using Data.SeaHavenIndustries;
using Data.SeaHavenIndustries.Enums;
using Microsoft.EntityFrameworkCore;
using SeaHaven.DataServices.Helpers;
using SeaHaven.DataServices.Interfaces;
using SeaHaven.DataServices.Models;

namespace SeaHaven.DataServices.Implementation
{
    public class NotificationFeedDataService : INotificationFeedDataService
    {
        private static readonly string[] TerminalDispatchStatuses = { "Completed", "Verified", "Cancelled", "Canceled" };

        // Uplift outcomes a requester is told about; "Denied" is the legacy spelling of Rejected.
        private static readonly string[] DecisionStatuses = { "Approved", "Rejected", "Denied", "Revoked" };

        private static readonly string[] SlaSeverities = { "1", "2", "3", "4", "5" };

        private const string AssignToAuditField = "AssignTo";
        private const string LegacyAssignedToAuditField = "AssignedTo";

        private readonly ApplicationDbContext _context;

        public NotificationFeedDataService(ApplicationDbContext context)
        {
            _context = context;
        }

        public async Task<UnassignedWorkOrdersSummary> GetUnassignedSummaryAsync(
            int? accountId, CancellationToken cancellationToken)
        {
            var summary = await OpenWorkOrders(new NotificationFeedScope(accountId, null))
                .Where(w => w.AssignTo == null || w.AssignTo == "")
                .GroupBy(_ => 1)
                .Select(group => new UnassignedWorkOrdersSummary
                {
                    Count = group.Count(),
                    LatestCreatedAt = group.Max(w => w.CreatedDate)
                })
                .FirstOrDefaultAsync(cancellationToken);

            return summary ?? new UnassignedWorkOrdersSummary();
        }

        public Task<NotificationCandidatePage> GetAvetaMissingAsync(
            NotificationFeedScope scope, DateOnly today, int limit, CancellationToken cancellationToken)
        {
            // Same rule as the dashboard's Aveta Pending tile so the two counts agree.
            var windowStart = today.ToDateTime(TimeOnly.MinValue);
            var windowEnd = today.AddDays(2).ToDateTime(TimeOnly.MinValue);
            var candidates = OpenWorkOrders(scope)
                .Where(w => w.AvetaRequired
                    && w.ScheduledDate >= windowStart
                    && w.ScheduledDate < windowEnd
                    && !w.workOrderAttachments!.Any(attachment =>
                        (attachment.IsDeleted == null || attachment.IsDeleted == false)
                        && attachment.Category == WorkOrderMediaCategory.Aveta));

            return PageAsync(candidates, limit, cancellationToken);
        }

        public Task<NotificationCandidatePage> GetNoVendorAsync(
            NotificationFeedScope scope, DateTime cutoff, int limit, CancellationToken cancellationToken)
        {
            // "Has a vendor" matches the vendor reminders: any live non-terminal dispatch that
            // points at the work order directly or links it through DispatchWorkOrders. Soft-deleted
            // dispatches are ignored so a removed dispatch does not keep the row out of No Vendor.
            var candidates = OpenWorkOrders(scope)
                .Where(w => w.ScheduledDate.HasValue
                    && w.ScheduledDate.Value <= cutoff
                    && !_context.Dispatches.Any(d => d.WorkOrderId == w.Id
                        && (d.IsDeleted == null || d.IsDeleted == false)
                        && !TerminalDispatchStatuses.Contains(d.Status ?? ""))
                    && !_context.DispatchWorkOrders.Any(link => link.WorkOrderId == w.Id
                        && link.Dispatch != null
                        && (link.Dispatch.IsDeleted == null || link.Dispatch.IsDeleted == false)
                        && !TerminalDispatchStatuses.Contains(link.Dispatch.Status ?? "")));

            return PageAsync(candidates, limit, cancellationToken);
        }

        public async Task<IReadOnlyList<NotificationAssignmentCandidate>> GetRecentAssignmentsAsync(
            NotificationPersonalScope scope, DateTime since, int limit, CancellationToken cancellationToken)
        {
            // Board create and board edits log "AssignTo" with user ids; the legacy assignment endpoint
            // logs "AssignedTo" with display names. Only the time and the actor are read, so both count.
            var assignmentLogs = _context.WorkOrderAuditLogs.AsNoTracking()
                .Where(log => log.FieldName == AssignToAuditField || log.FieldName == LegacyAssignedToAuditField);

