/*
  The MIT License (MIT)

  Copyright (c) 2014 Antonio SJ Musumeci <trapexit@spawn.link>

  Permission is hereby granted, free of charge, to any person obtaining a copy
  of this software and associated documentation files (the "Software"), to deal
  in the Software without restriction, including without limitation the rights
  to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
  copies of the Software, and to permit persons to whom the Software is
  furnished to do so, subject to the following conditions:

  The above copyright notice and this permission notice shall be included in
  all copies or substantial portions of the Software.

  THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
  IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
  FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
  AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
  LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
  OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN
  THE SOFTWARE.
*/

#include <string>
#include <vector>
#include <map>
#include <sstream>
#include <cstdlib>
#include <iterator>

#include <dirent.h>
#include <errno.h>
#include <fcntl.h>
#include <linux/fs.h>
#include <sys/ioctl.h>
#include <sys/stat.h>
#include <sys/statvfs.h>
#include <sys/types.h>
#include <unistd.h>
#include <glob.h>
#include <fnmatch.h>

#include "fs.hpp"
#include "xattr.hpp"
#include "str.hpp"

using std::string;
using std::vector;
using std::map;
using std::istringstream;

template <typename Iter>
Iter
random_element(Iter begin,
               Iter end)
{
  const unsigned long n = std::distance(begin, end);

  std::advance(begin, (std::rand() % n));

  return begin;
}

namespace fs
{
  string
  dirname(const string path)
  {
    string parent = path;
    string::reverse_iterator i;
    string::reverse_iterator bi;

    bi = parent.rend();
    i  = parent.rbegin();
    while(*i == '/' && i != bi)
      i++;

    while(*i != '/' && i != bi)
      i++;

    while(*i == '/' && i != bi)
      i++;

    parent.erase(i.base(),parent.end());

    return parent;
  }

  string
  basename(const string path)
  {
    return path.substr(path.find_last_of('/')+1);
  }

  bool
  dir_is_empty(const string path)
  {
    DIR           *dir;
    struct dirent *de;

    dir = ::opendir(path.c_str());
    if(!dir)
      return false;

    while((de = ::readdir(dir)))
      {
        const char *d_name = de->d_name;

        if(d_name[0] == '.'     &&
           ((d_name[1] == '\0') ||
            (d_name[1] == '.' && d_name[2] == '\0')))
          continue;

        ::closedir(dir);

        return false;
      }

    ::closedir(dir);

    return true;
  }

  string
  make_path(const string base,
            const string suffix)
  {
    if(suffix[0]      == '/' ||
       *base.rbegin() == '/')
      return base + suffix;
    return base + '/' + suffix;
  }

  bool
  path_exists(vector<string>::const_iterator begin,
              vector<string>::const_iterator end,
              const string                   fusepath)
  {
    for(vector<string>::const_iterator
          iter = begin; iter != end; ++iter)
      {
        int         rv;
        string      path;
        struct stat st;

        path = fs::make_path(*iter,fusepath);
        rv   = ::lstat(path.c_str(),&st);
        if(rv == 0)
          return true;
      }

    return false;
  }

  bool
  path_exists(const vector<string> &srcmounts,
              const string               fusepath)
  {
    return path_exists(srcmounts.begin(),
                       srcmounts.end(),
                       fusepath);
  }

  int
  listxattr(const string  path,
            vector<char> &attrs)
  {
#ifndef WITHOUT_XATTR
    int rv;
    int size;

    rv    = -1;
    errno = ERANGE;
    while(rv == -1 && errno == ERANGE)
      {
        size = ::listxattr(path.c_str(),NULL,0);
        attrs.resize(size);
        rv   = ::listxattr(path.c_str(),&attrs[0],size);
      }

    return rv;
#else
    errno = ENOTSUP;
    return -1;
#endif
  }

  int
  listxattr(const string         path,
            vector<string> &attrvector)
  {
    int rv;
    vector<char> attrs;

