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

namespace SeaHaven.Services.Implementation
{
    public class WorkOrderIngestService : IWorkOrderIngestService
    {
        private readonly IWorkOrderIngestDataService _ingestData;
        private readonly ISyncFieldMergePolicy _mergePolicy;
        private readonly IWorkOrderFieldLockService _fieldLocks;
        private readonly IWorkOrderAuditService _audit;
        private readonly IWorkOrderAccountResolver _accountResolver;

        public WorkOrderIngestService(
            IWorkOrderIngestDataService ingestData,
            ISyncFieldMergePolicy mergePolicy,
            IWorkOrderFieldLockService fieldLocks,
            IWorkOrderAuditService audit,
            IWorkOrderAccountResolver accountResolver)
        {
            _ingestData = ingestData;
            _mergePolicy = mergePolicy;
            _fieldLocks = fieldLocks;
            _audit = audit;
            _accountResolver = accountResolver;
        }

        public async Task<WorkOrderIngestBatchResultDto> UpsertBatchAsync(
            IReadOnlyList<WorkOrderIngestPayloadDto> items,
            CancellationToken cancellationToken = default)
        {
            var result = new WorkOrderIngestBatchResultDto();
            if (items.Count == 0)
                return result;

            // Existing work orders this batch may cancel hold the per-work-order lock until the
            // batch commits, so an uplift create on one of them either commits first (and is
            // cancelled below) or waits and then sees the work order cancelled.
            var cancellingExternalIds = items
                .Where(item => !string.IsNullOrWhiteSpace(item.ExternalWorkOrderId)
                    && PendingUpliftCancellation.IsCancelled(null, WorkOrderIngestFieldMapper.MapStatus(item.WoStatus)))
                .Select(item => item.ExternalWorkOrderId)
                .Distinct()
                .ToList();
            var lockedWorkOrderIds = cancellingExternalIds.Count == 0
                ? Array.Empty<int>()
                : await _ingestData.GetWorkOrderIdsByExternalIdsAsync(cancellingExternalIds, cancellationToken);

            await _ingestData.ExecuteTransactionalAsync(lockedWorkOrderIds, async cancellationToken =>
            {
                var nextSeed = await AllocateNextWoSeedAsync(cancellationToken);

                foreach (var item in items)
                {
                    if (string.IsNullOrWhiteSpace(item.ExternalWorkOrderId))
                    {
                        result.Skipped++;
                        continue;
                    }

                    try
                    {
                        var (upsert, updatedSeed) = await UpsertOneAsync(item, nextSeed, cancellationToken);
                        nextSeed = updatedSeed;
                        result.Results.Add(upsert);
                        if (upsert.Created)
                            result.Created++;
                        else
                            result.Updated++;
                    }
                    catch (Exceptions.WorkOrderBoardValidationException ex)
                        when (ex.Code == "AccountUnresolved")
                    {
                        result.Skipped++;
                    }
                }

                await _ingestData.SaveAsync(cancellationToken);
            }, cancellationToken);

            return result;
        }

        private async Task<(WorkOrderIngestItemResultDto Result, int NextSeed)> UpsertOneAsync(
            WorkOrderIngestPayloadDto item,
            int nextSeed,
            CancellationToken cancellationToken)
        {
            var existing = await _ingestData.GetTrackedByExternalIdAsync(item.ExternalWorkOrderId, cancellationToken);

            var locationId = await ResolveLocationIdAsync(
                item.SiteCode, item.Building, item.Address, cancellationToken);

            if (existing == null)
            {
                var accountId = await _accountResolver.ResolveForUnauthenticatedCreateAsync(
                    item.Customer, cancellationToken);
                var (woNumber, updatedSeed) = AllocateInternalWoNumber(nextSeed);
                var wo = new WorkOrder
                {
                    InternalWONumber = woNumber,
                    ExternalWorkOrderId = item.ExternalWorkOrderId,
                    WorkerOrderNumber = item.ExternalWorkOrderId,
                    WorkerOrderTitle = item.Description,
                    Description = item.Description,
                    Status = WorkOrderIngestFieldMapper.MapStatus(item.WoStatus) ?? "Open",
                    Priority = WorkOrderIngestFieldMapper.MapSeverityToPriority(item.Severity),
                    Severity = item.Severity,
                    Customer = item.Customer,
                    AccountId = accountId,
                    SiteCode = item.SiteCode,
                    Building = item.Building,
                    LocationId = locationId,
                    DueDate = item.DueDate,
                    DateReported = item.DateReported,
                    ScheduledStart = item.ScheduledStart,
                    SourceEmailS3Key = item.SourceEmailS3Key,
                    CreatedDate = item.CreatedAt ?? DateTime.UtcNow,
                    istemplate = false
                };
                _ingestData.TrackWorkOrder(wo);
                await _ingestData.SaveAsync(cancellationToken);

