using System.Reflection;
using Microsoft.Data.Sqlite;

namespace ClaudeDo.Data;

/// <summary>
/// Applies the embedded schema.sql script. Safe to call on every start — the script uses
/// IF NOT EXISTS / INSERT OR IGNORE.
/// </summary>
public static class SchemaInitializer
{
    private const string ResourceName = "ClaudeDo.Data.schema.sql";

    public static void Apply(SqliteConnectionFactory factory)
    {
        using var conn = factory.Open();
        ApplyTo(conn);
    }

    public static void ApplyTo(SqliteConnection conn)
    {
        var sql = LoadScript();
        using var tx = conn.BeginTransaction();
        using var cmd = conn.CreateCommand();
        cmd.Transaction = tx;
        cmd.CommandText = sql;
        cmd.ExecuteNonQuery();
        tx.Commit();

        ApplyMigrations(conn);
    }

    private static void ApplyMigrations(SqliteConnection conn)
    {
        string[] alterStatements =
        [
            "ALTER TABLE tasks ADD COLUMN model TEXT NULL",
            "ALTER TABLE tasks ADD COLUMN system_prompt TEXT NULL",
            "ALTER TABLE tasks ADD COLUMN agent_path TEXT NULL",
        ];

        foreach (var sql in alterStatements)
        {
            try
            {
                using var cmd = conn.CreateCommand();
                cmd.CommandText = sql;
                cmd.ExecuteNonQuery();
            }
            catch (SqliteException ex) when (ex.SqliteErrorCode == 1)
            {
                // Column already exists — safe to ignore.
            }
        }
    }

    private static string LoadScript()
    {
        var asm = typeof(SchemaInitializer).Assembly;
        using var stream = asm.GetManifestResourceStream(ResourceName)
            ?? throw new InvalidOperationException(
                $"Embedded resource '{ResourceName}' not found in {asm.GetName().Name}. " +
                $"Available: {string.Join(", ", asm.GetManifestResourceNames())}");
        using var reader = new StreamReader(stream);
        return reader.ReadToEnd();
    }
}