    rv = listxattr(path,attrs);
    if(rv != -1)
      {
        string tmp(attrs.begin(),attrs.end());
        str::split(attrvector,tmp,'\0');
      }

    return rv;
  }

  int
  listxattr(const string  path,
            string &attrstr)
  {
    int rv;
    vector<char> attrs;

    rv = listxattr(path,attrs);
    if(rv != -1)
      attrstr = string(attrs.begin(),attrs.end());

    return rv;
  }

  int
  getxattr(const string  path,
           const string  attr,
           vector<char> &value)
  {
#ifndef WITHOUT_XATTR
    int rv;
    int size;

    rv    = -1;
    errno = ERANGE;
    while(rv == -1 && errno == ERANGE)
      {
        size = ::getxattr(path.c_str(),attr.c_str(),NULL,0);
        value.resize(size);
        rv   = ::getxattr(path.c_str(),attr.c_str(),&value[0],size);
      }

    return rv;
#else
    errno = ENOTSUP;
    return -1;
#endif
  }

  int
  getxattr(const string  path,
           const string  attr,
           string       &value)
  {
    int          rv;
    vector<char> tmpvalue;

    rv = getxattr(path,attr,tmpvalue);
    if(rv != -1)
      value = string(tmpvalue.begin(),tmpvalue.end());

    return rv;
  }


  int
  getxattrs(const string        path,
            map<string,string> &attrs)
  {
    int rv;
    string attrstr;

    rv = listxattr(path,attrstr);
    if(rv == -1)
      return -1;

    {
      string key;
      istringstream ss(attrstr);

      while(getline(ss,key,'\0'))
        {
          string value;

          rv = getxattr(path,key,value);
          if(rv != -1)
            attrs[key] = value;
        }
    }

    return 0;
  }

  int
  setxattr(const string path,
           const string key,
           const string value,
           const int    flags)
  {
#ifndef WITHOUT_XATTR
    return ::setxattr(path.c_str(),
                      key.c_str(),
                      value.data(),
                      value.size(),
                      flags);
#else
    errno = ENOTSUP;
    return -1;
#endif
  }

  int
  setxattr(const int    fd,
           const string key,
           const string value,
           const int    flags)
  {
#ifndef WITHOUT_XATTR
    return ::fsetxattr(fd,
                       key.c_str(),
                       value.data(),
                       value.size(),
                       flags);
#else
    errno = ENOTSUP;
    return -1;
#endif
  }

  int
  setxattrs(const string              path,
            const map<string,string> &attrs)
  {
    int fd;

    fd = ::open(path.c_str(),O_RDONLY|O_NONBLOCK);
    if(fd == -1)
      return -1;

    for(map<string,string>::const_iterator
          i = attrs.begin(), ei = attrs.end(); i != ei; ++i)
      {
        setxattr(fd,i->first,i->second,0);
      }

    return ::close(fd);
  }

  int
  copyxattrs(const string from,
             const string to)
  {
    int rv;
    map<string,string> attrs;

    rv = getxattrs(from,attrs);
    if(rv == -1)
      return -1;

    return setxattrs(to,attrs);
  }

  int
  copyattr(const string from,
           const string to)
  {
    int fd;
    int rv;
    int flags;
    int error;
    const int openflags = O_RDONLY|O_NONBLOCK;

    fd = ::open(from.c_str(),openflags);
    if(fd == -1)
      return -1;

    rv = ::ioctl(fd,FS_IOC_GETFLAGS,&flags);
    if(rv == -1)
      {
        error = errno;
        ::close(fd);
        errno = error;
        return -1;
      }

    fd = ::open(to.c_str(),openflags);
    if(fd == -1)
      return -1;

    rv = ::ioctl(fd,FS_IOC_SETFLAGS,&flags);
    if(rv == -1)
      {
        error = errno;
        ::close(fd);
        errno = error;
        return -1;
      }

    return ::close(fd);
  }

  int
  clonepath(const string fromsrc,
            const string tosrc,
            const string relative)
  {
    int         rv;
    struct stat st;
    string      topath;
    string      frompath;
    string      dirname;

