using System;
using System.Threading;
using System.Threading.Tasks;
using FrameworkBLL.Page;
using FrameworkDAL.CustomCode.Promotion;
using FrameworkDAL.DTO.Page;
using GB5Shared.DTO.Framework.Login;
using GB5Shared.DTO.Promotion;
using GB5Shared.Promotion;
using Newtonsoft.Json;

namespace FrameworkBLL.Promotion.Adapters
{
    // ============================================================
    // PagePromotionAdapter — IPromotableEntity for MPAGE ("PAGE"). Parent row
    // only — MPAGE has no child/detail rows of its own (Dashboard->Page
    // placement lives on the Dashboard side, in MDASHBOARDPAGE, not here).
    //
    // PageCode is the natural key, resolved via the new IPageCodeLookupDAL —
    // this is also what unblocks DashboardPromotionAdapter's own PageId
    // references (MDASHBOARDPAGE rows) and ReportView's own PageId (still
    // blocked there pending this adapter's registration).
    //
    // ModuleId/ModuleCode reuses the existing IModuleCodeLookupDAL (module
    // codes are static/shared across installs, low risk, same reasoning as
    // ReportView/DrillDown's own Module reference).
    //
    // DefaultCriteriaConfigId and ImageId are raw AutoNumber-ID references
    // with no natural-key lookup built yet — conservatively BLOCKED if set to
    // a real (non-sentinel) value, same "carry it in Flags for validation to
    // see, never map it at import" pattern as ReportView's own risky fields.
    // ============================================================
    public class PagePromotionAdapter : IPromotableEntity
    {
        public string EntityTypeCode => "PAGE";

        private readonly IPageBLL _PageBLL;
        private readonly IPageCodeLookupDAL _PageCodeLookup;
        private readonly IModuleCodeLookupDAL _ModuleCodeLookup;

        public PagePromotionAdapter(
            IPageBLL pageBLL, IPageCodeLookupDAL pageCodeLookup, IModuleCodeLookupDAL moduleCodeLookup)
        {
            _PageBLL          = pageBLL;
            _PageCodeLookup   = pageCodeLookup;
            _ModuleCodeLookup = moduleCodeLookup;
        }

        private class RawFlags
        {
            public int DefaultCriteriaConfigId { get; set; }
            public int ImageId { get; set; }
        }

        private class PortablePayload
        {
            public string PageCode { get; set; } = string.Empty;
            public string PageName { get; set; } = string.Empty;
            public string? PageRemarks { get; set; }
            public string? PageLayOut { get; set; }
            public byte PageType { get; set; }
            public byte OverrideDashboardCriteria { get; set; }
            public string? ModuleCode { get; set; }
            public string? ImageLinkURL { get; set; }
            public short PageSortOrder { get; set; }

            /// <summary>Seen only by ValidateForPromotionAsync — ImportPromotedAsync never maps
            /// these onto the destination row. See the class header comment.</summary>
            public RawFlags Flags { get; set; } = new();
        }

        public async Task<PromotionBundleDTO> ExportForPromotionAsync(
            int originEntityId, LoginDTO login, CancellationToken ct)
        {
            var json = await _PageBLL.GetPage(originEntityId, login).ConfigureAwait(false);
            var dto = JsonConvert.DeserializeObject<PageDTO>(json)
                ?? throw new InvalidOperationException($"Page {originEntityId} not found.");

            string? moduleCode = null;
            if (dto.ModuleId != 0 && dto.ModuleId != -1)
            {
                moduleCode = await _ModuleCodeLookup.GetModuleCodeById(dto.ModuleId, login, ct).ConfigureAwait(false)
                    ?? throw new InvalidOperationException(
                        $"Page {originEntityId} references ModuleId {dto.ModuleId}, which has no ModuleCode — cannot promote.");
            }

