archy/core/archipelago/src/wallet/ecash.rs

//! Cashu ecash wallet for peer-to-peer micropayments and streaming data payments.
//!
//! Real Cashu protocol implementation using BDHKE blind signatures.
//! Connects to Cashu-compatible mints (local Fedimint or external) for
//! mint/melt/swap operations. Stores proofs locally in the data directory.

use super::cashu::{amount_to_denominations, CashuToken, Proof};
use super::mint_client::MintClient;
use anyhow::{Context, Result};
use serde::{Deserialize, Serialize};
use std::path::Path;
use tokio::fs;
use tracing::{debug, warn};

const WALLET_FILE: &str = "wallet/ecash.json";
const MINTS_FILE: &str = "wallet/accepted_mints.json";

/// Transaction type for history tracking.
#[derive(Debug, Clone, Serialize, Deserialize)]
#[serde(rename_all = "lowercase")]
pub enum TransactionType {
    Mint,
    Melt,
    Send,
    Receive,
    StreamingPayment,
    StreamingRevenue,
}

/// Transaction history entry.
#[derive(Debug, Clone, Serialize, Deserialize)]
pub struct EcashTransaction {
    pub id: String,
    pub tx_type: TransactionType,
    pub amount_sats: u64,
    pub timestamp: String,
    #[serde(default)]
    pub description: String,
    /// Mint URL involved in this transaction.
    #[serde(default)]
    pub mint_url: String,
    /// Peer identifier (DID, pubkey, or onion) if applicable.
    #[serde(default)]
    pub peer: String,
}

/// A stored proof with metadata.
#[derive(Debug, Clone, Serialize, Deserialize)]
pub struct StoredProof {
    /// The Cashu proof.
    #[serde(flatten)]
    pub proof: Proof,
    /// Mint URL this proof is from.
    pub mint_url: String,
    /// Whether this proof has been spent (sent to someone or melted).
    #[serde(default)]
    pub spent: bool,
    /// Whether this proof is reserved (allocated to an in-progress operation).
    #[serde(default)]
    pub reserved: bool,
    /// Timestamp when received.
    pub created_at: String,
}

/// Persistent wallet state.
#[derive(Debug, Default, Serialize, Deserialize)]
pub struct WalletState {
    /// All proofs (spent and unspent).
    pub proofs: Vec<StoredProof>,
    /// Transaction history.
    pub transactions: Vec<EcashTransaction>,
    /// Primary mint URL.
    #[serde(default)]
    pub mint_url: String,

    // ── Legacy compatibility ──
    // Old wallet format had a `tokens` field. If present during deserialization,
    // we migrate to proofs. This field is never written.
    #[serde(default, skip_serializing)]
    tokens: Vec<serde_json::Value>,
}

/// Accepted mints configuration.
#[derive(Debug, Default, Serialize, Deserialize)]
pub struct AcceptedMints {
    /// List of mint URLs we accept tokens from.
    pub mints: Vec<String>,
}

impl WalletState {
    /// Total balance of unspent, unreserved proofs.
    pub fn balance(&self) -> u64 {
        self.proofs
            .iter()
            .filter(|p| !p.spent && !p.reserved)
            .map(|p| p.proof.amount)
            .sum()
    }

    /// Balance from a specific mint.
    pub fn balance_for_mint(&self, mint_url: &str) -> u64 {
        self.proofs
            .iter()
            .filter(|p| !p.spent && !p.reserved && p.mint_url == mint_url)
            .map(|p| p.proof.amount)
            .sum()
    }

    /// Select unspent proofs that cover at least `amount` sats from a specific mint.
    /// Returns selected proofs and any overpayment amount.
    pub fn select_proofs(&self, mint_url: &str, amount: u64) -> Option<(Vec<usize>, u64)> {
        let mut candidates: Vec<(usize, u64)> = self
            .proofs
            .iter()
            .enumerate()
            .filter(|(_, p)| !p.spent && !p.reserved && p.mint_url == mint_url)
            .map(|(i, p)| (i, p.proof.amount))
            .collect();

