// Copyright 2014 The Bazel Authors. All rights reserved.
//
// Licensed under the Apache License, Version 2.0 (the "License");
// you may not use this file except in compliance with the License.
// You may obtain a copy of the License at
//
//    http://www.apache.org/licenses/LICENSE-2.0
//
// Unless required by applicable law or agreed to in writing, software
// distributed under the License is distributed on an "AS IS" BASIS,
// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
// See the License for the specific language governing permissions and
// limitations under the License.

#include "src/main/cpp/blaze_util.h"

#include <errno.h>
#include <fcntl.h>
#include <limits.h>
#include <pwd.h>
#include <stdarg.h>
#include <stdio.h>
#include <stdlib.h>
#include <string.h>
#include <sys/file.h>
#include <sys/ioctl.h>
#include <sys/socket.h>
#include <sys/stat.h>
#include <sys/types.h>
#include <unistd.h>

#include <sstream>

#include "src/main/cpp/blaze_util_platform.h"
#include "src/main/cpp/util/errors.h"
#include "src/main/cpp/util/exit_code.h"
#include "src/main/cpp/util/file.h"
#include "src/main/cpp/util/numbers.h"
#include "src/main/cpp/util/strings.h"
#include "src/main/cpp/util/port.h"

using blaze_util::die;
using blaze_util::pdie;
using std::vector;

namespace blaze {

string GetUserName() {
  const char *user = getenv("USER");
  if (user && user[0] != '\0') return user;
  errno = 0;
  passwd *pwent = getpwuid(getuid());  // NOLINT (single-threaded)
  if (pwent == NULL || pwent->pw_name == NULL) {
    pdie(blaze_exit_code::LOCAL_ENVIRONMENTAL_ERROR,
         "$USER is not set, and unable to look up name of current user");
  }
  return pwent->pw_name;
}

// Returns the given path in absolute form.  Does not change paths that are
// already absolute.
//
// If called from working directory "/bar":
//   MakeAbsolute("foo") --> "/bar/foo"
//   MakeAbsolute("/foo") ---> "/foo"
//   MakeAbsolute("C:/foo") ---> "C:/foo"
string MakeAbsolute(const string &path) {
  // Check if path is already absolute.
  if (path.empty() || path[0] == '/' || (isalpha(path[0]) && path[1] == ':')) {
    return path;
  }

  char cwdbuf[PATH_MAX];
  if (getcwd(cwdbuf, sizeof cwdbuf) == NULL) {
    pdie(blaze_exit_code::LOCAL_ENVIRONMENTAL_ERROR, "getcwd() failed");
  }

  // Determine whether the cwd ends with "/" or not.
  string separator = (cwdbuf[strlen(cwdbuf) - 1] == '/') ? "" : "/";
  return cwdbuf + separator + path;
}

// Runs "stat" on `path`. Returns -1 and sets errno if stat fails or
// `path` isn't a directory. If check_perms is true, this will also
// make sure that `path` is owned by the current user and has `mode`
// permissions (observing the umask). It attempts to run chmod to
// correct the mode if necessary. If `path` is a symlink, this will
// check ownership of the link, not the underlying directory.
static int GetDirectoryStat(const string& path, mode_t mode, bool check_perms) {
  struct stat filestat = {};
  if (stat(path.c_str(), &filestat) == -1) {
    return -1;
  }

  if (!S_ISDIR(filestat.st_mode)) {
    errno = ENOTDIR;
    return -1;
  }

  if (check_perms) {
    // If this is a symlink, run checks on the link. (If we did lstat above
    // then it would return false for ISDIR).
    struct stat linkstat = {};
    if (lstat(path.c_str(), &linkstat) != 0) {
      return -1;
    }
    if (linkstat.st_uid != geteuid()) {
      // The directory isn't owned by me.
      errno = EACCES;
      return -1;
    }

    mode_t mask = umask(022);
    umask(mask);
    mode = (mode & ~mask);
    if ((filestat.st_mode & 0777) != mode
        && chmod(path.c_str(), mode) == -1) {
      // errno set by chmod.
      return -1;
    }
  }
  return 0;
}

