using System.Reflection;
using adas_core.Application.Repositories.Interfaces;
using adas_core.Application.Services.Interfaces;
using adas_core.Domain.Models;
using adas_core.Domain.Models.AppSettings;
using adas_core.Domain.Models.MongoModels;
using adas_core.Domain.Models.Pumps;
using Microsoft.Extensions.Logging;
using Microsoft.Extensions.Options;

namespace adas_core.Application.Services;

/// <summary>
/// Implements <see cref="IConfigUnitsService"/> to manage configuration units,
/// using <paramref name="configUnitsRepository"/> for data persistence,
/// <paramref name="apiSettings"/> for API configuration values,
/// and <paramref name="logger"/> for diagnostic logging.
/// </summary>
/// <!-- aidoc:v1 sig=cc78d0f -->
public class ConfigUnitsService(
    IConfigUnitsRepository configUnitsRepository,
    IOptions<ApiSettings> apiSettings,
    ILogger<ConfigUnitsService> logger)
    : IConfigUnitsService
{
    private static ConfigUnits? _config;
    private static DateTime _nextRefresh = DateTime.MinValue;

    private readonly bool _configUnitsRequired = apiSettings.Value.ConfigUnitsRequired;

    private readonly string _key = apiSettings.Value.ConfigUnitsKey ?? "PV1";
    private readonly int? _refreshTimeout = apiSettings.Value.ConfigObservation?.Refresh;

    /// <summary>
    /// Maps a patient observation using the unit configuration when configuration units are required.
    /// If configuration units are not required, the observation's units are not specified, or no matching configuration is found, the original observation is returned unchanged.
    /// </summary>
    /// <param name="obs">The patient observation to be mapped.</param>
    /// <returns>The mapped observation when a matching unit configuration is resolved; otherwise, the original observation.</returns>
    /// <!-- aidoc:v1 sig=2c52e52 body=2db877e -->
    public async Task<T> Map<T>(T obs) where T : BasePatientObservation
    {
        if (!_configUnitsRequired) return obs;

        var conf = !string.IsNullOrEmpty(obs.Units) ? await Get(obs.Units) : null;

        return conf == null ? obs : MapConf(obs, conf);
    }

    /// <summary>
    /// Maps a <see cref="PumpObservation"/> by processing its pump value properties.
    /// If configuration units are not required, the observation is returned unchanged; otherwise, the pump values are mapped via <c>MapPumpValues</c> and the observation is returned.
    /// </summary>
    /// <param name="obs">The <see cref="PumpObservation"/> to be mapped.</param>
    /// <returns>The mapped <see cref="PumpObservation"/>, returned as-is when units configuration is not required or after pump value mapping otherwise.</returns>
    /// <!-- aidoc:v1 sig=daf9ea9 body=c2e84ce -->
    public async Task<PumpObservation> Map(PumpObservation obs)
    {
        if (!_configUnitsRequired) return obs;

        //Para cada propiedad de la observación que sea del tipo PumpValue llama a GetByCodeSysAndCode(PumpValue)
        await MapPumpValues(obs);

        // var conf = !string.IsNullOrEmpty(obs.Units) ? await Get(obs.Units) : null;
        // return conf == null ? obs : MapConf(obs, conf);

        return obs;
    }

    /// <summary>
    ///     Recorre recursivamente las propiedades del objeto para encontrar y convertir PumpValues.
    /// </summary>
    /// <!-- aidoc:v1 sig=01209a6 body=958cccd -->
    private async Task MapPumpValues(object? targetObject)
    {
        if (targetObject == null) return;

        var properties = targetObject.GetType().GetProperties(BindingFlags.Public | BindingFlags.Instance);

        foreach (var property in properties)
        {
            var propertyValue = property.GetValue(targetObject);

            if (propertyValue == null) continue;


            if (property.PropertyType == typeof(CommonPumpTypes.PumpValue))
            {
                var pumpValue = (CommonPumpTypes.PumpValue)propertyValue;

                if (string.IsNullOrEmpty(pumpValue.Units)) continue;

                var conf = await Get(pumpValue.Units);
                if (conf != null) pumpValue.Units = conf.Value;
            }
            // En este caso Syringe es una clase que tienen un pumpValue
            else if (property.PropertyType.IsClass && property.PropertyType != typeof(string))
            {
                // Llamada recursiva para inspeccionar las propiedades anidadas
                await MapPumpValues(propertyValue);
            }
        }
    }


    /// <summary>
    /// Maps a configuration unit value onto a patient observation. If the observation is not a <see cref="PatientObservation"/>, the original observation is returned unchanged; otherwise, its <c>Units</c> property is assigned from the configuration unit item's value.
    /// </summary>
    /// <param name="obs">The base patient observation to which the configured unit value will be applied.</param>
    /// <param name="conf">The configuration unit item whose <c>Value</c> is used as the unit to assign.</param>
    /// <returns>The input observation, with <c>Units</c> set from <paramref name="conf"/> when applicable, or the unchanged observation when it is not a <see cref="PatientObservation"/>.</returns>
    /// <!-- aidoc:v1 sig=ef286fc body=8674339 -->
    private T MapConf<T>(T obs, ConfigUnitItem conf) where T : BasePatientObservation
    {
        if (obs is not PatientObservation pobs) return obs;

        logger.LogDebug("Mapping config Unit obs: {obs} to units: {conf}", obs, conf.Value);
        pobs.Units = conf.Value;

        return obs;
    }

    /// <summary>
    /// Retrieves a configuration unit item by its unique code from the configuration store.
    /// Returns null when the configuration cannot be loaded or when no item matches the specified code.
    /// </summary>
    /// <param name="code">The unique code identifier of the configuration unit item to look up.</param>
    /// <returns>A task that represents the asynchronous operation. The task result contains the matching <see cref="ConfigUnitItem"/>, or null if the configuration is unavailable or no item is found.</returns>
    /// <!-- aidoc:v1 sig=b153e30 body=ca52840 -->
    public async Task<ConfigUnitItem?> Get(string code)
    {
        var result = await GetConfig();

        return result?.Items?.FirstOrDefault(i => i.Code == code);
    }

    /// <summary>
    /// Retrieves the <see cref="ConfigUnits"/> configuration associated with the current key, using a time-based cache
    /// to avoid repeated repository calls before the configured refresh timeout elapses. On any failure during the
    /// repository lookup, the error is logged and <c>null</c> is returned.
    /// </summary>
    /// <returns>
    /// A <see cref="Task{TResult}"/> containing the cached or freshly fetched <see cref="ConfigUnits"/>, or
    /// <c>null</c> if the repository lookup fails.
    /// </returns>
    /// <!-- aidoc:v1 sig=982237a body=0843e00 -->
    private async Task<ConfigUnits?> GetConfig()
    {
        try
        {
            if (_config != null && DateTime.Now <= _nextRefresh) return _config;

            _config = await configUnitsRepository.FindById(_key);
            _nextRefresh = _refreshTimeout.HasValue
                ? DateTime.Now.AddSeconds(_refreshTimeout.Value)
                : DateTime.MinValue;
            return _config;
        }
        catch (Exception ex)
        {
            logger.LogError(ex, "ERROR READ config_units: {_key}: {ex}", _key, ex.Message);
            return null;
        }
    }
}