// Generated from executable documentation examples. Edit the source region, then regenerate.
using System;
using System.IO;
using System.IO.Pipelines;
using System.Linq;
using System.Buffers;
using System.Collections.Generic;
using System.Dynamic;
using System.Globalization;
using System.Numerics;
using System.Runtime.CompilerServices;
using System.Threading;
using System.Threading.Tasks;
using CStructSharp;
using CStructSharp.Codecs;
using CStructSharp.Diagnostics;
using CStructSharp.Introspection;
using CStructSharp.Values;

internal static partial class Program
{
    public static void Main()
    {
        RecognizeFormat();
        Console.WriteLine("PASS recognize-format");
    }

    /// <summary>Recognizes a format by its magic with Matches, and reads the failure of a wrong magic.</summary>
    private static void RecognizeFormat()
    {
        byte[] ext = [0x10, 0x00, 0x00, 0x00, 0x53, 0xEF, 0x01, 0x00];
        byte[] other = [0x10, 0x00, 0x00, 0x00, 0x00, 0x00, 0x01, 0x00];

        // Matches decodes only the magic: no value is built and nothing is thrown, for wrong or short input alike.
        True(Disk.Matches(ext), "the magic is there");
        True(!Disk.Matches(other), "the magic is wrong");
        True(!Disk.Matches(ext.AsSpan(0, 5)), "the magic is cut off");
        Equal(0xEF53, Disk.EXT_MAGIC);

        // A broken magic is reported with the label and message the layout gave it.
        True(!Disk.TryParse(other, out _, out CStructException? failure), "the read stops at the magic");
        var constraint = (CStructConstraintException)failure!;
        Equal("ext.magic", constraint.Label);
        Equal("not an ext superblock", constraint.Description);

        // A layout compiled at run time answers the same question.
        var layout = new CStruct(Disk.Definition);
        True(layout.Matches("superblock", ext), "same answer at run time");
        True(!layout.Matches("superblock", other), "same answer at run time");
    }

    private static void Equal<T>(T expected, T actual)
    {
        if (!EqualityComparer<T>.Default.Equals(expected, actual))
        {
            throw new InvalidOperationException($"Expected '{expected}', received '{actual}'.");
        }
    }

    private static void True(bool condition, string message)
    {
        if (!condition)
        {
            throw new InvalidOperationException(message);
        }
    }

    // A magic names the format: it is checked first, and Matches answers from it alone. The #define becomes the constant Disk.EXT_MAGIC.
    /// <summary>A layout whose magic names the format and whose #define is a constant of the class.</summary>
    [CStructLayout("#define EXT_MAGIC 0xEF53\nstruct superblock { uint32 inodes; uint16 magic @magic(magic == EXT_MAGIC, \"ext.magic\", \"not an ext superblock\"); uint16 state @expect(state <= 2, \"ext.state\"); };", Root = "superblock", Surface = GeneratedSurface.Reader)]
    public static partial class Disk
    {
    }
}