using System.Text;
using Microsoft.AspNetCore.Mvc;
using Server.WatchBody.Core.Dal.Src.Domain;
using Server.WatchBody.Core.Dal.Src.Repository;
using Server.WatchBody.Web.Services;

namespace Server.WatchBody.Web.Controllers.Admin;

/// <summary>
/// Тренировки всех атлетов (spec 03 m08): список с фильтрами,
/// карточка (план/факт + facts-таймлайн), CSV выборки (КУ-4).
/// workout_select требует одного атлета — выборка «всех» собирается
/// обходом атлетов (v1: атлетов немного). 🛡3: только чтение.
/// </summary>
public class AdminWorkoutsController(
    AdminAuthService auth,
    IAthleteRepository athletesRepo,
    IWorkoutRepository workouts,
    IWorkoutMetricsRepository metrics,
    IExerciseRepository exercises,
    Core.Programs.ProgramStore programs) : AdminControllerBase(auth)
{
    private const int CsvLimit = 10_000;
    private static readonly string[] DayNames =
        ["monday", "tuesday", "wednesday", "thursday", "friday", "saturday", "sunday"];

    public ActionResult List(int? athleteId, string? dateFrom, string? dateTo, int? limit, int? offset)
    {
        if (Denied()) return UnauthorizedJson();
        var take = limit ?? 50;
        var skip = offset ?? 0;
        if (take is < 1 or > 100) return ErrorJson(400, "limit 1–100");
        if (skip < 0) return ErrorJson(400, "offset >= 0");

        var all = SelectAll(athleteId, dateFrom, dateTo, out var names);
        var page = all.OrderByDescending(w => w.StartedAt)
            .Skip(skip).Take(take)
            .Select(w => Card(w, names, withSets: false)).ToList();
        return new JsonResult(new { total = all.Count, items = page });
    }

    public ActionResult Get(string id)
    {
        if (Denied()) return UnauthorizedJson();
        if (!Guid.TryParse(id, out var workoutId)) return ErrorJson(400, "id не uuid");
        Workout? found = null;
        Dictionary<int, string> names = new();
        foreach (var athlete in athletesRepo.Select(null))
        {
            var candidate = workouts.Get(athlete.Id, workoutId);
            if (candidate == null) continue;
            found = candidate;
            names[athlete.Id] = athlete.Name;
            break;
        }
        if (found == null) return ErrorJson(404, "not_found");

        var card = Card(found, names, withSets: true);
        var (timeline, curve) = FactsTimeline.Parse(found.FactsJson, 0);
        card["timeline"] = timeline;
        card["hrCurve"] = curve;
        return new JsonResult(card);
    }

    public ActionResult Csv(int? athleteId, string? dateFrom, string? dateTo)
    {
        if (Denied()) return UnauthorizedJson();
        var all = SelectAll(athleteId, dateFrom, dateTo, out var names);

        // tech-req 2.4: ';' + UTF-8 BOM (Excel), заголовок первой строкой
        var csv = new StringBuilder();
        csv.AppendLine("athlete;date;duration_min;avg_hr;sets;exercises;adherence_pct");
        foreach (var workout in all.OrderByDescending(w => w.StartedAt).Take(CsvLimit))
            csv.AppendLine(CsvRow(workout, names));
        var bytes = Encoding.UTF8.GetPreamble()
            .Concat(Encoding.UTF8.GetBytes(csv.ToString())).ToArray();
        return File(bytes, "text/csv; charset=utf-8", "workouts.csv");
    }

    // ---------- вспомогательные ----------

    private List<Workout> SelectAll(int? athleteId, string? dateFrom, string? dateTo,
        out Dictionary<int, string> names)
    {
        names = athletesRepo.Select(null).ToDictionary(a => a.Id, a => a.Name);
        var from = ParseDate(dateFrom);
        var to = ParseDate(dateTo);
        var result = new List<Workout>();
        foreach (var athlete in names.Keys)
        {
            if (athleteId != null && athlete != athleteId.Value) continue;
            result.AddRange(workouts.Select(new WorkoutFilter
            {
                AthleteId = athlete, DateFrom = from, DateTo = to,
            }));
        }
        return result;
    }

    private static DateOnly? ParseDate(string? text) =>
        text != null && DateOnly.TryParse(text, out var date) ? date : null;

    private Dictionary<string, object?> Card(Workout w, Dictionary<int, string> names, bool withSets)
    {
        var durationMin = w.EndedAt != null
            ? (int)Math.Round((w.EndedAt.Value - w.StartedAt).TotalMinutes, MidpointRounding.AwayFromZero)
            : (int?)null;
        var metric = metrics.Select(new WorkoutMetricsFilter { AthleteId = w.AthleteId, WorkoutId = w.Id })
            .FirstOrDefault();
        var sets = w.Sets.ToList();
        var card = new Dictionary<string, object?>
        {
            ["workoutId"] = w.Id,
            ["athleteId"] = w.AthleteId,
            ["athleteName"] = names.GetValueOrDefault(w.AthleteId, $"#{w.AthleteId}"),
            ["startedAt"] = w.StartedAt,
            ["endedAt"] = w.EndedAt,
            ["durationMin"] = durationMin,
            ["status"] = w.Status,
            ["sessionKind"] = w.SessionKind,
            ["avgHr"] = w.AvgHr,
            ["setsCount"] = sets.Count,
            ["exercisesCount"] = sets.Where(s => s.ExerciseId != null)
                .Select(s => s.ExerciseId!.Value).Distinct().Count(),
            ["adherence"] = metric?.Adherence,
        };
        if (!withSets) return card;

