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/*
    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/>.
*/
/**
 * @date 2017
 * Abstract assembly interface, subclasses of which are to be used with the generic
 * bytecode generator.
 */

#pragma once

#include <libdevcore/CommonData.h>

#include <functional>

namespace dev
{
struct SourceLocation;
namespace solidity
{
enum class Instruction: uint8_t;
namespace assembly
{
struct Instruction;
struct Identifier;
}
}
namespace julia
{

///
/// Assembly class that abstracts both the libevmasm assembly and the new Yul assembly.
///
class AbstractAssembly
{
public:
    using LabelID = size_t;

    virtual ~AbstractAssembly() {}

    /// Set a new source location valid starting from the next instruction.
    virtual void setSourceLocation(SourceLocation const& _location) = 0;
    /// Retrieve the current height of the stack. This does not have to be zero
    /// at the beginning.
    virtual int stackHeight() const = 0;
    /// Append an EVM instruction.
    virtual void appendInstruction(solidity::Instruction _instruction) = 0;
    /// Append a constant.
    virtual void appendConstant(u256 const& _constant) = 0;
    /// Append a label.
    virtual void appendLabel(LabelID _labelId) = 0;
    /// Append a label reference.
    virtual void appendLabelReference(LabelID _labelId) = 0;
    /// Generate a new unique label.
    virtual LabelID newLabelId() = 0;
    /// Returns a label identified by the given name. Creates it if it does not yet exist.
    virtual LabelID namedLabel(std::string const& _name) = 0;
    /// Append a reference to a to-be-linked symbol.
    /// Currently, we assume that the value is always a 20 byte number.
    virtual void appendLinkerSymbol(std::string const& _name) = 0;

    /// Append a jump instruction.
    /// @param _stackDiffAfter the stack adjustment after this instruction.
    /// This is helpful to stack height analysis if there is no continuing control flow.
    virtual void appendJump(int _stackDiffAfter) = 0;

    /// Append a jump-to-immediate operation.
    /// @param _stackDiffAfter the stack adjustment after this instruction.
    virtual void appendJumpTo(LabelID _labelId, int _stackDiffAfter = 0) = 0;
    /// Append a jump-to-if-immediate operation.
    virtual void appendJumpToIf(LabelID _labelId) = 0;
    /// Start a subroutine identified by @a _labelId that takes @a _arguments
    /// stack slots as arguments.
    virtual void appendBeginsub(LabelID _labelId, int _arguments) = 0;
    /// Call a subroutine identified by @a _labelId, taking @a _arguments from the
    /// stack upon call and putting @a _returns arguments onto the stack upon return.
    virtual void appendJumpsub(LabelID _labelId, int _arguments, int _returns) = 0;
    /// Return from a subroutine.
    /// @param _stackDiffAfter the stack adjustment after this instruction.
    virtual void appendReturnsub(int _returns, int _stackDiffAfter = 0) = 0;

    /// Append the assembled size as a constant.
    virtual void appendAssemblySize() = 0;
};

enum class IdentifierContext { LValue, RValue };

/// Object that is used to resolve references and generate code for access to identifiers external
/// to inline assembly (not used in standalone assembly mode).
struct ExternalIdentifierAccess
{
    using Resolver = std::function<size_t(solidity::assembly::Identifier const&, IdentifierContext, bool /*_crossesFunctionBoundary*/)>;
    /// Resolve an external reference given by the identifier in the given context.
    /// @returns the size of the value (number of stack slots) or size_t(-1) if not found.
    Resolver resolve;
    using CodeGenerator = std::function<void(solidity::assembly::Identifier const&, IdentifierContext, julia::AbstractAssembly&)>;
    /// Generate code for retrieving the value (rvalue context) or storing the value (lvalue context)
    /// of an identifier. The code should be appended to the assembly. In rvalue context, the value is supposed
    /// to be put onto the stack, in lvalue context, the value is assumed to be at the top of the stack.
    CodeGenerator generateCode;
};



}
}