using System.Security.Claims;
using Data.SeaHavenIndustries;
using Data.SeaHavenIndustries.Enums;
using Microsoft.Extensions.Options;
using SeaHaven.DataServices.Interfaces;
using SeaHaven.Services.Configuration;
using SeaHaven.Services.DTOs;
using SeaHaven.Services.Exceptions;
using SeaHaven.Services.Helpers;
using SeaHaven.Services.Implementation;
using SeaHaven.Services.Interfaces;

namespace SeaHaven.Services.Implementation
{
    public class WorkOrderUpliftService : IWorkOrderUpliftService
    {
        private readonly IUpliftDataService _upliftData;
        private readonly IDispatchDataService _dispatchData;
        private readonly IWorkOrderDetailDataService _detailData;
        private readonly IWorkOrderAccountResolver _accountResolver;
        private readonly IUserDataService _userData;
        private readonly TimeProvider _timeProvider;
        private readonly ApprovalsOptions _approvalsOptions;

        public WorkOrderUpliftService(
            IUpliftDataService upliftData,
            IDispatchDataService dispatchData,
            IWorkOrderDetailDataService detailData,
            IWorkOrderAccountResolver accountResolver,
            IUserDataService userData,
            TimeProvider timeProvider,
            IOptions<ApprovalsOptions> approvalsOptions)
        {
            _upliftData = upliftData;
            _dispatchData = dispatchData;
            _detailData = detailData;
            _accountResolver = accountResolver;
            _userData = userData;
            _timeProvider = timeProvider;
            _approvalsOptions = approvalsOptions.Value;
        }

        public async Task<IReadOnlyList<WorkOrderUpliftDto>?> ListAsync(
            int workOrderId,
            ClaimsPrincipal user,
            CancellationToken cancellationToken)
        {
            if (!await HasWorkOrderAccessAsync(workOrderId, user, cancellationToken))
                return null;

            var rows = await _upliftData.GetForWorkOrderAsync(workOrderId, cancellationToken);
            return rows.Select(WorkOrderUpliftContractMapper.MapItem).ToList();
        }

        public async Task<WorkOrderUpliftDto?> CreateAsync(
            int workOrderId,
            CreateWorkOrderUpliftRequestDto request,
            ClaimsPrincipal user,
            CancellationToken cancellationToken)
        {
            if (!await HasWorkOrderAccessAsync(workOrderId, user, cancellationToken))
                return null;

            if (request.Amount <= 0)
                throw new InvalidOperationException("Uplift amount must be greater than zero");

            var userId = user.FindFirstValue(ClaimTypes.NameIdentifier);
            var requesterName = await ResolveUserDisplayNameAsync(userId, cancellationToken);
            var notes = request.Notes?.Trim() ?? "";
            var accountFilter = _accountResolver.ResolveAccountFilter(user);

            return await _upliftData.ExecuteWorkOrderMutationAsync(
                workOrderId,
                ct => CreateLockedAsync(
                    workOrderId,
                    request.Amount,
                    notes,
                    userId,
                    requesterName,
                    accountFilter,
                    ct),
                cancellationToken);
        }

        private async Task<WorkOrderUpliftDto?> CreateLockedAsync(
            int workOrderId,
            decimal amount,
            string notes,
            string? userId,
            string requesterName,
            int? accountFilter,
            CancellationToken cancellationToken)
        {
            var workOrder = await _detailData.GetWorkOrderForMediaAsync(
                workOrderId,
                cancellationToken,
                accountFilter);
            if (workOrder == null)
                throw new InvalidOperationException("Work order has no primary dispatch for uplift requests");

            if (workOrder.LifecycleStatus is LifecycleStatus.Completed or LifecycleStatus.Canceled)
            {
                throw new InvalidOperationException(
                    $"Cannot create an uplift on a '{workOrder.LifecycleStatus}' work order");
            }

