/*
* All or portions of this file Copyright (c) Amazon.com, Inc. or its affiliates or
* its licensors.
*
* For complete copyright and license terms please see the LICENSE at the root of this
* distribution (the "License"). All use of this software is governed by the License,
* or, if provided, by the license below or the license accompanying this file. Do not
* remove or modify any license notices. This file is distributed on an "AS IS" BASIS,
* WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
*
*/
// Original file Copyright Crytek GMBH or its affiliates, used under license.

#ifndef CRYINCLUDE_CRYAISYSTEM_SELECTIONTREE_SELECTIONCONDITION_H
#define CRYINCLUDE_CRYAISYSTEM_SELECTIONTREE_SELECTIONCONDITION_H
#pragma once

/*
    Simple logical expression for use as node conditions in the selection tree.
    The expression is pre-compiled and stored as a vector of byte-code ops.
*/

class SimpleLexer;
class SelectionVariables;
class SelectionVariableDeclarations;

class SelectionCondition
{
    struct ConditionOp;
public:
    SelectionCondition();
    SelectionCondition(const char* condition, const SelectionVariableDeclarations& variables);

    bool Evaluate(const SelectionVariables& variables) const;
    bool Valid() const;

private:
    int AddOp(const ConditionOp& op);
    int ParseLogical(SimpleLexer& lex, int tok, const SelectionVariableDeclarations& variables);
    int ParseCompOp(SimpleLexer& lex, int tok, const SelectionVariableDeclarations& variables);
    int ParseUnary(SimpleLexer& lex, int tok, const SelectionVariableDeclarations& variables);
    int ParseValue(SimpleLexer& lex, int tok, const SelectionVariableDeclarations& variables);
    int Parse(const char* condition, const SelectionVariableDeclarations& variables);
    void Optimise();

    bool EvaluateOp(const SelectionVariables& variables, const struct ConditionOp& op) const;

    struct ConditionOp
    {
        enum Type
        {
            Not = 1,
            And,
            Or,
            Xor,
            Equal,
            NotEqual,
            Constant,
            Variable,
        };

        ConditionOp()
            : value(false)
        {
        }

        ConditionOp(int type, int left, int right)
            : value(false)
            , opType((Type)type)
            , operandLeft((uint8)left)
            , operandRight((uint8)right)
        {
        }

        ConditionOp(int type, uint32 varID)
            : variableID(varID)
            , value(false)
            , opType((Type)type)
        {
        }

        ConditionOp(int type, bool val)
            : value(val)
            , opType((Type)type)
        {
        }

        uint32 variableID;
        bool value;

        uint8 opType;
        uint8 operandLeft;
        uint8 operandRight;
    };

    typedef std::vector<ConditionOp> ConditionOps;
    ConditionOps m_conditionOps;
    int m_rootID;
};

DECLARE_SMART_POINTERS(SelectionCondition)

#endif // CRYINCLUDE_CRYAISYSTEM_SELECTIONTREE_SELECTIONCONDITION_H