using System.Text.Json;
using Deal.Contracts.Integrations.Abstractions;
using Deal.Contracts.Integrations.Models;
using Deal.Modules.Kanban.Application.Abstractions;
using Deal.Modules.Settings.Application.Abstractions;
using Deal.Modules.Settings.Application.Models;

namespace Deal.Infrastructure.Integrations.Services;

/// <summary>
/// Локальная реализация <see cref="IMlClient"/> без внешнего ML-сервиса.
/// </summary>
/// <param name="store">KV-хранилище настроек тенанта (таблица settings).</param>
/// <param name="learningStore">Хранилище обучения ML: очередь MlOutbox + счётчик журнала CardMoves.</param>
public sealed class LocalMlClient(ISettingsStore store, IMlLearningStore learningStore) : IMlClient
{
    private static readonly IReadOnlyDictionary<string, double> EmptyClasses = new Dictionary<string, double>();

    private static readonly IReadOnlyDictionary<string, double> EmptyScores = new Dictionary<string, double>();

    /// <inheritdoc />
    public async Task<MlStatusResponseDto> StatusAsync(CancellationToken ct)
    {
        var service = new MlServiceStatusDto(
            Ready: false,
            Classes: EmptyClasses,
            Learned: 0,
            Eval: new MlEvalDto(Count: 0, Correct: 0, Accuracy: 0.0));

        bool enabled = await ReadMlEnabledAsync(ct);
        int mlDecisions = await ReadCounterAsync(SettingsKeys.MlDecisions, ct);
        int aiDecisions = await ReadCounterAsync(SettingsKeys.AiDecisions, ct);

        int learning = await learningStore.CountLearningAsync(ct);
        int outbox = await learningStore.CountOutboxAsync(ct);

        var stats = new MlStatsDto(
            Ml: mlDecisions,
            Ai: aiDecisions,
            Learning: learning,
            Ready: service.Ready,
            Classes: service.Classes,
            Learned: service.Learned,
            Reachable: true,
            Outbox: outbox);

        return new MlStatusResponseDto(Enabled: enabled, Service: service, Reachable: true, Stats: stats);
    }

    /// <inheritdoc />
    public Task<MlPredictResultDto> PredictAsync(string text, CancellationToken ct)
    {
        return Task.FromResult(new MlPredictResultDto(
            Take: false,
            Label: null,
            Scores: EmptyScores,
            Hits: 0,
            Ready: false,
            Margin: null,
            Terms: Array.Empty<string>(),
            Type: null));
    }

    /// <inheritdoc />
    public async Task<MlResetResultDto> ResetAsync(CancellationToken ct)
    {
        await learningStore.ClearOutboxAsync(ct);
        return new MlResetResultDto(Ok: true, Error: null);
    }

    /// <inheritdoc />
    public async Task PushAsync(
        string text,
        string label,
        double delta,
        CancellationToken ct)
    {
        await MlOutboxQueue.PushAsync(learningStore, text, label, delta, ct);
    }

    private async Task<bool> ReadMlEnabledAsync(CancellationToken ct)
    {
        SettingValue? row = await store.GetAsync(SettingsKeys.MlEnabled, ct);
        if (row is null)
        {
            return SettingsDefaults.MlEnabled;
        }

        try
        {
            using JsonDocument document = JsonDocument.Parse(row.ValueJson);
            if (document.RootElement.ValueKind is JsonValueKind.True or JsonValueKind.False)
            {
                return document.RootElement.GetBoolean();
            }
        }
        catch (JsonException)
        {
            // Повреждённая строка — дефолт (мягкая семантика, как в SettingsService).
        }

        return SettingsDefaults.MlEnabled;
    }

    // Читает целочисленный счётчик (mlDecisions/aiDecisions); отсутствие/повреждение → 0.
    // key: Внутренний KV-ключ счётчика.
    // ct: Токен отмены.
    // Возвращает: Значение счётчика из хранилища или 0.
    private async Task<int> ReadCounterAsync(string key, CancellationToken ct)
    {
        SettingValue? row = await store.GetAsync(key, ct);
        if (row is null)
        {
            return 0;
        }

        try
        {
            using JsonDocument document = JsonDocument.Parse(row.ValueJson);
            if (document.RootElement.ValueKind == JsonValueKind.Number
                && document.RootElement.TryGetInt64(out long wide))
            {
                return (int)Math.Clamp(wide, int.MinValue, int.MaxValue);
            }
        }
        catch (JsonException)
        {
            // Повреждённая строка — 0 (мягкая семантика, как в SettingsService).
        }

        return 0;
    }
}