/*
	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/>.
*/
/**
 * @author Christian <c@ethdev.com>
 * @date 2015
 * Type analyzer and checker.
 */

#pragma once

#include <liblangutil/EVMVersion.h>

#include <libsolidity/ast/Types.h>
#include <libsolidity/ast/ASTAnnotations.h>
#include <libsolidity/ast/ASTForward.h>
#include <libsolidity/ast/ASTVisitor.h>

namespace langutil
{
class ErrorReporter;
}

namespace dev
{
namespace solidity
{

/**
 * The module that performs type analysis on the AST, checks the applicability of operations on
 * those types and stores errors for invalid operations.
 * Provides a way to retrieve the type of an AST node.
 */
class TypeChecker: private ASTConstVisitor
{
public:
	/// @param _errorReporter provides the error logging functionality.
	TypeChecker(EVMVersion _evmVersion, langutil::ErrorReporter& _errorReporter):
		m_evmVersion(_evmVersion),
		m_errorReporter(_errorReporter)
	{}

	/// Performs type checking on the given contract and all of its sub-nodes.
	/// @returns true iff all checks passed. Note even if all checks passed, errors() can still contain warnings
	bool checkTypeRequirements(ASTNode const& _contract);

	/// @returns the type of an expression and asserts that it is present.
	TypePointer const& type(Expression const& _expression) const;
	/// @returns the type of the given variable and throws if the type is not present
	/// (this can happen for variables with non-explicit types before their types are resolved)
	TypePointer const& type(VariableDeclaration const& _variable) const;

private:

	bool visit(ContractDefinition const& _contract) override;
	/// Checks that all requirements for a library are fulfilled if this is a library.
	void checkLibraryRequirements(ContractDefinition const& _contract);
	/// Checks (and warns) if a tuple assignment might cause unexpected overwrites in storage.
	/// Should only be called if the left hand side is tuple-typed.
	void checkDoubleStorageAssignment(Assignment const& _assignment);
	// Checks whether the expression @arg _expression can be assigned from type @arg _type
	// and reports an error, if not.
	void checkExpressionAssignment(Type const& _type, Expression const& _expression);

	/// Performs type checks for ``abi.decode(bytes memory, (...))`` and returns the
	/// vector of return types (which is basically the second argument) if successful. It returns
	/// the empty vector on error.
	TypePointers typeCheckABIDecodeAndRetrieveReturnType(
		FunctionCall const& _functionCall,
		bool _abiEncoderV2
	);

	/// Performs type checks and determines result types for type conversion FunctionCall nodes.
	TypePointer typeCheckTypeConversionAndRetrieveReturnType(
		FunctionCall const& _functionCall
	);

	/// Performs type checks on function call and struct ctor FunctionCall nodes (except for kind ABIDecode).
	void typeCheckFunctionCall(
		FunctionCall const& _functionCall,
		FunctionTypePointer _functionType
	);

	/// Performs general number and type checks of arguments against function call and struct ctor FunctionCall node parameters.
	void typeCheckFunctionGeneralChecks(
		FunctionCall const& _functionCall,
		FunctionTypePointer _functionType
	);

	/// Performs general checks and checks specific to ABI encode functions
	void typeCheckABIEncodeFunctions(
		FunctionCall const& _functionCall,
		FunctionTypePointer _functionType
	);

	void endVisit(InheritanceSpecifier const& _inheritance) override;
	void endVisit(UsingForDirective const& _usingFor) override;
	bool visit(StructDefinition const& _struct) override;
	bool visit(FunctionDefinition const& _function) override;
	bool visit(VariableDeclaration const& _variable) override;
	/// We need to do this manually because we want to pass the bases of the current contract in
	/// case this is a base constructor call.
	void visitManually(ModifierInvocation const& _modifier, std::vector<ContractDefinition const*> const& _bases);
	bool visit(EventDefinition const& _eventDef) override;
	void endVisit(FunctionTypeName const& _funType) override;
	bool visit(InlineAssembly const& _inlineAssembly) override;
	bool visit(IfStatement const& _ifStatement) override;
	bool visit(WhileStatement const& _whileStatement) override;
	bool visit(ForStatement const& _forStatement) override;
	void endVisit(Return const& _return) override;
	bool visit(EmitStatement const&) override { m_insideEmitStatement = true; return true; }
	void endVisit(EmitStatement const& _emit) override;
	bool visit(VariableDeclarationStatement const& _variable) override;
	void endVisit(ExpressionStatement const& _statement) override;
	bool visit(Conditional const& _conditional) override;
	bool visit(Assignment const& _assignment) override;
	bool visit(TupleExpression const& _tuple) override;
	void endVisit(BinaryOperation const& _operation) override;
	bool visit(UnaryOperation const& _operation) override;
	bool visit(FunctionCall const& _functionCall) override;
	void endVisit(NewExpression const& _newExpression) override;
	bool visit(MemberAccess const& _memberAccess) override;
	bool visit(IndexAccess const& _indexAccess) override;
	bool visit(Identifier const& _identifier) override;
	void endVisit(ElementaryTypeNameExpression const& _expr) override;
	void endVisit(Literal const& _literal) override;

	bool contractDependenciesAreCyclic(
		ContractDefinition const& _contract,
		std::set<ContractDefinition const*> const& _seenContracts = std::set<ContractDefinition const*>()
	) const;

	/// @returns the referenced declaration and throws on error.
	Declaration const& dereference(Identifier const& _identifier) const;
	/// @returns the referenced declaration and throws on error.
	Declaration const& dereference(UserDefinedTypeName const& _typeName) const;

	/// Runs type checks on @a _expression to infer its type and then checks that it is implicitly
	/// convertible to @a _expectedType.
	bool expectType(Expression const& _expression, Type const& _expectedType);
	/// Runs type checks on @a _expression to infer its type and then checks that it is an LValue.
	void requireLValue(Expression const& _expression);

	ContractDefinition const* m_scope = nullptr;

	EVMVersion m_evmVersion;

	/// Flag indicating whether we are currently inside an EmitStatement.
	bool m_insideEmitStatement = false;

	/// Flag indicating whether we are currently inside a StructDefinition.
	bool m_insideStruct = false;

	langutil::ErrorReporter& m_errorReporter;
};

}
}