Get PinnedTags from database, use them if "PinnedTags": true

This need `GRANT SELECT ON web_settings TO mastodon_read;`
Fixes #25

src/Config.cs

@@ -11,17 +11,19 @@ public class Config
     public string FakeRelayUrl { get; }
     public string FakeRelayApiKey { get; }
     public string? MastodonPostgresConnectionString { get; }
+    public bool PinnedTags { get; }
     public ImmutableArray<string> Tags { get; }
     public ImmutableArray<SiteData> Sites { get; }
 
 
     private Config(string importedPath, string fakeRelayUrl, string fakeRelayApiKey, string? mastodonPostgresConnectionString,
-                    ImmutableArray<string> tags, ImmutableArray<SiteData> sites)
+                    bool pinnedTags, ImmutableArray<string> tags, ImmutableArray<SiteData> sites)
     {
         ImportedPath = importedPath;
         FakeRelayUrl = fakeRelayUrl;
         FakeRelayApiKey = fakeRelayApiKey;
         MastodonPostgresConnectionString = mastodonPostgresConnectionString;
+        PinnedTags = pinnedTags;
         Tags = tags;
         Sites = sites;
     }
@@ -68,7 +70,7 @@ public class Config
         }
 
         Instance = new Config(importedPath, data.FakeRelayUrl, apiKey, data.MastodonPostgresConnectionString,
-            data.Tags.ToImmutableArray(), data.GetImmutableSites());
+            data.PinnedTags, data.Tags.ToImmutableArray(), data.GetImmutableSites());
     }
 
     public class ConfigData
@@ -76,6 +78,7 @@ public class Config
         public string? FakeRelayUrl { get; set; }
         public string? FakeRelayApiKey { get; set; }
         public string? MastodonPostgresConnectionString { get; set; }
+        public bool PinnedTags { get; set; }
         public string[]? Instances { get; set; }
         public string[]? Tags { get; set; }
         public InternalSiteData[]? Sites { get; set; }

src/MastodonConnectionHelper.cs

@@ -23,4 +23,25 @@ public static class MastodonConnectionHelper
 
         return res;
     }
+
+    public static async Task<List<string>> GetPinnedTagsAsync()
+    {
+        if (Config.Instance == null) throw new Exception("Config object is not initialized");
+        if (Config.Instance.MastodonPostgresConnectionString.IsNullOrEmpty())
+        {
+            throw new Exception("Missing mastodon postgres connection string");
+        }
+        
+        await using var conn = new NpgsqlConnection(Config.Instance.MastodonPostgresConnectionString);
+        await conn.OpenAsync();
+
+        var res = new List<string>();
+        await using var cmd = new NpgsqlCommand("SELECT DISTINCT col->'params'->>'id' FROM web_settings, json_array_elements(data->'columns') col WHERE col->>'id' = 'HASHTAG' AND col->'params'->>'id' IS NOT NULL ORDER BY col->'params'->>'id' ASC", conn);
+        await using var reader = await cmd.ExecuteReaderAsync();
+        while (await reader.ReadAsync())
+            res.Add(reader.GetString(0));
+
+        return res;
+    }
+
 }

src/Program.cs

@@ -50,6 +50,10 @@ int numberOfTags;
 if (Config.Instance.MastodonPostgresConnectionString.HasValue())
 {
     var tags = await MastodonConnectionHelper.GetFollowedTagsAsync();
+    if (Config.Instance.PinnedTags)
+    {
+        tags = tags.Concat(await MastodonConnectionHelper.GetPinnedTagsAsync()).Distinct().ToList();
+    }
     numberOfTags = tags.Count;
     sitesTags = Config.Instance.Sites
         .SelectMany(s => tags.Select(t => (s.Host, t)))