using Distribution.Infra.UoW;
using Distribution.Models;

namespace Distribution.Features.SysConfig;

public class SysConfigService(ISysConfigRepository repo, IUnitOfWork uow)
{
    public const string KeyInvoiceCreationMode = "InvoiceCreationMode";

    public async Task<List<SysConfigResponse>> GetAllAsync()
    {
        var configs = await repo.GetAllAsync();
        return configs.Select(ToResponse).ToList();
    }

    public async Task<SysConfigResponse?> GetByKeyAsync(string key)
    {
        var config = await repo.GetByKeyAsync(key);
        return config is null ? null : ToResponse(config);
    }

    public async Task<SysConfigResponse> SetAsync(string key, string value, Guid userId, CancellationToken ct = default)
    {
        ValidateValue(key, value);

        var config = new Models.SysConfig
        {
            Key = key,
            Value = value,
            UpdatedAt = DateTime.Now,
            UpdatedBy = userId
        };

        await uow.BeginAsync(ct);
        try
        {
            await repo.UpsertAsync(config);
            await uow.CommitAsync(ct);
        }
        catch { await uow.RollbackAsync(ct); throw; }

        var saved = await repo.GetByKeyAsync(key);
        return ToResponse(saved!);
    }

    /// <summary>
    /// Returns the current InvoiceCreationMode, defaulting to ModeB if not configured.
    /// ModeA = invoice auto-created on ShopPO confirmation.
    /// ModeB = invoice created as a separate explicit step.
    /// </summary>
    public async Task<InvoiceCreationMode> GetInvoiceCreationModeAsync()
    {
        var config = await repo.GetByKeyAsync(KeyInvoiceCreationMode);
        if (config is null) return InvoiceCreationMode.ModeB;
        return Enum.TryParse<InvoiceCreationMode>(config.Value, out var mode) ? mode : InvoiceCreationMode.ModeB;
    }

    private static void ValidateValue(string key, string value)
    {
        if (key == KeyInvoiceCreationMode && !Enum.TryParse<InvoiceCreationMode>(value, out _))
            throw new InvalidOperationException(
                $"Invalid value '{value}' for '{key}'. Allowed values: {string.Join(", ", Enum.GetNames<InvoiceCreationMode>())}.");
    }

    private static SysConfigResponse ToResponse(Models.SysConfig c) =>
        new(c.Key, c.Value, c.UpdatedAt, c.UpdatedBy);
}