            // SH-393: write to a dispatch the work order's uplift reads resolve back to it.
            // Loading the primary by id alone accepted soft-deleted, unlinked, or other work
            // orders' dispatches, so the request never showed on this work order and never
            // consumed its allowance.
            var dispatch = await _upliftData.GetUpliftDispatchForWorkOrderAsync(
                workOrderId,
                workOrder.PrimaryDispatchId,
                cancellationToken);
            if (dispatch == null)
                throw new InvalidOperationException("Work order has no primary dispatch for uplift requests");

            if (IsTerminalForUplift(dispatch.Status))
                throw new InvalidOperationException($"Cannot request uplift on a '{dispatch.Status}' dispatch");

            if (await _upliftData.HasPendingForWorkOrderAsync(workOrderId, cancellationToken)
                || await _upliftData.HasActiveAsync(dispatch.Id, cancellationToken))
                throw new InvalidOperationException("An open uplift request already exists for this work order");

            var now = _timeProvider.GetUtcNow().UtcDateTime;
            var current = dispatch.NTEAmount ?? 0m;
            var consumed = await _upliftData.SumAutoApprovedAmountForWorkOrderAsync(workOrderId, cancellationToken);
            var remaining = WorkOrderUpliftAllowance.Remaining(
                WorkOrderUpliftAllowance.CapFor(workOrder.WorkOrderType),
                consumed);

            if (WorkOrderUpliftAllowance.AutoApproves(amount, remaining))
            {
                return await PersistCreatedAsync(
                    dispatch,
                    workOrderId,
                    userId,
                    requesterName,
                    current,
                    amount,
                    notes,
                    UpliftStatus.NoApprovalRequired,
                    requiredTier: 0,
                    expiresAt: null,
                    UpliftNotificationStatus.Sent,
                    "uplift_auto_approved",
                    now,
                    cancellationToken);
            }

            return await PersistCreatedAsync(
                dispatch,
                workOrderId,
                userId,
                requesterName,
                current,
                amount,
                notes,
                UpliftStatus.Pending,
                requiredTier: 1,
                now + _approvalsOptions.EffectiveExpiration,
                UpliftNotificationStatus.Pending,
                "uplift_requested",
                now,
                cancellationToken);
        }

        public async Task<WorkOrderUpliftDto?> CancelAsync(
            int workOrderId,
            int upliftId,
            ClaimsPrincipal user,
            CancellationToken cancellationToken)
        {
            if (!await HasWorkOrderAccessAsync(workOrderId, user, cancellationToken))
                return null;

            var req = await _upliftData.GetByIdAndWorkOrderAsync(upliftId, workOrderId, cancellationToken);
            if (req == null)
                throw new KeyNotFoundException("Uplift request not found");

            if (!UpliftStatus.CanTransition(req.Status, UpliftStatus.Withdrawn))
                throw new InvalidOperationException($"Cannot cancel a '{UpliftStatus.ToCanonical(req.Status)}' uplift request");

            var dispatch = await _dispatchData.GetByIdAsync(req.DispatchId);
            if (dispatch == null)
                throw new KeyNotFoundException("Dispatch not found");

            // SH-196: same terminal-lifecycle guard as revoke — the read-only dialog state
            // is UX only and does not stop a direct API call.
            await EnsureWorkOrderAcceptsUpliftMutationAsync(workOrderId, user, "cancel", cancellationToken);

            var userId = user.FindFirstValue(ClaimTypes.NameIdentifier);
            var now = _timeProvider.GetUtcNow().UtcDateTime;
            var previous = UpliftStatus.ToCanonical(req.Status);
            req.Status = UpliftStatus.Withdrawn;
            req.DecidedAt = now;
            req.DecidedByUserId = userId;
            req.LastModificationTime = now;

            await StageAuditAsync(
                dispatch,
                workOrderId,
                userId,
                previous,
                UpliftStatus.Withdrawn,
                "uplift_cancel",
                now,
                cancellationToken,
                isStatusTransition: true);
            await _upliftData.SaveChangesAsync(cancellationToken);

            var requesterName = req.RequestedByVendorName ?? await ResolveUserDisplayNameAsync(req.createdby, cancellationToken);
            return WorkOrderUpliftContractMapper.MapItem(req, requesterName, await ResolveUserDisplayNameAsync(userId, cancellationToken));
        }

        public async Task<WorkOrderUpliftDto?> RevokeAsync(
            int workOrderId,
            int upliftId,
            RevokeWorkOrderUpliftRequestDto request,
            ClaimsPrincipal user,
            CancellationToken cancellationToken)
        {
            if (!await HasWorkOrderAccessAsync(workOrderId, user, cancellationToken))
                return null;

