/*
	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/>.
*/
// SPDX-License-Identifier: GPL-3.0

#include <tools/yulPhaser/Program.h>

#include <liblangutil/CharStream.h>
#include <liblangutil/ErrorReporter.h>
#include <liblangutil/SourceReferenceFormatter.h>

#include <libyul/AsmAnalysis.h>
#include <libyul/AsmAnalysisInfo.h>
#include <libyul/AsmJsonConverter.h>
#include <libyul/AsmParser.h>
#include <libyul/AsmPrinter.h>
#include <libyul/AST.h>
#include <libyul/ObjectParser.h>
#include <libyul/YulString.h>
#include <libyul/backends/evm/EVMDialect.h>
#include <libyul/optimiser/Disambiguator.h>
#include <libyul/optimiser/ForLoopInitRewriter.h>
#include <libyul/optimiser/FunctionGrouper.h>
#include <libyul/optimiser/FunctionHoister.h>
#include <libyul/optimiser/Metrics.h>
#include <libyul/optimiser/OptimiserStep.h>
#include <libyul/optimiser/Suite.h>

#include <libsolutil/JSON.h>

#include <libsolidity/interface/OptimiserSettings.h>

#include <cassert>
#include <memory>

using namespace std;
using namespace solidity;
using namespace solidity::langutil;
using namespace solidity::yul;
using namespace solidity::util;
using namespace solidity::phaser;

namespace solidity::phaser
{

ostream& operator<<(ostream& _stream, Program const& _program);

}

Program::Program(Program const& program):
	m_ast(make_unique<Block>(get<Block>(ASTCopier{}(*program.m_ast)))),
	m_dialect{program.m_dialect},
	m_nameDispenser(program.m_nameDispenser)
{
}

variant<Program, ErrorList> Program::load(CharStream& _sourceCode)
{
	// ASSUMPTION: parseSource() rewinds the stream on its own
	Dialect const& dialect = EVMDialect::strictAssemblyForEVMObjects(EVMVersion{});

	variant<unique_ptr<Block>, ErrorList> astOrErrors = parseObject(dialect, _sourceCode);
	if (holds_alternative<ErrorList>(astOrErrors))
		return get<ErrorList>(astOrErrors);

	variant<unique_ptr<AsmAnalysisInfo>, ErrorList> analysisInfoOrErrors = analyzeAST(
		dialect,
		*get<unique_ptr<Block>>(astOrErrors)
	);
	if (holds_alternative<ErrorList>(analysisInfoOrErrors))
		return get<ErrorList>(analysisInfoOrErrors);

	Program program(
		dialect,
		disambiguateAST(
			dialect,
			*get<unique_ptr<Block>>(astOrErrors),
			*get<unique_ptr<AsmAnalysisInfo>>(analysisInfoOrErrors)
		)
	);
	program.optimise({
		FunctionHoister::name,
		FunctionGrouper::name,
		ForLoopInitRewriter::name,
	});

	return program;
}

void Program::optimise(vector<string> const& _optimisationSteps)
{
	m_ast = applyOptimisationSteps(m_dialect, m_nameDispenser, std::move(m_ast), _optimisationSteps);
}

ostream& phaser::operator<<(ostream& _stream, Program const& _program)
{
	return _stream << AsmPrinter()(*_program.m_ast);
}

string Program::toJson() const
{
	Json serializedAst = AsmJsonConverter(0)(*m_ast);
	return jsonPrettyPrint(removeNullMembers(std::move(serializedAst)));
}

variant<unique_ptr<Block>, ErrorList> Program::parseObject(Dialect const& _dialect, CharStream _source)
{
	ErrorList errors;
	ErrorReporter errorReporter(errors);
	auto scanner = make_shared<Scanner>(_source);

	ObjectParser parser(errorReporter, _dialect);
	shared_ptr<Object> object = parser.parse(scanner, false);
	if (object == nullptr || !errorReporter.errors().empty())
		// NOTE: It's possible to get errors even if the returned object is non-null.
		// For example when there are errors in a nested object.
		return errors;

	Object* deployedObject = nullptr;
	if (object->subObjects.size() > 0)
		for (auto& subObject: object->subObjects)
			// solc --ir produces an object with a subobject of the same name as the outer object
			// but suffixed with  "_deployed".
			// The other object references the nested one which makes analysis fail. Below we try to
			// extract just the nested one for that reason. This is just a heuristic. If there's no
			// subobject with such a suffix we fall back to accepting the whole object as is.
			if (subObject != nullptr && subObject->name.str() == object->name.str() + "_deployed")
			{
				deployedObject = dynamic_cast<Object*>(subObject.get());
				if (deployedObject != nullptr)
					break;
			}
	Object* selectedObject = (deployedObject != nullptr ? deployedObject : object.get());

	// NOTE: I'm making a copy of the whole AST to get unique_ptr rather than shared_ptr.
	// This is a slight performance hit but it's much less than the parsing itself.
	// unique_ptr lets me be sure that two Program instances can never share the AST by mistake.
	// The public API of the class does not provide access to the smart pointer so it won't be hard
	// to switch to shared_ptr if the copying turns out to be an issue (though it would be better
	// to refactor ObjectParser and Object to use unique_ptr instead).
	auto astCopy = make_unique<Block>(get<Block>(ASTCopier{}(*selectedObject->code)));

	return variant<unique_ptr<Block>, ErrorList>(std::move(astCopy));
}

variant<unique_ptr<AsmAnalysisInfo>, ErrorList> Program::analyzeAST(Dialect const& _dialect, Block const& _ast)
{
	ErrorList errors;
	ErrorReporter errorReporter(errors);
	auto analysisInfo = make_unique<AsmAnalysisInfo>();
	AsmAnalyzer analyzer(*analysisInfo, errorReporter, _dialect);

	bool analysisSuccessful = analyzer.analyze(_ast);
	if (!analysisSuccessful)
		return errors;

	assert(errorReporter.errors().empty());
	return variant<unique_ptr<AsmAnalysisInfo>, ErrorList>(std::move(analysisInfo));
}

unique_ptr<Block> Program::disambiguateAST(
	Dialect const& _dialect,
	Block const& _ast,
	AsmAnalysisInfo const& _analysisInfo
)
{
	set<YulString> const externallyUsedIdentifiers = {};
	Disambiguator disambiguator(_dialect, _analysisInfo, externallyUsedIdentifiers);

	return make_unique<Block>(get<Block>(disambiguator(_ast)));
}

unique_ptr<Block> Program::applyOptimisationSteps(
	Dialect const& _dialect,
	NameDispenser& _nameDispenser,
	unique_ptr<Block> _ast,
	vector<string> const& _optimisationSteps
)
{
	// An empty set of reserved identifiers. It could be a constructor parameter but I don't
	// think it would be useful in this tool. Other tools (like yulopti) have it empty too.
	set<YulString> const externallyUsedIdentifiers = {};
	OptimiserStepContext context{
		_dialect,
		_nameDispenser,
		externallyUsedIdentifiers,
		frontend::OptimiserSettings::standard().expectedExecutionsPerDeployment
	};

	for (string const& step: _optimisationSteps)
		OptimiserSuite::allSteps().at(step)->run(context, *_ast);

	return _ast;
}

size_t Program::computeCodeSize(Block const& _ast, CodeWeights const& _weights)
{
	return CodeSize::codeSizeIncludingFunctions(_ast, _weights);
}