using System.Globalization;
using System.Security.Claims;
using Data.SeaHavenIndustries.Enums;
using SeaHaven.DataServices.Interfaces;
using SeaHaven.Services.DTOs;
using SeaHaven.Services.Exceptions;
using SeaHaven.Services.Helpers;
using SeaHaven.Services.Interfaces;

namespace SeaHaven.Services.Implementation
{
    public class DashboardService : IDashboardService
    {
        private readonly IDashboardDataService _dataService;
        private readonly IWorkOrderAccountResolver _accountResolver;

        public DashboardService(
            IDashboardDataService dataService,
            IWorkOrderAccountResolver accountResolver)
        {
            _dataService = dataService;
            _accountResolver = accountResolver;
        }

        public async Task<DashboardStatsDTO> GetStatsAsync(
            ClaimsPrincipal user,
            DashboardStatsQueryDTO query,
            CancellationToken cancellationToken)
        {
            var accountId = _accountResolver.ResolveAccountFilter(user);
            var dispatcherId = ResolveDispatcherScope(user, query);

            var counts = await _dataService.GetWorkOrderCountsAsync(accountId, cancellationToken);
            var kpis = await _dataService.GetKpiCountsAsync(
                accountId,
                dispatcherId,
                DashboardBusinessTime.Today(),
                cancellationToken);
            var workOrders = await _dataService.GetDashboardWorkOrdersAsync(
                accountId,
                dispatcherId,
                query.DateFrom,
                query.DateTo,
                cancellationToken);
            var metrics = DashboardMetrics.Calculate(workOrders, DashboardBusinessTime.Today());
            var unassigned = await _dataService.CountOpenUnassignedAsync(
                accountId,
                dispatcherId,
                query.DateFrom,
                query.DateTo,
                cancellationToken);

            var useMetrics = query.DateFrom.HasValue && query.DateTo.HasValue || dispatcherId is not null;

            return new DashboardStatsDTO
            {
                Total = useMetrics ? metrics.Total : counts.Total,
                Open = useMetrics ? metrics.Open : counts.Open,
                NotDispatched = useMetrics ? metrics.NotDispatched : counts.NotDispatched,
                Completed = useMetrics ? metrics.Completed : counts.Completed,
                ScheduledTomorrow = kpis.ScheduledTomorrow,
                PendingUplifts = kpis.PendingUplifts,
                AvetaPending = kpis.AvetaPending,
                Unassigned = unassigned,
                Breakdown = metrics.Breakdown,
                DueCount = metrics.DueCount,
                CompletedDueCount = metrics.CompletedDueCount,
                CompletionRate = metrics.CompletionRate,
                AverageResolutionDays = metrics.AverageResolutionDays,
                StatusDistribution = metrics.StatusDistribution
            };
        }

        public async Task<DashboardWorkloadResponseDTO> GetWorkloadAsync(
            ClaimsPrincipal user,
            DashboardStatsQueryDTO query,
            int page,
            CancellationToken cancellationToken)
        {
            if (page < 1)
                throw new ArgumentOutOfRangeException(nameof(page));

            var accountId = _accountResolver.ResolveAccountFilter(user);
            var dispatcherId = ResolveDispatcherScope(user, query);

            var rows = await _dataService.GetDispatcherWorkloadAsync(
                accountId,
                dispatcherId,
                query.DateFrom,
                query.DateTo,
                cancellationToken);
            var orderedRows = rows
                .OrderByDescending(row => row.OpenCount)
                .ThenBy(row => row.DispatcherName, StringComparer.OrdinalIgnoreCase)
                .ThenBy(row => row.DispatcherId, StringComparer.Ordinal)
                .ToList();
            const int pageSize = 10;

            return new DashboardWorkloadResponseDTO
            {
                Items = orderedRows.Skip((page - 1) * pageSize).Take(pageSize)
                    .Select(row => new DashboardWorkloadRowDTO
                    {
                        DispatcherId = row.DispatcherId,
                        DispatcherName = row.DispatcherName,
                        Color = row.Color,
                        TotalCount = row.TotalCount,
                        OpenCount = row.OpenCount
                    }).ToList(),
                Page = page,
                PageSize = pageSize,
                TotalDispatchers = orderedRows.Count
            };
        }

