/*
 * This file is part of solidity.
 *
 * solidity is free software: you can redistribute it and/or modify
 * it under the terms of the GNU General Public License as published by
 * the Free Software Foundation, either version 3 of the License, or
 * (at your option) any later version.
 *
 * solidity is distributed in the hope that it will be useful,
 * but WITHOUT ANY WARRANTY; without even the implied warranty of
 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
 * GNU General Public License for more details.
 *
 * You should have received a copy of the GNU General Public License
 * along with solidity.  If not, see <http://www.gnu.org/licenses/>.
 *
 * This file is derived from the file "scanner.cc", which was part of the
 * V8 project. The original copyright header follows:
 *
 * Copyright 2006-2012, the V8 project authors. All rights reserved.
 * Redistribution and use in source and binary forms, with or without
 * modification, are permitted provided that the following conditions are
 * met:
 *
 * * Redistributions of source code must retain the above copyright
 *   notice, this list of conditions and the following disclaimer.
 * * Redistributions in binary form must reproduce the above
 *   copyright notice, this list of conditions and the following
 *   disclaimer in the documentation and/or other materials provided
 *   with the distribution.
 * * Neither the name of Google Inc. nor the names of its
 *   contributors may be used to endorse or promote products derived
 *   from this software without specific prior written permission.
 *
 * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
 * "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
 * LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR
 * A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT
 * OWNER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL,
 * SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT
 * LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
 * DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
 * THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
 * (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE
 * OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
*/
/**
 * Character stream / input file.
 */

#include <liblangutil/CharStream.h>
#include <liblangutil/Exceptions.h>

using namespace solidity;
using namespace solidity::langutil;

char CharStream::advanceAndGet(size_t _chars)
{
	if (isPastEndOfInput())
		return 0;
	m_position += _chars;
	if (isPastEndOfInput())
		return 0;
	return m_source[m_position];
}

char CharStream::rollback(size_t _amount)
{
	solAssert(m_position >= _amount, "");
	m_position -= _amount;
	return get();
}

char CharStream::setPosition(size_t _location)
{
	solAssert(_location <= m_source.size(), "Attempting to set position past end of source.");
	m_position = _location;
	return get();
}

std::string CharStream::lineAtPosition(int _position) const
{
	// if _position points to \n, it returns the line before the \n
	using size_type = std::string::size_type;
	size_type searchStart = std::min<size_type>(m_source.size(), size_type(_position));
	if (searchStart > 0)
		searchStart--;
	size_type lineStart = m_source.rfind('\n', searchStart);
	if (lineStart == std::string::npos)
		lineStart = 0;
	else
		lineStart++;
	std::string line = m_source.substr(
		lineStart,
		std::min(m_source.find('\n', lineStart), m_source.size()) - lineStart
	);
	if (!line.empty() && line.back() == '\r')
		line.pop_back();
	return line;
}

LineColumn CharStream::translatePositionToLineColumn(int _position) const
{
	using size_type = std::string::size_type;
	using diff_type = std::string::difference_type;
	size_type searchPosition = std::min<size_type>(m_source.size(), size_type(_position));
	int lineNumber = static_cast<int>(count(m_source.begin(), m_source.begin() + diff_type(searchPosition), '\n'));
	size_type lineStart;
	if (searchPosition == 0)
		lineStart = 0;
	else
	{
		lineStart = m_source.rfind('\n', searchPosition - 1);
		lineStart = lineStart == std::string::npos ? 0 : lineStart + 1;
	}
	return LineColumn{lineNumber, static_cast<int>(searchPosition - lineStart)};
}

std::string_view CharStream::text(SourceLocation const& _location) const
{
	if (!_location.hasText())
		return {};
	solAssert(_location.sourceName && *_location.sourceName == m_name, "");
	solAssert(static_cast<size_t>(_location.end) <= m_source.size(), "");
	return std::string_view{m_source}.substr(
		static_cast<size_t>(_location.start),
		static_cast<size_t>(_location.end - _location.start)
	);
}

std::string CharStream::singleLineSnippet(std::string const& _sourceCode, SourceLocation const& _location)
{
	if (!_location.hasText())
		return {};

	if (static_cast<size_t>(_location.start) >= _sourceCode.size())
		return {};

	std::string cut = _sourceCode.substr(static_cast<size_t>(_location.start), static_cast<size_t>(_location.end - _location.start));
	auto newLinePos = cut.find_first_of("\n\r");
	if (newLinePos != std::string::npos)
		cut = cut.substr(0, newLinePos) + "...";

	return cut;
}

std::optional<int> CharStream::translateLineColumnToPosition(LineColumn const& _lineColumn) const
{
	return translateLineColumnToPosition(m_source, _lineColumn);
}

std::optional<int> CharStream::translateLineColumnToPosition(std::string const& _text, LineColumn const& _input)
{
	if (_input.line < 0)
		return std::nullopt;

	size_t offset = 0;
	for (int i = 0; i < _input.line; i++)
	{
		offset = _text.find('\n', offset);
		if (offset == _text.npos)
			return std::nullopt;
		offset++; // Skip linefeed.
	}

	size_t endOfLine = _text.find('\n', offset);
	if (endOfLine == std::string::npos)
		endOfLine = _text.size();

	if (offset + static_cast<size_t>(_input.column) > endOfLine)
		return std::nullopt;
	return offset + static_cast<size_t>(_input.column);
}