using System.Net;
using System.Net.Sockets;
using System.Text;
using System.Text.Json;
using ZB.MOM.WW.ScadaBridge.CLI.Commands;

namespace ZB.MOM.WW.ScadaBridge.CLI.Tests.Commands;

/// <summary>
/// Tests for <c>scadabridge audit verify-heads</c> (ScadaBridge#107 item 1): reading off-box
/// exported chain heads (file-sink lines and syslog-collector lines), collapsing duplicates,
/// sending <c>VerifyAuditChainHeads</c>, and mapping the verdict to the exit code.
/// </summary>
[Collection("Console")]
public sealed class AuditVerifyHeadsCommandTests : IDisposable
{
    private readonly DirectoryInfo _dir = Directory.CreateTempSubdirectory("verify-heads-");

    /// <inheritdoc />
    public void Dispose() => _dir.Delete(recursive: true);

    private static string Line(string month, long seq, char hash, string exportedAt = "2026-05-02T00:00:00Z", string node = "central-a") =>
        "{\"v\":1,\"month\":\"" + month + "\",\"lastSeq\":" + seq + ",\"lastHash\":\"" + new string(hash, 64)
        + "\",\"purgedThroughSeq\":null,\"purgedThroughHash\":null,\"chainedRows\":" + seq + ",\"tombstones\":0,"
        + "\"headUpdatedAtUtc\":\"2026-05-02T00:00:00Z\",\"exportedAtUtc\":\"" + exportedAt + "\",\"node\":\"" + node + "\"}";

    /// <summary>
    /// File-sink lines and RFC 5424 syslog lines both parse; junk is skipped; the same head
    /// exported by both nodes (and re-exported) collapses to one record.
    /// </summary>
    [Fact]
    public void ReadRecords_ParsesFileAndSyslogLines_SkipsJunk_AndCollapsesDuplicates()
    {
        Directory.CreateDirectory(Path.Combine(_dir.FullName, "2026"));
        File.WriteAllLines(Path.Combine(_dir.FullName, "2026", "audit-chain-heads-2026-05-02-central-a.jsonl"),
        [
            Line("2026-05", 10, 'a'),
            Line("2026-05", 12, 'b'),
            "not json at all",
            "",
        ]);
        File.WriteAllLines(Path.Combine(_dir.FullName, "syslog.log"),
        [
            "Nov 10 03:00:00 collector <109>1 2026-05-02T00:00:00.000Z central-b scadabridge 42 chainhead - "
                + Line("2026-05", 12, 'b', "2026-05-02T01:00:00Z", "central-b"),
            "<109>1 2026-05-02T00:00:00.000Z central-b scadabridge 42 chainhead - " + Line("2026-04", 7, 'c'),
        ]);
        File.WriteAllText(Path.Combine(_dir.FullName, "ignored.csv"), Line("2026-03", 1, 'd'));

        var read = AuditVerifyHeadsHelpers.ReadRecords(_dir.FullName);

        Assert.Equal(2, read.Files);
        Assert.Equal(4, read.LinesRead);
        Assert.Equal(1, read.LinesSkipped);
        Assert.Equal(["2026-04/7", "2026-05/10", "2026-05/12"], read.Records.Select(r => $"{r.Month}/{r.LastSeq}"));
        // The duplicate kept is the latest export.
        Assert.Equal("central-b", read.Records.Single(r => r.LastSeq == 12).Node);
    }

    /// <summary>A record missing its hash or sequence is not a record.</summary>
    /// <param name="line">The line.</param>
    [Theory]
    [InlineData("{\"v\":1,\"month\":\"2026-05\",\"lastSeq\":0,\"lastHash\":\"aa\"}")]
    [InlineData("{\"v\":1,\"month\":\"2026-05\",\"lastSeq\":3}")]
    [InlineData("{\"month\":\"2026-05\",\"lastSeq\":3,\"lastHash\":\"aa\"}")]
    [InlineData("{ broken")]
    public void TryParseLine_RejectsIncompleteRecords(string line)
    {
        Assert.Null(AuditVerifyHeadsHelpers.TryParseLine(line));
    }

