#include "pchheader.hpp"
#include "hplog.hpp"
#include "util.hpp"

namespace util
{

    // rollover_hashset class methods

    rollover_hashset::rollover_hashset(const uint32_t maxsize)
    {
        this->maxsize = maxsize == 0 ? 1 : maxsize;
    }

    /**
 * Inserts the given hash to the list.
 * @return True on succesful insertion. False if hash already exists.
 */
    bool rollover_hashset::try_emplace(const std::string hash)
    {
        const auto itr = recent_hashes.find(hash);
        if (itr == recent_hashes.end()) // Not found
        {
            // Add the new message hash to the set.
            const auto [newitr, success] = recent_hashes.emplace(std::move(hash));

            // Insert a pointer to the stored hash value to the back of the ordered list of hashes.
            recent_hashes_list.push_back(&(*newitr));

            // Remove oldest hash if exceeding max size.
            if (recent_hashes_list.size() > maxsize)
            {
                const std::string &oldest_hash = *recent_hashes_list.front();
                recent_hashes.erase(oldest_hash);
                recent_hashes_list.pop_front();
            }

            return true; // Hash was inserted successfuly.
        }

        return false; // Hash already exists.
    }

    // ttl_set class methods.

    /**
 * If key does not exist, inserts it with the specified ttl. If key exists,
 * renews the expiration time to match the time-to-live from now onwards.
 * @param key Object to insert.
 * @param ttl Time to live in milliseonds.
 */
    void ttl_set::emplace(const std::string key, const uint64_t ttl_milli)
    {
        ttlmap[key] = util::get_epoch_milliseconds() + ttl_milli;
    }

    void ttl_set::erase(const std::string &key)
    {
        const auto itr = ttlmap.find(key);
        if (itr != ttlmap.end())
            ttlmap.erase(itr);
    }

    /**
 * Returns true of the key exists and not expired. Returns false if key does not exist
 * or has expired.
 */
    bool ttl_set::exists(const std::string &key)
    {
        const auto itr = ttlmap.find(key);
        if (itr == ttlmap.end()) // Not found
            return false;

        // Check whether we are passed the expiration time (itr->second is the expiration time)
        const bool expired = util::get_epoch_milliseconds() > itr->second;
        if (expired)
            ttlmap.erase(itr);

        return !expired;
    }

    /**
 * Encodes provided bytes to hex string.
 * 
 * @param encoded_string String reference to assign the hex encoded output.
 * @param bin Bytes to encode.
 * @param bin_len Bytes length.
 * @return Always returns 0.
 */
    int bin2hex(std::string &encoded_string, const unsigned char *bin, const size_t bin_len)
    {
        // Allocate the target string.
        encoded_string.resize(bin_len * 2);

        // Get encoded string.
        sodium_bin2hex(
            encoded_string.data(),
            encoded_string.length() + 1, // + 1 because sodium writes ending '\0' character as well.
            bin,
            bin_len);

        return 0;
    }

    /**
 * Decodes provided hex string into bytes.
 * 
 * @param decodedbuf Buffer to assign decoded bytes.
 * @param decodedbuf_len Decoded buffer size.
 * @param hex_str hex string to decode.
 */
    int hex2bin(unsigned char *decodedbuf, const size_t decodedbuf_len, std::string_view hex_str)
    {
        const char *hex_end;
        size_t bin_len;
        if (sodium_hex2bin(
                decodedbuf, decodedbuf_len,
                hex_str.data(),
                hex_str.length(),
                "", &bin_len, &hex_end))
        {
            return -1;
        }

        return 0;
    }

    std::string get_hex(std::string_view bin, const off_t skip, const size_t take)
    {
        std::string hex;
        const size_t len = (take ? take : (bin.size() - skip));
        bin2hex(hex, reinterpret_cast<unsigned char *>(const_cast<char *>(bin.data() + skip)), len);
        return hex;
    }

