RpgRoller/RpgRoller/Hosting/SqliteSchemaUpgrader.cs

using Microsoft.EntityFrameworkCore;
using RpgRoller.Data;

namespace RpgRoller.Hosting;

public static class SqliteSchemaUpgrader
{
    public static void ApplyPendingChanges(RpgRollerDbContext db)
    {
        if (db.Database.IsSqlite())
            EnsureLegacySchemaHistory(db);

        db.Database.Migrate();
    }

    private static void EnsureLegacySchemaHistory(RpgRollerDbContext db)
    {
        db.Database.OpenConnection();
        try
        {
            if (TableExists(db, "__EFMigrationsHistory"))
                return;

            if (!TableExists(db, "Skills"))
                return;

            if (!ColumnExists(db, "Skills", "WildDice") || !ColumnExists(db, "Skills", "AllowFumble"))
                return;

            using var createHistoryCommand = db.Database.GetDbConnection().CreateCommand();
            createHistoryCommand.CommandText = """
                                               CREATE TABLE IF NOT EXISTS "__EFMigrationsHistory" (
                                                   "MigrationId" TEXT NOT NULL CONSTRAINT "PK___EFMigrationsHistory" PRIMARY KEY,
                                                   "ProductVersion" TEXT NOT NULL
                                               );
                                               """;
            _ = createHistoryCommand.ExecuteNonQuery();

            using var insertHistoryCommand = db.Database.GetDbConnection().CreateCommand();
            insertHistoryCommand.CommandText = """
                                               INSERT OR IGNORE INTO "__EFMigrationsHistory" ("MigrationId", "ProductVersion")
                                               VALUES ($migrationId, $productVersion);
                                               """;

            var migrationParameter = insertHistoryCommand.CreateParameter();
            migrationParameter.ParameterName = "$migrationId";
            migrationParameter.Value = InitialMigrationId;
            insertHistoryCommand.Parameters.Add(migrationParameter);

            var productVersionParameter = insertHistoryCommand.CreateParameter();
            productVersionParameter.ParameterName = "$productVersion";
            productVersionParameter.Value = ProductVersion;
            insertHistoryCommand.Parameters.Add(productVersionParameter);

            _ = insertHistoryCommand.ExecuteNonQuery();
        }
        finally
        {
            db.Database.CloseConnection();
        }
    }

    private static bool TableExists(RpgRollerDbContext db, string tableName)
    {
        using var command = db.Database.GetDbConnection().CreateCommand();
        command.CommandText = "SELECT 1 FROM sqlite_master WHERE type='table' AND name=$name LIMIT 1;";
        var parameter = command.CreateParameter();
        parameter.ParameterName = "$name";
        parameter.Value = tableName;
        command.Parameters.Add(parameter);

        return command.ExecuteScalar() is not null;
    }

    private static bool ColumnExists(RpgRollerDbContext db, string tableName, string columnName)
    {
        using var command = db.Database.GetDbConnection().CreateCommand();
        command.CommandText = $"PRAGMA table_info('{tableName}');";
        using var reader = command.ExecuteReader();
        while (reader.Read())
        {
            var currentColumnName = reader.GetString(1);
            if (string.Equals(currentColumnName, columnName, StringComparison.OrdinalIgnoreCase))
                return true;
        }

        return false;
    }

    private const string InitialMigrationId = "20260226084000_InitialSchema";
    private const string ProductVersion = "10.0.2";
}