#include "buffer.h"

#include <algorithm>
#include <cassert>
#include <cstring>
#include <iomanip>
#include <sstream>

namespace saw {
error buffer::push(const uint8_t &value) {
	size_t write_remain = write_composite_length();
	if (write_remain > 0) {
		write() = value;
		write_advance(1);
	} else {
		return recoverable_error("Buffer too small");
	}
	return no_error();
}

error buffer::push(const uint8_t &buffer, size_t size) {
	error error = write_require_length(size);
	if (error.failed()) {
		return error;
	}
	const uint8_t *buffer_ptr = &buffer;
	while (size > 0) {
		size_t segment = std::min(write_segment_length(), size);
		memcpy(&write(), buffer_ptr, segment);
		write_advance(segment);
		size -= segment;
		buffer_ptr += segment;
	}
	return no_error();
}

error buffer::pop(uint8_t &value) {
	if (read_composite_length() > 0) {
		value = read();
		read_advance(1);
	} else {
		return recoverable_error("Buffer too small");
	}
	return no_error();
}

error buffer::pop(uint8_t &buffer, size_t size) {
	if (read_composite_length() >= size) {
		uint8_t *buffer_ptr = &buffer;
		while (size > 0) {
			size_t segment = std::min(read_segment_length(), size);
			memcpy(buffer_ptr, &read(), segment);
			read_advance(segment);
			size -= segment;
			buffer_ptr += segment;
		}
	} else {
		return recoverable_error("Buffer too small");
	}
	return no_error();
}

std::string buffer::to_string() const {
	std::ostringstream oss;
	for (size_t i = 0; i < read_composite_length(); ++i) {
		oss << read(i);
	}
	return oss.str();
}

std::string buffer::to_hex() const {
	std::ostringstream oss;
	oss << std::hex << std::setfill('0');
	for (size_t i = 0; i < read_composite_length(); ++i) {
		oss << std::setw(2) << (uint16_t)read(i);
		if ((i + 1) < read_composite_length()) {
			oss << ((i % 4 == 3) ? '\n' : ' ');
		}
	}
	return oss.str();
}

buffer_view::buffer_view(buffer &buffer)
	: buffer_{buffer}, read_offset_{0}, write_offset_{0} {}

size_t buffer_view::read_position() const {
	return read_offset_ + buffer_.read_position();
}

size_t buffer_view::read_composite_length() const {
	assert(read_offset_ <= buffer_.read_composite_length());
	if (read_offset_ > buffer_.read_composite_length()) {
		return 0;
	}

	return buffer_.read_composite_length() - read_offset_;
}

size_t buffer_view::read_segment_length(size_t offset) const {
	size_t off = offset + read_offset_;
	assert(off <= buffer_.read_composite_length());
	if (off > buffer_.read_composite_length()) {
		return 0;
	}

	return buffer_.read_segment_length(off);
}

void buffer_view::read_advance(size_t bytes) {
	size_t offset = bytes + read_offset_;
	assert(offset <= buffer_.read_composite_length());
	if (offset > buffer_.read_composite_length()) {
		read_offset_ += buffer_.read_composite_length();
		return;
	}

	read_offset_ += bytes;
}

uint8_t &buffer_view::read(size_t i) {
	size_t pos = i + read_offset_;

	assert(pos < buffer_.read_composite_length());

	return buffer_.read(pos);
}

const uint8_t &buffer_view::read(size_t i) const {
	size_t pos = i + read_offset_;

	assert(pos < buffer_.read_composite_length());

	return buffer_.read(pos);
}

size_t buffer_view::write_position() const {
	return write_offset_ + buffer_.write_position();
}

size_t buffer_view::write_composite_length() const {
	assert(write_offset_ <= buffer_.write_composite_length());
	if (write_offset_ > buffer_.write_composite_length()) {
		return 0;
	}

	return buffer_.write_composite_length() - write_offset_;
}

size_t buffer_view::write_segment_length(size_t offset) const {
	size_t off = offset + write_offset_;
	assert(off <= buffer_.write_composite_length());
	if (off > buffer_.write_composite_length()) {
		return 0;
	}

