feat(core): add log providers for journal and file sources

src/Vantage.Core/Logs/MockLogProvider.cs

@@ -0,0 +1,50 @@
+using Vantage.Core.Models;
+
+namespace Vantage.Core.Logs;
+
+public sealed class MockLogProvider : ILogProvider
+{
+    private static readonly string[] Templates =
+    {
+        "Started session {0} of user foksiu.",
+        "Accepted publickey for foksiu from 10.10.0.4 port {0}",
+        "GET /api/status 200 {0}ms",
+        "connection pool exhausted, retrying in {0}ms",
+        "flushed {0} pending writes to disk",
+        "renewed certificate, valid for {0} days",
+        "healthcheck ok, latency {0}ms"
+    };
+
+    private readonly Func<DateTimeOffset> clock;
+
+    public MockLogProvider(Func<DateTimeOffset>? clock = null)
+    {
+        this.clock = clock ?? (() => DateTimeOffset.UtcNow);
+    }
+
+    public Task<IReadOnlyList<LogLine>> ReadAsync(
+        HostConfig host,
+        LogSource source,
+        LogQuery query,
+        CancellationToken cancellationToken)
+    {
+        var random = new Random(source.Target.Length * 31 + query.Lines);
+        var unit = source.Kind == LogSourceKind.JournalUnit ? source.Target : "file";
+        var now = clock();
+        var count = Math.Clamp(query.Lines, 1, 200);
+
+        var lines = new List<LogLine>();
+        for (var i = count; i > 0; i--)
+        {
+            var timestamp = now.AddSeconds(-i * 3);
+            var message = string.Format(Templates[random.Next(Templates.Length)], random.Next(1, 4000));
+            var raw = $"{timestamp:yyyy-MM-ddTHH:mm:sszzz} {host.Name} {unit}[{1000 + i}]: {message}";
+            lines.Add(new LogLine(timestamp, unit, message, raw));
+        }
+
+        if (!string.IsNullOrWhiteSpace(query.Filter))
+            lines = lines.Where(l => l.Raw.Contains(query.Filter!, StringComparison.OrdinalIgnoreCase)).ToList();
+
+        return Task.FromResult<IReadOnlyList<LogLine>>(lines);
+    }
+}

src/Vantage.Core/Logs/SshLogProvider.cs

@@ -0,0 +1,25 @@
+using Vantage.Core.Models;
+using Vantage.Core.Ssh;
+
+namespace Vantage.Core.Logs;
+
+public sealed class SshLogProvider : ILogProvider
+{
+    private readonly ISshCommandRunner runner;
+
+    public SshLogProvider(ISshCommandRunner runner)
+    {
+        this.runner = runner;
+    }
+
+    public async Task<IReadOnlyList<LogLine>> ReadAsync(
+        HostConfig host,
+        LogSource source,
+        LogQuery query,
+        CancellationToken cancellationToken)
+    {
+        var command = LogCommand.Build(source, query);
+        var output = await runner.RunAsync(host, command, cancellationToken).ConfigureAwait(false);
+        return LogLineParser.Parse(output);
+    }
+}