// <copyright file="DatabaseMigrator.cs" company="alveus.dev">
// Copyright (c) alveus.dev. All rights reserved. Licensed under the MIT License.
// </copyright>

using Astral.Core.Exceptions;
using Astral.Core.Infrastructure;
using Dapper;
using Injectio.Attributes;
using Microsoft.Extensions.Logging;

namespace Astral.DAL.Infrastructure;

/// <inheritdoc />
[RegisterScoped]
public class DatabaseMigrator : IDatabaseMigrator
{
    private readonly IDbConnectionProvider _dbConnectionProvider;
    private readonly ILogger<DatabaseMigrator> _logger;
    private readonly ITransactionProvider _transactionProvider;

    /// <summary>
    /// Initializes a new instance of the <see cref="DatabaseMigrator" /> class.
    /// </summary>
    /// <param name="dbConnectionProvider">Instance of <see cref="IDbConnectionProvider" />.</param>
    /// <param name="transactionProvider">Instance of <see cref="ITransactionProvider" />.</param>
    /// <param name="logger">Instance of <see cref="ILogger" />.</param>
    public DatabaseMigrator(
        IDbConnectionProvider dbConnectionProvider,
        ITransactionProvider transactionProvider,
        ILogger<DatabaseMigrator> logger)
    {
        _dbConnectionProvider = dbConnectionProvider;
        _transactionProvider = transactionProvider;
        _logger = logger;
    }

    /// <inheritdoc />
    public async Task MigrateDatabaseAsync(string migrationsPath)
    {
        var connection = await _dbConnectionProvider.OpenConnectionAsync();

        _logger.LogInformation("Beginning database migrations");
        using var transaction = await _transactionProvider.BeginTransactionAsync();

        await connection.ExecuteAsync("""
                                      CREATE TABLE IF NOT EXISTS migrations (
                                          date_added TIMESTAMP NOT NULL,
                                          filename VARCHAR(128) NOT NULL,
                                           CONSTRAINT migrations_filename_pk PRIMARY KEY (filename)
                                           );
                                      """);

        var appliedMigrationsEnumerable = await
            connection.QueryAsync<string>("SELECT filename FROM migrations ORDER BY date_added;");

        // Prevent multiple enumeration.
        var appliedMigrations = appliedMigrationsEnumerable.ToList();

        var files = Directory.GetFiles(migrationsPath, "*.sql").ToList();

        files.Sort();
        foreach (var filename in files)
        {
            var file = filename.Replace(migrationsPath, string.Empty)
                .Trim(Path.DirectorySeparatorChar, Path.AltDirectorySeparatorChar);
            if (appliedMigrations.Contains(file))
            {
                _logger.LogInformation("Already applied: {file}", file);
                continue;
            }

            _logger.LogInformation("Applying {file}...", file);
            try
            {
                var sql = await File.ReadAllTextAsync(filename);
                await connection.ExecuteAsync(sql);

                await connection.ExecuteAsync(
                    "INSERT INTO migrations (date_added, filename) SELECT CURRENT_TIMESTAMP, @pFilename ;",
                    new
                    {
                        pFilename = file
                    });
            }
            catch (Exception e)
            {
                throw new MigrationException(file, e.Message);
            }
        }

        transaction.Commit();

        _logger.LogInformation("Database migrations complete");
    }
}