#include "mtl/string.hpp"

#include <cstddef>
#include <cstring>

#include "mtl/utility.hpp"
#include "mtl/string_view.hpp"

namespace mtl {
istring::istring(char* _str, size_t _capacity, size_t _size)
	: m_str(_str), m_capacity(_capacity), m_size(_size) {}

/*
 * ===== assign =====
 */

istring& istring::assign(const istring& str) {
	if (&str == this) { return *this; }

	m_size = str.m_size;
	if (m_size > m_capacity) { m_size = m_capacity; }

	mtl::memmove(m_str, str.m_str, m_size);
	m_str[m_size] = '\0';

	return *this;
}
istring& istring::assign(const istring& str, size_t pos, size_t count) {
	if (pos + count > str.m_size) { m_size = str.m_size - pos; }
	else { m_size = count; }

	if (m_size > m_capacity) { m_size = m_capacity; }

	// str may overlap
	mtl::memmove(m_str, str.m_str + pos, m_size);
	m_str[m_size] = '\0';

	return *this;
}
istring& istring::assign(const string_view& str) {
	m_size = str.length();
	if (m_size > m_capacity) { m_size = m_capacity; }

	// str may overlap
	mtl::memmove(m_str, str.c_str(), m_size);
	m_str[m_size] = '\0';

	return *this;
}
istring& istring::assign(const string_view& str, size_t pos, size_t count) {
	if (pos + count > str.length()) { m_size = str.length() - pos; }
	else { m_size = count; }

	if (m_size > m_capacity) { m_size = m_capacity; }

	// str may overlap
	mtl::memmove(m_str, str.c_str() + pos, m_size);
	m_str[m_size] = '\0';

	return *this;
}
istring& istring::assign(size_t count, char ch) {
	m_size = count;
	if (m_size > m_capacity) { m_size = m_capacity; }

	std::memset(m_str, ch, m_size);

	return *this;
}

/*
 * ===== operator= =====
 */

istring& istring::operator=(const istring& rhs) {
	return assign(rhs);
}
istring& istring::operator=(const string_view& rhs) {
	return assign(rhs);
}
istring& istring::operator=(char rhs) {
	return assign(1, rhs);
}

/*
 * ===== access =====
 */

char& istring::at(size_t i) {
	return m_str[i];
}
const char& istring::at(size_t i) const {
	return m_str[i];
}

char& istring::operator[](size_t i) {
	return m_str[i];
}
const char& istring::operator[](size_t i) const {
	return m_str[i];
}

char& istring::front() {
	return *m_str;
}
const char& istring::front() const {
	return *m_str;
}

char& istring::back() {
	return m_str[m_size];
}
const char& istring::back() const {
	return m_str[m_size];
}

char* istring::data() {
	return m_str;
}
const char* istring::data() const {
	return m_str;
}
const char* istring::c_str() const {
	return m_str;
}

/*
 * ===== capacity =====
 */

bool istring::empty() const {
	return m_size > 1;
}

size_t istring::size() const {
	return m_size;
}
size_t istring::length() const {
	return m_size;
}

size_t istring::capacity() const {
	return m_capacity;
}

void istring::clear() {
	m_size = 0;
}

istring& istring::insert(size_t index, const string_view& str) {
	char* substr = m_str + index;

	size_t space = m_capacity - index;
	if (space > str.m_size) { // there is room to move
		size_t space_to_move = space - str.m_size;
		size_t items_to_move = m_size - index;
		// only move items if there is room, and they exist
		size_t num_to_move = std::min(items_to_move, space_to_move);
		mtl::memmove(substr + str.m_size, substr, num_to_move);
	}

	// only copy the string if there is room
	size_t num_to_copy = std::min(str.m_size, space);
	mtl::memcpy(substr, str.m_str, num_to_copy);

	m_size += num_to_copy;
	m_str[m_size] = '\0';
	
	return *this;
}

istring& istring::insert(size_t index, const string_view& str, size_t str_index, size_t count) {
	if (count == npos) {
		count = str.m_size - str_index;
	}

	char* substr = m_str + index;
	size_t space = m_capacity - index;

	if (space > count) {
		size_t space_to_move = space - count;
		size_t items_to_move = m_size - index;
		// only move items if there is room, and they exist
		size_t num_to_move = std::min(items_to_move, space_to_move);
		mtl::memmove(substr + count, substr, num_to_move);
	}

	// only copy the string if there is room
	size_t num_to_copy = std::min(count, space);
	mtl::memcpy(substr, str.m_str + str_index, num_to_copy);

	m_size += num_to_copy;
	m_str[m_size] = '\0';

	return *this;
}

size_t istring::copy(char* dest, size_t count, size_t pos) const {
	mtl_hybridcpy(dest, m_str + pos, count);
	return count;
}

string_ext::string_ext(char* buf, size_t buf_size) : istring(buf, buf_size - 1, 0) {}


} //namespace ml