using System.Reflection;
using System.Text;
using Npgsql;

namespace TaxBaik.Infrastructure.Data;

public class MigrationRunner
{
    private readonly string _connectionString;
    private readonly IDbConnectionFactory _connectionFactory;

    public MigrationRunner(string connectionString, IDbConnectionFactory connectionFactory)
    {
        _connectionString = connectionString;
        _connectionFactory = connectionFactory;
    }

    public async Task RunAsync()
    {
        await EnsureMigrationTableAsync();
        await ExecutePendingMigrationsAsync();
    }

    private async Task EnsureMigrationTableAsync()
    {
        using var conn = new NpgsqlConnection(_connectionString);
        await conn.OpenAsync();

        using var cmd = conn.CreateCommand();
        cmd.CommandText = @"
            CREATE TABLE IF NOT EXISTS schema_migrations (
                version VARCHAR(50) PRIMARY KEY,
                description VARCHAR(500),
                installed_on TIMESTAMPTZ DEFAULT NOW()
            );";
        await cmd.ExecuteNonQueryAsync();
    }

    private async Task ExecutePendingMigrationsAsync()
    {
        var executedMigrations = await GetExecutedMigrationsAsync();
        var migrations = GetAvailableMigrations();

        foreach (var migration in migrations.OrderBy(x => x.Version))
        {
            if (!executedMigrations.Contains(migration.Version))
            {
                await ExecuteMigrationAsync(migration);
            }
        }
    }

    private async Task<HashSet<string>> GetExecutedMigrationsAsync()
    {
        var executed = new HashSet<string>();
        using var conn = new NpgsqlConnection(_connectionString);
        await conn.OpenAsync();

        using var cmd = conn.CreateCommand();
        cmd.CommandText = "SELECT version FROM schema_migrations ORDER BY version;";

        using var reader = await cmd.ExecuteReaderAsync();
        while (await reader.ReadAsync())
        {
            executed.Add(reader.GetString(0));
        }

        return executed;
    }

    private List<Migration> GetAvailableMigrations()
    {
        var migrations = new List<Migration>();
        var assembly = Assembly.GetExecutingAssembly();
        var resourceNames = assembly.GetManifestResourceNames()
            .Where(x => x.Contains("Migrations") && x.EndsWith(".sql"))
            .ToList();

        foreach (var resourceName in resourceNames.OrderBy(x => x))
        {
            var parts = resourceName.Split('.');
            var fileName = parts[parts.Length - 2];

            if (fileName.StartsWith("V"))
            {
                var version = fileName.Substring(1, fileName.IndexOf('_') - 1);
                var description = fileName.Substring(fileName.IndexOf('_') + 2);

                using var stream = assembly.GetManifestResourceStream(resourceName);
                using var reader = new StreamReader(stream);
                var sql = reader.ReadToEnd();

                migrations.Add(new Migration { Version = version, Description = description, Sql = sql });
            }
        }

        return migrations;
    }

    private async Task ExecuteMigrationAsync(Migration migration)
    {
        using var conn = new NpgsqlConnection(_connectionString);
        await conn.OpenAsync();

        try
        {
            using var cmd = conn.CreateCommand();
            cmd.CommandText = migration.Sql;
            await cmd.ExecuteNonQueryAsync();

            using var insertCmd = conn.CreateCommand();
            insertCmd.CommandText =
                "INSERT INTO schema_migrations (version, description) VALUES (@version, @description);";
            insertCmd.Parameters.AddWithValue("@version", migration.Version);
            insertCmd.Parameters.AddWithValue("@description", migration.Description);
            await insertCmd.ExecuteNonQueryAsync();

            Console.WriteLine($"✓ Migration {migration.Version} executed");
        }
        catch (Exception ex)
        {
            Console.WriteLine($"✗ Migration {migration.Version} failed: {ex.Message}");
            throw;
        }
    }

    private class Migration
    {
        public string Version { get; set; }
        public string Description { get; set; }
        public string Sql { get; set; }
    }
}