using System;
using System.Linq;
using SharpDlt.Headers;
using Shouldly;
using Xunit;

namespace SharpDlt.Tests;

public class StorageHeaderTests
{
    [Fact]
    public void Parse_ReadsAllFields()
    {
        var data = TestDlt.StorageHeader(seconds: 1_600_000_000, microseconds: 123_456, ecuId: "ECU");

        var header = StorageHeader.Parse(data);

        header.Seconds.ShouldBe(1_600_000_000u);
        header.Microseconds.ShouldBe(123_456);
        header.EcuId.ShouldBe("ECU");
    }

    [Fact]
    public void Parse_StripsNulPaddingOfEcuId()
    {
        var data = TestDlt.StorageHeader(ecuId: "AB");

        StorageHeader.Parse(data).EcuId.ShouldBe("AB");
    }

    [Fact]
    public void Parse_IgnoresTrailingData()
    {
        var data = TestDlt.StorageHeader().Concat<byte>([1, 2, 3]).ToArray();

        StorageHeader.Parse(data).EcuId.ShouldBe("ECU1");
    }

    [Fact]
    public void Timestamp_CombinesSecondsAndMicroseconds()
    {
        var header = new StorageHeader(1_600_000_000, 500_000, "ECU1");

        header.Timestamp.ShouldBe(DateTimeOffset.FromUnixTimeSeconds(1_600_000_000).AddMilliseconds(500));
    }

    [Fact]
    public void Parse_TooShortData_Throws()
    {
        var data = TestDlt.StorageHeader()[..15];

        Should.Throw<DltParseException>(() => StorageHeader.Parse(data));
    }

    [Fact]
    public void Parse_WithoutDltPattern_Throws()
    {
        var data = TestDlt.StorageHeader();
        data[0] = (byte)'X';

        Should.Throw<DltParseException>(() => StorageHeader.Parse(data));
    }

    [Fact]
    public void Equality_IsByValue()
    {
        new StorageHeader(1, 2, "ECU1").ShouldBe(new StorageHeader(1, 2, "ECU1"));
        new StorageHeader(1, 2, "ECU1").ShouldNotBe(new StorageHeader(1, 3, "ECU1"));
    }
}