        // Sort by amount ascending for efficient selection
        candidates.sort_by_key(|&(_, a)| a);

        let mut selected = Vec::new();
        let mut total = 0u64;

        for (idx, amt) in &candidates {
            if total >= amount {
                break;
            }
            selected.push(*idx);
            total += amt;
        }

        if total >= amount {
            Some((selected, total - amount))
        } else {
            None
        }
    }

    /// Mark proofs at given indices as spent.
    pub fn mark_spent(&mut self, indices: &[usize]) {
        for &i in indices {
            if i < self.proofs.len() {
                self.proofs[i].spent = true;
            }
        }
    }

    /// Add new proofs to the wallet.
    pub fn add_proofs(&mut self, mint_url: &str, proofs: Vec<Proof>) {
        let now = chrono::Utc::now().to_rfc3339();
        for proof in proofs {
            self.proofs.push(StoredProof {
                proof,
                mint_url: mint_url.to_string(),
                spent: false,
                reserved: false,
                created_at: now.clone(),
            });
        }
    }

    /// Record a transaction.
    pub fn record_tx(
        &mut self,
        tx_type: TransactionType,
        amount_sats: u64,
        description: &str,
        mint_url: &str,
        peer: &str,
    ) {
        self.transactions.push(EcashTransaction {
            id: uuid::Uuid::new_v4().to_string(),
            tx_type,
            amount_sats,
            timestamp: chrono::Utc::now().to_rfc3339(),
            description: description.to_string(),
            mint_url: mint_url.to_string(),
            peer: peer.to_string(),
        });
    }

    /// Prune spent proofs older than 30 days to keep wallet file manageable.
    pub fn prune_old_spent(&mut self) {
        let cutoff = chrono::Utc::now() - chrono::Duration::days(30);
        let cutoff_str = cutoff.to_rfc3339();
        self.proofs
            .retain(|p| !p.spent || p.created_at > cutoff_str);
    }
}

/// Load wallet state from disk.
pub async fn load_wallet(data_dir: &Path) -> Result<WalletState> {
    let path = data_dir.join(WALLET_FILE);
    if !path.exists() {
        return Ok(WalletState {
            mint_url: default_mint_url(),
            ..Default::default()
        });
    }
    let content = fs::read_to_string(&path)
        .await
        .context("Failed to read wallet file")?;
    let mut wallet: WalletState = serde_json::from_str(&content).unwrap_or_default();

    // Set default mint URL if empty
    if wallet.mint_url.is_empty() {
        wallet.mint_url = default_mint_url();
    }

    Ok(wallet)
}

/// Save wallet state to disk.
pub async fn save_wallet(data_dir: &Path, wallet: &WalletState) -> Result<()> {
    let dir = data_dir.join("wallet");
    fs::create_dir_all(&dir)
        .await
        .context("Failed to create wallet dir")?;
    let path = data_dir.join(WALLET_FILE);
    let content = serde_json::to_string_pretty(wallet).context("Failed to serialize wallet")?;
    fs::write(&path, content)
        .await
        .context("Failed to write wallet file")?;
    Ok(())
}

/// Load accepted mints list.
pub async fn load_accepted_mints(data_dir: &Path) -> Result<AcceptedMints> {
    let path = data_dir.join(MINTS_FILE);
    if !path.exists() {
        return Ok(AcceptedMints {
            mints: vec![default_mint_url()],
        });
    }
    let content = fs::read_to_string(&path)
        .await
        .context("Failed to read accepted mints")?;
    let mints: AcceptedMints = serde_json::from_str(&content).unwrap_or(AcceptedMints {
        mints: vec![default_mint_url()],
    });
    Ok(mints)
}

/// Save accepted mints list.
pub async fn save_accepted_mints(data_dir: &Path, mints: &AcceptedMints) -> Result<()> {
    let dir = data_dir.join("wallet");
    fs::create_dir_all(&dir)
        .await
        .context("Failed to create wallet dir")?;
    let path = data_dir.join(MINTS_FILE);
    let content =
        serde_json::to_string_pretty(mints).context("Failed to serialize accepted mints")?;
    fs::write(&path, content)
        .await
        .context("Failed to write accepted mints")?;
    Ok(())
}

