2018-03-20 14:52:46 -07:00
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//! A domain-specific language for payment plans. Users create Plan objects that
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//! are given to an interpreter. The interpreter listens for `Witness` events,
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//! which it uses to reduce the payment plan. When the plan is reduced to a
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//! `Payment`, the payment is executed.
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2018-03-17 13:42:43 -07:00
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use signature::PublicKey;
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use chrono::prelude::*;
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use std::mem;
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2018-03-20 14:31:28 -07:00
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pub enum Witness {
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Timestamp(DateTime<Utc>),
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Signature(PublicKey),
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}
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2018-03-20 14:31:28 -07:00
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#[derive(Serialize, Deserialize, Debug, PartialEq, Eq, Clone)]
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pub enum Condition {
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Timestamp(DateTime<Utc>),
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Signature(PublicKey),
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}
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impl Condition {
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pub fn is_satisfied(&self, event: &Witness) -> bool {
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match (self, event) {
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(&Condition::Signature(ref pubkey), &Witness::Signature(ref from)) => pubkey == from,
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(&Condition::Timestamp(ref dt), &Witness::Timestamp(ref last_time)) => dt <= last_time,
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_ => false,
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}
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}
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}
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2018-03-17 13:42:43 -07:00
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#[derive(Serialize, Deserialize, Debug, PartialEq, Eq, Clone)]
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pub struct Payment {
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2018-03-19 09:03:41 -07:00
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pub tokens: i64,
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pub to: PublicKey,
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}
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#[derive(Serialize, Deserialize, Debug, PartialEq, Eq, Clone)]
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pub enum Plan {
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Pay(Payment),
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After(Condition, Payment),
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Race((Condition, Payment), (Condition, Payment)),
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2018-03-17 13:42:43 -07:00
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}
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2018-03-17 13:42:50 -07:00
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impl Plan {
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pub fn new_payment(tokens: i64, to: PublicKey) -> Self {
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Plan::Pay(Payment { tokens, to })
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}
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pub fn new_authorized_payment(from: PublicKey, tokens: i64, to: PublicKey) -> Self {
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Plan::After(Condition::Signature(from), Payment { tokens, to })
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}
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pub fn new_future_payment(dt: DateTime<Utc>, tokens: i64, to: PublicKey) -> Self {
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Plan::After(Condition::Timestamp(dt), Payment { tokens, to })
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}
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pub fn new_cancelable_future_payment(
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dt: DateTime<Utc>,
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from: PublicKey,
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tokens: i64,
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to: PublicKey,
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) -> Self {
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Plan::Race(
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(Condition::Timestamp(dt), Payment { tokens, to }),
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(Condition::Signature(from), Payment { tokens, to: from }),
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2018-03-18 20:02:28 -07:00
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)
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}
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2018-03-20 15:52:47 -07:00
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pub fn is_complete(&self) -> bool {
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match *self {
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Plan::Pay(_) => true,
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_ => false,
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}
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}
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pub fn verify(&self, spendable_tokens: i64) -> bool {
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match *self {
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Plan::Pay(ref payment) => payment.tokens == spendable_tokens,
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Plan::After(_, ref payment) => payment.tokens == spendable_tokens,
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Plan::Race(ref a, ref b) => {
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a.1.tokens == spendable_tokens && b.1.tokens == spendable_tokens
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}
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}
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}
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pub fn process_witness(&mut self, event: Witness) {
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let mut new_payment = None;
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match *self {
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Plan::Pay(_) => (),
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Plan::After(ref cond, ref payment) => {
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if cond.is_satisfied(&event) {
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new_payment = Some(payment.clone());
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}
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}
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Plan::Race(ref a, ref b) => {
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if a.0.is_satisfied(&event) {
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new_payment = Some(a.1.clone());
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} else if b.0.is_satisfied(&event) {
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new_payment = Some(b.1.clone());
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}
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}
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}
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2018-03-20 14:43:04 -07:00
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if let Some(payment) = new_payment {
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mem::replace(self, Plan::Pay(payment));
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2018-03-17 13:42:43 -07:00
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}
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}
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}
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2018-03-18 20:02:28 -07:00
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#[cfg(test)]
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mod tests {
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use super::*;
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#[test]
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fn test_signature_satisfied() {
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let sig = PublicKey::default();
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assert!(Condition::Signature(sig).is_satisfied(&Witness::Signature(sig)));
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}
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#[test]
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fn test_timestamp_satisfied() {
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let dt1 = Utc.ymd(2014, 11, 14).and_hms(8, 9, 10);
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let dt2 = Utc.ymd(2014, 11, 14).and_hms(10, 9, 8);
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assert!(Condition::Timestamp(dt1).is_satisfied(&Witness::Timestamp(dt1)));
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assert!(Condition::Timestamp(dt1).is_satisfied(&Witness::Timestamp(dt2)));
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assert!(!Condition::Timestamp(dt2).is_satisfied(&Witness::Timestamp(dt1)));
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}
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#[test]
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fn test_verify_plan() {
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let dt = Utc.ymd(2014, 11, 14).and_hms(8, 9, 10);
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let from = PublicKey::default();
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let to = PublicKey::default();
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assert!(Plan::new_payment(42, to).verify(42));
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assert!(Plan::new_authorized_payment(from, 42, to).verify(42));
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assert!(Plan::new_future_payment(dt, 42, to).verify(42));
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assert!(Plan::new_cancelable_future_payment(dt, from, 42, to).verify(42));
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}
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#[test]
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fn test_authorized_payment() {
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let from = PublicKey::default();
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let to = PublicKey::default();
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let mut plan = Plan::new_authorized_payment(from, 42, to);
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plan.process_witness(Witness::Signature(from));
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assert_eq!(plan, Plan::new_payment(42, to));
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}
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#[test]
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fn test_future_payment() {
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let dt = Utc.ymd(2014, 11, 14).and_hms(8, 9, 10);
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let to = PublicKey::default();
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let mut plan = Plan::new_future_payment(dt, 42, to);
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plan.process_witness(Witness::Timestamp(dt));
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assert_eq!(plan, Plan::new_payment(42, to));
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}
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#[test]
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fn test_cancelable_future_payment() {
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let dt = Utc.ymd(2014, 11, 14).and_hms(8, 9, 10);
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let from = PublicKey::default();
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let to = PublicKey::default();
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let mut plan = Plan::new_cancelable_future_payment(dt, from, 42, to);
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plan.process_witness(Witness::Timestamp(dt));
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assert_eq!(plan, Plan::new_payment(42, to));
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let mut plan = Plan::new_cancelable_future_payment(dt, from, 42, to);
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plan.process_witness(Witness::Signature(from));
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assert_eq!(plan, Plan::new_payment(42, from));
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}
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}
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