using Microsoft.Data.Sqlite;

namespace MoShiro.Backend.Storage.Sqlite;

/// <summary>手写的参数化 SQL 的小帮手：禁止字符串拼接值，所有值都经过参数。</summary>
internal static class Sql
{
    public static SqliteCommand Cmd(this SqliteConnection connection, string sql, params (string Name, object? Value)[] parameters)
    {
        SqliteCommand command = connection.CreateCommand();
        command.CommandText = sql;
        foreach ((string name, object? value) in parameters)
        {
            command.Parameters.AddWithValue(name, value ?? DBNull.Value);
        }

        return command;
    }

    public static int Exec(this SqliteConnection connection, string sql, params (string Name, object? Value)[] parameters)
    {
        using SqliteCommand command = connection.Cmd(sql, parameters);
        return command.ExecuteNonQuery();
    }

    public static T? Scalar<T>(this SqliteConnection connection, string sql, params (string Name, object? Value)[] parameters)
    {
        using SqliteCommand command = connection.Cmd(sql, parameters);
        object? value = command.ExecuteScalar();
        return value is null or DBNull ? default : (T)Convert.ChangeType(value, Nullable.GetUnderlyingType(typeof(T)) ?? typeof(T), System.Globalization.CultureInfo.InvariantCulture);
    }

    public static List<T> Query<T>(this SqliteConnection connection, string sql, Func<SqliteDataReader, T> map, params (string Name, object? Value)[] parameters)
    {
        using SqliteCommand command = connection.Cmd(sql, parameters);
        using SqliteDataReader reader = command.ExecuteReader();
        var rows = new List<T>();
        while (reader.Read())
        {
            rows.Add(map(reader));
        }

        return rows;
    }

    public static T? QueryOne<T>(this SqliteConnection connection, string sql, Func<SqliteDataReader, T> map, params (string Name, object? Value)[] parameters)
        where T : class
    {
        using SqliteCommand command = connection.Cmd(sql, parameters);
        using SqliteDataReader reader = command.ExecuteReader();
        return reader.Read() ? map(reader) : null;
    }

    public static long? NullableLong(this SqliteDataReader reader, int ordinal) => reader.IsDBNull(ordinal) ? null : reader.GetInt64(ordinal);

    public static string? NullableString(this SqliteDataReader reader, int ordinal) => reader.IsDBNull(ordinal) ? null : reader.GetString(ordinal);

    public static byte[] Bytes(this SqliteDataReader reader, int ordinal) => (byte[])reader.GetValue(ordinal);

    public static byte[]? NullableBytes(this SqliteDataReader reader, int ordinal) => reader.IsDBNull(ordinal) ? null : (byte[])reader.GetValue(ordinal);
}