//
// Copyright(c) 2015 Gabi Melman.
// Distributed under the MIT License (http://opensource.org/licenses/MIT)
//

#pragma once

// Helper class for file sink
// When failing to open a file, retry several times(5) with small delay between the tries(10 ms)
// Can be set to auto flush on every line
// Throw spdlog_ex exception on errors

#include <string>
#include <thread>
#include <chrono>
#include "os.h"
#include "log_msg.h"

namespace spdlog {
namespace details {

class file_helper {
public:
    const int open_tries = 5;
    const int open_interval = 10;

    explicit file_helper(bool force_flush) : _fd(nullptr), _force_flush(force_flush) {}

    file_helper(const file_helper&) = delete;
    file_helper& operator=(const file_helper&) = delete;

    ~file_helper() { close(); }

    void
    open(const std::string& fname, bool truncate = false) {
        close();
        const char* mode = truncate ? "wb" : "ab";
        _filename = fname;
        for (int tries = 0; tries < open_tries; ++tries) {
            if (!os::fopen_s(&_fd, fname, mode)) return;

            std::this_thread::sleep_for(std::chrono::milliseconds(open_interval));
        }

        throw spdlog_ex("Failed opening file " + fname + " for writing");
    }

    void
    reopen(bool truncate) {
        if (_filename.empty()) throw spdlog_ex("Failed re opening file - was not opened before");
        open(_filename, truncate);
    }

    void
    flush() {
        std::fflush(_fd);
    }

    void
    close() {
        if (_fd) {
            std::fclose(_fd);
            _fd = nullptr;
        }
    }

    void
    write_string(const std::string& msg) {
        if (std::fwrite(msg.c_str(), 1, msg.size(), _fd) != msg.size())
            throw spdlog_ex("Failed writing to file " + _filename);

        if (_force_flush) std::fflush(_fd);
    }

    void
    write(const log_msg& msg) {
        size_t msg_size = msg.formatted.size();
        auto data = msg.formatted.data();
        if (std::fwrite(data, 1, msg_size, _fd) != msg_size)
            throw spdlog_ex("Failed writing to file " + _filename);

        if (_force_flush) std::fflush(_fd);
    }

    long
    size() {
        if (!_fd) throw spdlog_ex("Cannot use size() on closed file " + _filename);

        auto pos = ftell(_fd);
        if (fseek(_fd, 0, SEEK_END) != 0) throw spdlog_ex("fseek failed on file " + _filename);

        auto file_size = ftell(_fd);

        if (fseek(_fd, pos, SEEK_SET) != 0) throw spdlog_ex("fseek failed on file " + _filename);

        if (file_size == -1) throw spdlog_ex("ftell failed on file " + _filename);

        return file_size;
    }

    const std::string&
    filename() const {
        return _filename;
    }

    static bool
    file_exists(const std::string& name) {
        return os::file_exists(name);
    }

private:
    FILE* _fd;
    std::string _filename;
    bool _force_flush;
};
}
}
