/*
 * Copyright (c)2013-2020 ZeroTier, Inc.
 *
 * Use of this software is governed by the Business Source License included
 * in the LICENSE.TXT file in the project's root directory.
 *
 * Change Date: 2026-01-01
 *
 * On the date above, in accordance with the Business Source License, use
 * of this software will be governed by version 2.0 of the Apache License.
 */
/****/

#ifndef ZT_OSUTILS_HPP
#define ZT_OSUTILS_HPP

#include "../node/Constants.hpp"
#include "../node/InetAddress.hpp"

#include <map>
#include <stdexcept>
#include <stdint.h>
#include <stdio.h>
#include <stdlib.h>
#include <string.h>
#include <time.h>
#include <vector>

#ifdef __WINDOWS__
#include <shlwapi.h>
#include <windows.h>
#include <winsock2.h>
#else
#include <arpa/inet.h>
#include <errno.h>
#include <sys/stat.h>
#include <sys/time.h>
#include <unistd.h>
#ifdef __LINUX__
#include <sys/syscall.h>
#endif
#endif

#ifndef OMIT_JSON_SUPPORT
#include <nlohmann/json.hpp>
#endif

namespace ZeroTier {

/**
 * Miscellaneous utility functions and global constants
 */
class OSUtils {
  public:
    /**
     * Variant of snprintf that is portable and throws an exception
     *
     * This just wraps the local implementation whatever it's called, while
     * performing a few other checks and adding exceptions for overflow.
     *
     * @param buf Buffer to write to
     * @param len Length of buffer in bytes
     * @param fmt Format string
     * @param ... Format arguments
     * @throws std::length_error buf[] too short (buf[] will still be left null-terminated)
     */
    static unsigned int ztsnprintf(char* buf, unsigned int len, const char* fmt, ...);

    /**
     * Converts a uint64_t network ID into a string
     *
     * @param nwid network ID
     * @throws std::length_error buf[] too short (buf[] will still be left null-terminated)
     */
    static std::string networkIDStr(const uint64_t nwid);

    /**
     * Converts a uint64_t node ID into a string
     *
     * @param nid node ID
     * @throws std::length_error buf[] too short (buf[] will still be left null-terminated)
     */
    static std::string nodeIDStr(const uint64_t nid);

#ifdef __UNIX_LIKE__
    /**
     * Close STDOUT_FILENO and STDERR_FILENO and replace them with output to given path
     *
     * This can be called after fork() and prior to exec() to suppress output
     * from a subprocess, such as auto-update.
     *
     * @param stdoutPath Path to file to use for stdout
     * @param stderrPath Path to file to use for stderr, or NULL for same as stdout (default)
     * @return True on success
     */
    static bool redirectUnixOutputs(const char* stdoutPath, const char* stderrPath = (const char*)0) throw();
#endif   // __UNIX_LIKE__

    /**
     * Delete a file
     *
     * @param path Path to delete
     * @return True if delete was successful
     */
    static inline bool rm(const char* path)
    {
#ifdef __WINDOWS__
        return (DeleteFileA(path) != FALSE);
#else
        return (unlink(path) == 0);
#endif
    }
    static inline bool rm(const std::string& path)
    {
        return rm(path.c_str());
    }

    static inline bool mkdir(const char* path)
    {
#ifdef __WINDOWS__
        if (::PathIsDirectoryA(path))
            return true;
        return (::CreateDirectoryA(path, NULL) == TRUE);
#else
        if (::mkdir(path, 0755) != 0)
            return (errno == EEXIST);
        return true;
#endif
    }
    static inline bool mkdir(const std::string& path)
    {
        return OSUtils::mkdir(path.c_str());
    }

    static inline bool rename(const char* o, const char* n)
    {
#ifdef __WINDOWS__
        DeleteFileA(n);
        return (::rename(o, n) == 0);
#else
        return (::rename(o, n) == 0);
#endif
    }

    /**
     * List a directory's contents
     *
     * @param path Path to list
     * @param includeDirectories If true, include directories as well as files
     * @return Names of files in directory (without path prepended)
     */
    static std::vector<std::string> listDirectory(const char* path, bool includeDirectories = false);

    /**
     * Clean a directory of files whose last modified time is older than this
     *
     * This ignores directories, symbolic links, and other special files.
     *
     * @param olderThan Last modified older than timestamp (ms since epoch)
     * @return Number of cleaned files or negative on fatal error
     */
    static long cleanDirectory(const char* path, const int64_t olderThan);