    /**
    * Returns current time in UNIX epoch milliseconds.
    */
    uint64_t get_epoch_milliseconds()
    {
        return std::chrono::duration_cast<std::chrono::duration<std::uint64_t, std::milli>>(
                   std::chrono::system_clock::now().time_since_epoch())
            .count();
    }

    /**
     * Sleeps the current thread for specified no. of milliseconds.
     */
    void sleep(const uint64_t milliseconds)
    {
        std::this_thread::sleep_for(std::chrono::milliseconds(milliseconds));
    }

    /**
 * Compare two version strings in the format of "1.12.3".
 * v1 <  v2  -> returns -1
 * v1 == v2  -> returns  0
 * v1 >  v2  -> returns +1
 * Error     -> returns -2
 * 
 * Remark on string_view: In other places of the code-base we utilize string_view
 * to pass immutable string references around. However in this function we keep the 'const string&'
 * syntax because istringstream doesn't support string_view. It's not worth optmising
 * this code as it's not being used in high-scale processing.
 */
    int version_compare(const std::string &x, const std::string &y)
    {
        std::istringstream ix(x), iy(y);
        while (ix.good() || iy.good())
        {
            int cx = 0, cy = 0;
            ix >> cx;
            iy >> cy;

            if ((!ix.eof() && !ix.good()) || (!iy.eof() && !iy.good()))
                return -2;

            if (cx > cy)
                return 1;
            if (cx < cy)
                return -1;

            ix.ignore();
            iy.ignore();
        }

        return 0;
    }

    // Provide a safe std::string overload for realpath
    std::string realpath(const std::string &path)
    {
        std::array<char, PATH_MAX> buffer;
        ::realpath(path.c_str(), buffer.data());
        buffer[PATH_MAX] = '\0';
        return buffer.data();
    }

    // Applies signal mask to the calling thread.
    void mask_signal()
    {
        sigset_t mask;
        sigemptyset(&mask);
        sigaddset(&mask, SIGINT);
        sigaddset(&mask, SIGPIPE);
        pthread_sigmask(SIG_BLOCK, &mask, NULL);
    }

    /**
     * Clears signal mask and signal handlers from the caller.
     * Called by other processes forked from hpcore threads so they get detatched from
     * the hpcore signal setup.
     */
    void fork_detach()
    {
        // Restore signal handlers to defaults.
        signal(SIGINT, SIG_DFL);
        signal(SIGSEGV, SIG_DFL);
        signal(SIGABRT, SIG_DFL);

        // Remove any signal masks applied by hpcore.
        sigset_t mask;
        sigemptyset(&mask);
        pthread_sigmask(SIG_SETMASK, &mask, NULL);

        // Set process group id (so the terminal doesn't send kill signals to forked children).
        setpgrp();
    }

    // Kill a process with a signal and if specified, wait until it stops running.
    int kill_process(const pid_t pid, const bool wait, const int signal)
    {
        if (kill(pid, signal) == -1)
        {
            LOG_ERROR << errno << ": Error issuing signal to pid " << pid;
            return -1;
        }

        const int wait_options = wait ? 0 : WNOHANG;
        if (waitpid(pid, NULL, wait_options) == -1)
        {
            LOG_ERROR << errno << ": waitpid after kill (pid:" << pid << ") failed.";
            return -1;
        }

        return 0;
    }

    /**
     * Check whether given directory exists. 
     * @param path Directory path.
     * @return Returns true if given directory exists otherwise false.
     */
    bool is_dir_exists(std::string_view path)
    {
        struct stat st;
        return (stat(path.data(), &st) == 0 && S_ISDIR(st.st_mode));
    }

    /**
     * Check whether given file exists. 
     * @param path File path.
     * @return Returns true if give file exists otherwise false.
     */
    bool is_file_exists(std::string_view path)
    {
        struct stat st;
        return (stat(path.data(), &st) == 0 && S_ISREG(st.st_mode));
    }

    /**
     * Recursively creates directories and sub-directories if not exist. 
     * @param path Directory path.
     * @return Returns 0 operations succeeded otherwise -1.
     */
    int create_dir_tree_recursive(std::string_view path)
    {
        if (strcmp(path.data(), "/") == 0) // No need of checking if we are at root.
            return 0;

