Add super basic group model/command

PluralKit.Core/Database/Database.cs

@@ -20,7 +20,7 @@ namespace PluralKit.Core
     internal class Database: IDatabase
     {
         private const string RootPath = "PluralKit.Core.Database"; // "resource path" root for SQL files
-        private const int TargetSchemaVersion = 8;
+        private const int TargetSchemaVersion = 9;
         
         private readonly CoreConfig _config;
         private readonly ILogger _logger;
@@ -58,9 +58,11 @@ namespace PluralKit.Core
             SqlMapper.AddTypeHandler(new NumericIdHandler<SystemId, int>(i => new SystemId(i)));
             SqlMapper.AddTypeHandler(new NumericIdHandler<MemberId, int>(i => new MemberId(i)));
             SqlMapper.AddTypeHandler(new NumericIdHandler<SwitchId, int>(i => new SwitchId(i)));
+            SqlMapper.AddTypeHandler(new NumericIdHandler<GroupId, int>(i => new GroupId(i)));
             SqlMapper.AddTypeHandler(new NumericIdArrayHandler<SystemId, int>(i => new SystemId(i)));
             SqlMapper.AddTypeHandler(new NumericIdArrayHandler<MemberId, int>(i => new MemberId(i)));
             SqlMapper.AddTypeHandler(new NumericIdArrayHandler<SwitchId, int>(i => new SwitchId(i)));
+            SqlMapper.AddTypeHandler(new NumericIdArrayHandler<GroupId, int>(i => new GroupId(i)));
             
             // Register our custom types to Npgsql
             // Without these it'll still *work* but break at the first launch + probably cause other small issues

PluralKit.Core/Database/Functions/functions.sql

@@ -111,4 +111,14 @@ begin
         if not exists (select 1 from members where hid = new_hid) then return new_hid; end if;
     end loop;
 end
+$$ language plpgsql volatile;
+
+create function find_free_group_hid() returns char(5) as $$
+declare new_hid char(5);
+begin
+    loop
+        new_hid := generate_hid();
+        if not exists (select 1 from groups where hid = new_hid) then return new_hid; end if;
+    end loop;
+end
 $$ language plpgsql volatile;

PluralKit.Core/Database/Migrations/9.sql

@@ -0,0 +1,17 @@
+-- SCHEMA VERSION 9: 2020-xx-xx --
+
+create table groups (
+    id int primary key generated always as identity,
+    hid char(5) unique not null,
+    system int not null references systems(id) on delete cascade,
+    name text not null,
+    description text,
+    created timestamp with time zone not null default (current_timestamp at time zone 'utc')
+);
+
+create table group_members (
+    group_id int not null references groups(id) on delete cascade,
+    member_id int not null references members(id) on delete cascade
+);
+
+update info set schema_version = 9;

PluralKit.Core/Database/clean.sql

@@ -10,4 +10,5 @@ drop function if exists message_context;
 drop function if exists proxy_members;
 drop function if exists generate_hid;
 drop function if exists find_free_system_hid;
-drop function if exists find_free_member_hid;
+drop function if exists find_free_member_hid;
+drop function if exists find_free_group_hid;