        var exNames = exercises.Select(new ExerciseFilter { AthleteId = w.AthleteId })
            .ToDictionary(e => e.Id, e => e.Name);
        card["sets"] = sets.OrderBy(s => s.Seq).Select(s => new
        {
            s.Seq,
            exerciseName = s.ExerciseId != null && exNames.TryGetValue(s.ExerciseId.Value, out var n) ? n : null,
            s.WeightKg,
            s.Reps,
            s.InPlan,
            s.Rpe,
            s.KneePain,
        }).ToList();
        card["planFact"] = PlanFact(w, exNames);
        return card;
    }

    /// <summary>План/факт по упражнениям (spec 03 §2): план — первая
    /// сессия дня недели активной версии (v1 — без ротации недель).</summary>
    private object PlanFact(Workout w, Dictionary<Guid, string> exNames)
    {
        var active = programs.GetActive(w.AthleteId);
        var date = DateOnly.FromDateTime(w.StartedAt);
        var day = DayNames[((int)date.DayOfWeek + 6) % 7];
        var plan = new List<object>();
        if (active == null || string.IsNullOrWhiteSpace(active.Body))
            return new { day, plan };

        try
        {
            using var doc = System.Text.Json.JsonDocument.Parse(active.Body);
            foreach (var week in doc.RootElement.GetProperty("weeks").EnumerateArray())
            foreach (var session in week.GetProperty("sessions").EnumerateArray())
            {
                if (!session.TryGetProperty("day", out var d) ||
                    !string.Equals(d.GetString(), day, StringComparison.OrdinalIgnoreCase)) continue;
                foreach (var exercise in session.GetProperty("exercises").EnumerateArray())
                    plan.Add(PlanFactExercise(exercise, w, exNames));
                return new { day, plan }; // первая сессия дня
            }
        }
        catch (Exception ex) when (ex is System.Text.Json.JsonException or KeyNotFoundException)
        {
            // кривой body — только факт
        }
        return new { day, plan };
    }

    private static object PlanFactExercise(System.Text.Json.JsonElement exercise, Workout w,
        Dictionary<Guid, string> exNames)
    {
        var name = exercise.TryGetProperty("exercise_id", out var e) ? e.GetString() : "?";
        var setsNode = exercise.TryGetProperty("sets", out var s) ? s : default;
        var hasSets = setsNode.ValueKind == System.Text.Json.JsonValueKind.Array;
        var first = hasSets && setsNode.GetArrayLength() > 0 ? setsNode[0] : default;
        var weight = first.ValueKind == System.Text.Json.JsonValueKind.Object &&
                     first.TryGetProperty("weight_kg", out var wNode) &&
                     wNode.ValueKind == System.Text.Json.JsonValueKind.Number
            ? wNode.GetDecimal() : (decimal?)null;
        var reps = first.ValueKind == System.Text.Json.JsonValueKind.Object &&
                   first.TryGetProperty("reps", out var rNode) &&
                   rNode.ValueKind == System.Text.Json.JsonValueKind.Number
            ? rNode.GetInt32() : (int?)null;
        var factSets = w.Sets.Where(fs =>
                fs.ExerciseId != null && exNames.GetValueOrDefault(fs.ExerciseId.Value) == name)
            .ToList();
        return new
        {
            exercise = name,
            plannedSets = hasSets ? setsNode.GetArrayLength() : 0,
            plannedWeight = weight,
            plannedReps = reps,
            factSets = factSets.Count,
            factWeight = factSets.Count > 0 ? factSets.Max(fs => fs.WeightKg) : (decimal?)null,
            factReps = factSets.Count > 0 ? factSets.Max(fs => fs.Reps) : (int?)null,
        };
    }

    private string CsvRow(Workout w, Dictionary<int, string> names)
    {
        var metric = metrics.Select(new WorkoutMetricsFilter { AthleteId = w.AthleteId, WorkoutId = w.Id })
            .FirstOrDefault();
        var sets = w.Sets.ToList();
        var invariant = System.Globalization.CultureInfo.InvariantCulture;
        var durationMin = w.EndedAt != null
            ? ((int)Math.Round((w.EndedAt.Value - w.StartedAt).TotalMinutes, MidpointRounding.AwayFromZero))
            .ToString(invariant) : "";
        return string.Join(';',
            names.GetValueOrDefault(w.AthleteId, $"#{w.AthleteId}"),
            DateOnly.FromDateTime(w.StartedAt).ToString("yyyy-MM-dd"),
            durationMin,
            w.AvgHr?.ToString(invariant) ?? "",
            sets.Count.ToString(invariant),
            sets.Where(s => s.ExerciseId != null).Select(s => s.ExerciseId!.Value).Distinct().Count()
                .ToString(invariant),
            metric != null ? metric.Adherence.ToString("0.0", invariant) : "");
    }
}