/// Request a mint quote — returns a Lightning invoice to pay.
pub async fn mint_quote(data_dir: &Path, amount_sats: u64) -> Result<super::mint_client::MintQuote> {
    let wallet = load_wallet(data_dir).await?;
    let client = MintClient::new(&wallet.mint_url)?;
    client.mint_quote(amount_sats).await
}

/// Mint new ecash tokens after a Lightning invoice has been paid.
pub async fn mint_tokens(data_dir: &Path, quote_id: &str, amount_sats: u64) -> Result<u64> {
    let mut wallet = load_wallet(data_dir).await?;
    let mint_url = wallet.mint_url.clone();
    let client = MintClient::new(&mint_url)?;

    let result = client.mint_tokens(quote_id, amount_sats).await?;
    let minted: u64 = result.proofs.iter().map(|p| p.amount).sum();

    wallet.add_proofs(&mint_url, result.proofs);
    wallet.record_tx(
        TransactionType::Mint,
        minted,
        &format!("Minted {} sats from Lightning", minted),
        &mint_url,
        "",
    );
    save_wallet(data_dir, &wallet).await?;

    debug!("Minted {} sats ecash", minted);
    Ok(minted)
}

/// Request a melt quote — how much to pay a Lightning invoice with ecash.
pub async fn melt_quote(
    data_dir: &Path,
    bolt11: &str,
) -> Result<super::mint_client::MeltQuote> {
    let wallet = load_wallet(data_dir).await?;
    let client = MintClient::new(&wallet.mint_url)?;
    client.melt_quote(bolt11).await
}

/// Melt ecash tokens to pay a Lightning invoice.
pub async fn melt_tokens(data_dir: &Path, quote_id: &str, bolt11: &str) -> Result<u64> {
    let mut wallet = load_wallet(data_dir).await?;
    let mint_url = wallet.mint_url.clone();
    let client = MintClient::new(&mint_url)?;

    // Get the melt quote to know the amount needed
    let quote = client.melt_quote(bolt11).await?;
    let total_needed = quote.amount + quote.fee_reserve;

    // Select proofs to cover the amount
    let (indices, _overpayment) = wallet
        .select_proofs(&mint_url, total_needed)
        .ok_or_else(|| {
            anyhow::anyhow!(
                "Insufficient balance: need {} sats, have {} sats",
                total_needed,
                wallet.balance_for_mint(&mint_url)
            )
        })?;

    let proofs: Vec<Proof> = indices.iter().map(|&i| wallet.proofs[i].proof.clone()).collect();
    let spent_amount: u64 = proofs.iter().map(|p| p.amount).sum();

    // Execute melt
    let result = client.melt_tokens(quote_id, &proofs).await?;

    // Mark proofs as spent
    wallet.mark_spent(&indices);
    wallet.record_tx(
        TransactionType::Melt,
        quote.amount,
        &format!("Melted {} sats to Lightning (fee: {})", quote.amount, quote.fee_reserve),
        &mint_url,
        "",
    );

    // If there was overpayment and the melt returned change, we could handle it here.
    // For now, any overpayment beyond fee_reserve is lost (mints may return change in future NUTs).
    let _ = result;
    let _ = spent_amount;

    save_wallet(data_dir, &wallet).await?;
    debug!("Melted {} sats to Lightning", quote.amount);
    Ok(quote.amount)
}

/// Create a cashuA token string to send to a peer.
pub async fn send_token(data_dir: &Path, amount_sats: u64) -> Result<String> {
    let mut wallet = load_wallet(data_dir).await?;
    let mint_url = wallet.mint_url.clone();

    // Select proofs covering the amount
    let (indices, overpayment) = wallet
        .select_proofs(&mint_url, amount_sats)
        .ok_or_else(|| {
            anyhow::anyhow!(
                "Insufficient balance: need {} sats, have {} sats",
                amount_sats,
                wallet.balance_for_mint(&mint_url)
            )
        })?;

    let selected_proofs: Vec<Proof> = indices.iter().map(|&i| wallet.proofs[i].proof.clone()).collect();

