using Data.SeaHavenIndustries;
using Microsoft.Extensions.Logging;
using Microsoft.Extensions.Options;
using SeaHaven.DataServices.Interfaces;
using SeaHaven.Services.Configuration;
using SeaHaven.Services.Interfaces;

namespace SeaHaven.Services.Implementation
{
    public class UpliftLifecycleService : IUpliftLifecycleService
    {
        private readonly IUpliftDataService _upliftData;
        private readonly IDispatchDataService _dispatchData;
        private readonly IUserDataService _userData;
        private readonly IEmailSender _emailSender;
        private readonly FrontendOptions _frontendOptions;
        private readonly ApprovalsOptions _approvalsOptions;
        private readonly TimeProvider _timeProvider;
        private readonly ILogger<UpliftLifecycleService> _logger;

        public UpliftLifecycleService(
            IUpliftDataService upliftData,
            IDispatchDataService dispatchData,
            IUserDataService userData,
            IEmailSender emailSender,
            IOptions<FrontendOptions> frontendOptions,
            IOptions<ApprovalsOptions> approvalsOptions,
            TimeProvider timeProvider,
            ILogger<UpliftLifecycleService> logger)
        {
            _upliftData = upliftData;
            _dispatchData = dispatchData;
            _userData = userData;
            _emailSender = emailSender;
            _frontendOptions = frontendOptions.Value;
            _approvalsOptions = approvalsOptions.Value;
            _timeProvider = timeProvider;
            _logger = logger;
        }

        public async Task<int> ExpireDueAsync(CancellationToken cancellationToken)
        {
            var now = _timeProvider.GetUtcNow().UtcDateTime;
            var due = await _upliftData.GetDueForExpiryAsync(now, 50, cancellationToken);
            var expired = 0;
            foreach (var req in due)
            {
                if (!UpliftStatus.CanTransition(req.Status, UpliftStatus.Expired))
                    continue;

                var dispatch = await _dispatchData.GetByIdAsync(req.DispatchId);
                if (dispatch == null)
                {
                    _logger.LogError("Uplift expiry skipped for orphan request {UpliftId}; dispatch {DispatchId} was not found.", req.Id, req.DispatchId);
                    continue;
                }

                var previous = UpliftStatus.ToCanonical(req.Status);

                req.Status = UpliftStatus.Expired;
                req.DecidedAt = now;
                req.LastModificationTime = now;

                await _dispatchData.StageAuditLogAsync(new WorkOrderAuditLog
                {
                    WorkOrderId = dispatch?.WorkOrderId ?? 0,
                    FieldName = $"Dispatch {dispatch?.DispatchNumber} Uplift",
                    OldValue = previous,
                    NewValue = UpliftStatus.Expired,
                    Action = "uplift_expired",
                    CreatedAt = now
                }, cancellationToken);

                await _upliftData.SaveChangesAsync(cancellationToken);
                expired++;
            }

            return expired;
        }

        public async Task<int> SendDueInitialNotificationsAsync(CancellationToken cancellationToken)
        {
            var due = await _upliftData.GetDueForInitialNotificationAsync(50, cancellationToken);
            var sent = 0;
            foreach (var req in due)
            {
                var dispatch = await _dispatchData.GetByIdAsync(req.DispatchId);
                if (dispatch == null) continue;

                var recipients = await ResolveInitialRecipientsAsync(dispatch, req, cancellationToken);
                if (recipients.Count == 0)
                {
                    await PersistNotificationOutcomeAsync(req, delivered: false, "No notification recipients are configured for this dispatch.", cancellationToken);
                    continue;
                }

                var (subject, body) = UpliftNotificationMessage.BuildInitial(dispatch, req, req.RequestedByVendorName ?? "Vendor", _frontendOptions.FrontendBaseUrl ?? string.Empty);
                var delivered = await SendToAllAsync(recipients, subject, body);
                await PersistNotificationOutcomeAsync(req, delivered, delivered ? null : "The uplift notification could not be delivered.", cancellationToken);
                if (delivered) sent++;
            }

            return sent;
        }

        public async Task<int> EscalateDueAsync(CancellationToken cancellationToken)
        {
            var candidates = await _upliftData.GetDueForEscalationAsync(50, cancellationToken);
            var escalationThreshold = _approvalsOptions.EffectiveEscalation;
            var now = _timeProvider.GetUtcNow().UtcDateTime;
            var escalated = 0;

            foreach (var req in candidates)
            {
                if (req.InitialNotificationSentAt == null || req.EscalatedAt != null)
                    continue;
                if (now - req.InitialNotificationSentAt.Value < escalationThreshold)
                    continue;

                var recipients = await ResolveEscalationRecipientsAsync(req, cancellationToken);
                if (recipients.Count == 0)
                    continue;

