#pragma once

#include <cstdint>
#include <cstdio>

#ifdef _WIN32
#include <Windows.h>
#else
#include <sys/mman.h>
#include <unistd.h>
#endif

struct DataMap {
    void* data = nullptr;
    size_t size = 0;

#ifdef _WIN32
    HANDLE map_handle = nullptr;
#endif

    bool map_from_reader(void* reader_data, size_t reader_size) {
        size = reader_size;
        if (size == 0) return true;
#ifdef _WIN32
        HANDLE file_handle = reader_data;
        map_handle = CreateFileMappingA(file_handle, nullptr, PAGE_READONLY, 0, 0, nullptr);
        if (!map_handle) return false;
        data = MapViewOfFile(map_handle, FILE_MAP_READ, 0, 0, 0);
        if (!data) {
            CloseHandle(map_handle);
            map_handle = nullptr;
            return false;
        }
        return true;
#else
        int fd = fileno((FILE*)reader_data);
        if (fd < 0) return false;
        data = mmap(nullptr, size, PROT_READ | PROT_WRITE, MAP_PRIVATE, fd, 0);
        if (data == MAP_FAILED) {
            data = nullptr;
            return false;
        }
        return true;
#endif
    }

    void close() {
        if (data) {
#ifdef _WIN32
            UnmapViewOfFile(data);
#else
            munmap(data, size);
#endif
            data = nullptr;
        }
#ifdef _WIN32
        if (map_handle) { CloseHandle(map_handle); map_handle = nullptr; }
#endif
        size = 0;
    }

    ~DataMap() { close(); }
};

inline void delete_map(void* ptr, size_t length, void* deleter_data) {
    DataMap* dm = static_cast<DataMap*>(deleter_data);
    if (dm) dm->close();
    delete dm;
}