#include "RAM.hpp"

#include <spider/runtime/cpu/Register.hpp>

#include <spider/runtime/memory/Types.hpp>

#include <cstring>

namespace spider {

    // Constructors & Destructors //

    RAM::RAM(u64 length) : _mem(nullptr), _size(length), _oob(0) {
        if (_size > 0) {
            _mem = new u8[_size];
            std::memset(_mem, 0, _size);
        }
    }

    RAM::RAM(const RAM& other) : _size(other._size), _oob(0) {
        _mem = new u8[_size];
        std::copy(other._mem, other._mem + _size, _mem);
    }

    RAM::RAM(RAM&& other) noexcept : _mem(other._mem), _size(other._size), _oob(0) {
        other._mem = nullptr;
        other._size = 0;
    }

    RAM::~RAM() {
        delete[] _mem;
    }

    // Assign Operators //

    RAM& RAM::operator=(const RAM& other) {
        if (this == &other) return *this; // lock self

        u8* new_mem = new u8[other._size];
        std::copy(other._mem, other._mem + other._size, new_mem);

        delete[] _mem;
        _mem = new_mem;
        _size = other._size;

        return *this;
    }

    RAM& RAM::operator=(RAM&& other) noexcept {
        if (this == &other) return *this; // lock self

        delete[] _mem;

        _mem = other._mem; // time to steal!
        _size = other._size;

        other._mem = nullptr; // leave as a husk
        other._size = 0;

        return *this;
    }

    // Unsafe Access //

    u8& RAM::operator[](u64 i) { return _mem[i]; }

    u8  RAM::operator[](u64 i) const { return _mem[i]; }

    // Managed Access //

    u8& RAM::at(u64 i) {
        return (i < _size) ? _mem[i] : _oob;
    }

    u8 RAM::at(u64 i) const {
        return (i < _size) ? _mem[i] : _oob;
    }

    void RAM::loadRegister(u64 i, u8 size_code, register_t* r) {
        i = std::min(i, _size);
        spider::loadRegister[size_code](r, _mem + i, _size - i);
    }

    // Misc //

    void RAM::resize(u64 new_size) {
        // Special case 1
        if (new_size == _size) return;

        // Special case 2
        if (new_size == 0) {
            delete[] _mem;
            _mem = nullptr;
            _size = 0;
            return;
        }

        // 1. Allocate the new block
        u8* new_mem = new u8[new_size];

        // 2. Zero-initialize
        std::memset(new_mem, 0, new_size);

        // 3. Preserve data
        // If shrinking, copy 'new_size' bytes. If growing, copy 'old_size' bytes.
        u64 bytes_to_copy = (new_size < _size) ? new_size : _size;

        // 3.1 Previous size could be zero, where _mem would be null
        if (_mem != nullptr) {
            std::copy(_mem, _mem + bytes_to_copy, new_mem);
        }

        // 4. Swap and Clean up
        delete[] _mem;
        _mem = new_mem;
        _size = new_size;
    }

    u64 RAM::size() const {
        return _size;
    }

    u8* RAM::begin() {
        return this->_mem;
    }

    u8* RAM::end() {
        return this->_mem + this->_size;
    }

    const u8* RAM::begin() const {
        return this->_mem;
    }

    const u8* RAM::end() const {
        return this->_mem + this->_size;
    }

}