            // The latest assignment entry of each work order the user holds now.
            var candidates =
                from log in assignmentLogs
                join w in OpenWorkOrders(new NotificationFeedScope(scope.AccountId, scope.UserId))
                    on log.WorkOrderId equals w.Id
                where log.CreatedAt >= since
                    && (log.UserId == null || log.UserId != scope.UserId)
                    && !assignmentLogs.Any(later => later.WorkOrderId == log.WorkOrderId
                        && (later.CreatedAt > log.CreatedAt || (later.CreatedAt == log.CreatedAt && later.Id > log.Id)))
                orderby log.CreatedAt descending, w.Id descending
                select new NotificationAssignmentCandidate
                {
                    WorkOrderId = w.Id,
                    Number = w.InternalWONumber ?? w.WorkerOrderNumber,
                    AssignedAt = log.CreatedAt,
                    AssignedBy = log.UserId
                };

            return await candidates.Take(limit).ToListAsync(cancellationToken);
        }

        public async Task<IReadOnlyList<NotificationCommentCandidate>> GetUnansweredCommentsAsync(
            NotificationPersonalScope scope, DateTime since, int limit, CancellationToken cancellationToken)
        {
            var userId = scope.UserId;
            // SH-217 stores a mention as the token "@[userId:Display Name]" inside the comment text.
            var mentionToken = "@[" + userId + ":";
            var ownComments = _context.Comments.AsNoTracking()
                .Where(own => own.UserId == userId && own.IsDeleted != true);

            var candidates =
                from c in _context.Comments.AsNoTracking()
                join w in ScopedWorkOrders(scope.AccountId) on c.WorkerOrderId equals w.Id
                where c.IsDeleted != true
                    && c.CreatedDate != null
                    && c.CreatedDate >= since
                    && (c.UserId == null || c.UserId != userId)
                    && (w.AssignTo == userId
                        || (c.Commenttext != null && c.Commenttext.Contains(mentionToken))
                        || ownComments.Any(own => own.WorkerOrderId == w.Id))
                    && !ownComments.Any(own => own.WorkerOrderId == w.Id && own.CreatedDate >= c.CreatedDate)
                orderby c.CreatedDate descending, c.Id descending
                select new NotificationCommentCandidate
                {
                    CommentId = c.Id,
                    WorkOrderId = w.Id,
                    WorkOrderNumber = w.InternalWONumber ?? w.WorkerOrderNumber,
                    AuthorFirstName = c.ApplicationUser != null ? c.ApplicationUser.FirstName : null,
                    AuthorLastName = c.ApplicationUser != null ? c.ApplicationUser.LastName : null,
                    Commenter = c.Commenter,
                    Text = c.Commenttext,
                    CreatedAt = c.CreatedDate!.Value
                };

