name is now in [begin_name, begin_offset) and caller
         // offset in [begin_offset, end_offset). now apply
         // __cxa_demangle():
         int status;
         char* ret = abi::__cxa_demangle(begin_name, funcname, &funcnamesize, &status);

         write(fd_out, symbollist[i], strlen(symbollist[i]));
         write(fd_out, " ( ", 3);
         if (status == 0) {
            write(fd_out, ret, strlen(ret));
         } else {
            write(fd_out, begin_name, strlen(begin_name));
         }

         if (begin_offset) {
            write(fd_out, " + ", 3);
            write(fd_out, begin_offset, strlen(begin_offset));
         } else {
            write(fd_out, "         ", 9);
         }
         write(fd_out, ") ", 1);
         write(fd_out, end_offset, strlen(end_offset));
      } else {
         // couldn't parse the line? print the whole line.
         write(fd_out, symbollist[i], strlen(symbollist[i]));
      }
      write(fd_out, "\n", 1);
#endif
   }

   free(funcname);
   free(symbollist);

   write(fd_out, "End of stack trace\n", 19);
}

#endif

void printInfo(int fd_out) {
   write(fd_out, "Game Version: ", 14);
   write(fd_out, GAME_VERSION, strlen(GAME_VERSION));
   write(fd_out, "\n", 1);

   write(fd_out, "OS: ", 4);
   #if defined WINDOWS
      write(fd_out, "Windows", 7);
   #elif defined LINUX
      write(fd_out, "Linux", 5);
   #elif defined MAC
      write(fd_out, "Mac", 3);
   #else
      write(fd_out, "Unknown", 7);
   #endif
   write(fd_out, "\n", 1);

   write(fd_out, "\n", 1);
}