    dirname = fs::dirname(relative);
    if(!dirname.empty())
      {
        rv = clonepath(fromsrc,tosrc,dirname);
        if(rv == -1)
          return -1;
      }

    frompath = fs::make_path(fromsrc,relative);

    rv = ::stat(frompath.c_str(),&st);
    if(rv == -1)
      return -1;
    else if(!S_ISDIR(st.st_mode))
      return (errno = ENOTDIR,-1);

    topath = fs::make_path(tosrc,relative);
    rv = ::mkdir(topath.c_str(),st.st_mode);
    if(rv == -1)
      return -1;

    rv = ::chown(topath.c_str(),st.st_uid,st.st_gid);
    if(rv == -1)
      return -1;

    // It may not support it... it's fine...
    rv = copyattr(frompath,topath);
    if(rv == -1 && errno != ENOTTY)
      return -1;

    rv = copyxattrs(frompath,topath);
    if(rv == -1 && errno != ENOTTY)
      return -1;

    return (errno = 0);
  }

  void
  glob(const vector<string> &patterns,
       vector<string>       &strs)
  {
    int flags;
    glob_t gbuf;

    flags = 0;
    for(size_t i = 0; i < patterns.size(); i++)
      {
        glob(patterns[i].c_str(),flags,NULL,&gbuf);
        flags = GLOB_APPEND;
      }

    for(size_t i = 0; i < gbuf.gl_pathc; ++i)
      strs.push_back(gbuf.gl_pathv[i]);

    globfree(&gbuf);
  }

  void
  erase_fnmatches(const vector<string> &patterns,
                  vector<string>       &strs)
  {
    vector<string>::iterator si;
    vector<string>::const_iterator pi;

    si = strs.begin();
    while(si != strs.end())
      {
        int match = FNM_NOMATCH;

        for(pi = patterns.begin();
            pi != patterns.end() && match != 0;
            ++pi)
          {
            match = fnmatch(pi->c_str(),si->c_str(),0);
          }

        if(match == 0)
          si = strs.erase(si);
        else
          ++si;
      }
  }

  namespace find
  {
    int
    invalid(const vector<string> &basepaths,
            const string          fusepath,
            PathVector           &paths)
    {
      return (errno = EINVAL,-1);
    }

    int
    ff(const vector<string> &basepaths,
       const string          fusepath,
       PathVector           &paths)
    {
      errno = ENOENT;
      for(vector<string>::const_iterator
            iter = basepaths.begin(), eiter = basepaths.end();
          iter != eiter;
          ++iter)
        {
          int         rv;
          string      path;
          struct stat st;

          path = fs::make_path(*iter,fusepath);
          rv = ::lstat(path.c_str(),&st);
          if(rv == 0)
            return (paths.push_back(Path(*iter,path)),0);
        }

      return -1;
    }

    int
    ffwp(const vector<string> &basepaths,
         const string          fusepath,
         PathVector           &paths)
    {
      Path fallback;

      errno = ENOENT;
      for(vector<string>::const_iterator
            iter = basepaths.begin(), eiter = basepaths.end();
          iter != eiter;
          ++iter)
        {
          int         rv;
          string      path;
          struct stat st;

          path = fs::make_path(*iter,fusepath);
          rv = ::lstat(path.c_str(),&st);
          if(rv == 0)
            {
              return (paths.push_back(Path(*iter,path)),0);
            }
          else if(errno == EACCES)
            {
              fallback.base = *iter;
              fallback.full = path;
            }
        }

      if(!fallback.base.empty())
        return (paths.push_back(fallback),0);

      return -1;
    }

    int
    newest(const vector<string> &basepaths,
           const string          fusepath,
           PathVector           &paths)
    {
      time_t newest;
      string npath;
      vector<string>::const_iterator niter;