            var req = await _upliftData.GetByIdAndWorkOrderAsync(upliftId, workOrderId, cancellationToken);
            if (req == null)
                throw new KeyNotFoundException("Uplift request not found");

            var canonical = UpliftStatus.ToCanonical(req.Status);
            var userId = user.FindFirstValue(ClaimTypes.NameIdentifier);

            if (canonical == UpliftStatus.NoApprovalRequired)
            {
                if (string.IsNullOrWhiteSpace(userId)
                    || !string.Equals(req.createdby, userId, StringComparison.Ordinal))
                {
                    throw new UpliftForbiddenException("Only the request owner can revoke an auto-approved uplift");
                }
            }
            else if (canonical == UpliftStatus.Approved)
            {
                if (!user.IsInRole("Admin"))
                    throw new UpliftForbiddenException("Admin role is required to revoke an approved uplift");

                if (string.IsNullOrWhiteSpace(request.Reason))
                    throw new InvalidOperationException("A reason is required when revoking an approved uplift");
            }
            else
            {
                throw new InvalidOperationException($"Cannot revoke a '{canonical}' uplift request");
            }

            var dispatch = await _dispatchData.GetByIdAsync(req.DispatchId);
            if (dispatch == null)
                throw new KeyNotFoundException("Dispatch not found");

            // SH-196: revoking is blocked once the work order is Completed or Canceled.
            // The board dialog enforces this in the UI only, so without a service-side
            // guard a direct API call could still mutate uplifts on a terminal WO.
            await EnsureWorkOrderAcceptsUpliftMutationAsync(workOrderId, user, "revoke", cancellationToken);

            var now = _timeProvider.GetUtcNow().UtcDateTime;
            var previous = canonical;

            // SH-196: revoking must free the work order's uplift capacity again. Create
            // raises the dispatch NTE for BOTH auto-approved and approved uplifts, so
            // revoke has to compensate symmetrically. Restoring only on Approved left the
            // NTE raised while SumAutoApprovedAmountForWorkOrderAsync stopped counting the
            // revoked request, so every create -> auto-approve -> revoke cycle compounded
            // the inflation and handed back allowance that was never actually released.
            if (canonical == UpliftStatus.Approved || canonical == UpliftStatus.NoApprovalRequired)
            {
                var oldNte = dispatch.NTEAmount ?? 0m;
                dispatch.NTEAmount = req.CurrentNTE ?? oldNte;
                dispatch.LastModificationTime = now;
            }

            req.Status = UpliftStatus.Revoked;
            req.DecidedAt = now;
            req.DecidedByUserId = userId;
            req.DecisionNote = string.IsNullOrWhiteSpace(request.Reason) ? null : request.Reason.Trim();
            req.LastModificationTime = now;

            await StageAuditAsync(
                dispatch,
                workOrderId,
                userId,
                previous,
                UpliftStatus.Revoked,
                "uplift_revoke",
                now,
                cancellationToken,
                isStatusTransition: true);
            await _upliftData.SaveChangesAsync(cancellationToken);

            var decidedByName = await ResolveUserDisplayNameAsync(userId, cancellationToken);
            var requesterName = req.RequestedByVendorName ?? await ResolveUserDisplayNameAsync(req.createdby, cancellationToken);
            return WorkOrderUpliftContractMapper.MapRevokedItem(req, requesterName, decidedByName);
        }

        public async Task WithdrawPendingForWorkOrderAsync(
            int workOrderId,
            string? actorId,
            CancellationToken cancellationToken)
        {
            var pending = await _upliftData.GetPendingForWorkOrderAsync(workOrderId, cancellationToken);
            if (pending.Count == 0)
                return;

            var now = _timeProvider.GetUtcNow().UtcDateTime;
            foreach (var req in pending)
            {
                if (!UpliftStatus.CanTransition(req.Status, UpliftStatus.Withdrawn))
                    continue;

                var dispatch = req.Dispatch ?? await _dispatchData.GetByIdAsync(req.DispatchId);
                if (dispatch == null)
                    continue;

                var previous = UpliftStatus.ToCanonical(req.Status);
                req.Status = UpliftStatus.Withdrawn;
                req.DecidedAt = now;
                req.DecidedByUserId = actorId;
                req.LastModificationTime = now;

