feat(wallet)!: use miniscript plan in place of old policy mod

crates/wallet/src/descriptor/policy.rs

@@ -63,6 +63,7 @@ use crate::descriptor::ExtractPolicy;
 use crate::keys::ExtScriptContext;
 use crate::wallet::signer::{SignerId, SignersContainer};
 use crate::wallet::utils::{After, Older, SecpCtx};
+use crate::Condition;
 
 use super::checksum::calc_checksum;
 use super::error::Error;
@@ -444,18 +445,6 @@ pub struct Policy {
     pub contribution: Satisfaction,
 }
 
-/// An extra condition that must be satisfied but that is out of control of the user
-/// TODO: use `bitcoin::LockTime` and `bitcoin::Sequence`
-#[derive(Hash, Clone, Copy, Debug, PartialEq, Eq, PartialOrd, Default, Serialize)]
-pub struct Condition {
-    /// Optional CheckSequenceVerify condition
-    #[serde(skip_serializing_if = "Option::is_none")]
-    pub csv: Option<Sequence>,
-    /// Optional timelock condition
-    #[serde(skip_serializing_if = "Option::is_none")]
-    pub timelock: Option<absolute::LockTime>,
-}
-
 impl Condition {
     fn merge_nlocktime(
         a: absolute::LockTime,
@@ -478,7 +467,7 @@ impl Condition {
         }
     }
 
-    pub(crate) fn merge(mut self, other: &Condition) -> Result<Self, PolicyError> {
+    fn merge(mut self, other: &Condition) -> Result<Self, PolicyError> {
         match (self.csv, other.csv) {
             (Some(a), Some(b)) => self.csv = Some(Self::merge_nsequence(a, b)?),
             (None, any) => self.csv = any,

crates/wallet/src/types.rs

@@ -10,13 +10,15 @@
 // licenses.
 
 use alloc::boxed::Box;
-use chain::{ChainPosition, ConfirmationBlockTime};
 use core::convert::AsRef;
+use serde::{Deserialize, Serialize};
 
 use bitcoin::transaction::{OutPoint, Sequence, TxOut};
-use bitcoin::{psbt, Weight};
+use bitcoin::{absolute, psbt, Weight};
+use chain::{ChainPosition, ConfirmationBlockTime};
 
-use serde::{Deserialize, Serialize};
+use crate::error::PlanError;
+use crate::utils::merge_nsequence;
 
 /// Types of keychains
 #[derive(Serialize, Deserialize, Debug, Clone, Copy, PartialEq, Eq, Hash, Ord, PartialOrd)]
@@ -133,3 +135,51 @@ impl Utxo {
         }
     }
 }
+
+/// Represents a condition of a spending path that must be satisfied
+#[derive(Hash, Clone, Copy, Debug, PartialEq, Eq, PartialOrd, Default, serde::Serialize)]
+pub struct Condition {
+    /// sequence value used as the argument to `OP_CHECKSEQUENCEVERIFY`
+    #[serde(skip_serializing_if = "Option::is_none")]
+    pub csv: Option<Sequence>,
+    /// absolute timelock value used as the argument to `OP_CHECKLOCKTIMEVERIFY`
+    #[serde(skip_serializing_if = "Option::is_none")]
+    pub timelock: Option<absolute::LockTime>,
+}
+
+impl Condition {
+    /// Merges two absolute locktimes. Errors if `a` and `b` do not have the same unit.
+    pub(crate) fn merge_abs_locktime(
+        a: Option<absolute::LockTime>,
+        b: Option<absolute::LockTime>,
+    ) -> Result<Option<absolute::LockTime>, PlanError> {
+        match (a, b) {
+            (None, b) => Ok(b),
+            (a, None) => Ok(a),
+            (Some(a), Some(b)) => {
+                if a.is_block_height() != b.is_block_height() {
+                    Err(PlanError::MixedTimelockUnits)
+                } else if b > a {
+                    Ok(Some(b))
+                } else {
+                    Ok(Some(a))
+                }
+            }
+        }
+    }
+
+    /// Merges the conditions of `other` with `self` keeping the greater of the two
+    /// for each individual condition. Locktime types must not be mixed or else a
+    /// [`PlanError`] is returned.
+    pub(crate) fn merge_condition(mut self, other: Condition) -> Result<Self, PlanError> {
+        self.timelock = Self::merge_abs_locktime(self.timelock, other.timelock)?;
+
+        match (self.csv, other.csv) {
+            (Some(a), Some(b)) => self.csv = Some(merge_nsequence(a, b)?),
+            (None, b) => self.csv = b,
+            _ => {}
+        }
+
+        Ok(self)
+    }
+}

crates/wallet/src/wallet/error.rs

@@ -11,13 +11,12 @@
 
 //! Errors that can be thrown by the [`Wallet`](crate::wallet::Wallet)
 