            var payload = new PortablePayload
            {
                PageCode                  = dto.PageCode,
                PageName                  = dto.PageName,
                PageRemarks               = dto.PageRemarks,
                PageLayOut                = dto.PageLayOut,
                PageType                  = dto.PageType,
                OverrideDashboardCriteria = dto.OverrideDashboardCriteria,
                ModuleCode                = moduleCode,
                ImageLinkURL              = dto.ImageLinkURL,
                PageSortOrder             = dto.PageSortOrder,
                Flags = new RawFlags
                {
                    DefaultCriteriaConfigId = dto.DefaultCriteriaConfigId,
                    ImageId                 = dto.ImageId
                }
            };

            return new PromotionBundleDTO
            {
                EntityTypeCode = EntityTypeCode,
                OriginEntityId = originEntityId,
                PayloadJson    = System.Text.Json.JsonSerializer.Serialize(payload)
            };
        }

        public Task<PromotionValidationResultDTO> ValidateForPromotionAsync(
            PromotionBundleDTO bundle, CancellationToken ct)
        {
            var payload = System.Text.Json.JsonSerializer.Deserialize<PortablePayload>(bundle.PayloadJson);
            if (payload is null)
                return Task.FromResult(PromotionValidationResultDTO.Block("Page payload could not be parsed."));

            var reasons = new System.Collections.Generic.List<string>();
            var flags = payload.Flags;

            if (flags.DefaultCriteriaConfigId != 0 && flags.DefaultCriteriaConfigId != -1)
                reasons.Add("Page.DefaultCriteriaConfigId is set — criteria-config remapping is not yet supported.");
            if (flags.ImageId != 0 && flags.ImageId != -1)
                reasons.Add("Page.ImageId is set — image remapping is not yet supported.");

            var result = reasons.Count == 0
                ? PromotionValidationResultDTO.Ok()
                : new PromotionValidationResultDTO { IsPromotable = false, BlockingReasons = reasons };
            return Task.FromResult(result);
        }

        public async Task<int> ImportPromotedAsync(
            PromotionBundleDTO bundle, byte destinationSourceType, int? existingDestinationId,
            LoginDTO login, CancellationToken ct)
        {
            var payload = System.Text.Json.JsonSerializer.Deserialize<PortablePayload>(bundle.PayloadJson)
                ?? throw new InvalidOperationException("Page promotion payload could not be parsed.");

            var moduleId = -1;
            if (!string.IsNullOrWhiteSpace(payload.ModuleCode))
            {
                moduleId = await _ModuleCodeLookup.GetModuleIdByCode(payload.ModuleCode, login, ct).ConfigureAwait(false)
                    ?? throw new InvalidOperationException(
                        $"No Module with ModuleCode '{payload.ModuleCode}' exists at this destination.");
            }

            // If this is an update to a previously-promoted page, existingDestinationId already
            // identifies it directly. Otherwise, check whether a page with this code already exists
            // at the destination (created independently, not via a prior promotion) so Import
            // updates it rather than violating PageCode's own unique constraint with a duplicate.
            var resolvedId = existingDestinationId
                ?? await _PageCodeLookup.GetPageIdByCode(payload.PageCode, login, ct).ConfigureAwait(false)
                ?? 0;

            var dto = new PageDTO
            {
                PageId                    = resolvedId,
                PageCode                  = payload.PageCode,
                PageName                  = payload.PageName,
                PageRemarks               = payload.PageRemarks,
                PageLayOut                = payload.PageLayOut,
                PageType                  = payload.PageType,
                OverrideDashboardCriteria = payload.OverrideDashboardCriteria,
                ModuleId                  = moduleId,
                ImageId                   = -1, // never mapped — see class header comment
                ImageLinkURL              = payload.ImageLinkURL,
                PageSortOrder             = payload.PageSortOrder,
                PageSourceType            = destinationSourceType,
                DefaultCriteriaConfigId   = -1 // never mapped — see class header comment
            };

            await _PageBLL.SavePage(dto, login).ConfigureAwait(false);
            return dto.PageId; // mutated in place by SavePage when isNew
        }
    }
}