// Licensed to the .NET Foundation under one or more agreements.
// The .NET Foundation licenses this file to you under the MIT license.
 
using System;
using Microsoft.Build.BackEnd.Logging;
using Microsoft.Build.Shared;
 
#nullable disable
 
namespace Microsoft.Build.Evaluation
{
    /// <summary>
    /// Base class for all expression nodes.
    /// </summary>
    internal abstract class GenericExpressionNode
    {
        internal abstract bool TryBoolEvaluate(ConditionEvaluator.IConditionEvaluationState state, out bool result);
        internal abstract bool TryNumericEvaluate(ConditionEvaluator.IConditionEvaluationState state, out double result);
        internal abstract bool TryVersionEvaluate(ConditionEvaluator.IConditionEvaluationState state, out Version result);
 
        /// <summary>
        /// Returns true if this node evaluates to an empty string,
        /// otherwise false.
        /// (It may be cheaper to determine whether an expression will evaluate
        /// to empty than to fully evaluate it.)
        /// Implementations should cache the result so that calls after the first are free.
        /// </summary>
        internal virtual bool EvaluatesToEmpty(ConditionEvaluator.IConditionEvaluationState state)
        {
            return false;
        }
 
        /// <summary>
        /// Value after any item and property expressions are expanded
        /// </summary>
        /// <returns></returns>
        internal abstract string GetExpandedValue(ConditionEvaluator.IConditionEvaluationState state);
 
        /// <summary>
        /// Value before any item and property expressions are expanded
        /// </summary>
        /// <returns></returns>
        internal abstract string GetUnexpandedValue(ConditionEvaluator.IConditionEvaluationState state);
 
        /// <summary>
        /// Checks if value is empty before any item and property expressions are expanded
        /// </summary>
        /// <returns></returns>
        internal abstract bool IsUnexpandedValueEmpty();
 
        /// <summary>
        /// If any expression nodes cache any state for the duration of evaluation,
        /// now's the time to clean it up
        /// </summary>
        internal abstract void ResetState();
 
        /// <summary>
        /// The main evaluate entry point for expression trees
        /// </summary>
        /// <param name="state"></param>
        /// <returns></returns>
        internal bool Evaluate(ConditionEvaluator.IConditionEvaluationState state)
        {
            if (!TryBoolEvaluate(state, out bool boolValue))
            {
                ProjectErrorUtilities.ThrowInvalidProject(
                    state.ElementLocation,
                    "ConditionNotBooleanDetail",
                    state.Condition,
                    GetExpandedValue(state));
            }
 
            return boolValue;
        }
 
        /// <summary>
        /// Get display string for this node for use in the debugger.
        /// </summary>
        internal virtual string DebuggerDisplay { get; }
 
 
        #region REMOVE_COMPAT_WARNING
        internal virtual bool PossibleAndCollision
        {
            set { /* do nothing */ }
            get { return false; }
        }
 
        internal virtual bool PossibleOrCollision
        {
            set { /* do nothing */ }
            get { return false; }
        }
 
        internal bool PotentialAndOrConflict()
        {
            // The values of the functions are assigned to boolean locals
            // in order to force evaluation of the functions even when the
            // first one returns false
            bool detectOr = DetectOr();
            bool detectAnd = DetectAnd();
            return detectOr && detectAnd;
        }
 
        internal abstract bool DetectOr();
        internal abstract bool DetectAnd();
        #endregion
 
    }
}