#pragma once

#include <exception>
#include <cstdint>
#include <cmath>

namespace hv
{
  /// A typed span of continuous memory with a bound.
  template<typename T>
  struct span
  {
    inline span(T* ptr, std::size_t len)
      : ptr(ptr),len(len){}

    inline operator T*() {return ptr;}
    inline operator const T* const() {return ptr;}
    inline T& operator*() {return *ptr;}
    inline const T& operator*() const {return *ptr;}
    
    inline T& operator[](std::size_t index)
    {
#ifdef DEBUG
      if (index>=len) std::terminate(); // "tried to index out of bounds of array";
#endif
      return ptr[index];
    }
    inline const T& operator[](std::size_t index) const
    {
#ifdef DEBUG
      if (index>=len) std::terminate(); // "tried to index out of bounds of array";
#endif
      return ptr[index];
    }

    inline span<T> slice(std::size_t off, std::size_t len)
    {
      len = std::min(this->len, len);
      if(len+off>=len || len < off) std::terminate(); // "tried to index out of bounds of array";
      return span<T>(ptr+off, len-off);
    }
    inline span<T> slice(std::size_t off)
    {
      if(len+off>=len || len < off) std::terminate(); // "tried to index out of bounds of array";
      
      return span<T>(ptr+off, len-off);
    }

    template<typename U>
    inline span<U> reinterpret()
    {
      return span<U>((U*)ptr, size_bytes() / sizeof(U));
    }

    inline T* operator ->()
    {
      return ptr;
    }
    inline const T* operator ->() const
    {
      return ptr;
    }
    
    inline T* raw() {
      return ptr;
    }
    inline const T* raw() const {
      return ptr;
    }
    inline std::size_t size() const {
      return len;
    }
    inline std::size_t size_bytes() const {
      return len * sizeof(T);
    }
  private:
    T* const ptr;
    std::size_t len;
  };
}