#include <sys/wait.h>
#include <sys/stat.h>
#include <unistd.h>
#include <linux/limits.h>
#include <stdio.h>
#include <stdlib.h>
#include <errno.h>
#include <time.h>
#include <string.h>

#define RELEASE_MODE

#ifdef RELEASE_MODE
#define CC "gcc", "-O3"
#else
#define CC "gcc", "-fsanitize=address", "-g"
#endif

#define EXE_NAME "backbencher"

int status;

#define RUN_CMD(...) do { \
  if (fork() == 0) { \
    char* args[] = __VA_ARGS__; \
    print_cmd(args); \
    execvp(args[0], args); \
    return 0; \
  } else { \
    wait(&status); \
  } \
} while (0);

void print_cmd(char** args) {
  int i = 0;
  while (args[i] != NULL) {
    printf("%s ", args[i++]);
  }
  printf("\n");
}

// https://github.com/tsoding/nob.h/blob/0a08926d8094fc4ae678155c5d73ae21d1f96f3f/nob.h#L2413
int needs_rebuild(char* bin_file, char* source_file) {
  struct stat statbuf = {0};
  if (stat(bin_file, &statbuf) < 0) {
    if (errno == ENOENT) return 1;
    return -1;
  }
  time_t output_path_time = statbuf.st_mtime;

  if (stat(source_file, &statbuf) < 0) {
    fprintf(stderr, "could not stat %s: %s", source_file, strerror(errno));
    return -1;
  }

  time_t input_path_time = statbuf.st_mtime;
  return input_path_time > output_path_time;
}

void getlibgit2(char *output, int output_max_size) {
  int link[2];
  pid_t pid;

  pipe(link);
  pid = fork();

  if (pid == 0) {
    dup2(link[1], STDOUT_FILENO);
    close(link[0]);
    close(link[1]);
    execl("/usr/bin/pkg-config", "--cflags", "--libs", "libgit2", (char*)0);
    exit(0);
  }

  close(link[1]);
  int nbytes = read(link[0], output, output_max_size);
  wait(NULL);

  int i = -1;
  while (++i < nbytes) {
    if (output[i] >= 32) continue;
    nbytes = i - 1;
    break;
  }
  output[nbytes] = 0;
  return;
}

int main(int argc, char** argv) {
  if (needs_rebuild(argv[0], __FILE__)) {
    RUN_CMD({CC, __FILE__, "-o", argv[0], NULL});
    if (status != 0) {
      // cc error
      return 0;
    }
    print_cmd(argv);
    execvp(argv[0], argv);
  }

  if (argc >= 2 && strcmp(argv[1], "install") == 0) {
    printf("install -m 755 " EXE_NAME " /usr/local/bin/" EXE_NAME);
    char dest[PATH_MAX];
    snprintf(dest, sizeof(dest), "/usr/local/bin/%s", EXE_NAME);
    char *install_args[] = {"install", "-m", "755", EXE_NAME, dest, NULL};
    execvp("install", install_args);
    perror("execvp");
    return 0;
  }
  if (argc >= 2 && strcmp(argv[1], "release") == 0) {
    char libgit[4096];
    getlibgit2(libgit, 4096);
    RUN_CMD({CC, "src/main.c", libgit, "-o", EXE_NAME, "-O3", NULL});
    return 0;
  }

  char libgit[4096];
  getlibgit2(libgit, 4096);
  RUN_CMD({CC, "src/main.c", libgit, "-o", EXE_NAME, "-O0", "-g", NULL});

  if (status == 0 && argc >= 2) {
    argv[1] = malloc(1024);
    strncpy(argv[1], "./" EXE_NAME, 1024);
    print_cmd(argv + 1);
    execvp(argv[1], argv + 1);
  }
}