    /// <summary>
    /// Round trip: the request carries <c>VerifyAuditChainHeads</c> with the distinct records,
    /// and the verdict drives the exit code (0 verified, 3 not).
    /// </summary>
    /// <param name="verified">Whether the fake server reports verified.</param>
    /// <param name="format">Output format.</param>
    /// <param name="expectedExit">Expected exit code.</param>
    /// <param name="expectedText">Text the report must contain.</param>
    /// <returns>A task that represents the asynchronous operation.</returns>
    [Theory]
    [InlineData(true, "table", 0, "Verified        : yes")]
    [InlineData(false, "table", 3, "Mismatch")]
    [InlineData(false, "json", 3, "\"verified\":false")]
    public async Task VerifyHeads_SendsTheRecords_AndMapsVerdictToExitCode(bool verified, string format, int expectedExit, string expectedText)
    {
        var file = Path.Combine(_dir.FullName, "heads.jsonl");
        File.WriteAllLines(file, [Line("2026-05", 12, 'b'), Line("2026-05", 12, 'b', "2026-05-02T02:00:00Z")]);
        var body = "{\"verified\":" + (verified ? "true" : "false") + ",\"recordsChecked\":1,\"checks\":[{\"month\":\"2026-05\","
            + "\"exportedSeq\":12,\"exportedAtUtc\":\"2026-05-02T02:00:00Z\",\"node\":\"central-a\",\"status\":\""
            + (verified ? "Matches" : "Mismatch") + "\",\"databaseSeq\":12,\"detail\":\"d\"}]}";

        var listener = new TcpListener(IPAddress.Loopback, 0);
        listener.Start();
        try
        {
            var port = ((IPEndPoint)listener.LocalEndpoint).Port;
            string? requestBody = null;
            var server = Task.Run(async () =>
            {
                using var client = await listener.AcceptTcpClientAsync();
                await using var stream = client.GetStream();
                using var reader = new StreamReader(stream, Encoding.UTF8, leaveOpen: true);
                var length = 0;
                while (await reader.ReadLineAsync() is { Length: > 0 } line)
                    if (line.StartsWith("Content-Length:", StringComparison.OrdinalIgnoreCase))
                        length = int.Parse(line[15..].Trim());
                var buffer = new char[length];
                var read = 0;
                while (read < length)
                {
                    var count = await reader.ReadAsync(buffer.AsMemory(read));
                    if (count == 0) throw new EndOfStreamException();
                    read += count;
                }
                requestBody = new string(buffer);
                var bytes = Encoding.UTF8.GetBytes(body);
                var headers = Encoding.ASCII.GetBytes(
                    $"HTTP/1.1 200 OK\r\nContent-Type: application/json\r\nContent-Length: {bytes.Length}\r\nConnection: close\r\n\r\n");
                await stream.WriteAsync(headers);
                await stream.WriteAsync(bytes);
            });

            var root = AuditCommandTestHarness.BuildRoot();
            var (exit, output, _) = AuditCommandTestHarness.Invoke(
                root, "audit", "verify-heads", "--path", file,
                "--url", $"http://127.0.0.1:{port}", "--username", "u", "--password", "p", "--format", format);
            await server.WaitAsync(TimeSpan.FromSeconds(5));

            Assert.Equal(expectedExit, exit);
            Assert.Contains(expectedText, output);
            using var payload = JsonDocument.Parse(requestBody!);
            Assert.Equal("VerifyAuditChainHeads", payload.RootElement.GetProperty("command").GetString());
            var records = payload.RootElement.GetProperty("payload").EnumerateObject()
                .First(p => string.Equals(p.Name, "records", StringComparison.OrdinalIgnoreCase)).Value;
            Assert.Equal(1, records.GetArrayLength());
            Assert.Equal(new string('b', 64), records[0].EnumerateObject()
                .First(p => string.Equals(p.Name, "lastHash", StringComparison.OrdinalIgnoreCase)).Value.GetString());
        }
        finally
        {
            listener.Stop();
        }
    }

    /// <summary>No records found is an input error, and nothing is sent.</summary>
    [Fact]
    public void VerifyHeads_NoRecords_ExitsOneWithoutContactingTheServer()
    {
        var file = Path.Combine(_dir.FullName, "empty.jsonl");
        File.WriteAllText(file, "nothing here\n");
        var root = AuditCommandTestHarness.BuildRoot();
        var (exit, _, _) = AuditCommandTestHarness.Invoke(
            root, "audit", "verify-heads", "--path", file, "--url", "http://127.0.0.1:1", "--username", "u", "--password", "p");

        Assert.Equal(1, exit);
    }
}