Browser: Store cookies in a LibSQL database :^)

Currently, cookies are ephemeral and only survive for the lifetime of
Browser instance. This will make Browser instead store cookies in a SQL
database for persisted access.

Userland/Applications/Browser/Database.h

@@ -0,0 +1,77 @@
+/*
+ * Copyright (c) 2022, Tim Flynn <trflynn89@serenityos.org>
+ *
+ * SPDX-License-Identifier: BSD-2-Clause
+ */
+
+#pragma once
+
+#include <AK/Error.h>
+#include <AK/Function.h>
+#include <AK/HashMap.h>
+#include <AK/NonnullRefPtr.h>
+#include <AK/Optional.h>
+#include <AK/RefCounted.h>
+#include <AK/StringView.h>
+#include <AK/Vector.h>
+#include <LibSQL/SQLClient.h>
+#include <LibSQL/Type.h>
+#include <LibSQL/Value.h>
+
+namespace Browser {
+
+class Database : public RefCounted<Database> {
+    using OnResult = Function<void(Span<SQL::Value const>)>;
+    using OnComplete = Function<void()>;
+    using OnError = Function<void(StringView)>;
+
+public:
+    static ErrorOr<NonnullRefPtr<Database>> create();
+    static ErrorOr<NonnullRefPtr<Database>> create(NonnullRefPtr<SQL::SQLClient>);
+
+    ErrorOr<SQL::StatementID> prepare_statement(StringView statement);
+
+    template<typename... PlaceholderValues>
+    void execute_statement(SQL::StatementID statement_id, OnResult on_result, OnComplete on_complete, OnError on_error, PlaceholderValues&&... placeholder_values)
+    {
+        PendingExecution pending_execution {
+            .on_result = move(on_result),
+            .on_complete = move(on_complete),
+            .on_error = move(on_error),
+        };
+
+        Vector<SQL::Value> values { SQL::Value(forward<PlaceholderValues>(placeholder_values))... };
+        execute_statement(statement_id, move(values), move(pending_execution));
+    }
+
+private:
+    struct ExecutionKey {
+        constexpr bool operator==(ExecutionKey const&) const = default;
+
+        SQL::StatementID statement_id { 0 };
+        SQL::ExecutionID execution_id { 0 };
+    };
+
+    struct PendingExecution {
+        OnResult on_result { nullptr };
+        OnComplete on_complete { nullptr };
+        OnError on_error { nullptr };
+    };
+
+    struct ExecutionKeyTraits : public Traits<ExecutionKey> {
+        static constexpr unsigned hash(ExecutionKey const& key)
+        {
+            return pair_int_hash(u64_hash(key.statement_id), u64_hash(key.execution_id));
+        }
+    };
+
+    Database(NonnullRefPtr<SQL::SQLClient> sql_client, SQL::ConnectionID connection_id);
+    void execute_statement(SQL::StatementID statement_id, Vector<SQL::Value> placeholder_values, PendingExecution pending_execution);
+
+    NonnullRefPtr<SQL::SQLClient> m_sql_client;
+    SQL::ConnectionID m_connection_id { 0 };
+
+    HashMap<ExecutionKey, PendingExecution, ExecutionKeyTraits> m_pending_executions;
+};
+
+}