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

namespace SeaHaven.Services.Implementation
{
    public class UpliftService : IUpliftService
    {
        private readonly IUpliftDataService _upliftData;
        private readonly IDispatchDataService _dispatchData;
        private readonly ApprovalsOptions _approvalsOptions;

        public UpliftService(IUpliftDataService upliftData, IDispatchDataService dispatchData, IOptions<ApprovalsOptions> approvalsOptions)
        {
            _upliftData = upliftData;
            _dispatchData = dispatchData;
            _approvalsOptions = approvalsOptions.Value;
        }

        public async Task<UpliftListResultDTO> ListAsync(ClaimsPrincipal user, string? status, int? tier, int page, int pageSize, CancellationToken cancellationToken)
        {
            var (total, items) = await _upliftData.GetPagedAsync(status, tier, page, pageSize, cancellationToken);

            var mapped = items.Select(r => new UpliftListItemDTO
            {
                Id = r.Id,
                DispatchId = r.DispatchId,
                DispatchNumber = r.DispatchNumber,
                PONumber = r.PONumber,
                WorkOrderId = r.WorkOrderId,
                VendorCompanyName = r.VendorCompanyName,
                CurrentNTE = r.CurrentNTE,
                RequestedNTE = r.RequestedNTE,
                Delta = r.RequestedNTE - (r.CurrentNTE ?? 0m),
                VendorReason = r.VendorReason,
                RequiredTier = r.RequiredTier,
                Status = r.Status,
                RequestedAt = r.CreatedDate,
                DecidedAt = r.DecidedAt,
                DecisionNote = r.DecisionNote,
                CanDecide = UserCanApprove(user, r.RequiredTier)
            }).ToList();

            return new UpliftListResultDTO
            {
                Total = total,
                Page = page,
                PageSize = pageSize,
                Items = mapped
            };
        }

        public async Task<IEnumerable<UpliftForDispatchDTO>> ListForDispatchAsync(ClaimsPrincipal user, int dispatchId, CancellationToken cancellationToken)
        {
            var rows = await _upliftData.GetForDispatchAsync(dispatchId, cancellationToken);

            return rows.Select(r => new UpliftForDispatchDTO
            {
                Id = r.Id,
                DispatchId = r.DispatchId,
                CurrentNTE = r.CurrentNTE,
                RequestedNTE = r.RequestedNTE,
                Delta = r.RequestedNTE - (r.CurrentNTE ?? 0m),
                VendorReason = r.VendorReason,
                Status = r.Status,
                RequiredTier = r.RequiredTier,
                RequestedByVendorName = r.RequestedByVendorName,
                RequestedAt = r.CreatedDate,
                DecidedAt = r.DecidedAt,
                DecisionNote = r.DecisionNote,
                DecidedByName = string.Join(" ", new[] { r.DecidedByFirstName, r.DecidedByLastName }
                    .Where(s => !string.IsNullOrWhiteSpace(s))).Trim(),
                CanDecide = UserCanApprove(user, r.RequiredTier)
            }).ToList();
        }

        public async Task<UpliftApproveResultDTO> ApproveAsync(ClaimsPrincipal user, int id, string? note, CancellationToken cancellationToken)
        {
            var req = await _upliftData.GetByIdAsync(id, cancellationToken);
            if (req == null) throw new KeyNotFoundException("Uplift request not found");
            if (req.Status != "Pending") throw new InvalidOperationException($"Cannot approve a '{req.Status}' request");
            if (!UserCanApprove(user, req.RequiredTier))
                throw new UpliftForbiddenException($"Approval requires a Tier {req.RequiredTier} role");

            var dispatch = await _dispatchData.GetByIdAsync(req.DispatchId);
            if (dispatch == null) throw new KeyNotFoundException("Dispatch not found");
            if (dispatch.Status == "Verified" || dispatch.Status == "Cancelled")
                throw new InvalidOperationException($"Cannot approve uplift on a '{dispatch.Status}' dispatch");

            var userId = user.FindFirst(ClaimTypes.NameIdentifier)?.Value;
            var now = DateTime.UtcNow;
            var oldNTE = dispatch.NTEAmount ?? 0m;

            dispatch.NTEAmount = req.RequestedNTE;
            dispatch.LastModificationTime = now;

            req.Status = "Approved";
            req.DecidedAt = now;
            req.DecidedByUserId = userId;
            req.DecisionNote = string.IsNullOrWhiteSpace(note) ? null : note!.Trim();
            req.LastModificationTime = now;

            await _dispatchData.StageAuditLogAsync(new WorkOrderAuditLog
            {
                WorkOrderId = dispatch.WorkOrderId ?? 0,
                UserId = userId,
                FieldName = $"Dispatch {dispatch.DispatchNumber} NTE",
                OldValue = $"${oldNTE:F2}",
                NewValue = $"${req.RequestedNTE:F2}",
                Action = "uplift_approved",
                CreatedAt = now
            }, cancellationToken);

            await _upliftData.SaveChangesAsync(cancellationToken);
            return new UpliftApproveResultDTO { Id = req.Id, Status = req.Status, NTEAmount = dispatch.NTEAmount };
        }

        public async Task<UpliftDenyResultDTO> DenyAsync(ClaimsPrincipal user, int id, string? note, CancellationToken cancellationToken)
        {
            if (string.IsNullOrWhiteSpace(note))
                throw new InvalidOperationException("A note is required when denying");

            var req = await _upliftData.GetByIdAsync(id, cancellationToken);
            if (req == null) throw new KeyNotFoundException("Uplift request not found");
            if (req.Status != "Pending") throw new InvalidOperationException($"Cannot deny a '{req.Status}' request");
            if (!UserCanApprove(user, req.RequiredTier))
                throw new UpliftForbiddenException($"Decision requires a Tier {req.RequiredTier} role");

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

            var userId = user.FindFirst(ClaimTypes.NameIdentifier)?.Value;
            var now = DateTime.UtcNow;

            req.Status = "Denied";
            req.DecidedAt = now;
            req.DecidedByUserId = userId;
            req.DecisionNote = note!.Trim();
            req.LastModificationTime = now;

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

            await _upliftData.SaveChangesAsync(cancellationToken);
            return new UpliftDenyResultDTO { Id = req.Id, Status = req.Status };
        }

        public bool CanApprove(ClaimsPrincipal user, int tier) => UserCanApprove(user, tier);

        private bool UserCanApprove(ClaimsPrincipal user, int requiredTier)
        {
            var roles = RolesForTier(requiredTier);
            foreach (var r in roles)
            {
                if (!string.IsNullOrWhiteSpace(r) && user.IsInRole(r)) return true;
            }
            return false;
        }

        private string[] RolesForTier(int requiredTier) => requiredTier switch
        {
            1 => _approvalsOptions.Tier1Roles,
            2 => _approvalsOptions.Tier2Roles,
            _ => Array.Empty<string>()
        };
    }
}