        // Check whether this dir exists or not.
        struct stat st;
        if (stat(path.data(), &st) != 0 || !S_ISDIR(st.st_mode))
        {
            // Check and create parent dir tree first.
            char *path2 = strdup(path.data());
            char *parent_dir_path = dirname(path2);
            if (create_dir_tree_recursive(parent_dir_path) == -1)
                return -1;

            // Create this dir.
            if (mkdir(path.data(), S_IRWXU | S_IRWXG | S_IROTH) == -1)
                return -1;
        }

        return 0;
    }

    /**
     * Fetch all the files and directiries inside the given directory. 
     * @param path Directory path.
     * @return Returns the list of entries inside the directory.
     */
    std::list<std::string> fetch_dir_entries(std::string_view path)
    {
        std::list<std::string> entries;
        DIR *dr;

        // Open the directory stream.
        if (dr = opendir(path.data()))
        {
            // Take next directory entry from the directory stream.
            struct dirent *en;
            while (en = readdir(dr))
            {
                // Push into the entries list if reading directory entry is not current directory entry
                // or previous directory entry.
                if (std::strcmp(en->d_name, ".") != 0 && std::strcmp(en->d_name, "..") != 0)
                {
                    entries.push_back(en->d_name);
                }
            }
            // Close directory stream.
            closedir(dr);
        }

        return entries;
    }

    /**
     * Fetch file extension from the file path. 
     * @param path File path.
     * @return Returns the file extension as a string_view.
     */
    std::string_view fetch_file_extension(std::string_view path)
    {
        // Get the position of right most "." in the file path.
        const std::size_t pos = path.rfind('.');

        if (pos != std::string::npos)
        {
            // Take the sub string after the ".".
            return path.substr(pos);
        }

        return "";
    }

    /**
     * Remove file extension from file name. 
     * @param file_name File name.
     * @return Returns the file name without extension.
     */
    std::string_view remove_file_extension(std::string_view file_name)
    {
        // Get the position of right most "." in the file name.
        const std::size_t pos = file_name.rfind('.');

        if (pos != std::string::npos)
        {
            // Take the sub string till the "." from the beginning.
            return file_name.substr(0, pos);
        }

        return file_name;
    }

    /**
     * Deletes a file. 
     * @param path File path.
     * @return Returs 0 if succeed else -1.
     */
    int remove_file(std::string_view path)
    {
        return remove(path.data());
    }

    /**
     * Clears all files from a directory (not recursive).
     */
    int clear_directory(std::string_view dir_path)
    {
        return nftw(
            dir_path.data(), [](const char *fpath, const struct stat *sb, int typeflag, struct FTW *ftwbuf) {
                if (typeflag == FTW_F) // Is file.
                    return remove(fpath);
                return 0;
            },
            1, FTW_PHYS);
    }

    void split_string(std::vector<std::string> &collection, std::string_view str, std::string_view delimeter)
    {
        if (str.empty())
            return;

        size_t start = 0;
        size_t end = str.find(delimeter);

        while (end != std::string::npos)
        {
            // Do not add empty strings.
            if (start != end)
                collection.push_back(std::string(str.substr(start, end - start)));
            start = end + delimeter.length();
            end = str.find(delimeter, start);
        }

        // If there are any leftover from the source string add the remaining.
        if (start < str.size())
            collection.push_back(std::string(str.substr(start)));
    }

    /**
     * Converts given string to a uint_64. A wrapper function for std::stoull. 
     * @param str String variable.
     * @param result Variable to store the answer from the conversion.
     * @return Returns 0 in a successful conversion and -1 on error.
    */
    int stoull(const std::string &str, uint64_t &result)
    {
        try
        {
            result = std::stoull(str);
        }
        catch (const std::exception &e)
        {
            // Return -1 if any exceptions are captured.
            return -1;
        }
        return 0;
    }

} // namespace util