Use null reference checks (and enforce them) (#11)

src/Config.cs

@@ -34,6 +34,10 @@ public class Config
         }
 
         var data = JsonSerializer.Deserialize(File.ReadAllText(path), JsonContext.Default.ConfigData);
+        if (data == null)
+        {
+            throw new Exception("Could not deserialize the config file");
+        }
         
         var importedPath = Path.Join(Path.GetDirectoryName(path), "imported.txt");
         var apiKey = string.IsNullOrEmpty(data.FakeRelayApiKey)
@@ -47,7 +51,9 @@ public class Config
         
         if (data.Sites is { Length: > 0 })
         {
-            Console.WriteLine("Warning: Sites is deprecated, please use Instances instead");
+            Console.WriteLine("|============================================================|");
+            Console.WriteLine("| Warning: Sites is deprecated, please use Instances instead |");
+            Console.WriteLine("|============================================================|\n");
         }
 
         data.Tags ??= Array.Empty<string>();
@@ -56,13 +62,18 @@ public class Config
             throw new Exception("You can't specify both MastodonPostgresConnectionString and Tags");
         }
 
+        if (data.FakeRelayUrl.IsNullOrEmpty())
+        {
+            throw new Exception("Missing FakeRelayUrl");
+        }
+
         Instance = new Config(importedPath, data.FakeRelayUrl, apiKey, data.MastodonPostgresConnectionString,
             data.Tags.ToImmutableArray(), data.GetImmutableSites());
     }
 
     public class ConfigData
     {
-        public string FakeRelayUrl { get; set; }
+        public string? FakeRelayUrl { get; set; }
         public string? FakeRelayApiKey { get; set; }
         public string? MastodonPostgresConnectionString { get; set; }
         public string[]? Instances { get; set; }
@@ -72,11 +83,11 @@ public class Config
         public ImmutableArray<SiteData> GetImmutableSites()
         {
             // the plan is to stop supporting Sites in favor of Instances. SiteSpecificTags add complexity and 
-            // don't make sense when pulling tags from Mastodon. Also, pulling is fast and multithreaded!
+            // don't make sense when pulling tags from Mastodon. Also, pulling is fast and multi threaded!
             if (Instances != null)
             {
                 return Instances
-                    .Select(i => new SiteData { Host = i, SiteSpecificTags = ImmutableArray<string>.Empty })
+                    .Select(i => new SiteData(i, ImmutableArray<string>.Empty))
                     .ToImmutableArray();
             }
             
@@ -88,24 +99,18 @@ public class Config
 
         public class InternalSiteData
         {
-            public string Host { get; set; }
+            public InternalSiteData(string host, string[]? siteSpecificTags)
-            public string[]? SiteSpecificTags { get; set; }
+            {
+                Host = host;
+                SiteSpecificTags = siteSpecificTags;
+            }
 
+            public string Host { get; }
+            public string[]? SiteSpecificTags { get; }
             public SiteData ToSiteData() =>
-                new()
+                new(Host, SiteSpecificTags?.ToImmutableArray() ?? ImmutableArray<string>.Empty);
-                {
-                    Host = Host,
-                    SiteSpecificTags =
-                        SiteSpecificTags == null
-                        ? ImmutableArray<string>.Empty
-                        : SiteSpecificTags.ToImmutableArray()
-                };
         }
     }
 
-    public class SiteData
+    public record SiteData(string Host, ImmutableArray<string> SiteSpecificTags);
-    {
-        public string Host { get; init; }
-        public ImmutableArray<string> SiteSpecificTags { get; init; }
-    }
 }

src/Extensions.cs

@@ -1,8 +1,10 @@
+using System.Diagnostics.CodeAnalysis;
+
 namespace GetMoarFediverse;
 
 public static class Extensions
 {
-    public static bool IsNullOrEmpty(this string s) => string.IsNullOrEmpty(s);
+    public static bool IsNullOrEmpty([NotNullWhen(returnValue: false)]this string? s) => string.IsNullOrEmpty(s);
 
-    public static bool HasValue(this string s) => !s.IsNullOrEmpty();
+    public static bool HasValue([NotNullWhen(returnValue: true)]this string? s) => !s.IsNullOrEmpty();
 }

src/GetMoarFediverse.csproj

@@ -5,6 +5,7 @@
     <TargetFramework>net6.0</TargetFramework>
     <ImplicitUsings>enable</ImplicitUsings>
     <Nullable>enable</Nullable>
+    <TreatWarningsAsErrors>true</TreatWarningsAsErrors>
   </PropertyGroup>
 