static int MakeDirectories(const string& path, mode_t mode, bool childmost) {
  if (path.empty() || path == "/") {
    errno = EACCES;
    return -1;
  }

  int retval = GetDirectoryStat(path, mode, childmost);
  if (retval == 0) {
    return 0;
  }

  if (errno == ENOENT) {
    // Path does not exist, attempt to create its parents, then it.
    string parent = blaze_util::Dirname(path);
    if (MakeDirectories(parent, mode, false) == -1) {
      // errno set by stat.
      return -1;
    }

    if (mkdir(path.c_str(), mode) == -1) {
      if (errno == EEXIST) {
        if (childmost) {
          // If there are multiple bazel calls at the same time then the
          // directory could be created between the MakeDirectories and mkdir
          // calls. This is okay, but we still have to check the permissions.
          return GetDirectoryStat(path, mode, childmost);
        } else {
          // If this isn't the childmost directory, we don't care what the
          // permissions were. If it's not even a directory then that error will
          // get caught when we attempt to create the next directory down the
          // chain.
          return 0;
        }
      }
      // errno set by mkdir.
      return -1;
    }
    return 0;
  }

  return retval;
}

// mkdir -p path. Returns 0 if the path was created or already exists and could
// be chmod-ed to exactly the given permissions. If final part of the path is a
// symlink, this ensures that the destination of the symlink has the desired
// permissions. It also checks that the directory or symlink is owned by us.
// On failure, this returns -1 and sets errno.
int MakeDirectories(const string& path, mode_t mode) {
  return MakeDirectories(path, mode, true);
}

// Replaces 'contents' with contents of 'fd' file descriptor.
// Returns false on error.
bool ReadFileDescriptor(int fd, string *content) {
  content->clear();
  char buf[4096];
  // OPT:  This loop generates one spurious read on regular files.
  while (int r = read(fd, buf, sizeof buf)) {
    if (r == -1) {
      if (errno == EINTR || errno == EAGAIN) continue;
      return false;
    }
    content->append(buf, r);
  }
  close(fd);
  return true;
}

// Replaces 'content' with contents of file 'filename'.
// Returns false on error.
bool ReadFile(const string &filename, string *content) {
  int fd = open(filename.c_str(), O_RDONLY);
  if (fd == -1) return false;
  return ReadFileDescriptor(fd, content);
}

// Writes 'content' into file 'filename', and makes it executable.
// Returns false on failure, sets errno.
bool WriteFile(const string &content, const string &filename) {
  UnlinkPath(filename);  // We don't care about the success of this.
  int fd = open(filename.c_str(), O_CREAT|O_WRONLY|O_TRUNC, 0755);  // chmod +x
  if (fd == -1) {
    return false;
  }
  int r = write(fd, content.data(), content.size());
  if (r == -1) {
    return false;
  }
  int saved_errno = errno;
  if (close(fd)) {
    return false;  // Can fail on NFS.
  }
  errno = saved_errno;  // Caller should see errno from write().
  return static_cast<uint>(r) == content.size();
}

bool UnlinkPath(const string &file_path) {
  return unlink(file_path.c_str()) == 0;
}

// Returns true iff both stdout and stderr are connected to a
// terminal, and it can support color and cursor movement
// (this is computed heuristically based on the values of
// environment variables).
bool IsStandardTerminal() {
  string term = getenv("TERM") == nullptr ? "" : getenv("TERM");
  string emacs = getenv("EMACS") == nullptr ? "" : getenv("EMACS");
  if (term == "" || term == "dumb" || term == "emacs" || term == "xterm-mono" ||
      term == "symbolics" || term == "9term" || emacs == "t") {
    return false;
  }
  return isatty(STDOUT_FILENO) && isatty(STDERR_FILENO);
}