                await StageAuditAsync(
                    dispatch,
                    workOrderId,
                    actorId,
                    previous,
                    UpliftStatus.Withdrawn,
                    "uplift_cancel",
                    now,
                    cancellationToken,
                    isStatusTransition: true);
            }
        }

        private async Task<WorkOrderUpliftDto> PersistCreatedAsync(
            Dispatch dispatch,
            int workOrderId,
            string? userId,
            string requesterName,
            decimal currentNte,
            decimal amount,
            string notes,
            string status,
            int requiredTier,
            DateTime? expiresAt,
            string notificationStatus,
            string auditAction,
            DateTime now,
            CancellationToken cancellationToken)
        {
            var created = new DispatchUpliftRequest
            {
                DispatchId = dispatch.Id,
                CurrentNTE = currentNte,
                RequestedNTE = amount,
                VendorReason = notes,
                Status = status,
                RequiredTier = requiredTier,
                RequestedByVendorName = requesterName,
                CreatedDate = now,
                createdby = userId,
                ExpiresAt = expiresAt,
                NotificationStatus = notificationStatus,
            };
            if (status == UpliftStatus.NoApprovalRequired)
            {
                dispatch.NTEAmount = currentNte + amount;
                dispatch.LastModificationTime = now;
            }
            await _upliftData.StageAsync(created, cancellationToken);
            await StageAuditAsync(dispatch, workOrderId, userId, currentNte, amount, auditAction, now, cancellationToken);
            await _upliftData.SaveChangesAsync(cancellationToken);
            return WorkOrderUpliftContractMapper.MapItem(created, requesterName, null);
        }

        /// <summary>
        /// SH-196: uplifts may not be mutated once the work order reaches a terminal
        /// lifecycle state. Enforced in the service so a direct API call is rejected too,
        /// not only the board dialog's read-only state.
        /// </summary>
        private async Task EnsureWorkOrderAcceptsUpliftMutationAsync(
            int workOrderId,
            ClaimsPrincipal user,
            string action,
            CancellationToken cancellationToken)
        {
            var accountFilter = _accountResolver.ResolveAccountFilter(user);
            var workOrder = await _detailData.GetWorkOrderForMediaAsync(workOrderId, cancellationToken, accountFilter);
            var lifecycle = workOrder?.LifecycleStatus;

            if (lifecycle == LifecycleStatus.Completed || lifecycle == LifecycleStatus.Canceled)
                throw new InvalidOperationException(
                    $"Cannot {action} an uplift on a '{lifecycle}' work order");
        }

        private async Task<bool> HasWorkOrderAccessAsync(
            int workOrderId,
            ClaimsPrincipal user,
            CancellationToken cancellationToken)
        {
            var accountId = _accountResolver.ResolveAccountFilter(user);
            return await _detailData.ExistsAsync(workOrderId, cancellationToken, accountId);
        }

        private async Task<string> ResolveUserDisplayNameAsync(string? userId, CancellationToken cancellationToken)
        {
            if (string.IsNullOrWhiteSpace(userId))
                return "";

            var names = await _userData.GetDisplayNamesByIdsAsync(new[] { userId });
            return names.TryGetValue(userId, out var name) ? name : "";
        }

        private async Task StageAuditAsync(
            Dispatch dispatch,
            int workOrderId,
            string? userId,
            object oldValue,
            object newValue,
            string action,
            DateTime now,
            CancellationToken cancellationToken,
            bool isStatusTransition = false)
        {
            await _dispatchData.StageAuditLogAsync(new WorkOrderAuditLog
            {
                WorkOrderId = workOrderId,
                UserId = userId,
                FieldName = $"Dispatch {dispatch.DispatchNumber} Uplift",
                OldValue = isStatusTransition ? oldValue.ToString() : $"${Convert.ToDecimal(oldValue):F2}",
                NewValue = isStatusTransition ? newValue.ToString() : $"${Convert.ToDecimal(newValue):F2}",
                Action = action,
                ActorType = "internal",
                CreatedAt = now,
            }, cancellationToken);
        }

        private static bool IsTerminalForUplift(string? status) =>
            status is "Verified" or "Cancelled" or "Canceled" or "Refused";
    }
}