            return await candidates.Take(limit).ToListAsync(cancellationToken);
        }

        public async Task<IReadOnlyList<NotificationUpliftDecisionCandidate>> GetUpliftDecisionsAsync(
            NotificationPersonalScope scope, DateTime since, int limit, CancellationToken cancellationToken)
        {
            var userId = scope.UserId;
            // Same work-order resolution as the uplift reads: the dispatch's own work order,
            // otherwise the first work order linked through DispatchWorkOrders.
            var candidates =
                from u in _context.DispatchUpliftRequests.AsNoTracking()
                join d in _context.Dispatches.AsNoTracking() on u.DispatchId equals d.Id
                let workOrderId = d.WorkOrderId
                    ?? d.DispatchWorkOrders!.Select(link => (int?)link.WorkOrderId).FirstOrDefault()
                join w in ScopedWorkOrders(scope.AccountId) on workOrderId equals (int?)w.Id
                where u.IsDeleted != true
                    && d.IsDeleted != true
                    && u.createdby == userId
                    && u.DecidedAt != null
                    && u.DecidedAt >= since
                    && (u.DecidedByUserId == null || u.DecidedByUserId != userId)
                    && DecisionStatuses.Contains(u.Status)
                orderby u.DecidedAt descending, u.Id descending
                select new NotificationUpliftDecisionCandidate
                {
                    UpliftId = u.Id,
                    WorkOrderId = w.Id,
                    WorkOrderNumber = w.InternalWONumber ?? w.WorkerOrderNumber,
                    Status = u.Status,
                    Amount = u.RequestedNTE,
                    DecisionNote = u.DecisionNote,
                    DecidedAt = u.DecidedAt!.Value
                };

            return await candidates.Take(limit).ToListAsync(cancellationToken);
        }

        public async Task<NotificationSlaCandidates> GetSlaCandidatesAsync(
            NotificationFeedScope scope,
            NotificationSlaCutoffs atRisk,
            NotificationSlaCutoffs breached,
            int breachedLimit,
            CancellationToken cancellationToken)
        {
            var eligible = SlaEligibleWorkOrders(scope);

            // Bounded by the longest window: nothing created more than 72 hours ago is still at risk.
            var atRiskItems = await ProjectSla(CreatedAfter(CreatedAtOrBefore(eligible, atRisk), breached))
                .OrderBy(candidate => candidate.CreatedAt)
                .ThenBy(candidate => candidate.Id)
                .ToListAsync(cancellationToken);

            // Breaches stay until acknowledged, so legacy open work orders can make this set large.
            var unacknowledged = CreatedAtOrBefore(eligible, breached)
                .Where(w => !_context.WorkOrderAuditLogs.Any(log => log.WorkOrderId == w.Id
                    && log.FieldName == SlaBreachAcknowledgementAudit.FieldName
                    && log.NewValue == w.Severity));
            var breachedTotal = await unacknowledged.CountAsync(cancellationToken);
            var breachedItems = breachedTotal == 0
                ? new List<NotificationSlaCandidate>()
                : await ProjectSla(unacknowledged)
                    .OrderByDescending(candidate => candidate.CreatedAt)
                    .ThenByDescending(candidate => candidate.Id)
                    .Take(breachedLimit)
                    .ToListAsync(cancellationToken);

            return new NotificationSlaCandidates
            {
                AtRisk = atRiskItems,
                Breached = breachedItems,
                BreachedTotal = breachedTotal
            };
        }

        public Task<NotificationSlaCandidate?> GetSlaCandidateAsync(
            NotificationFeedScope scope, int workOrderId, CancellationToken cancellationToken)
            => ProjectSla(SlaEligibleWorkOrders(scope).Where(w => w.Id == workOrderId))
                .FirstOrDefaultAsync(cancellationToken);

        // Same rule as the board's severity facet: Reactive or Emergency with a stored SEV level "1"–"5".
        private IQueryable<WorkOrder> SlaEligibleWorkOrders(NotificationFeedScope scope)
            => OpenWorkOrders(scope).Where(w =>
                (w.WorkOrderType == WorkOrderType.Reactive || w.WorkOrderType == WorkOrderType.Emergency)
                && SlaSeverities.Contains(w.Severity ?? "")
                && w.CreatedDate != null);

