using Strata.SqlTools.SqlBreakdown.Extensions;

namespace Strata.SqlTools.SqlBreakdown.Classes;

/// <summary>
/// Represents a SQL FROM clause with optional JOIN clauses.
/// </summary>
public class SqlFrom
{
    private readonly SqlTable _firstTable;
    private readonly List<SqlJoin> _joins;

    /// <summary>
    /// Initializes a new instance of the <see cref="SqlFrom"/> class.
    /// </summary>
    /// <param name="tableExpression">The primary table expression.</param>
    /// <param name="tableAlias">The primary table alias.</param>
    public SqlFrom(string tableExpression, string tableAlias)
    {
        _firstTable = new SqlTable(tableExpression, tableAlias);
        _joins = [];
    }

    /// <summary>
    /// Adds a JOIN to the FROM clause.
    /// </summary>
    /// <param name="table2Expression">The table expression to join.</param>
    /// <param name="table2Alias">The alias for the joined table.</param>
    /// <param name="table1Column">The column from the primary table.</param>
    /// <param name="table2Column">The column from the joined table.</param>
    public void Join(string table2Expression, string table2Alias, string table1Column, string table2Column)
    {
        var theJoin = new SqlJoin(table2Expression, table2Alias, table1Column, table2Column);
        Join(theJoin);
    }

    /// <summary>
    /// Adds a pre-constructed JOIN to the FROM clause.
    /// </summary>
    /// <param name="join">The join to add.</param>
    public void Join(SqlJoin join)
    {
        _joins.Add(join);
    }

    /// <summary>
    /// Returns the SQL FROM clause as a string.
    /// </summary>
    /// <returns>The FROM clause with all JOINs.</returns>
    public override string ToString()
    {
        var output = new StringBuilderEx();
        output.AppendFormat($"\t{_firstTable.TableExpression} {_firstTable.TableAlias}\n");

        foreach (var join in _joins)
        {
            output.AppendFormat($"\tINNER JOIN {join.TableExpression} {join.TableAlias} ON {join.GetJoinOn(_firstTable.TableAlias)}\n");
        }

        return output.ToString();
    }
}