using System.Collections.Generic;
using System.Diagnostics;
using System.Linq;
using System.Threading.Tasks;
using Sozsoft.Platform.Data.Seeds;
using Sozsoft.Platform.DynamicData;
using Sozsoft.Platform.Enums;
using Volo.Abp.Domain.Services;

namespace Sozsoft.Mcp.Services;

/// <summary>
/// Sorguyu istegin kapsamindaki veri kaynaginda kosturur ve satir tavanini uygular.
/// Veri kaynagi cozumu tek yerde kalsin diye burada toplanmistir.
/// </summary>
public interface IMcpQueryExecutor
{
    /// <param name="dataSourceCode">
    /// Sunucu kaydindaki kod. Bos ya da <c>!Tenant</c> ise veri kaynagi istegin kiracisindan
    /// cozulur; host baglaminda varsayilan kaynaga duser.
    /// </param>
    Task<McpDataSourceContext> ResolveDataSourceAsync(string? dataSourceCode);

    /// <summary>
    /// Sorguyu kosturur. Sonuc kumesi <paramref name="maxRows"/> satirda kesilir; kesilme
    /// olduysa sonuc bunu bildirir.
    /// </summary>
    Task<McpQueryRows> ExecuteAsync(
        McpDataSourceContext context,
        string sql,
        IReadOnlyDictionary<string, object> parameters,
        int maxRows);
}

public class McpQueryExecutor(IDynamicDataManager dynamicDataManager) : DomainService, IMcpQueryExecutor
{
    public async Task<McpDataSourceContext> ResolveDataSourceAsync(string? dataSourceCode)
    {
        var useTenantScope = string.IsNullOrWhiteSpace(dataSourceCode)
                          || dataSourceCode == McpConsts.TenantDataSourceMarker;

        var resolvedCode = useTenantScope
            ? SeedConsts.DataSources.DefaultCode
            : dataSourceCode!;

        var (repository, connectionString, dataSourceType) =
            await dynamicDataManager.GetAsync(useTenantScope, resolvedCode);

        return new McpDataSourceContext(repository, connectionString, dataSourceType);
    }

    public async Task<McpQueryRows> ExecuteAsync(
        McpDataSourceContext context,
        string sql,
        IReadOnlyDictionary<string, object> parameters,
        int maxRows)
    {
        var stopwatch = Stopwatch.StartNew();
        var rows = await context.Repository.QueryAsync(
            sql,
            context.ConnectionString,
            parameters.ToDictionary(entry => entry.Key, entry => entry.Value));
        stopwatch.Stop();

        var columns = new List<string>();
        var materialized = new List<Dictionary<string, object?>>();
        var truncated = false;

        foreach (var row in rows)
        {
            if (materialized.Count >= maxRows)
            {
                truncated = true;
                break;
            }

            if (row is not IDictionary<string, object> values)
            {
                continue;
            }

            if (columns.Count == 0)
            {
                columns = [.. values.Keys];
            }

            materialized.Add(values.ToDictionary(entry => entry.Key, entry => (object?)entry.Value));
        }

        return new McpQueryRows(columns, materialized, truncated, stopwatch.ElapsedMilliseconds);
    }
}

/// <summary>Cozumlenmis veri kaynagi: hangi depo, hangi baglanti, hangi saglayici.</summary>
public sealed record McpDataSourceContext(
    IDynamicDataRepository Repository,
    string ConnectionString,
    DataSourceTypeEnum DataSourceType);

/// <summary>Sorgu sonucunun ham hali.</summary>
public sealed record McpQueryRows(
    List<string> Columns,
    List<Dictionary<string, object?>> Rows,
    bool Truncated,
    long ExecutionTimeMs);