   <ItemGroup>

src/MastodonConnectionHelper.cs

@@ -8,15 +8,18 @@ public static class MastodonConnectionHelper
     {
         var res = new List<string>();
 
+        if (Config.Instance == null)
+        {
+            throw new Exception("Config object is not initialized");
+        }
+        
         await using var conn = new NpgsqlConnection(Config.Instance.MastodonPostgresConnectionString);
         await conn.OpenAsync();
 
-        await using (var cmd = new NpgsqlCommand("SELECT DISTINCT tags.name FROM tag_follows JOIN tags ON tag_id = tags.id ORDER BY tags.name ASC;", conn))
+        await using var cmd = new NpgsqlCommand("SELECT DISTINCT tags.name FROM tag_follows JOIN tags ON tag_id = tags.id ORDER BY tags.name ASC;", conn);
-        await using (var reader = await cmd.ExecuteReaderAsync())
+        await using var reader = await cmd.ExecuteReaderAsync();
-        {
         while (await reader.ReadAsync())
             res.Add(reader.GetString(0));
-        }
 
         return res;
     }

src/Program.cs

@@ -7,8 +7,18 @@ if (args.Length == 1){
     configPath = args[0];
 }
 
+if (configPath.IsNullOrEmpty())
+{
+    throw new Exception("Missing config path");
+}
+
 Config.Init(configPath);
 
+if (Config.Instance == null)
+{
+    throw new Exception("Error initializing config object");
+}
+
 var client = new HttpClient();
 var authClient = new HttpClient
 {
@@ -27,7 +37,14 @@ var imported = importedList.ToHashSet();
 var statusesToLoadBag = new ConcurrentBag<string>();
 
 List<(string host, string tag)> sitesTags;
-if (string.IsNullOrEmpty(Config.Instance.MastodonPostgresConnectionString))
+if (Config.Instance.MastodonPostgresConnectionString.HasValue())
+{
+    var tags = await MastodonConnectionHelper.GetFollowedTagsAsync();
+    sitesTags = Config.Instance.Sites
+        .SelectMany(s => tags.Select(t => (s.Host, t)))
+        .ToList();
+}
+else
 {
     sitesTags = Config.Instance.Sites
         .SelectMany(s => Config.Instance.Tags.Select(tag => (s.Host, tag)))
@@ -35,13 +52,6 @@ if (string.IsNullOrEmpty(Config.Instance.MastodonPostgresConnectionString))
         .OrderBy(t => t.tag)
         .ToList();
 }
-else
-{
-    var tags = await MastodonConnectionHelper.GetFollowedTagsAsync();
-    sitesTags = Config.Instance.Sites
-        .SelectMany(s => tags.Select(t => (s.Host, t)))
-        .ToList();
-}
 
 ParallelOptions parallelOptions = new()
 {
@@ -66,6 +76,11 @@ await Parallel.ForEachAsync(sitesTags, parallelOptions, async (st, _) =>
 
     var json = await response.Content.ReadAsStringAsync();
     var data = JsonSerializer.Deserialize(json, CamelCaseJsonContext.Default.TagResponse);
+    if (data == null)
+    {
+        Console.WriteLine($"Error deserializing the response when pulling #{tag} posts from {site}");
+        return;
+    }
 
     foreach (var statusLink in data.OrderedItems.Where(i=>!imported.Contains(i)))
     {
@@ -79,8 +94,10 @@ foreach (var statusLink in statusesToLoad)
     Console.WriteLine($"Bringing in {statusLink}");
     try
     {
-        var content = new List<KeyValuePair<string, string>>();
+        var content = new List<KeyValuePair<string, string>>
-        content.Add(new KeyValuePair<string, string>("statusUrl", statusLink));
+        {
+            new("statusUrl", statusLink)
+        };
 
         var res = await authClient.PostAsync("index", new FormUrlEncodedContent(content));
         res.EnsureSuccessStatusCode();
@@ -103,5 +120,10 @@ File.WriteAllLines(importedPath, importedList);
 
 public class TagResponse
 {
-    public string[] OrderedItems { get; set; }
+    public string[] OrderedItems { get; }
+    
+    public TagResponse(string[] orderedItems)
+    {
+        OrderedItems = orderedItems;
+    }
 }