    /**
     * Delete a directory and all its files and subdirectories recursively
     *
     * @param path Path to delete
     * @return True on success
     */
    static bool rmDashRf(const char* path);

    /**
     * Set modes on a file to something secure
     *
     * This locks a file so that only the owner can access it. What it actually
     * does varies by platform.
     *
     * @param path Path to lock
     * @param isDir True if this is a directory
     */
    static void lockDownFile(const char* path, bool isDir);

    /**
     * Get file last modification time
     *
     * Resolution is often only second, not millisecond, but the return is
     * always in ms for comparison against now().
     *
     * @param path Path to file to get time
     * @return Last modification time in ms since epoch or 0 if not found
     */
    static uint64_t getLastModified(const char* path);

    /**
     * @param path Path to check
     * @param followLinks Follow links (on platforms with that concept)
     * @return True if file or directory exists at path location
     */
    static bool fileExists(const char* path, bool followLinks = true);

    /**
     * @param path Path to file
     * @return File size or -1 if nonexistent or other failure
     */
    static int64_t getFileSize(const char* path);

    /**
     * Get IP (v4 and/or v6) addresses for a given host
     *
     * This is a blocking resolver.
     *
     * @param name Host name
     * @return IP addresses in InetAddress sort order or empty vector if not found
     */
    static std::vector<InetAddress> resolve(const char* name);

    /**
     * @return Current time in milliseconds since epoch
     */
    static inline int64_t now()
    {
#ifdef __WINDOWS__
        FILETIME ft;
        SYSTEMTIME st;
        ULARGE_INTEGER tmp;
        GetSystemTime(&st);
        SystemTimeToFileTime(&st, &ft);
        tmp.LowPart = ft.dwLowDateTime;
        tmp.HighPart = ft.dwHighDateTime;
        return (int64_t)(((tmp.QuadPart - 116444736000000000LL) / 10000L) + st.wMilliseconds);
#else
        struct timeval tv;
        gettimeofday(&tv, (struct timezone*)0);
        return ((1000LL * (int64_t)tv.tv_sec) + (int64_t)(tv.tv_usec / 1000));
#endif
    };

    /**
     * Read the full contents of a file into a string buffer
     *
     * The buffer isn't cleared, so if it already contains data the file's data will
     * be appended.
     *
     * @param path Path of file to read
     * @param buf Buffer to fill
     * @return True if open and read successful
     */
    static bool readFile(const char* path, std::string& buf);

    /**
     * Write a block of data to disk, replacing any current file contents
     *
     * @param path Path to write
     * @param buf Buffer containing data
     * @param len Length of buffer
     * @return True if entire file was successfully written
     */
    static bool writeFile(const char* path, const void* buf, unsigned int len);

    /**
     * Split a string by delimiter, with optional escape and quote characters
     *
     * @param s String to split
     * @param sep One or more separators
     * @param esc Zero or more escape characters
     * @param quot Zero or more quote characters
     * @return Vector of tokens
     */
    static std::vector<std::string> split(const char* s, const char* const sep, const char* esc, const char* quot);

    /**
     * Write a block of data to disk, replacing any current file contents
     *
     * @param path Path to write
     * @param s Data to write
     * @return True if entire file was successfully written
     */
    static inline bool writeFile(const char* path, const std::string& s)
    {
        return writeFile(path, s.data(), (unsigned int)s.length());
    }

    /**
     * @param c ASCII character to convert
     * @return Lower case ASCII character or unchanged if not a letter
     */
    static inline char toLower(char c) throw()
    {
        return (char)OSUtils::TOLOWER_TABLE[(unsigned long)c];
    }

    /**
     * @return Platform default ZeroTier One home path
     */
    static std::string platformDefaultHomePath();

#ifndef OMIT_JSON_SUPPORT
    static nlohmann::json jsonParse(const std::string& buf);
    static std::string jsonDump(const nlohmann::json& j, int indentation = 1);
    static uint64_t jsonInt(const nlohmann::json& jv, const uint64_t dfl);
    static double jsonDouble(const nlohmann::json& jv, const double dfl);
    static uint64_t jsonIntHex(const nlohmann::json& jv, const uint64_t dfl);
    static bool jsonBool(const nlohmann::json& jv, const bool dfl);
    static std::string jsonString(const nlohmann::json& jv, const char* dfl);
    static std::string jsonBinFromHex(const nlohmann::json& jv);
#endif   // OMIT_JSON_SUPPORT

  private:
    static const unsigned char TOLOWER_TABLE[256];
};

}   // namespace ZeroTier

#endif