      newest = 0;
      errno  = ENOENT;
      for(vector<string>::const_iterator
            iter = basepaths.begin(), eiter = basepaths.end();
          iter != eiter;
          ++iter)
        {
          int          rv;
          struct stat  st;
          const string path = fs::make_path(*iter,fusepath);

          rv  = ::lstat(path.c_str(),&st);
          if(rv == 0 && st.st_mtime > newest)
            {
              newest = st.st_mtime;
              niter  = iter;
              npath  = path;
            }
        }

      if(newest)
        return (paths.push_back(Path(*niter,npath)),0);

      return -1;
    }

    int
    all(const vector<string> &basepaths,
        const string          fusepath,
        PathVector           &paths)
    {
      errno = ENOENT;
      for(vector<string>::const_iterator
            iter = basepaths.begin(), eiter = basepaths.end();
          iter != eiter;
          ++iter)
        {
          int         rv;
          string      path;
          struct stat st;

          path = fs::make_path(*iter,fusepath);
          rv   = ::lstat(path.c_str(),&st);
          if(rv == 0)
            paths.push_back(Path(*iter,path));
        }

      return paths.empty() ? -1 : 0;
    }

    int
    mfs(const vector<string> &basepaths,
        const string          fusepath,
        PathVector           &paths)
    {
      fsblkcnt_t mfs;
      string mfspath;
      string fullmfspath;

      mfs   = 0;
      errno = ENOENT;
      for(vector<string>::const_iterator
            iter = basepaths.begin(), eiter = basepaths.end();
          iter != eiter;
          ++iter)
        {
          int rv;
          struct statvfs fsstats;
          const string   mountpoint = *iter;

          rv = ::statvfs(mountpoint.c_str(),&fsstats);
          if(rv == 0)
            {
              fsblkcnt_t  spaceavail;

              spaceavail = (fsstats.f_frsize * fsstats.f_bavail);
              if(spaceavail > mfs)
                {
                  mfs     = spaceavail;
                  mfspath = mountpoint;
                }
            }
        }

      if(mfs == 0)
        return -1;

      fullmfspath = fs::make_path(mfspath,fusepath);

      paths.push_back(Path(mfspath,fullmfspath));

      return 0;
    }

    int
    epmfs(const vector<string> &basepaths,
          const string          fusepath,
          PathVector           &paths)
    {
      fsblkcnt_t existingmfs = 0;
      fsblkcnt_t generalmfs  = 0;
      string     path;
      string     generalmfspath;
      string     existingmfspath;
      vector<string>::const_iterator iter  = basepaths.begin();
      vector<string>::const_iterator eiter = basepaths.end();

      if(iter == eiter)
        return (errno = ENOENT,-1);

      do
        {
          int rv;
          struct statvfs fsstats;
          const string   mountpoint = *iter;

          rv = ::statvfs(mountpoint.c_str(),&fsstats);
          if(rv == 0)
            {
              fsblkcnt_t  spaceavail;
              struct stat st;

              spaceavail = (fsstats.f_frsize * fsstats.f_bavail);
              if(spaceavail > generalmfs)
                {
                  generalmfs     = spaceavail;
                  generalmfspath = mountpoint;
                }

              path = fs::make_path(mountpoint,fusepath);
              rv   = ::lstat(path.c_str(),&st);
              if(rv == 0)
                {
                  if(spaceavail > existingmfs)
                    {
                      existingmfs     = spaceavail;
                      existingmfspath = mountpoint;
                    }
                }
            }

          ++iter;
        }
      while(iter != eiter);

      if(existingmfspath.empty())
        existingmfspath = generalmfspath;

      paths.push_back(Path(existingmfspath,path));

      return 0;
    }

    int
    rand(const vector<string> &basepaths,
         const string          fusepath,
         PathVector           &paths)
    {
      string randombasepath;
      string randomfullpath;

      randombasepath = *random_element(basepaths.begin(),
                                       basepaths.end());

      randomfullpath = fs::make_path(randombasepath,
                                     fusepath);

      paths.push_back(Path(randombasepath,randomfullpath));

      return 0;
    }
  }
};