using General_Ledger_Service.DTOs.AuditLog;
using General_Ledger_Service.DTOs.Common;
using General_Ledger_Service.Enums;
using General_Ledger_Service.Interfaces.Repositories;
using General_Ledger_Service.Interfaces.Services;

namespace General_Ledger_Service.Services
{
    public class AuditLogService(IAuditLogRepository auditLogRepository) : IAuditLogService
    {
        private readonly IAuditLogRepository _auditLogRepository = auditLogRepository;

        public async Task<ApiResponse> ListAsync(ListAuditLogRequest request)
        {
            // No default page/pageSize - paging is only applied when the caller explicitly
            // supplies both (RepositoryHelpers.ApplyPaging); a non-positive value is treated as
            // "not supplied" rather than silently substituted with one.
            var page = request.Page is > 0 ? request.Page : null;
            var pageSize = request.PageSize is > 0 ? request.PageSize : null;
            var paged = page.HasValue && pageSize.HasValue;

            List<AuditCategory> categories;
            if (request.Category is null || request.Category.Count == 0)
            {
                categories = [AuditCategory.Ledger, AuditCategory.Administrative];
            }
            else
            {
                categories = [.. request.Category
                    .Select(c => Enum.TryParse<AuditCategory>(c, ignoreCase: true, out var parsed) ? (AuditCategory?)parsed : null)
                    .Where(c => c.HasValue)
                    .Select(c => c!.Value)
                    .Distinct()];

                // A typo'd category matches nothing, rather than falling back to "match everything".
                if (categories.Count == 0)
                {
                    return EmptyResponse(paged ? page : null, paged ? pageSize : null);
                }
            }

            AuditAction? action = null;
            if (!string.IsNullOrWhiteSpace(request.Action))
            {
                if (!Enum.TryParse<AuditAction>(request.Action, ignoreCase: true, out var parsedAction))
                {
                    return EmptyResponse(paged ? page : null, paged ? pageSize : null);
                }
                action = parsedAction;
            }

            var (items, totalCount) = await _auditLogRepository.ListAsync(
                categories, request.EntityName, action, request.PerformedBy, request.From, request.To, page, pageSize);

            return ResponseHelpers.Ok("Audit log retrieved successfully",
                new AuditLogListResponse { Items = items, TotalCount = totalCount, Page = paged ? page : null, PageSize = paged ? pageSize : null });
        }

        private static ApiResponse EmptyResponse(int? page, int? pageSize) =>
            ResponseHelpers.Ok("Audit log retrieved successfully",
                new AuditLogListResponse { Items = [], TotalCount = 0, Page = page, PageSize = pageSize });
    }
}