        public async Task<DashboardPerformanceResponseDTO> GetPerformanceAsync(
            ClaimsPrincipal user,
            DashboardStatsQueryDTO query,
            int page,
            CancellationToken cancellationToken)
        {
            if (page < 1)
                throw new ArgumentOutOfRangeException(nameof(page));

            var accountId = _accountResolver.ResolveAccountFilter(user);
            var dispatcherId = ResolveDispatcherScope(user, query);

            var directory = await _dataService.GetDispatcherWorkloadAsync(
                accountId, dispatcherId, query.DateFrom, query.DateTo, cancellationToken);
            var workOrders = await _dataService.GetDashboardWorkOrdersAsync(
                accountId, dispatcherId, query.DateFrom, query.DateTo, cancellationToken);
            var today = DashboardBusinessTime.Today();
            var rows = directory.Select(dispatcher =>
            {
                var metrics = DashboardMetrics.Calculate(
                    workOrders.Where(workOrder => workOrder.AssignTo == dispatcher.DispatcherId).ToList(),
                    today);
                return new DashboardPerformanceRowDTO
                {
                    DispatcherId = dispatcher.DispatcherId,
                    DispatcherName = dispatcher.DispatcherName,
                    Color = dispatcher.Color,
                    CompletionRate = metrics.CompletionRate,
                    AverageResolutionDays = metrics.AverageResolutionDays,
                    AssignedCount = metrics.Total,
                    CompletedCount = metrics.Completed
                };
            })
                .OrderByDescending(row => row.CompletionRate)
                .ThenBy(row => row.DispatcherName, StringComparer.OrdinalIgnoreCase)
                .ThenBy(row => row.DispatcherId, StringComparer.Ordinal)
                .ToList();
            const int pageSize = 10;

            return new DashboardPerformanceResponseDTO
            {
                Items = rows.Skip((page - 1) * pageSize).Take(pageSize).ToList(),
                Page = page,
                PageSize = pageSize,
                TotalDispatchers = rows.Count
            };
        }

        public async Task<DashboardRegionResponseDTO> GetRegionsAsync(
            ClaimsPrincipal user,
            DashboardStatsQueryDTO query,
            CancellationToken cancellationToken)
        {
            var accountId = _accountResolver.ResolveAccountFilter(user);
            var dispatcherId = ResolveDispatcherScope(user, query);

            var workOrders = await _dataService.GetDashboardWorkOrdersAsync(
                accountId, dispatcherId, query.DateFrom, query.DateTo, cancellationToken);
            var counts = DashboardRegions.Count(workOrders);
            return new DashboardRegionResponseDTO
            {
                Items = DashboardRegions.Names
                    .Select(region => new DashboardRegionRowDTO
                    {
                        Region = region,
                        WorkOrderCount = counts[region]
                    })
                    .ToList()
            };
        }

        public async Task<DashboardTrendResponseDTO> GetTrendAsync(
            ClaimsPrincipal user,
            DashboardTrendQueryDTO query,
            CancellationToken cancellationToken)
        {
            var accountId = _accountResolver.ResolveAccountFilter(user);
            var dispatcherId = ResolveDispatcherScope(user, query);

            var today = DashboardBusinessTime.Today();
            var (windowFrom, windowTo, granularity) = ResolveTrendWindow(query, today);
            var firstBucketStart = BucketStart(windowFrom, granularity);
            var lastBucketStart = BucketStart(windowTo, granularity);
            var lastBucketEnd = BucketEnd(lastBucketStart, granularity);

            var workOrders = await _dataService.GetDashboardWorkOrdersAsync(
                accountId,
                dispatcherId,
                firstBucketStart.AddDays(-1),
                lastBucketEnd.AddDays(1),
                cancellationToken);

