#pragma once

#include<assert.h>
namespace wdz
{

    class string
    {

        friend ostream& operator<<(ostream& _cout, const wdz::string& s);
        friend istream& operator>>(istream& _cin, wdz::string& s);

    public:

        typedef char* iterator;

    public:

        string(const char* str = "")
            :_str(nullptr)
            , _capacity(strlen(str))
            , _size(strlen(str))
        {
            _str = new char[_capacity + 1];
            strcpy(_str, str);
        }

        string(const string& s)
            :_str(nullptr)
            , _capacity(0)
            , _size(0)
        {
            string tmp(s._str);
            swap(tmp);
        }

        string& operator=(const string& s)
        {
            if (this != &s)
            {
                string tmp(s);
                swap(tmp);
            }
            return *this;
        }

        ~string()
        {
            delete[] _str;
            _str = nullptr;
            _size = _capacity = 0;
        }


        //////////////////////////////////////////////////////////////

        // iterator

        const iterator begin()const
        {
            return _str;
        }

        iterator begin()
        {
            return _str;
        }

        const iterator end()const
        {
            return _str + _size;
        }
        
        iterator end()
        {
            return _str + _size;
        }
        /////////////////////////////////////////////////////////////

        // modify

        void push_back(char c)
        {
            if (_size == _capacity)
            {
                reserve(_capacity == 0 ? 4 : _capacity * 2);
                
            }

            _str[_size++] = c;
            _str[_size] = '\0';

        }

        string& operator+=(char c)
        {
            push_back(c);
            return *this;
        }

        void append(const char* str)
        {
            int len = strlen(str);
            if (len + _size > _capacity)
            {
                reserve(len + _size);
            }
            strncpy(_str + _size, str, len);
            _size += len;
            _str[_size] = '\0';
        }

        string& operator+=(const char* str)
        {
            append(str);
            return *this;
        }

        void clear()
        {
            _size = 0;
        }

        void swap(string& s)
        {
            std::swap(s._str, _str);
            std::swap(s._size, _size);
            std::swap(s._capacity, _capacity);
        }

        const char* c_str()const
        {
            return _str;
        }



        /////////////////////////////////////////////////////////////

        // capacity

        size_t size()const
        {
            return _size;
        }

        size_t capacity()const
        {
            return _capacity;
        }

        bool empty()const
        {
            return _size == 0;
        }

        void resize(size_t n, char c = '\0')
        {
            if (n <= _size)
            {
                _str[_size] = '\0';
                _size = n;
            }
            else
            {
                if (n > _capacity)
                {
                    reserve(n);
                }
                while (_size < n)
                {
                    _str[_size++] = c;
                }
                _str[_size] = '\0';
                
            }
            
        }

        void reserve(size_t n)
        {
            if (n > _capacity)
            {
                char* ptr = new char[n + 1];
                strcpy(ptr, _str);
                delete[] _str;
                _str = ptr;
                _capacity = n;
            }
        }



        /////////////////////////////////////////////////////////////

        // access

        char& operator[](size_t index)
        {
            assert(index < _size);
            return _str[index];
        }

        const char& operator[](size_t index)const
        {
            assert(index < _size);
            return _str[index];
        }

        /////////////////////////////////////////////////////////////

        //relational operators

        bool operator<(const string& s)
        {
            return strcmp(_str, s._str) < 0;
        }

        bool operator<=(const string& s)
        {
            return *this < s || *this == s;
        }

        bool operator>(const string& s)
        {
            return !(*this <= s);
        }

        bool operator>=(const string& s)
        {
            return !(*this < s);
        }

        bool operator==(const string& s)
        {
            return strcmp(_str, s._str) == 0;
        }

        bool operator!=(const string& s)
        {
            return !(*this == s);
        }


        // 返回c在string中第一次出现的位置

        size_t find(char c, size_t pos = 0) const
        {
            for (size_t i = 0 + pos; i < _size; i++)
            {
                if (_str[i] == c)
                {
                    return i;
                }
            }
            return npos;
        }

        // 返回子串s在string中第一次出现的位置

        size_t find(const char* s, size_t pos = 0) const
        {
            char* ptr = strstr(_str + pos, s);
            if (ptr == nullptr)
            {
                return npos;
            }
            else
            {
                return ptr - _str;
            }
        }

        // 在pos位置上插入字符c/字符串str，并返回该字符的位置

        string& insert(size_t pos, char c)
        {
            assert(pos <= _size);
            if (_size == _capacity)
            {
                reserve(_capacity == 0 ? 4 : 2 * _capacity);
            }

            int end = _size;
            while (end >= (int)pos)
            {
                _str[end + 1] = _str[end];
                end--;
            }
            _size++;
            _str[pos] = c;

        }

        string& insert(size_t pos, const char* str)
        {
            assert(pos <= _size);
            int len = strlen(str);
            if (_size + len > _capacity)
            {
                reserve(_size + len);
            }
            int end = _size;
            while (end >= (int)pos)
            {
                _str[end + len] = _str[end];
                end--;
            }
            _size += len;
            strncpy(_str + pos, str, len);
            return *this;
        }



        // 删除pos位置上的元素，并返回该元素的下一个位置

        string& erase(size_t pos, size_t len = npos)
        {
            assert(pos < _size);
            if (len == npos || len >= _capacity - _size)
            {
                _str[pos] = '\0';
                _size = pos;
            }
            else
            {
                strcpy(_str + pos, _str + pos + len);
                _size -= len;
            }
        }



    public:
        static const size_t npos = -1;

    private:

        char* _str;

        size_t _capacity;

        size_t _size;

    };

    ostream& operator<<(ostream& _cout, const wdz::string& s)
    {
        for (auto& ch : s)
        {
            _cout << ch ;
        }

        return _cout;
    }
    istream& operator>>(istream& _cin, wdz::string& s)
    {
        s.clear();

        char buff[129] = { 0 };
        size_t i = 0;

        char ch = _cin.get();

        while (ch != '\n' && ch != ' ')
        {
            buff[i++] = ch;
            if (i == 128)
            {
                buff[i] = '\0';
                s += buff;
                i = 0;
            }
            ch = _cin.get();
        }

        if (i != 0)
        {
            buff[i] = '\0';
            s += buff;
        }

        return _cin;
    }

    void test1()
    {
        cout << wdz::string::npos << endl;
        wdz::string s;
        cin >> s;
        cout << s << endl;
    }

    void test2()
    {
        string s1("hello world");
        s1.insert(0, "wdz");
        cout << s1 << endl;
        s1.insert(14, "wdz");
        cout << s1 << endl;
        

    }


};