using Data.SeaHavenIndustries.Enums;
using SeaHaven.DataServices.Interfaces;
using SeaHaven.Services.DTOs;

namespace SeaHaven.Services.Helpers;

public static class DashboardMetrics
{
    public static DashboardMetricResult Calculate(
        IReadOnlyList<DashboardWorkOrder> workOrders,
        DateOnly today)
    {
        var breakdown = new DashboardBreakdownDTO();
        var dueCount = 0;
        var completedDueCount = 0;
        var resolutionDays = new List<decimal>();

        foreach (var workOrder in workOrders)
        {
            var status = workOrder.LifecycleStatus
                ?? LifecycleStatusMapper.ParseLifecycleStatus(workOrder.LegacyStatus);
            var completed = status == LifecycleStatus.Completed;
            var canceled = status == LifecycleStatus.Canceled;
            AddBreakdownCount(breakdown, workOrder.WorkOrderType);

            var due = completed || (workOrder.ScheduledDate is DateTime scheduled
                && DateOnly.FromDateTime(scheduled.Date) <= today);
            if (due)
            {
                dueCount++;
                if (completed)
                    completedDueCount++;
            }

            if (completed && workOrder.CompletedDate is DateTime completedDate)
            {
                var anchor = workOrder.OriginalDate
                    ?? (workOrder.ScheduledDate is DateTime scheduledDate
                        ? DateOnly.FromDateTime(scheduledDate.Date)
                        : null);
                if (anchor is DateOnly originalDate)
                    resolutionDays.Add((decimal)(completedDate.Date - originalDate.ToDateTime(TimeOnly.MinValue)).TotalDays);
            }
        }

        return new DashboardMetricResult(
            workOrders.Count,
            workOrders.Count(workOrder =>
            {
                var status = workOrder.LifecycleStatus
                    ?? LifecycleStatusMapper.ParseLifecycleStatus(workOrder.LegacyStatus);
                return status is not LifecycleStatus.Completed and not LifecycleStatus.Canceled;
            }),
            workOrders.Count(workOrder => string.IsNullOrWhiteSpace(workOrder.AssignTo)),
            workOrders.Count(workOrder =>
                (workOrder.LifecycleStatus ?? LifecycleStatusMapper.ParseLifecycleStatus(workOrder.LegacyStatus))
                == LifecycleStatus.Completed),
            breakdown,
            dueCount,
            completedDueCount,
            dueCount == 0 ? 0 : Math.Round((decimal)completedDueCount / dueCount * 100, 2),
            resolutionDays.Count == 0 ? null : Math.Round(resolutionDays.Average(), 2),
            BuildStatusDistribution(workOrders));
    }

    private static IReadOnlyList<DashboardStatusBucketDTO> BuildStatusDistribution(
        IReadOnlyList<DashboardWorkOrder> workOrders)
        => workOrders
            .GroupBy(workOrder => workOrder.LifecycleStatus
                ?? LifecycleStatusMapper.ParseLifecycleStatus(workOrder.LegacyStatus))
            .Select(group => new DashboardStatusBucketDTO
            {
                Status = group.Key.HasValue
                    ? LifecycleStatusMapper.ToFeLabel(group.Key.Value)
                    : "Unknown",
                Count = group.Count()
            })
            .OrderByDescending(bucket => bucket.Count)
            .ThenBy(bucket => bucket.Status, StringComparer.OrdinalIgnoreCase)
            .ToList();

    // Partition by the stored type only; past due is an overlay on any type, not a bucket.
    private static void AddBreakdownCount(
        DashboardBreakdownDTO breakdown,
        WorkOrderType? type)
    {
        switch (type)
        {
            case WorkOrderType.PM:
                breakdown.PM++;
                break;
            case WorkOrderType.Emergency:
                breakdown.Emergency++;
                break;
            case WorkOrderType.Reactive:
                breakdown.Reactive++;
                break;
            case WorkOrderType.Overdue:
                breakdown.Overdue++;
                break;
            default:
                breakdown.Other++;
                break;
        }
    }
}

public sealed record DashboardMetricResult(
    int Total,
    int Open,
    int NotDispatched,
    int Completed,
    DashboardBreakdownDTO Breakdown,
    int DueCount,
    int CompletedDueCount,
    decimal CompletionRate,
    decimal? AverageResolutionDays,
    IReadOnlyList<DashboardStatusBucketDTO> StatusDistribution);