using SuiteLink.Client.Protocol;

namespace SuiteLink.Client.Tests.Protocol;

public sealed class SuiteLinkConnectCodecTests
{
    [Fact]
    public void EncodeConnect_WritesConnectMessageTypeAndEndMarker()
    {
        var options = new SuiteLinkConnectionOptions(
            host: "127.0.0.1",
            application: "App",
            topic: "Topic",
            clientName: "Client",
            clientNode: "Node",
            userName: "User",
            serverNode: "Server",
            timezone: "UTC");

        var bytes = SuiteLinkConnectCodec.Encode(options);

        Assert.Equal(0x80, bytes[2]);
        Assert.Equal(0x01, bytes[3]);
        Assert.Equal(0xA5, bytes[^1]);
    }

    [Fact]
    public void EncodeConnect_WritesExpectedFieldOrderReservedSegmentsAndTimezoneStrings()
    {
        var options = new SuiteLinkConnectionOptions(
            host: "127.0.0.1",
            application: "App",
            topic: "Topic",
            clientName: "Client",
            clientNode: "Node",
            userName: "User",
            serverNode: "Server",
            timezone: "UTC");

        var bytes = SuiteLinkConnectCodec.Encode(options);
        var frame = SuiteLinkFrameReader.ParseFrame(bytes);
        var payload = frame.Payload.Span;
        var index = 0;

        var app = SuiteLinkEncoding.EncodeLengthPrefixedUtf16("App");
        Assert.True(payload[index..].StartsWith(app));
        index += app.Length;

        var topic = SuiteLinkEncoding.EncodeLengthPrefixedUtf16("Topic");
        Assert.True(payload[index..].StartsWith(topic));
        index += topic.Length;

        Assert.True(payload[index..(index + 3)].ToArray().All(static b => b == 0x00));
        index += 3;

        var client = SuiteLinkEncoding.EncodeLengthPrefixedUtf16("Client");
        Assert.True(payload[index..].StartsWith(client));
        index += client.Length;

        var clientNode = SuiteLinkEncoding.EncodeLengthPrefixedUtf16("Node");
        Assert.True(payload[index..].StartsWith(clientNode));
        index += clientNode.Length;

        var user = SuiteLinkEncoding.EncodeLengthPrefixedUtf16("User");
        Assert.True(payload[index..].StartsWith(user));
        index += user.Length;

        var serverNode = SuiteLinkEncoding.EncodeLengthPrefixedUtf16("Server");
        Assert.True(payload[index..].StartsWith(serverNode));
        index += serverNode.Length;

        Assert.True(payload[index..(index + 20)].ToArray().All(static b => b == 0x00));
        index += 20;

        var timezone1 = SuiteLinkEncoding.DecodeNullTerminatedUtf16(payload[index..], out var timezone1ConsumedBytes);
        index += timezone1ConsumedBytes;
        Assert.Equal("UTC", timezone1);

        Assert.True(payload[index..(index + 38)].ToArray().All(static b => b == 0x00));
        index += 38;

        var timezone2 = SuiteLinkEncoding.DecodeNullTerminatedUtf16(payload[index..], out var timezone2ConsumedBytes);
        index += timezone2ConsumedBytes;
        Assert.Equal("UTC", timezone2);
        Assert.Equal(timezone1, timezone2);

        Assert.Equal(payload.Length, index);
    }

    [Fact]
    public void EncodeConnect_WhenTimezoneNotProvided_UsesUtcDefault()
    {
        var options = new SuiteLinkConnectionOptions(
            host: "127.0.0.1",
            application: "App",
            topic: "Topic",
            clientName: "Client",
            clientNode: "Node",
            userName: "User",
            serverNode: "Server");

        var frame = SuiteLinkFrameReader.ParseFrame(SuiteLinkConnectCodec.Encode(options));
        var payload = frame.Payload.Span;
        var index = 0;

        index += SuiteLinkEncoding.EncodeLengthPrefixedUtf16("App").Length;
        index += SuiteLinkEncoding.EncodeLengthPrefixedUtf16("Topic").Length;
        index += 3;
        index += SuiteLinkEncoding.EncodeLengthPrefixedUtf16("Client").Length;
        index += SuiteLinkEncoding.EncodeLengthPrefixedUtf16("Node").Length;
        index += SuiteLinkEncoding.EncodeLengthPrefixedUtf16("User").Length;
        index += SuiteLinkEncoding.EncodeLengthPrefixedUtf16("Server").Length;
        index += 20;

        var timezone1 = SuiteLinkEncoding.DecodeNullTerminatedUtf16(payload[index..], out var timezone1ConsumedBytes);
        index += timezone1ConsumedBytes + 38;
        var timezone2 = SuiteLinkEncoding.DecodeNullTerminatedUtf16(payload[index..], out _);

        Assert.Equal("UTC", timezone1);
        Assert.Equal("UTC", timezone2);
    }
}