import Foundation
import CoreData

class TransactionRepository {
    private let context: NSManagedObjectContext

    init(context: NSManagedObjectContext = CoreDataStack.shared.viewContext) {
        self.context = context
    }

    func fetchTransactions(for source: InvestmentSource) -> [Transaction] {
        let request: NSFetchRequest<Transaction> = Transaction.fetchRequest()
        request.predicate = NSPredicate(format: "source == %@", source)
        request.sortDescriptors = [
            NSSortDescriptor(keyPath: \Transaction.date, ascending: false)
        ]
        return (try? context.fetch(request)) ?? []
    }

    @discardableResult
    func createTransaction(
        source: InvestmentSource,
        type: TransactionType,
        date: Date,
        shares: Decimal?,
        price: Decimal?,
        amount: Decimal?,
        notes: String?
    ) -> Transaction {
        let transaction = Transaction(context: context)
        transaction.source = source
        transaction.type = type.rawValue
        transaction.date = date
        if let shares = shares {
            transaction.shares = NSDecimalNumber(decimal: shares)
        }
        if let price = price {
            transaction.price = NSDecimalNumber(decimal: price)
        }
        if let amount = amount {
            transaction.amount = NSDecimalNumber(decimal: amount)
        }
        transaction.notes = notes

        save()
        return transaction
    }

    func deleteTransaction(_ transaction: Transaction) {
        context.delete(transaction)
        save()
    }

    private func save() {
        guard context.hasChanges else { return }
        do {
            try context.save()
        } catch {
            print("Failed to save transaction: \(error)")
        }
    }
}