module ecs.std;

import core.stdc.stdlib : malloc, free, realloc;
import core.stdc.string : memcpy;
import std.traits;
import core.time;

version (Windows)
{
    import core.sys.windows.windows;
    extern(Windows) void* _aligned_malloc(size_t size,size_t alignment) @nogc nothrow @system;
    extern(Windows) void _aligned_free(void* ptr) @nogc nothrow @system;
    
    version(LDC)
    {
        /*extern(Windows) void* __alloca(size_t size) @nogc nothrow @system;
        alias alloca = __alloca;*/

        private const uint max_alloca = 10000; 
        private char[max_alloca] alloca_array;
        private uint alloca_pos = 0;
        void* alloca(size_t length) @nogc nothrow  
        {
            if(alloca_pos + length > max_alloca)alloca_pos = 0;
            void* ret = &alloca_array[alloca_pos];
            alloca_pos += length;
            return ret;
        }

        extern(Windows) void ___chkstk_ms() @nogc nothrow @system;
    
        extern(Windows) void __chkstk()
        {
            ___chkstk_ms();
        }
    }
    else
    {
        private const uint max_alloca = 10000; 
        private char[max_alloca] alloca_array;
        private uint alloca_pos = 0;
        void* alloca(size_t length) @nogc nothrow  
        {
            if(alloca_pos + length > max_alloca)alloca_pos = 0;
            void* ret = &alloca_array[alloca_pos];
            alloca_pos += length;
            return ret;
        }
    }
}
else version (Posix)
{
    import core.sys.posix.pthread;
    import core.sys.posix.stdlib;
    public import core.stdc.stdlib : alloca;
}

static struct Mallocator
{
    static T[] makeArray(T)(size_t length) nothrow @nogc
    {
        T[] ret = (cast(T*)malloc(T.sizeof * length))[0 .. length];

        /*static if(__traits(isPOD, T))
        {
            static immutable T init = T.init;
            
            foreach(i;0..ret.length)
            {
                memcpy(&ret[i], &init, T.sizeof);
            }
        }
        else
        {*/
            static import std.conv;
            foreach(i;0..ret.length)
            {
                std.conv.emplace(&ret[i]);
            }
       // }
       
        //static if(is(T == struct))std.conv.emplace(ret);
        //static import std.conv;
        //emplace
        /*foreach(i;0..ret.length)
        {
            memcpy(ret);
        }*/
        return ret;
    }

    static T[] makeArray(T)(size_t length, T initializer) nothrow @nogc
    {
        T[] ret = (cast(T*)malloc(T.sizeof * length))[0 .. length];
        foreach(ref v; ret)v = initializer;
        return ret;
        //return (cast(T*)ret)[0 .. length];
    }

    static T[] expandArray(T)(T[] array, size_t length) nothrow @nogc
    {
        size_t new_length = array.length + length;
        return (cast(T*)realloc(array.ptr, T.sizeof * new_length))[0 .. new_length];
    }

    static T[] makeArray(T)(T[] array) nothrow @nogc
    {
        T[] ret = (cast(T*)malloc(T.sizeof * array.length))[0 .. array.length];//Mallocator.makeArray!(T)(array.length);
        foreach(i, ref v;ret)v = array[i];
        //ret[0 .. $] = array;
        return ret;
    }

    static T* make(T, Args...)(Args args) 
    {
        T* ret = cast(T*)malloc(T.sizeof);
        //*ret = T.init;
        //static immutable T init = T();
        //memcpy(ret, &init, T.sizeof);
        //static if(__traits(hasMember, T, "__ctor"))ret.__ctor(args);
        static import std.conv;
        static if(__traits(isPOD, T))
        {
            static immutable T init = T.init;
            memcpy(ret, &init, T.sizeof);
        }
        else static if(is(T == struct))std.conv.emplace(ret, args);
        //else std.conv.emplace(ret, args);
        return ret;
    }

    static void* alignAlloc(size_t length, size_t alignment) nothrow @nogc
    {

        void* ret;
        version(Posix)ret = aligned_alloc(alignment, length);
        else version(Windows)ret = _aligned_malloc(length, alignment);
        else static assert(0, "Unimplemented platform!");
        //posix_memalign(&ret, alignment, length);
        return ret;
    }

    static void dispose(T)(T object) nothrow @nogc
    {
        static if(__traits(hasMember, T, "__dtor"))object.__dtor();
        free(cast(void*)object);
    }

    static void alignDispose(T)(T object)
    {
        static if(__traits(hasMember, T, "__dtor"))object.__dtor();
        version(Posix)aligned_free(cast(void*)object);
        else version(Windows)_aligned_free(cast(void*)object);
        else static assert(0, "Unimplemented platform!");
        
    }
}

struct Mutex
{

    version (Windows)
    {
        void initialize() nothrow @nogc
        {
            InitializeCriticalSection(cast(CRITICAL_SECTION*) &m_handle);
        }

        void destroy() nothrow @nogc
        {
            DeleteCriticalSection(&m_handle);
        }

        void lock() nothrow @nogc
        {
            EnterCriticalSection(&m_handle);
        }

        void unlock() nothrow @nogc
        {
            LeaveCriticalSection(&m_handle);
        }

        int tryLock() nothrow @nogc
        {
            return TryEnterCriticalSection(&m_handle) != 0;
        }

        CRITICAL_SECTION    m_handle;
    }
    else version (Posix)
    {
        void initialize() nothrow @nogc
        {
            pthread_mutexattr_t attr = void;

            pthread_mutexattr_init(&attr);
            
            pthread_mutexattr_settype(&attr, PTHREAD_MUTEX_RECURSIVE);
            pthread_mutex_init(cast(pthread_mutex_t*) &m_handle, &attr);

            pthread_mutexattr_destroy(&attr);
        }

        void destroy() nothrow @nogc
        {
            pthread_mutex_destroy(&m_handle);
        }

        void lock() nothrow @nogc
        {
            pthread_mutex_lock(&m_handle);
        }

        void unlock() nothrow @nogc
        {
            pthread_mutex_unlock(&m_handle);
        }

        int tryLock() nothrow @nogc
        {
            return pthread_mutex_trylock(&m_handle) == 0;
        }

        private pthread_mutex_t m_handle;
    }
}