using System;
using System.Runtime.InteropServices;

namespace Misaki.HighPerformance.Image.Runtime;

internal static unsafe class CRuntime
{
    private static readonly string s_numbers = "0123456789";

    public static void* malloc(ulong size)
    {
        return malloc((long)size);
    }

    public static void* malloc(long size)
    {
        var ptr = NativeMemory.Alloc((nuint)size);

        MemoryStats.Allocated();

        return ptr;
    }

    public static void free(void* ptr)
    {
        if (ptr == null)
        {
            return;
        }

        NativeMemory.Free(ptr);
        MemoryStats.Freed();
    }

    public static void memcpy(void* a, void* b, long size)
    {
        NativeMemory.Copy(b, a, (nuint)size);
    }

    public static void memcpy(void* a, void* b, ulong size)
    {
        memcpy(a, b, (long)size);
    }

    public static void memmove(void* a, void* b, long size)
    {
        void* temp = null;

        try
        {
            temp = malloc(size);
            memcpy(temp, b, size);
            memcpy(a, temp, size);
        }

        finally
        {
            if (temp != null)
            {
                free(temp);
            }
        }
    }

    public static int memcmp(void* a, void* b, long size)
    {
        var result = 0;
        var ap = (byte*)a;
        var bp = (byte*)b;
        for (long i = 0; i < size; ++i)
        {
            if (*ap != *bp)
            {
                result += 1;
            }

            ap++;
            bp++;
        }

        return result;
    }

    public static void memset(void* ptr, int value, long size)
    {
        var bptr = (byte*)ptr;
        var bval = (byte)value;
        for (long i = 0; i < size; ++i)
        {
            *bptr++ = bval;
        }
    }

    public static void memset(void* ptr, int value, ulong size)
    {
        memset(ptr, value, (long)size);
    }

    public static uint _lrotl(uint x, int y)
    {
        return (x << y) | (x >> (32 - y));
    }

    public static void* realloc(void* ptr, long newSize)
    {
        if (ptr == null)
        {
            return malloc(newSize);
        }

        var result = NativeMemory.Realloc(ptr, (nuint)newSize);

        return result;
    }

    public static void* realloc(void* a, ulong newSize)
    {
        return realloc(a, (long)newSize);
    }

    public static int abs(int v)
    {
        return Math.Abs(v);
    }

    public static double pow(double a, double b)
    {
        return Math.Pow(a, b);
    }

    public static double ldexp(double number, int exponent)
    {
        return number * Math.Pow(2, exponent);
    }

    public static int strcmp(sbyte* src, string token)
    {
        var result = 0;

        for (var i = 0; i < token.Length; ++i)
        {
            if (src[i] != token[i])
            {
                ++result;
            }
        }

        return result;
    }

    public static int strncmp(sbyte* src, string token, ulong size)
    {
        var result = 0;

        for (var i = 0; i < Math.Min(token.Length, (int)size); ++i)
        {
            if (src[i] != token[i])
            {
                ++result;
            }
        }

        return result;
    }

    public static long strtol(sbyte* start, sbyte** end, int radix)
    {
        // First step - determine length
        var length = 0;
        var ptr = start;
        while (s_numbers.IndexOf((char)*ptr) != -1)
        {
            ++ptr;
            ++length;
        }

        long result = 0;

        // Now build up the number
        ptr = start;
        while (length > 0)
        {
            long num = s_numbers.IndexOf((char)*ptr);
            var pow = (long)Math.Pow(10, length - 1);
            result += num * pow;

            ++ptr;
            --length;
        }

        if (end != null)
        {
            *end = ptr;
        }

        return result;
    }
}