            var buckets = BuildBucketStarts(firstBucketStart, windowTo, granularity)
                .Select(start => new TrendBucket(start))
                .ToList();
            var bucketStarts = buckets.Select(bucket => bucket.Start).ToList();

            foreach (var workOrder in workOrders)
            {
                if (workOrder.ScheduledDate is not DateTime scheduled)
                    continue;
                var businessDate = DateOnly.FromDateTime(scheduled.Date);
                if (businessDate < firstBucketStart || businessDate > lastBucketEnd)
                    continue;
                var bucket = buckets[LocateBucket(bucketStarts, businessDate)];
                var status = workOrder.LifecycleStatus
                    ?? LifecycleStatusMapper.ParseLifecycleStatus(workOrder.LegacyStatus);
                bucket.Total++;
                if (status == LifecycleStatus.Completed)
                    bucket.Completed++;
                else if (status == LifecycleStatus.Canceled)
                    bucket.Canceled++;
                else
                {
                    bucket.Open++;
                    if (businessDate < today)
                        bucket.Overdue++;
                }
            }

            DateOnly? currentStart = today < firstBucketStart || today > lastBucketEnd
                ? null
                : buckets[LocateBucket(bucketStarts, today)].Start;

            return new DashboardTrendResponseDTO
            {
                Granularity = granularity,
                Today = today,
                Buckets = buckets.Select(bucket => new DashboardTrendBucketDTO
                {
                    Date = bucket.Start,
                    Label = bucket.Start.ToString("yyyy-MM-dd", CultureInfo.InvariantCulture),
                    Total = bucket.Total,
                    Open = bucket.Open,
                    Completed = bucket.Completed,
                    Canceled = bucket.Canceled,
                    Overdue = bucket.Overdue,
                    IsCurrent = bucket.Start == currentStart
                }).ToList()
            };
        }

        private static (DateOnly From, DateOnly To, string Granularity) ResolveTrendWindow(
            DashboardTrendQueryDTO query,
            DateOnly today)
        {
            if (query.Year is int year)
            {
                if (year < DateOnly.MinValue.Year || year > DateOnly.MaxValue.Year)
                    throw new ArgumentOutOfRangeException(nameof(query));
                return (new DateOnly(year, 1, 1), new DateOnly(year, 12, 31), "month");
            }

            if (string.Equals(query.Range, ThreeMonthRange, StringComparison.OrdinalIgnoreCase))
            {
                var weeklyTo = query.DateTo ?? today;
                var weeklyFrom = query.DateFrom ?? weeklyTo.AddMonths(-3).AddDays(1);
                if (weeklyFrom > weeklyTo)
                    throw new ArgumentOutOfRangeException(nameof(query));
                return (weeklyFrom, weeklyTo, "week");
            }

            if (query.DateFrom is DateOnly dailyFrom && query.DateTo is DateOnly dailyTo)
            {
                if (dailyFrom > dailyTo)
                    throw new ArgumentOutOfRangeException(nameof(query));
                return (dailyFrom, dailyTo, "day");
            }

            if (query.DateFrom.HasValue != query.DateTo.HasValue)
                throw new ArgumentOutOfRangeException(nameof(query));

            return (today, today, "day");
        }

        private static List<DateOnly> BuildBucketStarts(DateOnly from, DateOnly to, string granularity)
        {
            var starts = new List<DateOnly>();
            var current = BucketStart(from, granularity);
            while (current <= to)
            {
                starts.Add(current);
                current = granularity switch
                {
                    "week" => current.AddDays(7),
                    "month" => current.AddMonths(1),
                    _ => current.AddDays(1)
                };
            }
            return starts;
        }

        private static DateOnly BucketStart(DateOnly date, string granularity) => granularity switch
        {
            "week" => date.AddDays(-(((int)date.DayOfWeek + 6) % 7)),
            "month" => new DateOnly(date.Year, date.Month, 1),
            _ => date
        };

