chore: Create Midnight Transaction Builder

Cargo.toml

@@ -28,11 +28,17 @@ actix-governor = "0.8"
 actix-rt = "2.0.0"
 actix-web = "4"
 alloy = { version = "0.9", features = ["full"] }
-apalis = { version = "0.7", features = ["limit", "retry", "catch-panic", "timeout"] }
+apalis = { version = "0.7", features = [
+    "limit",
+    "retry",
+    "catch-panic",
+    "timeout",
+] }
 apalis-cron = { version = "0.7" }
 apalis-redis = { version = "0.7" }
 async-trait = "0.1"
-base64 = { version =  "0.22" }
+backoff = { version = "0.4.0", features = ["tokio"] }
+base64 = { version = "0.22" }
 bech32 = "0.11.0"
 bincode = { version = "1.3" }
 bs58 = "0.5"
@@ -46,19 +52,21 @@ eyre = "0.6"
 futures = "0.3"
 google-cloud-auth = "0.20.0"
 governor = "0.8.0"
-hex = { version = "0.4"}
+hex = { version = "0.4" }
 hmac = { version = "0.12" }
 http = { version = "1.3.1" }
 itertools = "0.12.0" # Required by midnight
 k256 = { version = "0.13" }
 lazy_static = "1.5"
 libsodium-sys = "0.2.7"
 log = "0.4"
+midnight-ledger-prototype = { git = "https://github.com/midnightntwrk/midnight-ledger-prototype", package = "midnight-ledger", tag = "ledger-4.0.0" }
 midnight-node-ledger-helpers = { git = "https://github.com/midnightntwrk/midnight-node", package = "midnight-node-ledger-helpers", tag = "node-0.12.0" }
+midnight-node-res = { git = "https://github.com/midnightntwrk/midnight-node", package = "midnight-node-res", tag = "node-0.12.0" }
 mpl-token-metadata = { version = "5.1" }
 num_enum = { version = "0.7", default-features = false }
 once_cell = "1.17"
-oz-keystore = { version = "0.1.4"}
+oz-keystore = { version = "0.1.4" }
 p256 = { version = "0.13.2" }
 parking_lot = "0.12"
 pem = { version = "3" }
@@ -67,7 +75,7 @@ rand = "0.9"
 redis = { version = "0.31" }
 regex = "1"
 reqwest = { version = "0.12", features = ["json"] }
-secrets = { version = "1.2"}
+secrets = { version = "1.2" }
 serde = { version = "1.0", features = ["derive", "alloc"] }
 serde_json = "1"
 sha2 = { version = "0.10" }
@@ -83,6 +91,7 @@ stellar-strkey = "0.0.12"
 strum = { version = "0.27", default-features = false, features = ["derive"] }
 strum_macros = "0.27"
 subtle = "2.6"
+subxt = "0.37.0"
 sysinfo = "0.35"
 thiserror = "2"
 tokio = { version = "1.43", features = ["sync", "io-util", "time"] }