    // If there's overpayment, swap to get exact change
    let send_proofs = if overpayment > 0 {
        let client = MintClient::new(&mint_url)?;
        let send_denoms = amount_to_denominations(amount_sats);
        let change_denoms = amount_to_denominations(overpayment);

        let mut all_target: Vec<u64> = send_denoms.clone();
        all_target.extend(&change_denoms);

        let swap_result = client.swap(&selected_proofs, &all_target).await?;

        // Mark original proofs as spent
        wallet.mark_spent(&indices);

        // Separate send proofs from change proofs
        let (send, change): (Vec<_>, Vec<_>) = swap_result
            .new_proofs
            .into_iter()
            .partition(|p| send_denoms.contains(&p.amount));

        // Add change proofs back to wallet
        if !change.is_empty() {
            wallet.add_proofs(&mint_url, change);
        }

        send
    } else {
        // Exact amount — just mark as spent and use directly
        wallet.mark_spent(&indices);
        selected_proofs
    };

    // Serialize as cashuA token
    let token = CashuToken::new(&mint_url, send_proofs);
    let token_str = token.serialize()?;

    wallet.record_tx(
        TransactionType::Send,
        amount_sats,
        &format!("Sent {} sats ecash", amount_sats),
        &mint_url,
        "",
    );
    save_wallet(data_dir, &wallet).await?;

    debug!("Created send token for {} sats", amount_sats);
    Ok(token_str)
}

/// Receive a cashuA token from a peer — swaps proofs at the mint for fresh ones.
pub async fn receive_token(data_dir: &Path, token_str: &str) -> Result<u64> {
    // Handle legacy format for backwards compatibility
    if token_str.starts_with("cashuSend_") {
        return receive_legacy_token(data_dir, token_str).await;
    }

    let token = CashuToken::deserialize(token_str)?;
    let total_amount = token.total_amount();

    if total_amount == 0 {
        anyhow::bail!("Token has zero value");
    }

    // Verify all mints in the token are accepted
    let accepted = load_accepted_mints(data_dir).await?;
    for mint_url in token.mint_urls() {
        if !accepted.mints.iter().any(|m| m == mint_url) {
            anyhow::bail!("Mint '{}' is not in accepted mints list", mint_url);
        }
    }

    let mut wallet = load_wallet(data_dir).await?;
    let mut received_total = 0u64;

    // Swap proofs at each mint
    for entry in &token.token {
        let client = MintClient::new(&entry.mint)?;
        match client.receive_token(&token).await {
            Ok(new_proofs) => {
                let amount: u64 = new_proofs.iter().map(|p| p.amount).sum();
                wallet.add_proofs(&entry.mint, new_proofs);
                received_total += amount;
            }
            Err(e) => {
                warn!("Failed to swap proofs from mint {}: {}", entry.mint, e);
                // Continue with other mints if any
            }
        }
    }

    if received_total == 0 {
        anyhow::bail!("Failed to receive any proofs from token");
    }

    wallet.record_tx(
        TransactionType::Receive,
        received_total,
        &format!("Received {} sats ecash", received_total),
        &token.token.first().map(|e| e.mint.as_str()).unwrap_or(""),
        "",
    );
    save_wallet(data_dir, &wallet).await?;

    debug!("Received {} sats ecash token", received_total);
    Ok(received_total)
}

/// Receive a legacy format token (cashuSend_{amount}_{uuid}_{timestamp}).
/// For backwards compatibility during migration period.
async fn receive_legacy_token(data_dir: &Path, token_str: &str) -> Result<u64> {
    let amount_sats = token_str
        .split('_')
        .nth(1)
        .and_then(|s| s.parse::<u64>().ok())
        .unwrap_or(0);

    if amount_sats == 0 {
        anyhow::bail!("Invalid legacy ecash token");
    }

    let mut wallet = load_wallet(data_dir).await?;