                return (new WorkOrderIngestItemResultDto
                {
                    ExternalWorkOrderId = item.ExternalWorkOrderId,
                    WorkOrderId = wo.Id,
                    Created = true
                }, updatedSeed);
            }

            var syncContext = new WorkOrderSyncContext
            {
                WorkOrder = existing,
                FieldLocks = _fieldLocks,
                Audit = _audit
            };

            if (item.Description != null)
            {
                await _mergePolicy.TryApplyAsync(syncContext, "Description", item.Description);
                await _mergePolicy.TryApplyAsync(syncContext, "WorkerOrderTitle", item.Description);
            }

            var mappedStatus = WorkOrderIngestFieldMapper.MapStatus(item.WoStatus);
            if (mappedStatus != null)
            {
                var statusBefore = existing.Status;
                await _mergePolicy.TryApplyAsync(syncContext, "Status", mappedStatus);

                // A sync cancellation cancels the work order's pending uplifts in the same save.
                if (PendingUpliftCancellation.AppliesToStatusText(statusBefore, existing.Status))
                    await _ingestData.StageCancelPendingUpliftsAsync(existing.Id, cancellationToken);
            }

            var priority = WorkOrderIngestFieldMapper.MapSeverityToPriority(item.Severity);
            if (priority != null)
                await _mergePolicy.TryApplyAsync(syncContext, "Priority", priority);

            if (item.Severity != null)
                await _mergePolicy.TryApplyAsync(syncContext, "Severity", item.Severity);

            if (item.SiteCode != null)
                await _mergePolicy.TryApplyAsync(syncContext, "SiteCode", item.SiteCode);

            if (item.Building != null)
                await _mergePolicy.TryApplyAsync(syncContext, "Building", item.Building);

            if (locationId.HasValue)
                await _mergePolicy.TryApplyAsync(syncContext, "LocationId", locationId.Value);

            if (item.DueDate.HasValue)
                await _mergePolicy.TryApplyAsync(syncContext, "DueDate", item.DueDate.Value);

            if (item.Customer != null)
                existing.Customer = item.Customer;

            // Sync-owned metadata (not in ShocOwnedFieldSet)
            existing.DateReported = item.DateReported ?? existing.DateReported;
            existing.ScheduledStart = item.ScheduledStart ?? existing.ScheduledStart;
            existing.SourceEmailS3Key = item.SourceEmailS3Key ?? existing.SourceEmailS3Key;

            return (new WorkOrderIngestItemResultDto
            {
                ExternalWorkOrderId = item.ExternalWorkOrderId,
                WorkOrderId = existing.Id,
                Created = false
            }, nextSeed);
        }

        private async Task<int> AllocateNextWoSeedAsync(CancellationToken cancellationToken)
        {
            var maxId = await _ingestData.GetMaxWorkOrderIdAsync(cancellationToken);
            return Math.Max(maxId + 1, 1);
        }

        private static (string Number, int NextSeed) AllocateInternalWoNumber(int seed)
        {
            if (!WorkOrderNumberNormalizer.TryNormalize(seed.ToString(), out var normalized, out _))
                normalized = seed.ToString().PadLeft(11, '0');
            return (normalized, seed + 1);
        }

        private async Task<int?> ResolveLocationIdAsync(
            string? siteCode,
            string? building,
            string? address,
            CancellationToken cancellationToken)
        {
            if (string.IsNullOrWhiteSpace(siteCode) && string.IsNullOrWhiteSpace(building))
                return null;

            var matchCode = siteCode ?? building;
            var existing = await _ingestData.FindLocationAsync(matchCode, cancellationToken);

            if (existing != null)
                return existing.Id;

            var location = new Locations
            {
                Name = matchCode,
                Title = building,
                Address1 = address,
                Status = "Active"
            };

            await _ingestData.AddAndSaveLocationAsync(location, cancellationToken);
            return location.Id;
        }
    }
}