using Oms.Application.Dtos.Channels;
using Oms.Domain.ChannelsAggregate.Consts;
using Oms.Domain.ChannelsAggregate.Entities;
using Oms.Domain.OrdersAggregate.Entities;

namespace Oms.Application.Shared;

/// <summary>
/// 排货规则运行时选渠。
/// </summary>
public static class AllocationResolver
{
    public sealed class ChannelCandidate
    {
        public SalesProductAllocationProviderSnapshotDto Provider { get; init; } = null!;

        public ServiceChannel Channel { get; init; } = null!;

        public decimal TotalPayableCost { get; init; }

        /// <summary>候选渠道已算出的应付费用（选渠后可直接落库，避免重复算价）。</summary>
        public IReadOnlyList<OrderFee> PayableFees { get; init; } = [];
    }

    public static List<SalesProductAllocationProviderSnapshotDto> FilterProviders(
        IEnumerable<SalesProductAllocationProviderSnapshotDto> providers,
        int? customerId) =>
        providers
            .Where(x => x.ServiceChannelId.HasValue && x.ServiceChannelId > 0)
            .Where(x => x.CustomerIds.Count == 0
                        || (customerId.HasValue && x.CustomerIds.Contains(customerId.Value)))
            .OrderBy(x => x.SerialNumber)
            .ToList();

    public static ServiceChannel SelectChannel(string? scheme, IReadOnlyList<ChannelCandidate> candidates) =>
        SelectCandidate(scheme, candidates).Channel;

    public static ChannelCandidate SelectCandidate(string? scheme, IReadOnlyList<ChannelCandidate> candidates)
    {
        if (candidates.Count == 0)
        {
            throw new InvalidOperationException("无可用排货候选渠道");
        }

        var normalizedScheme = string.IsNullOrWhiteSpace(scheme)
            ? AllocationSchemeCodes.CostLowest
            : scheme.Trim();

        return normalizedScheme switch
        {
            AllocationSchemeCodes.TimeFastest => candidates
                .OrderBy(x => x.Channel.MinTime ?? int.MaxValue)
                .ThenBy(x => x.Provider.SerialNumber)
                .First(),
            AllocationSchemeCodes.OverallBest => candidates
                .OrderByDescending(x => x.Provider.Weight)
                .ThenBy(x => x.Provider.SerialNumber)
                .First(),
            _ => candidates
                .OrderBy(x => x.TotalPayableCost)
                .ThenBy(x => x.Provider.SerialNumber)
                .First()
        };
    }
}