// Returns the number of columns of the terminal to which stdout is
// connected, or $COLUMNS (default 80) if there is no such terminal.
int GetTerminalColumns() {
  struct winsize ws;
  if (ioctl(STDOUT_FILENO, TIOCGWINSZ, &ws) != -1) {
    return ws.ws_col;
  }
  const char* columns_env = getenv("COLUMNS");
  if (columns_env != NULL && columns_env[0] != '\0') {
    char* endptr;
    int columns = blaze_util::strto32(columns_env, &endptr, 10);
    if (*endptr == '\0') {  // $COLUMNS is a valid number
      return columns;
    }
  }
  return 80;  // default if not a terminal.
}

const char* GetUnaryOption(const char *arg,
                           const char *next_arg,
                           const char *key) {
  const char *value = blaze_util::var_strprefix(arg, key);
  if (value == NULL) {
    return NULL;
  } else if (value[0] == '=') {
    return value + 1;
  } else if (value[0]) {
    return NULL;  // trailing garbage in key name
  }

  return next_arg;
}

bool GetNullaryOption(const char *arg, const char *key) {
  const char *value = blaze_util::var_strprefix(arg, key);
  if (value == NULL) {
    return false;
  } else if (value[0] == '=') {
    die(blaze_exit_code::BAD_ARGV,
        "In argument '%s': option '%s' does not take a value.", arg, key);
  } else if (value[0]) {
    return false;  // trailing garbage in key name
  }

  return true;
}

bool VerboseLogging() {
  return getenv("VERBOSE_BLAZE_CLIENT") != NULL;
}

// Read the Jvm version from a file descriptor. The read fd
// should contains a similar output as the java -version output.
string ReadJvmVersion(int fd) {
  string version_string;
  if (ReadFileDescriptor(fd, &version_string)) {
    // try to look out for 'version "'
    static const string version_pattern = "version \"";
    size_t found = version_string.find(version_pattern);
    if (found != string::npos) {
      found += version_pattern.size();
      // If we found "version \"", process until next '"'
      size_t end = version_string.find("\"", found);
      if (end == string::npos) {  // consider end of string as a '"'
        end = version_string.size();
      }
      return version_string.substr(found, end - found);
    }
  }
  return "";
}

string GetJvmVersion(const string &java_exe) {
  vector<string> args;
  args.push_back("java");
  args.push_back("-version");

  int fds[2];
  if (pipe(fds)) {
    pdie(blaze_exit_code::INTERNAL_ERROR, "pipe creation failed");
  }

  int child = fork();
  if (child == -1) {
    pdie(blaze_exit_code::INTERNAL_ERROR, "fork() failed");
  } else if (child > 0) {  // we're the parent
    close(fds[1]);         // parent keeps only the reading side
    return ReadJvmVersion(fds[0]);
  } else {
    close(fds[0]);  // child keeps only the writing side
    // Redirect output to the writing side of the dup.
    dup2(fds[1], STDOUT_FILENO);
    dup2(fds[1], STDERR_FILENO);
    // Execute java -version
    ExecuteProgram(java_exe, args);
    pdie(blaze_exit_code::INTERNAL_ERROR, "Failed to run java -version");
  }
  // The if never falls through here.
  return NULL;
}

bool CheckJavaVersionIsAtLeast(const string &jvm_version,
                               const string &version_spec) {
  vector<string> jvm_version_vect = blaze_util::Split(jvm_version, '.');
  int jvm_version_size = static_cast<int>(jvm_version_vect.size());
  vector<string> version_spec_vect = blaze_util::Split(version_spec, '.');
  int version_spec_size = static_cast<int>(version_spec_vect.size());
  int i;
  for (i = 0; i < jvm_version_size && i < version_spec_size; i++) {
    int jvm = blaze_util::strto32(jvm_version_vect[i].c_str(), NULL, 10);
    int spec = blaze_util::strto32(version_spec_vect[i].c_str(), NULL, 10);
    if (jvm > spec) {
      return true;
    } else if (jvm < spec) {
      return false;
    }
  }
  if (i < version_spec_size) {
    for (; i < version_spec_size; i++) {
      if (version_spec_vect[i] != "0") {
        return false;
      }
    }
  }
  return true;
}

}  // namespace blaze