using System.Linq.Expressions;

namespace JdeScoping.ExcelIO.Mapping;

/// <summary>
/// Interface for Excel class maps (non-generic access).
/// </summary>
public interface IExcelClassMap
{
    /// <summary>The type this map applies to.</summary>
    Type MappedType { get; }

    /// <summary>Excel table name (for named ranges).</summary>
    string? TableName { get; }

    /// <summary>Worksheet tab name.</summary>
    string? TabName { get; }

    /// <summary>Ordered column definitions.</summary>
    IReadOnlyList<ColumnDefinition> Columns { get; }
}

/// <summary>
/// Base class for defining Excel column mappings via fluent API.
/// </summary>
/// <typeparam name="T">The model type to map.</typeparam>
public abstract class ExcelClassMap<T> : IExcelClassMap
{
    private readonly List<ColumnDefinition> _columns = [];

    /// <inheritdoc />
    public Type MappedType => typeof(T);

    /// <inheritdoc />
    public string? TableName { get; private set; }

    /// <inheritdoc />
    public string? TabName { get; private set; }

    /// <inheritdoc />
    public IReadOnlyList<ColumnDefinition> Columns =>
        _columns.OrderBy(c => c.Order).ThenBy(c => c.PropertyName).ToList();

    /// <summary>
    /// Configures the table and tab names for this model.
    /// </summary>
    protected void Table(string tableName, string tabName)
    {
        TableName = tableName;
        TabName = tabName;
    }

    /// <summary>
    /// Maps a property to an Excel column.
    /// </summary>
    protected ColumnBuilder<T, TProperty> Map<TProperty>(Expression<Func<T, TProperty>> property)
    {
        var memberExpr = property.Body as MemberExpression
            ?? throw new ArgumentException("Expression must be a property access", nameof(property));

        var propertyName = memberExpr.Member.Name;
        var compiled = property.Compile();

        var definition = new ColumnDefinition
        {
            PropertyName = propertyName,
            PropertyType = typeof(TProperty),
            ValueGetter = obj => compiled((T)obj),
            HeaderText = propertyName // Default to property name
        };

        _columns.Add(definition);
        return new ColumnBuilder<T, TProperty>(definition);
    }
}