    // Store as a synthetic proof (legacy tokens can't be verified cryptographically)
    let proof = Proof {
        amount: amount_sats,
        id: "legacy".to_string(),
        secret: token_str.to_string(),
        c: "0000000000000000000000000000000000000000000000000000000000000000ff".to_string(),
    };
    wallet.add_proofs(&wallet.mint_url.clone(), vec![proof]);

    wallet.record_tx(
        TransactionType::Receive,
        amount_sats,
        &format!("Received {} sats (legacy format)", amount_sats),
        &wallet.mint_url.clone(),
        "",
    );
    save_wallet(data_dir, &wallet).await?;

    debug!("Received {} sats legacy ecash token", amount_sats);
    Ok(amount_sats)
}

/// Verify a payment token and receive it into the wallet.
/// Returns the verified amount, or error if verification fails.
/// Used by the content server and streaming gate to verify incoming payments.
pub async fn verify_and_receive_payment(
    data_dir: &Path,
    token_str: &str,
    required_sats: u64,
) -> Result<u64> {
    // Handle legacy tokens
    if token_str.starts_with("cashuSend_") {
        let amount = token_str
            .split('_')
            .nth(1)
            .and_then(|s| s.parse::<u64>().ok())
            .unwrap_or(0);
        if amount < required_sats {
            anyhow::bail!(
                "Insufficient payment: {} sats, need {} sats",
                amount,
                required_sats
            );
        }
        let received = receive_legacy_token(data_dir, token_str).await?;
        return Ok(received);
    }

    // Parse and validate cashuA token
    let token = CashuToken::deserialize(token_str)?;
    let total = token.total_amount();

    if total < required_sats {
        anyhow::bail!(
            "Insufficient payment: {} sats, need {} sats",
            total,
            required_sats
        );
    }

    // Verify mints are accepted
    let accepted = load_accepted_mints(data_dir).await?;
    for mint_url in token.mint_urls() {
        if !accepted.mints.iter().any(|m| m == mint_url) {
            anyhow::bail!("Mint '{}' not accepted", mint_url);
        }
    }

    // Swap proofs at mint (this verifies they're unspent and gives us fresh proofs)
    let mut wallet = load_wallet(data_dir).await?;
    let mut received_total = 0u64;

    for entry in &token.token {
        let client = MintClient::new(&entry.mint)?;
        let entry_total: u64 = entry.proofs.iter().map(|p| p.amount).sum();
        let target_amounts = amount_to_denominations(entry_total);

        match client.swap(&entry.proofs, &target_amounts).await {
            Ok(result) => {
                let amount: u64 = result.new_proofs.iter().map(|p| p.amount).sum();
                wallet.add_proofs(&entry.mint, result.new_proofs);
                received_total += amount;
            }
            Err(e) => {
                warn!("Payment verification failed at mint {}: {}", entry.mint, e);
            }
        }
    }

    if received_total < required_sats {
        anyhow::bail!(
            "Payment verification failed: only {} of {} sats verified",
            received_total,
            required_sats
        );
    }

    wallet.record_tx(
        TransactionType::Receive,
        received_total,
        &format!("Payment received: {} sats", received_total),
        &token.token.first().map(|e| e.mint.as_str()).unwrap_or(""),
        "",
    );
    save_wallet(data_dir, &wallet).await?;

    Ok(received_total)
}

/// Check the wallet balance.
pub async fn get_balance(data_dir: &Path) -> Result<u64> {
    let wallet = load_wallet(data_dir).await?;
    Ok(wallet.balance())
}

/// Default mint URL (local Fedimint).
fn default_mint_url() -> String {
    "http://127.0.0.1:8175".to_string()
}

#[cfg(test)]
mod tests {
    use super::*;
    use tempfile::TempDir;

    #[test]
    fn test_wallet_state_balance_empty() {
        let wallet = WalletState::default();
        assert_eq!(wallet.balance(), 0);
    }

    #[test]
    fn test_wallet_state_balance_with_proofs() {
        let mut wallet = WalletState::default();
        wallet.add_proofs(
            "http://mint",
            vec![
                Proof { amount: 100, id: "ks1".into(), secret: "s1".into(), c: "c1".into() },
                Proof { amount: 200, id: "ks1".into(), secret: "s2".into(), c: "c2".into() },
            ],
        );
        assert_eq!(wallet.balance(), 300);
    }

