Refactor import/export database code

2020-06-11 21:11:50 +02:00
parent 3d69a00716
commit 39f92309b7
6 changed files with 381 additions and 229 deletions
--- a/PluralKit.Core/Utils/QueryBuilder.cs
+++ b/PluralKit.Core/Utils/QueryBuilder.cs
@@ -0,0 +1,88 @@
+#nullable enable
+using System;
+using System.Text;
+
+namespace PluralKit.Core
+{
+    public class QueryBuilder
+    {
+        private readonly string? _conflictField;
+        private readonly string? _condition;
+        private StringBuilder _insertFragment = new StringBuilder();
+        private StringBuilder _valuesFragment = new StringBuilder();
+        private StringBuilder _updateFragment = new StringBuilder();
+        private bool _firstInsert = true;
+        private bool _firstUpdate = true;
+        public QueryType Type { get; }
+        public string Table { get; }
+
+        private QueryBuilder(QueryType type, string table, string? conflictField, string? condition)
+        {
+            Type = type;
+            Table = table;
+            _conflictField = conflictField;
+            _condition = condition;
+        }
+        
+        public static QueryBuilder Insert(string table) => new QueryBuilder(QueryType.Insert, table,  null, null);
+        public static QueryBuilder Update(string table, string condition) => new QueryBuilder(QueryType.Update, table, null, condition);
+        public static QueryBuilder Upsert(string table, string conflictField) => new QueryBuilder(QueryType.Upsert, table, conflictField, null);
+
+        public QueryBuilder Constant(string fieldName, string paramName)
+        {
+            if (_firstInsert) _firstInsert = false;
+            else 
+            {
+                _insertFragment.Append(", ");
+                _valuesFragment.Append(", ");
+            }
+            
+            _insertFragment.Append(fieldName);
+            _valuesFragment.Append(paramName);
+            return this;
+        }
+        
+        public QueryBuilder Variable(string fieldName, string paramName)
+        {
+            Constant(fieldName, paramName);
+            
+            if (_firstUpdate) _firstUpdate = false;
+            else _updateFragment.Append(", ");
+            
+            _updateFragment.Append(fieldName);
+            _updateFragment.Append("=");
+            _updateFragment.Append(paramName);
+            return this;
+        }
+
+        public string Build(string? suffix = null)
+        {
+            if (_firstInsert)
+                throw new ArgumentException("No fields have been added to the query.");
+            
+            StringBuilder query = new StringBuilder(Type switch
+            {
+                QueryType.Insert => $"insert into {Table} ({_insertFragment}) values ({_valuesFragment})",
+                QueryType.Upsert => $"insert into {Table} ({_insertFragment}) values ({_valuesFragment}) on conflict ({_conflictField}) do update set {_updateFragment}",
+                QueryType.Update => $"update {Table} set {_updateFragment}",
+                _ => throw new ArgumentOutOfRangeException($"Unknown query type {Type}")
+            });
+
+            if (Type == QueryType.Update && _condition != null)
+                query.Append($" where {_condition}");
+            
+            if (suffix != null)
+                query.Append($" {suffix}");
+            query.Append(";");
+
+            return query.ToString();
+        }
+
+        public enum QueryType
+        {
+            Insert,
+            Update,
+            Upsert
+        }
+    }
+}