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

                var (subject, body) = UpliftNotificationMessage.BuildEscalation(dispatch, req, req.RequestedByVendorName ?? "Vendor", _frontendOptions.FrontendBaseUrl ?? string.Empty);
                var delivered = await SendToAllAsync(recipients, subject, body);
                if (!delivered)
                {
                    // Escalation send failure is logged only; it does not alter workflow status.
                    _logger.LogWarning("Uplift escalation delivery failed for request {UpliftId}", req.Id);
                    continue;
                }

                req.EscalatedAt = now;
                req.LastModificationTime = now;

                await _dispatchData.StageAuditLogAsync(new WorkOrderAuditLog
                {
                    WorkOrderId = dispatch.WorkOrderId ?? 0,
                    FieldName = $"Dispatch {dispatch.DispatchNumber} Uplift",
                    OldValue = "Pending",
                    NewValue = "Escalated",
                    Action = "uplift_escalated",
                    CreatedAt = now
                }, cancellationToken);

                await _upliftData.SaveChangesAsync(cancellationToken);
                escalated++;
            }

            return escalated;
        }

        private async Task<HashSet<string>> ResolveInitialRecipientsAsync(Dispatch dispatch, DispatchUpliftRequest req, CancellationToken cancellationToken)
        {
            var recipients = new HashSet<string>(StringComparer.OrdinalIgnoreCase);

            var dispatcherUserId = await _dispatchData.GetDispatchDispatcherUserIdAsync(dispatch.WorkOrderId ?? 0, cancellationToken);
            if (!string.IsNullOrWhiteSpace(dispatcherUserId))
            {
                var dispatcherEmail = await _userData.GetEmailByIdAsync(dispatcherUserId, cancellationToken);
                if (!string.IsNullOrWhiteSpace(dispatcherEmail))
                    recipients.Add(dispatcherEmail);
            }

            var tierRecipients = req.RequiredTier == 2
                ? _approvalsOptions.Tier2NotificationRecipients
                : _approvalsOptions.Tier1NotificationRecipients;
            if (tierRecipients != null)
            {
                foreach (var recipient in tierRecipients)
                {
                    if (!string.IsNullOrWhiteSpace(recipient))
                        recipients.Add(recipient.Trim());
                }
            }

            return recipients;
        }

        private Task<HashSet<string>> ResolveEscalationRecipientsAsync(DispatchUpliftRequest req, CancellationToken cancellationToken)
        {
            var recipients = new HashSet<string>(StringComparer.OrdinalIgnoreCase);
            if (_approvalsOptions.EscalationRecipients != null)
            {
                foreach (var recipient in _approvalsOptions.EscalationRecipients)
                {
                    if (!string.IsNullOrWhiteSpace(recipient))
                        recipients.Add(recipient.Trim());
                }
            }

            var tierRecipients = req.RequiredTier == 2
                ? _approvalsOptions.Tier2NotificationRecipients
                : _approvalsOptions.Tier1NotificationRecipients;
            if (tierRecipients != null)
            {
                foreach (var recipient in tierRecipients)
                {
                    if (!string.IsNullOrWhiteSpace(recipient))
                        recipients.Add(recipient.Trim());
                }
            }

            return Task.FromResult(recipients);
        }

        private async Task<bool> SendToAllAsync(HashSet<string> recipients, string subject, string body)
        {
            try
            {
                foreach (var recipient in recipients)
                {
                    var delivered = await _emailSender.SendEmailAsync(recipient, subject, body);
                    if (!delivered)
                        return false;
                }
                return true;
            }
            catch (OperationCanceledException)
            {
                throw;
            }
            catch (Exception)
            {
                // Never leak addresses or exception details; the persisted signal is safe text.
                return false;
            }
        }

        private async Task PersistNotificationOutcomeAsync(DispatchUpliftRequest req, bool delivered, string? errorMessage, CancellationToken cancellationToken)
        {
            var now = _timeProvider.GetUtcNow().UtcDateTime;
            if (delivered)
            {
                req.InitialNotificationSentAt = now;
                req.NotificationStatus = UpliftNotificationStatus.Sent;
                req.NotificationError = null;
            }
            else
            {
                req.NotificationStatus = UpliftNotificationStatus.Error;
                req.NotificationError = errorMessage;
            }
            req.LastModificationTime = now;
            await _upliftData.SaveChangesAsync(cancellationToken);
        }
    }
}