    #[test]
    fn test_wallet_state_balance_excludes_spent() {
        let mut wallet = WalletState::default();
        wallet.add_proofs(
            "http://mint",
            vec![
                Proof { amount: 100, id: "ks1".into(), secret: "s1".into(), c: "c1".into() },
                Proof { amount: 200, id: "ks1".into(), secret: "s2".into(), c: "c2".into() },
            ],
        );
        wallet.proofs[0].spent = true;
        assert_eq!(wallet.balance(), 200);
    }

    #[test]
    fn test_wallet_state_balance_excludes_reserved() {
        let mut wallet = WalletState::default();
        wallet.add_proofs(
            "http://mint",
            vec![
                Proof { amount: 100, id: "ks1".into(), secret: "s1".into(), c: "c1".into() },
            ],
        );
        wallet.proofs[0].reserved = true;
        assert_eq!(wallet.balance(), 0);
    }

    #[test]
    fn test_select_proofs_sufficient() {
        let mut wallet = WalletState::default();
        wallet.add_proofs(
            "http://mint",
            vec![
                Proof { amount: 1, id: "ks1".into(), secret: "s1".into(), c: "c1".into() },
                Proof { amount: 4, id: "ks1".into(), secret: "s2".into(), c: "c2".into() },
                Proof { amount: 8, id: "ks1".into(), secret: "s3".into(), c: "c3".into() },
            ],
        );

        let (indices, overpayment) = wallet.select_proofs("http://mint", 5).unwrap();
        let total: u64 = indices.iter().map(|&i| wallet.proofs[i].proof.amount).sum();
        assert!(total >= 5);
        assert_eq!(total - 5, overpayment);
    }

    #[test]
    fn test_select_proofs_insufficient() {
        let mut wallet = WalletState::default();
        wallet.add_proofs(
            "http://mint",
            vec![
                Proof { amount: 1, id: "ks1".into(), secret: "s1".into(), c: "c1".into() },
            ],
        );

        assert!(wallet.select_proofs("http://mint", 100).is_none());
    }

    #[test]
    fn test_select_proofs_wrong_mint() {
        let mut wallet = WalletState::default();
        wallet.add_proofs(
            "http://mint-a",
            vec![
                Proof { amount: 100, id: "ks1".into(), secret: "s1".into(), c: "c1".into() },
            ],
        );

        assert!(wallet.select_proofs("http://mint-b", 100).is_none());
    }

    #[test]
    fn test_balance_for_mint() {
        let mut wallet = WalletState::default();
        wallet.add_proofs(
            "http://mint-a",
            vec![Proof { amount: 100, id: "ks1".into(), secret: "s1".into(), c: "c1".into() }],
        );
        wallet.add_proofs(
            "http://mint-b",
            vec![Proof { amount: 200, id: "ks2".into(), secret: "s2".into(), c: "c2".into() }],
        );

        assert_eq!(wallet.balance_for_mint("http://mint-a"), 100);
        assert_eq!(wallet.balance_for_mint("http://mint-b"), 200);
        assert_eq!(wallet.balance(), 300);
    }

    #[tokio::test]
    async fn test_load_wallet_creates_default_when_missing() {
        let tmp = TempDir::new().unwrap();
        let wallet = load_wallet(tmp.path()).await.unwrap();
        assert_eq!(wallet.balance(), 0);
        assert!(wallet.proofs.is_empty());
        assert!(wallet.transactions.is_empty());
        assert_eq!(wallet.mint_url, default_mint_url());
    }

    #[tokio::test]
    async fn test_save_and_load_wallet_roundtrip() {
        let tmp = TempDir::new().unwrap();
        let mut wallet = WalletState {
            mint_url: "http://127.0.0.1:8175".into(),
            ..Default::default()
        };
        wallet.add_proofs(
            "http://127.0.0.1:8175",
            vec![Proof {
                amount: 42,
                id: "ks1".into(),
                secret: "test_secret".into(),
                c: "test_c".into(),
            }],
        );
        wallet.record_tx(
            TransactionType::Mint,
            42,
            "Test mint",
            "http://127.0.0.1:8175",
            "",
        );

        save_wallet(tmp.path(), &wallet).await.unwrap();
        let loaded = load_wallet(tmp.path()).await.unwrap();
        assert_eq!(loaded.proofs.len(), 1);
        assert_eq!(loaded.proofs[0].proof.amount, 42);
        assert!(!loaded.proofs[0].spent);
        assert_eq!(loaded.transactions.len(), 1);
        assert_eq!(loaded.balance(), 42);
    }

