using Shouldly;
using Xunit;
using ZB.MOM.WW.OtOpcUa.Admin.Hubs;

namespace ZB.MOM.WW.OtOpcUa.Admin.Tests;

/// <summary>
///     Unit tests for <see cref="ScriptLogHub"/> helper logic — line parsing, filter matching,
///     and the tail/append file reading utilities. The SignalR streaming method itself
///     (TailLogAsync) is not integration-tested here; the helpers are tested in isolation.
/// </summary>
[Trait("Category", "Unit")]
public sealed class ScriptLogHubTests
{
    // ── ParseLine ──────────────────────────────────────────────────────────────

    [Fact]
    public void ParseLine_extracts_INF_level_from_serilog_format()
    {
        var line = ScriptLogHub.ParseLine("[12:34:56 INF] Script ran successfully");
        line.Level.ShouldBe("INF");
    }

    [Fact]
    public void ParseLine_extracts_WRN_level()
    {
        var line = ScriptLogHub.ParseLine("2026-05-18T12:34:56.000Z [WRN] Script timed out");
        line.Level.ShouldBe("WRN");
    }

    [Fact]
    public void ParseLine_extracts_ERR_level()
    {
        var line = ScriptLogHub.ParseLine("[ERR] NullReferenceException in script");
        line.Level.ShouldBe("ERR");
    }

    [Fact]
    public void ParseLine_defaults_to_INF_when_no_level_token()
    {
        var line = ScriptLogHub.ParseLine("Some unformatted log text with no level");
        line.Level.ShouldBe("INF");
    }

    [Fact]
    public void ParseLine_extracts_ScriptName_property()
    {
        var raw = """[INF] Evaluation complete ScriptName="line-rate-calc" Value=42""";
        var line = ScriptLogHub.ParseLine(raw);
        line.ScriptName.ShouldBe("line-rate-calc");
    }

    [Fact]
    public void ParseLine_ScriptName_is_null_when_property_absent()
    {
        var raw = "[INF] Server started";
        var line = ScriptLogHub.ParseLine(raw);
        line.ScriptName.ShouldBeNull();
    }

    [Fact]
    public void ParseLine_preserves_Raw_text_unchanged()
    {
        var raw = "[WRN] Script error ScriptName=\"my-alarm\" Details=\"bad value\"";
        var line = ScriptLogHub.ParseLine(raw);
        line.Raw.ShouldBe(raw);
    }

    // ── Matches ────────────────────────────────────────────────────────────────

    [Fact]
    public void Matches_null_filter_accepts_all_lines()
    {
        var line = new ScriptLogLine("raw", "INF", null, DateTime.UtcNow);
        ScriptLogHub.Matches(line, null).ShouldBeTrue();
    }

    [Fact]
    public void Matches_empty_filter_accepts_all_lines()
    {
        var line = new ScriptLogLine("raw", "INF", "some-script", DateTime.UtcNow);
        ScriptLogHub.Matches(line, "").ShouldBeTrue();
    }

    [Fact]
    public void Matches_whitespace_filter_accepts_all_lines()
    {
        var line = new ScriptLogLine("raw", "INF", null, DateTime.UtcNow);
        ScriptLogHub.Matches(line, "   ").ShouldBeTrue();
    }

    [Fact]
    public void Matches_filter_matches_script_name_case_insensitive()
    {
        var line = new ScriptLogLine("raw", "INF", "line-rate-calc", DateTime.UtcNow);
        ScriptLogHub.Matches(line, "Line-Rate").ShouldBeTrue();
    }

    [Fact]
    public void Matches_filter_rejects_line_with_different_script_name()
    {
        var line = new ScriptLogLine("raw", "INF", "oven-temp-alarm", DateTime.UtcNow);
        ScriptLogHub.Matches(line, "line-rate").ShouldBeFalse();
    }

    [Fact]
    public void Matches_filter_rejects_line_with_null_script_name()
    {
        var line = new ScriptLogLine("raw", "INF", null, DateTime.UtcNow);
        ScriptLogHub.Matches(line, "line-rate").ShouldBeFalse();
    }

    [Fact]
    public void Matches_filter_supports_partial_match()
    {
        var line = new ScriptLogLine("raw", "INF", "line-rate-calc", DateTime.UtcNow);
        ScriptLogHub.Matches(line, "rate").ShouldBeTrue();
    }

    // ── ReadTailLines / ReadNewLines ──────────────────────────────────────────

    [Fact]
    public void ReadTailLines_returns_empty_list_for_empty_file()
    {
        var path = Path.GetTempFileName();
        try
        {
            File.WriteAllText(path, string.Empty);
            var lines = ScriptLogHub.ReadTailLines(path, 50, out var pos);
            lines.ShouldBeEmpty();
            pos.ShouldBe(0);
        }
        finally { File.Delete(path); }
    }

    [Fact]
    public void ReadTailLines_returns_all_lines_when_fewer_than_n()
    {
        var path = Path.GetTempFileName();
        try
        {
            File.WriteAllLines(path, ["line1", "line2", "line3"]);
            var lines = ScriptLogHub.ReadTailLines(path, 50, out _);
            lines.ShouldContain("line1");
            lines.ShouldContain("line2");
            lines.ShouldContain("line3");
        }
        finally { File.Delete(path); }
    }

    [Fact]
    public void ReadTailLines_returns_last_n_lines_when_file_is_large()
    {
        var path = Path.GetTempFileName();
        try
        {
            var allLines = Enumerable.Range(1, 20).Select(i => $"line{i}").ToArray();
            File.WriteAllLines(path, allLines);
            var lines = ScriptLogHub.ReadTailLines(path, 5, out _);
            lines.Count.ShouldBe(5);
            lines[^1].ShouldBe("line20");
        }
        finally { File.Delete(path); }
    }

    [Fact]
    public void ReadNewLines_returns_empty_when_nothing_appended()
    {
        var path = Path.GetTempFileName();
        try
        {
            File.WriteAllText(path, "existing content\n");
            ScriptLogHub.ReadTailLines(path, 10, out var pos);  // seed position
            var newLines = ScriptLogHub.ReadNewLines(path, ref pos);
            newLines.ShouldBeEmpty();
        }
        finally { File.Delete(path); }
    }

    [Fact]
    public void ReadNewLines_returns_appended_lines()
    {
        var path = Path.GetTempFileName();
        try
        {
            File.WriteAllText(path, "existing\n");
            ScriptLogHub.ReadTailLines(path, 10, out var pos);  // set position to end

            // Append new content
            File.AppendAllText(path, "appended-line-1\nappended-line-2\n");

            var newLines = ScriptLogHub.ReadNewLines(path, ref pos);
            newLines.ShouldContain("appended-line-1");
            newLines.ShouldContain("appended-line-2");
        }
        finally { File.Delete(path); }
    }
}