/*-*- mode:c;indent-tabs-mode:nil;c-basic-offset:2;tab-width:8;coding:utf-8 -*-│
│vi: set net ft=c ts=2 sts=2 sw=2 fenc=utf-8                                :vi│
╞══════════════════════════════════════════════════════════════════════════════╡
│ Copyright 2022 Justine Alexandra Roberts Tunney                              │
│                                                                              │
│ Permission to use, copy, modify, and/or distribute this software for         │
│ any purpose with or without fee is hereby granted, provided that the         │
│ above copyright notice and this permission notice appear in all copies.      │
│                                                                              │
│ THE SOFTWARE IS PROVIDED "AS IS" AND THE AUTHOR DISCLAIMS ALL                │
│ WARRANTIES WITH REGARD TO THIS SOFTWARE INCLUDING ALL IMPLIED                │
│ WARRANTIES OF MERCHANTABILITY AND FITNESS. IN NO EVENT SHALL THE             │
│ AUTHOR BE LIABLE FOR ANY SPECIAL, DIRECT, INDIRECT, OR CONSEQUENTIAL         │
│ DAMAGES OR ANY DAMAGES WHATSOEVER RESULTING FROM LOSS OF USE, DATA OR        │
│ PROFITS, WHETHER IN AN ACTION OF CONTRACT, NEGLIGENCE OR OTHER               │
│ TORTIOUS ACTION, ARISING OUT OF OR IN CONNECTION WITH THE USE OR             │
│ PERFORMANCE OF THIS SOFTWARE.                                                │
╚─────────────────────────────────────────────────────────────────────────────*/
#include "libc/calls/calls.h"
#include "libc/calls/copyfile.h"
#include "libc/calls/struct/stat.h"
#include "libc/errno.h"
#include "libc/fmt/conv.h"
#include "libc/fmt/fmt.h"
#include "libc/intrin/kprintf.h"
#include "libc/runtime/gc.h"
#include "libc/runtime/runtime.h"
#include "libc/stdio/stdio.h"
#include "libc/str/str.h"
#include "libc/sysv/consts/at.h"
#include "libc/sysv/consts/ex.h"
#include "libc/sysv/consts/exit.h"
#include "libc/sysv/consts/ok.h"
#include "libc/sysv/consts/s.h"
#include "libc/x/x.h"
#include "third_party/getopt/getopt.h"
#include "third_party/musl/ftw.h"

#define USAGE \
  " SRC... DST\n\
\n\
SYNOPSIS\n\
\n\
  Copies Files\n\
\n\
FLAGS\n\
\n\
  -?\n\
  -h      help\n\
  -f      force\n\
  -r      recursive\n\
  -n      no clobber\n\
  -a      preserve all\n\
  -p      preserve owner and timestamps\n\
\n"

int flags;
bool force;
int striplen;
bool recursive;
const char *prog;
char mkbuf[PATH_MAX];
char srcdir[PATH_MAX];
char dstdir[PATH_MAX];
char srcfile[PATH_MAX];
char dstfile[PATH_MAX];
char linkbuf[PATH_MAX];

void Cp(char *, char *);

bool IsDirectory(const char *path) {
  int e;
  bool res;
  struct stat st;
  e = errno;
  res = stat(path, &st) != -1 && S_ISDIR(st.st_mode);
  errno = e;
  return res;
}

bool IsSymlink(const char *path) {
  int e;
  bool res;
  struct stat st;
  e = errno;
  res = fstatat(AT_FDCWD, path, &st, AT_SYMLINK_NOFOLLOW) != -1 &&
        S_ISLNK(st.st_mode);
  errno = e;
  return res;
}

wontreturn void PrintUsage(int rc, FILE *f) {
  fputs("usage: ", f);
  fputs(prog, f);
  fputs(USAGE, f);
  exit(rc);
}

