using FinancialApi.Domain;
using Wolverine.Persistence;

namespace FinancialApi.Application;

public record ReverseJournalCommand(Guid OriginalJournalId, string Reason);

public record JournalReversedEvent(Guid OriginalJournalId, Guid ReversalJournalId);

public record ReversalData(JournalEntry OriginalJournalEntry, IReadOnlyList<Account> AffectedAccounts);

public interface IReversalQuery
{
    Task<ReversalData?> GetReversalDataAsync(Guid journalEntryId);
}

public static class ReverseJournalHandler
{
    public static async Task<ReversalData?> LoadAsync(ReverseJournalCommand cmd, IReversalQuery query)
    {
        var data = await query.GetReversalDataAsync(cmd.OriginalJournalId);
        return data ?? throw new InvalidOperationException($"Journal Entry {cmd.OriginalJournalId} does not exist");
    }

    public static (
        IStorageAction<JournalEntry> JournalWrite,
        UnitOfWork<Account> AccountWrites,
        JournalReversedEvent Event) Handle(ReverseJournalCommand cmd, ReversalData data)
    {
        var reversalJournal =
            BalancedJournal.CreateReversal(data.OriginalJournalEntry, $"Reversal: {cmd.Reason}", DateTimeOffset.UtcNow);
        var accountState = data.AffectedAccounts.ToDictionary(a => a.Id);

        reversalJournal.Entry.Lines.ForEach(l =>
        {
            var currentAccount = accountState[l.AccountId];
            accountState[l.AccountId] = currentAccount.ApplyPosting(l.Amount, l.Type);
        });
        var accountUow = new UnitOfWork<Account>();
        foreach (var account in accountState.Values)
        {
            accountUow.Update(account);
        }
        return (
            Storage.Insert(reversalJournal.Entry),
            accountUow,
            new JournalReversedEvent(cmd.OriginalJournalId, reversalJournal.Entry.Id)
        );
    }
}