        private static DateOnly BucketEnd(DateOnly start, string granularity) => granularity switch
        {
            "week" => start.AddDays(6),
            "month" => start.AddMonths(1).AddDays(-1),
            _ => start
        };

        private static int LocateBucket(List<DateOnly> starts, DateOnly date)
        {
            var low = 0;
            var high = starts.Count - 1;
            while (low < high)
            {
                var middle = (low + high + 1) / 2;
                if (starts[middle] <= date)
                    low = middle;
                else
                    high = middle - 1;
            }
            return low;
        }

        private const string ThreeMonthRange = "3m";

        private sealed class TrendBucket(DateOnly start)
        {
            public DateOnly Start { get; } = start;
            public int Total { get; set; }
            public int Open { get; set; }
            public int Completed { get; set; }
            public int Canceled { get; set; }
            public int Overdue { get; set; }
        }

        public async Task<DashboardVendorInsightsResponseDTO> GetVendorInsightsAsync(
            ClaimsPrincipal user,
            CancellationToken cancellationToken)
        {
            var accountId = _accountResolver.ResolveAccountFilter(user);
            var workOrders = await _dataService.GetDashboardWorkOrdersAsync(
                accountId, null, null, null, cancellationToken);
            var activeVendorOrders = workOrders
                .Where(workOrder => workOrder.VendorCompanyId.HasValue
                    && workOrder.VendorIsActive
                    && !workOrder.VendorCompanyIsDeleted)
                .ToList();
            var today = DashboardBusinessTime.Today();
            var rows = activeVendorOrders
                .GroupBy(workOrder => new
                {
                    Id = workOrder.VendorCompanyId!.Value,
                    Name = workOrder.VendorCompanyName ?? string.Empty
                })
                .Select(group =>
                {
                    var orders = group.ToList();
                    var metrics = DashboardMetrics.Calculate(orders, today);
                    var rescheduled = orders.Count(order => order.RescheduleCount >= 1);
                    return new DashboardVendorInsightsRowDTO
                    {
                        VendorCompanyId = group.Key.Id,
                        VendorCompanyName = group.Key.Name,
                        CompletionRate = metrics.CompletionRate,
                        RescheduleRate = Math.Round((decimal)rescheduled / orders.Count * 100, 2),
                        AverageResolutionDays = metrics.AverageResolutionDays,
                        TotalJobs = orders.Count
                    };
                })
                .OrderByDescending(row => row.CompletionRate)
                .ThenBy(row => row.VendorCompanyName, StringComparer.OrdinalIgnoreCase)
                .ThenBy(row => row.VendorCompanyId)
                .ToList();
            const int pageSize = 10;

            return new DashboardVendorInsightsResponseDTO
            {
                Items = rows.Take(pageSize).ToList(),
                Page = 1,
                PageSize = pageSize,
                TotalVendors = rows.Count
            };
        }

        private string? ResolveDispatcherScope(ClaimsPrincipal user, DashboardStatsQueryDTO query)
        {
            if (user.IsInRole("Dispatcher"))
            {
                var dispatcherId = user.FindFirstValue(ClaimTypes.NameIdentifier);
                if (string.IsNullOrWhiteSpace(dispatcherId))
                    throw new WorkOrderBoardValidationException("Forbidden", "Dispatcher identity is required.");
                return dispatcherId;
            }

            if (user.IsInRole("Admin") || user.IsInRole("Manager") || user.IsInRole("Scheduler"))
            {
                var selected = query.DispatcherId;
                if (string.IsNullOrWhiteSpace(selected))
                    return null;
                if (selected.Equals("mine", StringComparison.OrdinalIgnoreCase))
                {
                    var identity = user.FindFirstValue(ClaimTypes.NameIdentifier);
                    if (string.IsNullOrWhiteSpace(identity))
                        throw new WorkOrderBoardValidationException("Forbidden", "Dispatcher identity is required.");
                    return identity;
                }
                return selected;
            }

            throw new WorkOrderBoardValidationException("Forbidden", "Dashboard access requires an authorized role.");
        }
    }
}