From 7c6009abd22d8461039be15d0fd069a460340585 Mon Sep 17 00:00:00 2001
From: Jake Mannens <jake@asger.xyz>
Date: Fri, 20 Sep 2024 16:13:30 +1000
Subject: v0.1

---
 PagerFetchService.cs | 62 ++++++++++++++++++++++++++++++++++++++++++++++++++++
 1 file changed, 62 insertions(+)
 create mode 100644 PagerFetchService.cs

(limited to 'PagerFetchService.cs')

diff --git a/PagerFetchService.cs b/PagerFetchService.cs
new file mode 100644
index 0000000..97a03d5
--- /dev/null
+++ b/PagerFetchService.cs
@@ -0,0 +1,62 @@
+using PagerParser.Sites;
+
+namespace PagerParser;
+
+// Self-explanatory... Hosted background services that periodically fetches
+// pager messages, tries to parse them, then adds both the raw pager message
+// as well as the parsed message contents to the DB, ignoring already fetched
+// messages in the process.
+public class PagerFetchService : IHostedService {
+    private readonly TimeSpan FetchInterval = TimeSpan.FromMinutes(15);
+
+    private IServiceProvider serviceProvider;
+    private IPagerMessageParserService parser;
+
+    private Timer fetchTimer;
+
+    private PagerMon pagerMon = new();
+
+    public PagerFetchService(IServiceProvider serviceProvider, IPagerMessageParserService parser) {
+        this.serviceProvider = serviceProvider;
+        this.parser          = parser;
+        fetchTimer           = new Timer(Fetch);
+    }
+
+    public Task StartAsync(CancellationToken cancellationToken) {
+        fetchTimer.Change(TimeSpan.Zero, FetchInterval);
+        return Task.CompletedTask;
+    }
+
+    public Task StopAsync(CancellationToken cancellationToken) {
+        fetchTimer.Change(Timeout.Infinite, Timeout.Infinite);
+        return Task.CompletedTask;
+    }
+
+    private void Fetch(object? state) {
+        using var scope = serviceProvider.CreateScope();
+        var db = scope.ServiceProvider.GetRequiredService<PagerContext>();
+
+        // Fetch pager messages, ignoring message we've already got
+        var messages = pagerMon
+            .Fetch()
+            .Where(m =>
+                !db.PagerMessages
+                .Select(m => m.Message)
+                .Contains(m.Message));
+
+        // Attempt to parse each newly-fetched message.
+        // Failure to parse isn't critical, as we still keep the raw message.
+        foreach(var message in messages) {
+            message.ParsedMessage = parser.TryParse(message.Message);
+            if(message.ParsedMessage is not null)
+                message.ParsedMessage.GpsPosition =
+                    PositionCalculator.GetGpsPosition(message.ParsedMessage);
+        }
+
+        db.AddRange(messages);
+        db.SaveChanges();
+    }
+
+    public void Dispose() =>
+        fetchTimer.Dispose();
+}
-- 
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