using FinancialApi.Domain.Entities;

namespace FinancialApi.Domain.Aggregates;

public record BalancedJournal
{
    public JournalEntry Entry { get; }

    private BalancedJournal(JournalEntry entry)
    {
        Entry = entry;
    }

    public static BalancedJournal Create(Guid id, string description, DateTimeOffset createdAt, List<JournalLine> lines)
    {
        var debits = lines.Where(l => l.Type == EntryType.Debit)
            .Sum(l => l.Amount);
        var credits = lines.Where(l => l.Type == EntryType.Credit)
            .Sum(l => l.Amount);

        if (debits != credits)
        {
            throw new InvalidOperationException(
                $"GAAP Violation: Total Debits ({debits}) must equal Total Credits ({credits})!"
            );
        }

        return new BalancedJournal(new JournalEntry(id, description, createdAt, lines));
    }

    public static BalancedJournal CreateReversal(JournalEntry original, string reason, DateTimeOffset now)
    {
        var reversedLines = original.Lines.Select(l =>
                l with { Type = l.Type == EntryType.Debit ? EntryType.Credit : EntryType.Debit }
            )
            .ToList();

        return Create(Guid.NewGuid(), reason, now, reversedLines);
    }
}