        private static IQueryable<WorkOrder> CreatedAtOrBefore(IQueryable<WorkOrder> workOrders, NotificationSlaCutoffs cutoffs)
        {
            var (sev1, sev2, sev3, sev4, sev5) = (cutoffs.Sev1, cutoffs.Sev2, cutoffs.Sev3, cutoffs.Sev4, cutoffs.Sev5);
            return workOrders.Where(w =>
                (w.Severity == "1" && w.CreatedDate <= sev1)
                || (w.Severity == "2" && w.CreatedDate <= sev2)
                || (w.Severity == "3" && w.CreatedDate <= sev3)
                || (w.Severity == "4" && w.CreatedDate <= sev4)
                || (w.Severity == "5" && w.CreatedDate <= sev5));
        }

        private static IQueryable<WorkOrder> CreatedAfter(IQueryable<WorkOrder> workOrders, NotificationSlaCutoffs cutoffs)
        {
            var (sev1, sev2, sev3, sev4, sev5) = (cutoffs.Sev1, cutoffs.Sev2, cutoffs.Sev3, cutoffs.Sev4, cutoffs.Sev5);
            return workOrders.Where(w =>
                (w.Severity == "1" && w.CreatedDate > sev1)
                || (w.Severity == "2" && w.CreatedDate > sev2)
                || (w.Severity == "3" && w.CreatedDate > sev3)
                || (w.Severity == "4" && w.CreatedDate > sev4)
                || (w.Severity == "5" && w.CreatedDate > sev5));
        }

        private IQueryable<NotificationSlaCandidate> ProjectSla(IQueryable<WorkOrder> workOrders)
            => workOrders.Select(w => new NotificationSlaCandidate
            {
                Id = w.Id,
                Number = w.InternalWONumber ?? w.WorkerOrderNumber,
                Severity = w.Severity!,
                CreatedAt = w.CreatedDate!.Value,
                BreachAcknowledged = _context.WorkOrderAuditLogs.Any(log => log.WorkOrderId == w.Id
                    && log.FieldName == SlaBreachAcknowledgementAudit.FieldName
                    && log.NewValue == w.Severity)
            });

        private IQueryable<WorkOrder> ScopedWorkOrders(int? accountId)
        {
            var workOrders = WorkOrderBoardQueryFilters.ApplyBaseScope(_context.workOrders.AsNoTracking());
            return accountId is int id
                ? WorkOrderBoardQueryFilters.ApplyAccountScope(workOrders, id)
                : workOrders;
        }

        private IQueryable<WorkOrder> OpenWorkOrders(NotificationFeedScope scope)
        {
            var workOrders = ScopedWorkOrders(scope.AccountId);
            if (scope.DispatcherId != null)
                workOrders = workOrders.Where(w => w.AssignTo == scope.DispatcherId);

            return workOrders.Where(w => w.LifecycleStatus != LifecycleStatus.Completed
                && w.LifecycleStatus != LifecycleStatus.Canceled
                && (w.LifecycleStatus != null
                    || ((w.LegacyStatus ?? w.Status) != "Done"
                        && (w.LegacyStatus ?? w.Status) != "Completed"
                        && (w.LegacyStatus ?? w.Status) != "Complete"
                        && (w.LegacyStatus ?? w.Status) != "Closed"
                        && (w.LegacyStatus ?? w.Status) != "Canceled"
                        && (w.LegacyStatus ?? w.Status) != "Cancelled")));
        }

        private static async Task<NotificationCandidatePage> PageAsync(
            IQueryable<WorkOrder> candidates, int limit, CancellationToken cancellationToken)
        {
            var total = await candidates.CountAsync(cancellationToken);
            if (total == 0)
                return new NotificationCandidatePage();

            var items = await candidates
                .OrderByDescending(w => w.ScheduledDate)
                .ThenByDescending(w => w.Id)
                .Take(limit)
                .Select(w => new NotificationWorkOrderCandidate
                {
                    Id = w.Id,
                    Number = w.InternalWONumber ?? w.WorkerOrderNumber,
                    ScheduledDate = w.ScheduledDate!.Value
                })
                .ToListAsync(cancellationToken);

            return new NotificationCandidatePage { Total = total, Items = items };
        }
    }
}