#include "kernel/fs.h"
#include "kernel/stat.h"
#include "kernel/types.h"
#include "user/user.h"

int match_pattern(const char *name, const char *pattern) {
  const char *star = 0;
  const char *name_ptr = name;
  const char *pattern_ptr = pattern;

  while (1) {
    if (*pattern_ptr == '*') {
      star = pattern_ptr++;
      name_ptr = name;
      continue;
    }

    if (!*name)
      return (!*pattern_ptr || (star && !*++pattern_ptr));
    if (*pattern_ptr == '?' || *pattern_ptr == *name) {
      pattern_ptr++;
      name++;
      continue;
    }

    if (star) {
      pattern_ptr = star + 1;
      name = ++name_ptr;
      continue;
    }
    return 0;
  }
}

void find(char *path, char *pattern) {
  char buf[512], *p;
  int fd;
  struct dirent de;
  struct stat st;

  if ((fd = open(path, 0)) < 0) {
    fprintf(2, "find: cannot open %s\n", path);
    return;
  }

  if (fstat(fd, &st) < 0) {
    fprintf(2, "find: cannot stat %s\n", path);
    close(fd);
    return;
  }

  if (st.type != T_DIR) {
    fprintf(2, "find: %s is not a directory\n", path);
    close(fd);
    return;
  }

  if (strlen(path) + 1 + DIRSIZ + 1 > sizeof buf) {
    fprintf(2, "find: path too long\n");
    close(fd);
    return;
  }

  strcpy(buf, path);
  p = buf + strlen(buf);
  *p++ = '/';

  while (read(fd, &de, sizeof(de)) == sizeof(de)) {
    if (de.inum == 0 || !strcmp(de.name, ".") || !strcmp(de.name, ".."))
      continue;

    memmove(p, de.name, DIRSIZ);
    p[DIRSIZ] = 0;

    if (stat(buf, &st) < 0) {
      fprintf(2, "find: cannot stat %s\n", buf);
      continue;
    }

    if (st.type == T_DIR) {
      find(buf, pattern);
    } else if (st.type == T_FILE) {
      if (match_pattern(de.name, pattern)) {
        fprintf(1, "%s\n", buf);
      }
    }
  }
  close(fd);
}

int main(int argc, char *argv[]) {
  if (argc != 3) {
    fprintf(2, "Usage: find <path> <pattern>\n");
    exit(1);
  }
  find(argv[1], argv[2]);
  exit(0);
}