Hastlayer-SDK

using Hast.Layer;
using System;
using System.Diagnostics;
using System.Linq.Expressions;

namespace Hast.Transformer.Configuration;

[DebuggerDisplay("{MemberNamePrefix + \": \" + MaxInvocationInstanceCount}")]
public class MemberInvocationInstanceCountConfiguration
{
    /// <summary>
    /// Gets the prefix of the member's name. Use the same convention as with <see
    /// cref="HardwareGenerationConfiguration.HardwareEntryPointMemberNamePrefixes"/>. For lambda expressions use the
    /// pattern "Hast.Samples.SampleAssembly.PrimeCalculator.ParallelizedArePrimeNumbers.LambdaExpression.0", i.e.
    /// specify the name prefix of the calling member, then add ".LambdaExpression" and finally add the lambda's index
    /// inside the calling member (so if it's the first lambda in the member then it should have the index 0, if it's
    /// the second, the index 1 and so on).
    /// </summary>
    public string MemberNamePrefix { get; private set; }

    /// <summary>
    /// Gets or sets the maximal recursion depth of the member. When using (even indirectly) recursive invocations
    /// between members set the maximal depth here.
    /// </summary>
    /// <example>
    /// A value of 3 would mean that the member can invoke itself three times recursively, i.e. there is the member,
    /// then it calls itself (depth 1), then it calls itself (depth 2), then it calls itself (depth 3) before returning.
    /// </example>
    public int MaxRecursionDepth { get; set; }

    private int _maxDegreeOfParallelism;

    /// <summary>
    /// Gets or sets the maximal degree of parallelism that will be attempted to build into the generated hardware when
    /// constructs suitable for hardware-level parallelisation are found.
    /// </summary>
    /// <example>A value of 3 would mean that maximally 3 instances will be able to be executed in parallel.</example>
    public int MaxDegreeOfParallelism
    {
        get => _maxDegreeOfParallelism;
        set
        {
            if (value < 1)
            {
                throw new ArgumentOutOfRangeException(
                    nameof(MaxDegreeOfParallelism),
                    "The max degree of parallelism should be at least 1, otherwise the member wouldn't be " +
                    "transformed at all.");
            }

            _maxDegreeOfParallelism = value;
        }
    }

    public int MaxInvocationInstanceCount => (MaxRecursionDepth + 1) * MaxDegreeOfParallelism;

    /// <summary>
    /// Initializes a new instance of the <see cref="MemberInvocationInstanceCountConfiguration"/> class.
    /// </summary>
    /// <param name="memberNamePrefix">
    /// The prefix of the member's name. Use the same convention as with <see cref="MemberNamePrefix"/>.
    /// </param>
    public MemberInvocationInstanceCountConfiguration(string memberNamePrefix)
    {
        MemberNamePrefix = memberNamePrefix;
        MaxDegreeOfParallelism = 1;
    }

    /// <summary>
    /// Adds the index of a lambda expression to the simple name of a member, to be used as the member name prefix when
    /// constructing a <see cref="MemberInvocationInstanceCountConfiguration"/>.
    /// </summary>
    public static string AddLambdaExpressionIndexToSimpleName(string simpleName, int lambdaExpressionIndex) =>
        FormattableString.Invariant($"{simpleName}.LambdaExpression.{lambdaExpressionIndex}");
}

public class MemberInvocationInstanceCountConfigurationForMethod<T> : MemberInvocationInstanceCountConfiguration
{
    /// <summary>
    /// Initializes a new instance of the <see cref="MemberInvocationInstanceCountConfigurationForMethod{T}"/> class.
    /// </summary>
    /// <param name="methodNamePrefix">The prefix of the method's name (or methods' names).</param>
    public MemberInvocationInstanceCountConfigurationForMethod(
        string methodNamePrefix)
        : base(typeof(T).FullName + "." + methodNamePrefix) { }

    /// <summary>
    /// Initializes a new instance of the <see cref="MemberInvocationInstanceCountConfigurationForMethod{T}"/> class.
    /// </summary>
    /// <param name="expression">An expression with a call to the method.</param>
    public MemberInvocationInstanceCountConfigurationForMethod(
        Expression<Action<T>> expression)
        : base(expression.GetMethodSimpleName()) { }

    /// <summary>
    /// Initializes a new instance of the <see cref="MemberInvocationInstanceCountConfigurationForMethod{T}"/> class.
    /// </summary>
    /// <param name="expression">An expression with a call to the method.</param>
    /// <param name="lambdaExpressionIndex">
    /// The lambda expression's zero-based index (i.e. is it the 0th, or 1st lambda in the method?).
    /// </param>
    public MemberInvocationInstanceCountConfigurationForMethod(
        Expression<Action<T>> expression, int lambdaExpressionIndex)
        : base(AddLambdaExpressionIndexToSimpleName(expression.GetMethodSimpleName(), lambdaExpressionIndex)) { }
}