#pragma once

#include <iostream>
#include <assert.h>

using namespace std;

namespace Lenyiin
{
    template <class T>
    class Vector
    {
    public:
        typedef T *iterator;
        typedef const T *const_iterator;

        iterator begin()
        {
            return _start;
        }

        iterator end()
        {
            return _finish;
        }

        const_iterator begin() const
        {
            return _start;
        }

        const_iterator end() const
        {
            return _finish;
        }

        size_t size() const
        {
            return _finish - _start;
        }

        size_t capacity() const
        {
            return _endofstorage - _start;
        }

        // 默认构造
        Vector()
            : _start(nullptr), _finish(nullptr), _endofstorage(nullptr)
        {
        }

        // 拷贝构造
        // Vector(const Vector<T>& v)
        //{
        //	_start = new T[v.capacity()];
        //	_finish = _start;
        //	_endofstorage = _start + v.capacity();

        //	for (size_t i = 0; i < v.size(); i++)
        //	{
        //		*_finish = v[i];
        //		++_finish;
        //	}
        //}

        // 进阶写法
        Vector(const Vector<T> &v)
            : _start(nullptr), _finish(nullptr), _endofstorage(nullptr)
        {
            reserve(v.capacity());
            for (const auto &e : v)
            {
                push_back(e);
            }
        }

        // 赋值运算符重载
        // Vector<T>& operator=(const Vector<T>& v)
        //{
        //	if (this != &v)
        //	{
        //		delete[] _start;
        //		_start = new T[v.capacity()];

        //		//memcpy(_start, v._start, sizeof(T) * v.size());	按字节拷贝，浅拷贝
        //		for (size_t i = 0; i < v.size(); i++)
        //		{
        //			_start[i] = v._start[i];	// 调用的是 operator= 深拷贝
        //		}

        //		_finish = _start + v.size();
        //		_endofstorage = _start + v.capacity();
        //	}
        //	return *this;
        //}

        // 进阶写法
        void swap(Vector<T> &v) // 自己写的swap是浅拷贝，代价小
        {
            std::swap(_start, v._start);
            std::swap(_finish, v._finish);
            std::swap(_endofstorage, v._endofstorage);
        }

        Vector<T> &operator=(Vector<T> v)
        {
            swap(v); // 库里面的swap是深拷贝，代价极大
            return *this;
        }

        // 移动构造函数
        Vector(Vector &&v) noexcept
            : _start(v._start), _finish(v._finish), _endofstorage(v._endofstorage)
        {
            v._start = nullptr;
            v._finish = nullptr;
            v._endofstorage = nullptr;
        }

        // 移动赋值运算符
        Vector &operator=(Vector &&v) noexcept
        {
            if (this != &v)
            {
                delete[] _start;
                _start = v._start;
                _finish = v._start + v.size();
                _endofstorage = v._start + v.capacity();
                v._start = nullptr;
                v._finish = nullptr;
                v._endofstorage = nullptr;
            }
            return *this;
        }

        // 析构函数
        ~Vector()
        {
            if (_start)
            {
                delete[] _start;
            }
            _start = _finish = _endofstorage = nullptr;
        }

        // 下标运算符重载
        T &operator[](size_t index)
        {
            if (index >= size())
            {
                throw std::out_of_range("Index out of range");
            }
            return _start[index];
        }

        const T &operator[](size_t index) const
        {
            if (index >= size())
            {
                throw std::out_of_range("Index out of range");
            }
            return _start[index];
        }

        // 动态扩容
        void reserve(size_t newcapacity)
        {
            if (newcapacity > capacity())
            {
                T *tmp = new T[newcapacity]; // 分配新内存
                size_t len = size();
                if (_start)
                {
                    for (size_t i = 0; i < len; i++)
                    {
                        tmp[i] = std::move(_start[i]); // 移动已有数据
                    }
                    delete[] _start; // 释放旧的内存
                }
                // 更新指针
                _start = tmp;
                _finish = tmp + len;
                _endofstorage = tmp + newcapacity;
            }
        }

        // resize 不仅会开空间，还会初始化
        void resize(size_t newsize, const T &val = T())
        {
            if (newsize < size())
            {
                _finish = _start + newsize;
            }
            else
            {
                if (newsize > capacity())
                {
                    reserve(newsize);
                }

                while (_finish < _start + newsize)
                {
                    *_finish = val;
                    ++_finish;
                }
            }
        }

        void push_back(const T &data)
        {
            if (_finish == _endofstorage)
            {
                size_t newcapacity = capacity() == 0 ? 4 : capacity() * 2;
                reserve(newcapacity);
            }

            *_finish = data;
            ++_finish;
        }

        // 移动版本
        void push_back(T &&data)
        {
            if (_finish == _endofstorage)
            {
                reserve(capacity() == 0 ? 4 : capacity() * 2);
            }
            *_finish = std::move(data); // 使用 move 语义
            ++_finish;
        }

        // 更安全的访问方式
        T &at(size_t index)
        {
            if (index >= size())
            {
                throw std::out_of_range("Index out of bounds");
            }
            return _start[index];
        }

        void pop_back()
        {
            assert(_start < _finish);

            --_finish;
        }

        void clear()
        {
            _finish = _start;
        }

        iterator insert(iterator pos, const T &data)
        {
            assert(pos <= _finish);

            if (_finish == _endofstorage)
            {
                size_t len = pos - _start;
                size_t newcapacity = capacity() == 0 ? 4 : capacity() * 2;
                reserve(newcapacity);

                // 如果增容，原来的pos就失效了，这里需要重新计算位置
                pos = _start + len;
            }

            iterator end = _finish - 1;
            while (end >= pos)
            {
                *(end + 1) = *end;
                --end;
            }

            *pos = data;
            ++_finish;

            return pos;
        }

        iterator erase(iterator pos)
        {
            assert(pos < _finish);

            iterator it = pos;
            while (it < _finish)
            {
                *it = *(it + 1);
                ++it;
            }
            --_finish;

            return pos;
        }

    private:
        iterator _start;
        iterator _finish;
        iterator _endofstorage;
    };
}