    #[tokio::test]
    async fn test_save_wallet_creates_directory() {
        let tmp = TempDir::new().unwrap();
        let wallet_dir = tmp.path().join("wallet");
        assert!(!wallet_dir.exists());

        let wallet = WalletState::default();
        save_wallet(tmp.path(), &wallet).await.unwrap();
        assert!(wallet_dir.exists());
    }

    #[tokio::test]
    async fn test_receive_legacy_token() {
        let tmp = TempDir::new().unwrap();
        let amount = receive_token(tmp.path(), "cashuSend_500_abc123_1700000000")
            .await
            .unwrap();
        assert_eq!(amount, 500);

        let wallet = load_wallet(tmp.path()).await.unwrap();
        assert_eq!(wallet.balance(), 500);
        assert_eq!(wallet.proofs.len(), 1);
        assert!(!wallet.proofs[0].spent);
    }

    #[tokio::test]
    async fn test_receive_token_invalid_format() {
        let tmp = TempDir::new().unwrap();
        let result = receive_token(tmp.path(), "invalid_token_string").await;
        assert!(result.is_err());
    }

    #[tokio::test]
    async fn test_receive_legacy_token_zero_amount() {
        let tmp = TempDir::new().unwrap();
        let result = receive_token(tmp.path(), "cashuSend_0_abc_1700000000").await;
        assert!(result.is_err());
    }

    #[test]
    fn test_prune_old_spent() {
        let mut wallet = WalletState::default();
        // Add an old spent proof
        wallet.proofs.push(StoredProof {
            proof: Proof { amount: 100, id: "ks1".into(), secret: "old".into(), c: "c".into() },
            mint_url: "http://mint".into(),
            spent: true,
            reserved: false,
            created_at: "2020-01-01T00:00:00Z".into(),
        });
        // Add a recent unspent proof
        wallet.proofs.push(StoredProof {
            proof: Proof { amount: 200, id: "ks1".into(), secret: "new".into(), c: "c".into() },
            mint_url: "http://mint".into(),
            spent: false,
            reserved: false,
            created_at: chrono::Utc::now().to_rfc3339(),
        });

        wallet.prune_old_spent();
        assert_eq!(wallet.proofs.len(), 1);
        assert_eq!(wallet.proofs[0].proof.amount, 200);
    }

    #[tokio::test]
    async fn test_accepted_mints_default() {
        let tmp = TempDir::new().unwrap();
        let mints = load_accepted_mints(tmp.path()).await.unwrap();
        assert_eq!(mints.mints.len(), 1);
        assert_eq!(mints.mints[0], default_mint_url());
    }

    #[tokio::test]
    async fn test_accepted_mints_roundtrip() {
        let tmp = TempDir::new().unwrap();
        let mints = AcceptedMints {
            mints: vec!["http://mint-a".into(), "http://mint-b".into()],
        };
        save_accepted_mints(tmp.path(), &mints).await.unwrap();
        let loaded = load_accepted_mints(tmp.path()).await.unwrap();
        assert_eq!(loaded.mints.len(), 2);
    }

    #[test]
    fn test_transaction_type_serialization() {
        let tx = EcashTransaction {
            id: "tx-test".into(),
            tx_type: TransactionType::StreamingPayment,
            amount_sats: 100,
            timestamp: "2025-01-01T00:00:00Z".into(),
            description: "test".into(),
            mint_url: String::new(),
            peer: String::new(),
        };
        let json = serde_json::to_string(&tx).unwrap();
        assert!(json.contains("\"streamingpayment\""));
    }

    #[test]
    fn test_default_mint_url() {
        assert_eq!(default_mint_url(), "http://127.0.0.1:8175");
    }
}