src/domain/transaction/midnight/builder.rs

@@ -0,0 +1,141 @@
+//! Midnight transaction builder
+//!
+//! This module provides a builder pattern for constructing Midnight transactions
+//! following the midnight-node patterns.
+//!
+//! IMPORTANT: When creating transactions, always include a change output back to the sender
+//! if there's any remaining value after accounting for the recipient amount and fees.
+//! This ensures the indexer recognizes the transaction as relevant to the sender's wallet
+//! during synchronization.
+
+use midnight_node_ledger_helpers::{
+    FromContext,
+    IntentInfo,
+    LedgerContext,
+    OfferInfo,
+    Proof,
+    ProofProvider,
+    // StandardTrasactionInfo has a typo and may be changed in the future
+    StandardTrasactionInfo,
+    Transaction,
+    WellFormedStrictness,
+    DB,
+};
+use std::sync::Arc;
+
+use crate::models::TransactionError;
+
+/// Builder for constructing Midnight transactions using midnight-node patterns
+pub struct MidnightTransactionBuilder<D: DB> {
+    /// The ledger context containing wallet and network information
+    context: Option<Arc<LedgerContext<D>>>,
+    /// The proof provider for generating ZK proofs
+    proof_provider: Option<Box<dyn ProofProvider<D>>>,
+    /// Random seed for transaction building
+    rng_seed: Option<[u8; 32]>,
+    /// The guaranteed offer to be added
+    guaranteed_offer: Option<OfferInfo<D>>,
+    /// Intent info containing all fallible offers with segment information preserved
+    intent_info: Option<IntentInfo<D>>,
+}
+
+impl<D: DB> MidnightTransactionBuilder<D> {
+    /// Creates a new transaction builder
+    pub fn new() -> Self {
+        Self {
+            context: None,
+            proof_provider: None,
+            rng_seed: None,
+            guaranteed_offer: None,
+            intent_info: None,
+        }
+    }
+
+    /// Sets the ledger context
+    pub fn with_context(mut self, context: std::sync::Arc<LedgerContext<D>>) -> Self {
+        self.context = Some(context);
+        self
+    }
+
+    /// Sets the proof provider
+    pub fn with_proof_provider(mut self, proof_provider: Box<dyn ProofProvider<D>>) -> Self {
+        self.proof_provider = Some(proof_provider);
+        self
+    }
+
+    /// Sets the RNG seed
+    pub fn with_rng_seed(mut self, seed: [u8; 32]) -> Self {
+        self.rng_seed = Some(seed);
+        self
+    }
+
+    /// Sets the entire guaranteed offer
+    pub fn with_guaranteed_offer(mut self, offer: OfferInfo<D>) -> Self {
+        self.guaranteed_offer = Some(offer);
+        self
+    }
+
+    /// Set the intent info
+    pub fn with_intent_info(mut self, intent: IntentInfo<D>) -> Self {
+        self.intent_info = Some(intent);
+        self
+    }
+
+    /// Builds the final transaction
+    pub async fn build(self) -> Result<Transaction<Proof, D>, TransactionError> {
+        let context_arc = self
+            .context
+            .ok_or_else(|| TransactionError::ValidationError("Context not provided".to_string()))?;
+        let proof_provider = self.proof_provider.ok_or_else(|| {
+            TransactionError::ValidationError("Proof provider not provided".to_string())
+        })?;
+        let rng_seed = self.rng_seed.ok_or_else(|| {
+            TransactionError::ValidationError("RNG seed not provided".to_string())
+        })?;
+
+        // Create StandardTransactionInfo with the context
+        let mut tx_info = StandardTrasactionInfo::new_from_context(
+            context_arc.clone(),
+            proof_provider.into(),
+            Some(rng_seed),
+        );
+
+        // Set the guaranteed offer if present
+        if let Some(offer) = self.guaranteed_offer {
+            tx_info.set_guaranteed_coins(offer);
+        }
+
+        // Set the intent info if present to preserve segment information
+        if let Some(intent) = self.intent_info {
+            tx_info.set_intents(vec![intent]);
+        }
+
+        // Build transaction and generate proofs
+        let proven_tx = tx_info.prove().await;
+
+        // Get the ledger state from the context
+        let ledger_state_guard = context_arc.ledger_state.lock().map_err(|e| {
+            TransactionError::UnexpectedError(format!("Failed to acquire ledger state lock: {}", e))
+        })?;
+
+        let ref_state = &*ledger_state_guard;
+
+        // Perform well_formed validation
+        proven_tx
+            .well_formed(ref_state, WellFormedStrictness::default())
+            .map_err(|e| {
+                TransactionError::ValidationError(format!(
+                    "Transaction failed well_formed validation: {:?}",
+                    e
+                ))
+            })?;
+
+        Ok(proven_tx)
+    }
+}
+
+impl<D: DB> Default for MidnightTransactionBuilder<D> {
+    fn default() -> Self {
+        Self::new()
+    }
+}