#pragma once
#include<iostream>
using namespace std;
#include<assert.h>
namespace bit
{
	class String
	{
	public:
		typedef char* Iterator;
		Iterator Begin()
		{
			return _str;
		}

		Iterator End()
		{
			return _str + _size;
		}

		String(const char* str = "")
		{
			if(str == NULL)
			{
				return ;
			}
			_size = strlen(str);
			_capacity = _size;
			_str = new char[_capacity+1];
			strcpy(_str, str);
		}

		String(const String& s)
			:_str(NULL)
			,_size(0)
			,_capacity(0)
		{
			_size = s._size;
			_capacity = s._capacity;
			_str = new char[_capacity+1];
			strcpy(_str, s._str);
		}

		void Swap(String& s)
		{
			swap(_str, s._str);
			swap(_size, s._size);
			swap(_capacity, s._capacity);
		}
		String& operator=(const String& s)
		{
			if(this != &s)
			{
				String tmp(s);
				Swap(tmp);
			}
			return *this;
		}

		~String()
		{
			if(_str)
			{
				delete[] _str;
				_size = _capacity = 0;
			}
		}

		inline size_t Size()const
		{
			return _size;
		}

		inline size_t Capacity()const
		{
			return _capacity;
		}

		inline char* C_str()const
		{
			return _str;
		}

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

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

		void Reserve(size_t n)
		{
			if(n >_capacity)
			{
				char* tmp = new char[n+1];
				strcpy(tmp, _str);
				delete[] _str;
				_str = tmp;
				_capacity = n;
			}
		}
		void PushBack(const char ch)
		{
			if(_size == _capacity)
			{
				size_t newcapacity = _capacity == 0 ? 15 : _capacity*2;
				Reserve(newcapacity);
			}
			_str[_size] = ch;
			_size++;
			_str[_size] = '\0';
		}
		
		void Append(const char* str = "")
		{
			size_t len = strlen(str);
			for(size_t i=0; i<len; i++)
			{
				PushBack(str[i]);
			}
		}

		String& operator+=(const char& ch)
		{
			PushBack(ch);
			return *this;
		}

		String& operator+=(const char* str)
		{
			Append(str);
			return *this;
		}


		void Resize(size_t newsize, char c = ' ')
		{
			if(newsize>_size)
			{
				if(newsize>_size)
				{
					Reserve(newsize);
				}
				memset(_str+_size, c, newsize-_size);
			}
			_size = newsize;
			_str[_size] = '\0';

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

		size_t Find(const char* str, size_t pos = 0)const
		{
			assert(pos < _size);
			char* ret = strstr(_str, str);
			if(ret == NULL)
			{
				return npos;
			}
			else
			{
				return ret-_str;
			}
		}

		String Substr(size_t pos, size_t n)
		{
			
			char* tmp = new char[n+1];
			if(n>_size)
				n = _size;
			size_t i = 0;
			for(i=0; i<n; i++)
			{
				tmp[i] = _str[pos+i];
			}
			tmp[i] = '\0';
			String ret(tmp);
			delete[] tmp;
			return ret;
		}

		String& Insert(size_t pos, const char c)
		{
		
			assert(pos<_size);
			if(_size+1>=_capacity)
			{
				size_t newcapacity = _capacity == 0 ? 15 : _capacity*2;
				Reserve(newcapacity);
			}
			size_t end = _size+1;
			while(end>pos);
			{
				_str[end] = _str[end-1];
				--end;
			}
			_str[pos] = c;
			_size++;
			return *this;
		}

		String& Insert(size_t pos, const char* str)
		{
			size_t len = strlen(str);
			assert(pos<_size);
			if(_size+len>=_capacity)
			{
				Reserve(_size+len);
			}
			size_t end = _size+1;
			while(_size>pos)
			{
				_str[end+len-1] = _str[end-1];
				--end;
			}
			for(size_t i=0; i<len; i++)
			{
				_str[pos+i] = _str[i];
			}
			_size += len;
			return *this;
		}
		String& Erase(size_t pos, size_t len = npos)
		{
			assert(pos<_size);
			if(pos+len>=_size)
			{
				_size = pos;
				_str[_size] = '\0';
			}
			else
			{
				size_t end = pos+len;
				while(end<=_size)
				{
					_str[pos] = _str[end];
					pos++;
					_size++;
				}
				_size -= len;
			}
			return *this;
		}
	private:
		char* _str;
		size_t _size;
		size_t _capacity;
		const static size_t npos = -1;
	};
}