-use crate::descriptor::policy::PolicyError;
-use crate::descriptor::DescriptorError;
+use crate::descriptor::{self, DescriptorError};
 use crate::wallet::coin_selection;
-use crate::{descriptor, KeychainKind};
 use alloc::string::String;
 use bitcoin::{absolute, psbt, Amount, OutPoint, Sequence, Txid};
 use core::fmt;
+use miniscript::{DefiniteDescriptorKey, Descriptor};
 
 /// Errors returned by miniscript when updating inconsistent PSBTs
 #[derive(Debug, Clone)]
@@ -43,17 +42,34 @@ impl fmt::Display for MiniscriptPsbtError {
 #[cfg(feature = "std")]
 impl std::error::Error for MiniscriptPsbtError {}
 
+/// Error when preparing the conditions of a spending plan
+#[derive(Debug, Clone)]
+pub enum PlanError {
+    /// Attempted to mix height- and time-based locktimes
+    MixedTimelockUnits,
+    /// Error creating a spend [`Plan`](miniscript::plan::Plan)
+    Plan(Descriptor<DefiniteDescriptorKey>),
+}
+
+impl fmt::Display for PlanError {
+    fn fmt(&self, f: &mut fmt::Formatter<'_>) -> fmt::Result {
+        match self {
+            Self::MixedTimelockUnits => write!(f, "cannot mix locktime units"),
+            Self::Plan(d) => write!(f, "failed to create plan for descriptor {}", d),
+        }
+    }
+}
+
+#[cfg(feature = "std")]
+impl std::error::Error for PlanError {}
+
 #[derive(Debug)]
 /// Error returned from [`TxBuilder::finish`]
 ///
 /// [`TxBuilder::finish`]: crate::wallet::tx_builder::TxBuilder::finish
 pub enum CreateTxError {
     /// There was a problem with the descriptors passed in
     Descriptor(DescriptorError),
-    /// There was a problem while extracting and manipulating policies
-    Policy(PolicyError),
-    /// Spending policy is not compatible with this [`KeychainKind`]
-    SpendingPolicyRequired(KeychainKind),
     /// Requested invalid transaction version '0'
     Version0,
     /// Requested transaction version `1`, but at least `2` is needed to use OP_CSV
@@ -104,16 +120,14 @@ pub enum CreateTxError {
     MissingNonWitnessUtxo(OutPoint),
     /// Miniscript PSBT error
     MiniscriptPsbt(MiniscriptPsbtError),
+    /// Error creating a spending plan
+    Plan(PlanError),
 }
 
 impl fmt::Display for CreateTxError {
     fn fmt(&self, f: &mut fmt::Formatter<'_>) -> fmt::Result {
         match self {
             Self::Descriptor(e) => e.fmt(f),
-            Self::Policy(e) => e.fmt(f),
-            CreateTxError::SpendingPolicyRequired(keychain_kind) => {
-                write!(f, "Spending policy required: {:?}", keychain_kind)
-            }
             CreateTxError::Version0 => {
                 write!(f, "Invalid version `0`")
             }
@@ -171,6 +185,9 @@ impl fmt::Display for CreateTxError {
             CreateTxError::MiniscriptPsbt(err) => {
                 write!(f, "Miniscript PSBT error: {}", err)
             }
+            CreateTxError::Plan(e) => {
+                write!(f, "{}", e)
+            }
         }
     }
 }
@@ -181,12 +198,6 @@ impl From<descriptor::error::Error> for CreateTxError {
     }
 }
 
-impl From<PolicyError> for CreateTxError {
-    fn from(err: PolicyError) -> Self {
-        CreateTxError::Policy(err)
-    }
-}
-
 impl From<MiniscriptPsbtError> for CreateTxError {
     fn from(err: MiniscriptPsbtError) -> Self {
         CreateTxError::MiniscriptPsbt(err)