	return buffer_.write_segment_length(off);
}

void buffer_view::write_advance(size_t bytes) {
	size_t offset = bytes + write_offset_;
	assert(offset <= buffer_.write_composite_length());
	if (offset > buffer_.write_composite_length()) {
		write_offset_ += buffer_.write_composite_length();
		return;
	}

	write_offset_ += bytes;
}

uint8_t &buffer_view::write(size_t i) {
	size_t pos = i + write_offset_;

	assert(pos < buffer_.write_composite_length());

	return buffer_.write(pos);
}

const uint8_t &buffer_view::write(size_t i) const {
	size_t pos = i + write_offset_;

	assert(pos < buffer_.write_composite_length());

	return buffer_.write(pos);
}

error buffer_view::write_require_length(size_t bytes) {
	return buffer_.write_require_length(bytes + write_offset_);
}

size_t buffer_view::read_offset() const { return read_offset_; }

size_t buffer_view::write_offset() const { return write_offset_; }

ring_buffer::ring_buffer() : read_position_{0}, write_position_{0} {
	buffer_.resize(RING_BUFFER_MAX_SIZE);
}

ring_buffer::ring_buffer(size_t size) : read_position_{0}, write_position_{0} {
	buffer_.resize(size);
}

size_t ring_buffer::read_position() const { return read_position_; }

/*
 * If write is ahead of read it is a simple distance, but if read ist ahead of
 * write then there are two segments
 *
 */
size_t ring_buffer::read_composite_length() const {
	return write_position() < read_position()
			   ? buffer_.size() - (read_position() - write_position())
			   : (write_reached_read_ ? buffer_.size()
									  : write_position() - read_position());
}

/*
 * If write is ahead then it's the simple distance again. If read is ahead it's
 * until the end of the buffer/segment
 */
size_t ring_buffer::read_segment_length(size_t offset) const {
	size_t read_composite = read_composite_length();
	assert(offset <= read_composite);
	offset = std::min(offset, read_composite);
	size_t remaining = read_composite - offset;

	size_t read_offset = read_position() + offset;
	read_offset = read_offset >= buffer_.size() ? read_offset - buffer_.size()
												: read_offset;

	// case 1 write is located before read and reached read
	// then offset can be used normally
	// case 2 write is located at read, but read reached write
	// then it is set to zero by readCompositeLength()
	// case 3 write is located after read
	// since std::min you can use simple subtraction
	if (write_position() < read_offset) {
		return buffer_.size() - read_offset;
	}

	if (write_position() == read_offset) {
		if (remaining > 0) {
			return buffer_.size() - read_offset;
		} else {
			return 0;
		}
	}

	return write_position() - read_offset;
}

void ring_buffer::read_advance(size_t bytes) {
	size_t read_composite = read_composite_length();

	assert(bytes <= read_composite);
	bytes = std::min(bytes, read_composite);
	size_t advanced = read_position_ + bytes;
	read_position_ = advanced >= buffer_.size() ? advanced - buffer_.size()
												: advanced;
	write_reached_read_ = bytes > 0 ? false : write_reached_read_;
}

uint8_t &ring_buffer::read(size_t i) {
	assert(i < read_composite_length());
	size_t pos = read_position_ + i;
	pos = pos >= buffer_.size() ? pos - buffer_.size() : pos;
	return buffer_[pos];
}

const uint8_t &ring_buffer::read(size_t i) const {
	assert(i < read_composite_length());
	size_t pos = read_position_ + i;
	pos = pos >= buffer_.size() ? pos - buffer_.size() : pos;
	return buffer_[pos];
}

size_t ring_buffer::write_position() const { return write_position_; }

size_t ring_buffer::write_composite_length() const {
	return read_position() > write_position()
			   ? (read_position() - write_position())
			   : (write_reached_read_
					  ? 0
					  : buffer_.size() - (write_position() - read_position()));
}

size_t ring_buffer::write_segment_length(size_t offset) const {
	size_t write_composite = write_composite_length();
	assert(offset <= write_composite);
	offset = std::min(offset, write_composite);

