using IceImportDAL.DTO.IceImportPipeline;

namespace IceImportBLL.FieldResolvers;

// ValueType = 0 (Source). Reads the source cell, coerces to the destination member's declared
// data type. On coercion failure, returns null with a Warning-severity error — never a silent
// default (legacy defaulted a bad int conversion to 0 without recording it).
public class SourceValueResolver : IIceFieldValueResolver
{
    public int ValueType => 0;

    public Task<FieldResolutionResult> ResolveAsync(FieldResolutionContext ctx, CancellationToken ct)
    {
        var fieldName = ctx.DetailConfig.IceMapDetailsSourceFieldName?.Trim().ToUpperInvariant();

        string? raw = null;
        if (!string.IsNullOrEmpty(fieldName) && ctx.SourceRow.Table.Columns.Contains(fieldName))
            raw = ctx.SourceRow[fieldName]?.ToString();
        else if (ctx.DetailConfig.IceMapDetailsIsOptional == 0)
            // Optional field whose source column isn't present in this file — fall back to the
            // configured default. Mandatory-and-missing is instead caught up front, once per file,
            // by HeaderFieldExistenceValidator.
            raw = ctx.DetailConfig.IceMapDetailsOptionalFiledValue;

        if (!IceImportTypeCoercion.TryCoerce(raw, ctx.DetailConfig.DestinationMemberDataType, out var value))
        {
            var warning = new IceImportFieldErrorDTO
            {
                RowNumber = ctx.RowNumber,
                EntityCode = ctx.DetailConfig.EntityCode ?? string.Empty,
                FieldName = ctx.DetailConfig.DestinationMemberMemberName ?? fieldName ?? string.Empty,
                Message = $"Value '{raw}' could not be converted to the destination field's declared type.",
                Severity = IceImportSeverity.Warning
            };
            return Task.FromResult(FieldResolutionResult.WithWarning(null, warning));
        }

        return Task.FromResult(FieldResolutionResult.Ok(value));
    }
}