using NBitcoin;
using PalladiumWallet.Core.Chain;
using PalladiumWallet.Core.Crypto;
using PalladiumWallet.Core.Storage;
using PalladiumWallet.Core.Wallet;

namespace PalladiumWallet.Tests.Wallet;

/// <summary>Spend-policy limits: send-all affordability and the standard-size cap.</summary>
public class TransactionFactoryLimitsTests
{
    private static readonly Network Net = PalladiumNetworks.Regtest;

    private static HdAccount Account()
    {
        Assert.True(Bip39.TryParse(
            "abandon abandon abandon abandon abandon abandon abandon abandon abandon abandon abandon about",
            out var mnemonic));
        return HdAccount.FromMnemonic(mnemonic!, null, ScriptKind.NativeSegwit, ChainProfiles.Regtest);
    }

    /// <summary>One funding tx with <paramref name="count"/> outputs to receive/0, each a verified UTXO.</summary>
    private static (List<CachedUtxo>, Dictionary<string, Transaction>) Fund(HdAccount account, int count, long satsEach)
    {
        var funding = Net.CreateTransaction();
        funding.Inputs.Add(new TxIn(new OutPoint(uint256.One, 0)));
        for (var i = 0; i < count; i++)
            funding.Outputs.Add(Money.Satoshis(satsEach), account.GetReceiveAddress(0));
        var txid = funding.GetHash().ToString();
        var utxos = Enumerable.Range(0, count).Select(i => new CachedUtxo
        {
            Txid = txid, Vout = i, ValueSats = satsEach,
            Address = account.GetReceiveAddress(0).ToString(),
            AddressIndex = 0, Height = 100, Verified = true,
        }).ToList();
        return (utxos, new Dictionary<string, Transaction> { [txid] = funding });
    }

    [Fact]
    public void SendAll_WithBalanceBelowTheFee_IsRejectedAsInsufficientFunds()
    {
        var account = Account();
        var (utxos, txs) = Fund(account, 1, 50); // 50 sat cannot pay for a ~110 vB transaction

        var ex = Assert.Throws<WalletSpendException>(() => new TransactionFactory(account).Build(
            utxos, txs, account.GetReceiveAddress(5), amountSats: 0,
            feeRateSatPerVByte: 2, changeIndex: 0, tipHeight: 1_000, sendAll: true));
        Assert.Contains("Insufficient funds", ex.Message);
    }

    [Fact]
    public void SendAll_OverTheStandardSizeCap_IsRejectedWithGuidance()
    {
        var account = Account();
        // ~68 vB per P2WPKH input: 1,700 inputs exceed the 100,000 vB standard limit.
        var (utxos, txs) = Fund(account, 1_700, 10_000);

        var ex = Assert.Throws<WalletSpendException>(() => new TransactionFactory(account).Build(
            utxos, txs, account.GetReceiveAddress(5), amountSats: 0,
            feeRateSatPerVByte: 1, changeIndex: 0, tipHeight: 1_000, sendAll: true));
        Assert.Contains("Send-all cannot fit in one standard transaction", ex.Message);
    }

    [Fact]
    public void AmountAboveTheBalance_IsRejectedAsInsufficientFunds()
    {
        var account = Account();
        var (utxos, txs) = Fund(account, 1, 100_000);

        Assert.Throws<WalletSpendException>(() => new TransactionFactory(account).Build(
            utxos, txs, account.GetReceiveAddress(5), amountSats: 500_000,
            feeRateSatPerVByte: 2, changeIndex: 0, tipHeight: 1_000));
    }
}