	size_t write_offset = write_position() + offset;
	write_offset = write_offset >= buffer_.size()
					   ? write_offset - buffer_.size()
					   : write_offset;

	if (read_position_ > write_offset) {
		return read_position_ - write_offset;
	}

	if (write_reached_read_) {
		return 0;
	}

	return buffer_.size() - write_offset;
}

void ring_buffer::write_advance(size_t bytes) {
	assert(bytes <= write_composite_length());
	size_t advanced = write_position_ + bytes;
	write_position_ = advanced >= buffer_.size() ? advanced - buffer_.size()
												 : advanced;

	write_reached_read_ =
		(write_position_ == read_position_ && bytes > 0 ? true : false);
}

uint8_t &ring_buffer::write(size_t i) {
	assert(i < write_composite_length());
	size_t pos = write_position_ + i;
	pos = pos >= buffer_.size() ? pos - buffer_.size() : pos;
	return buffer_[pos];
}

const uint8_t &ring_buffer::write(size_t i) const {
	assert(i < write_composite_length());
	size_t pos = write_position_ + i;
	pos = pos >= buffer_.size() ? pos - buffer_.size() : pos;
	return buffer_[pos];
}
/*
	Error RingBuffer::increaseSize(size_t size){
		size_t old_size = buffer.size();
		size_t new_size = old_size + size;
		buffer.resize(new_size);
		if(readPosition() > writePosition() || (readPosition() ==
   writePosition() && write_reached_read)){ size_t remaining = old_size -
   writePosition(); size_t real_remaining = 0; while(remaining > 0){ size_t
   segment = std::min(remaining, size); memcpy(&buffer[new_size-segment],
   &buffer[old_size-segment], segment); remaining -= segment; size -= segment;
				old_size -= segment;
				new_size -= segment;
			}
		}

		return noError();
	}
*/
error ring_buffer::write_require_length(size_t bytes) {
	size_t write_remain = write_composite_length();
	if (bytes > write_remain) {
		return recoverable_error("Buffer too small");
	}
	return no_error();
}

array_buffer::array_buffer(size_t size)
	: read_position_{0}, write_position_{0} {
	buffer_.resize(size);
}

size_t array_buffer::read_position() const { return read_position_; }

size_t array_buffer::read_composite_length() const {
	return write_position_ - read_position_;
}

size_t array_buffer::read_segment_length(size_t offset) const {
	size_t read_composite = read_composite_length();
	assert(offset <= read_composite);

	offset = std::min(read_composite, offset);
	size_t read_offset = read_position_ + offset;

	return write_position_ - read_offset;
}

void array_buffer::read_advance(size_t bytes) {
	assert(bytes <= read_composite_length());
	read_position_ += bytes;
}

uint8_t &array_buffer::read(size_t i) {
	assert(i < read_composite_length());

	return buffer_[i + read_position_];
}

const uint8_t &array_buffer::read(size_t i) const {
	assert(i + read_position_ < buffer_.size());

	return buffer_[i + read_position_];
}

size_t array_buffer::write_position() const { return write_position_; }

size_t array_buffer::write_composite_length() const {
	assert(write_position_ <= buffer_.size());
	return buffer_.size() - write_position_;
}

size_t array_buffer::write_segment_length(size_t offset) const {
	assert(write_position_ <= buffer_.size());
	size_t write_composite = write_composite_length();

	assert(offset <= write_composite);
	offset = std::min(write_composite, offset);
	size_t write_offset = write_position_ + offset;

	return buffer_.size() - write_offset;
}

void array_buffer::write_advance(size_t bytes) {
	assert(bytes <= write_composite_length());
	write_position_ += bytes;
}

uint8_t &array_buffer::write(size_t i) {
	assert(i < write_composite_length());
	return buffer_[i + write_position_];
}

const uint8_t &array_buffer::write(size_t i) const {
	assert(i < write_composite_length());
	return buffer_[i + write_position_];
}
error array_buffer::write_require_length(size_t bytes) {
	size_t write_remain = write_composite_length();
	if (bytes > write_remain) {
		return recoverable_error("Buffer too small");
	}
	return no_error();
}

} // namespace saw