void GetOpts(int argc, char *argv[]) {
  int opt;
  while ((opt = getopt(argc, argv, "?hfnaprR")) != -1) {
    switch (opt) {
      case 'f':
        force = true;
        break;
      case 'r':
      case 'R':
        recursive = true;
        break;
      case 'n':
        flags |= COPYFILE_NOCLOBBER;
        break;
      case 'a':
      case 'p':
        flags |= COPYFILE_PRESERVE_OWNER;
        flags |= COPYFILE_PRESERVE_TIMESTAMPS;
        break;
      case 'h':
      case '?':
        PrintUsage(EXIT_SUCCESS, stdout);
      default:
        PrintUsage(EX_USAGE, stderr);
    }
  }
}

int Visit(const char *fpath, const struct stat *sb, int tflag,
          struct FTW *ftwbuf) {
  char *src;
  strcpy(srcfile, fpath);
  src = srcfile + striplen;
  strcpy(dstfile, dstdir);
  if (!endswith(dstfile, "/")) {
    strcat(dstfile, "/");
  }
  strcat(dstfile, src);
  strcpy(srcfile, fpath);
  switch (tflag) {
    case FTW_D:
      return 0;
    case FTW_F:
    case FTW_SL:
    case FTW_SLN:
      Cp(srcfile, dstfile);
      return 0;
    default:
      fputs(fpath, stderr);
      fputs(": can't handle file type\n", stderr);
      exit(1);
  }
}

char *Join(const char *a, const char *b) {
  size_t n, m;
  n = strlen(a);
  m = strlen(b);
  if (n + 1 + m + 1 > sizeof(dstfile)) {
    fputs("error: cp: path too long\n", stderr);
    exit(1);
  }
  stpcpy(stpcpy(stpcpy(dstfile, a), "/"), b);
  return dstfile;
}

void Cp(char *src, char *dst) {
  ssize_t rc;
  const char *s;
  if (strlen(src) + 1 > PATH_MAX) _Exit(2);
  if (strlen(dst) + 1 > PATH_MAX) _Exit(2);
  basename(src);
  basename(dst);
  if (IsDirectory(src)) {
    if (!recursive) {
      fputs(prog, stderr);
      fputs(": won't copy directory without -r flag.\n", stderr);
      exit(1);
    }
    strcpy(dstdir, dst);
    if (IsDirectory(dst)) {
      strcpy(srcdir, src);
      basename(srcdir);
      striplen = 0;
      strcpy(srcdir, basename(src));
    } else {
      strcpy(srcdir, src);
      basename(srcdir);
      striplen = strlen(srcdir);
      strcpy(srcdir, "");
    }
    if (nftw(src, Visit, 20, 0) == -1) {
      fputs(prog, stderr);
      fputs(": nftw failed: ", stderr);
      fputs(strerdoc(errno), stderr);
      fputs("\n", stderr);
      exit(1);
    }
    return;
  }
  if (IsDirectory(dst)) {
    dst = Join(dst, basename(src));
  }
  if (!force && access(dst, W_OK) == -1 && errno != ENOENT) goto OnFail;
  strcpy(mkbuf, dst);
  if (makedirs(dirname(mkbuf), 0755) == -1) goto OnFail;
  if (IsSymlink(src)) {
    if ((rc = readlink(src, linkbuf, sizeof(linkbuf) - 1)) == -1) goto OnFail;
    linkbuf[rc] = 0;
    if (symlink(linkbuf, dst) == -1) goto OnFail;
  } else {
    if (copyfile(src, dst, flags) == -1) goto OnFail;
  }
  return;
OnFail:
  s = strerdoc(errno);
  fputs(prog, stderr);
  fputs(": ", stderr);
  fputs(src, stderr);
  fputs(" ", stderr);
  fputs(dst, stderr);
  fputs(": ", stderr);
  fputs(s, stderr);
  fputs("\n", stderr);
  exit(1);
}

int main(int argc, char *argv[]) {
  int i;
  prog = argc > 0 ? argv[0] : "cp.com";
  GetOpts(argc, argv);
  if (argc - optind < 2) PrintUsage(EX_USAGE, stderr);
  for (i = optind; i < argc - 1; ++i) {
    Cp(argv[i], argv[argc - 1]);
  }
  return 0;
}