Refactor analyzepsbt for use outside RPC code

Refactor the analyzepsbt RPC into (1) an AnalyzePSBT function, which returns
its output as a new strongly-typed PSBTAnalysis struct, and (2) a thin wrapper
which converts the struct into a UniValue for RPC use.

1 files changed, 39 insertions, 1 deletions

diff --git a/src/psbt.h b/src/psbt.h
index d89fd68c21..0f17a71a44 100644
--- a/src/psbt.h
+++ b/src/psbt.h
@@ -7,6 +7,8 @@
 
 #include <attributes.h>
 #include <node/transaction.h>
+#include <optional.h>
+#include <policy/feerate.h>
 #include <primitives/transaction.h>
 #include <pubkey.h>
 #include <script/sign.h>
@@ -548,8 +550,36 @@ struct PartiallySignedTransaction
     }
 };
 
+enum class PSBTRole {
+    UPDATER,
+    SIGNER,
+    FINALIZER,
+    EXTRACTOR
+};
+
+struct PSBTInputAnalysis {
+    bool has_utxo;
+    bool is_final;
+    PSBTRole next;
+
+    std::vector<CKeyID> missing_pubkeys;
+    std::vector<CKeyID> missing_sigs;
+    uint160 missing_redeem_script;
+    uint256 missing_witness_script;
+};
+
+struct PSBTAnalysis {
+    Optional<size_t> estimated_vsize;
+    Optional<CFeeRate> estimated_feerate;
+    Optional<CAmount> fee;
+    std::vector<PSBTInputAnalysis> inputs;
+    PSBTRole next;
+};
+
+std::string PSBTRoleName(PSBTRole role);
+
 /** Checks whether a PSBTInput is already signed. */
-bool PSBTInputSigned(PSBTInput& input);
+bool PSBTInputSigned(const PSBTInput& input);
 
 /** Signs a PSBTInput, verifying that all provided data matches what is being signed. */
 bool SignPSBTInput(const SigningProvider& provider, PartiallySignedTransaction& psbt, int index, int sighash = SIGHASH_ALL, SignatureData* out_sigdata = nullptr, bool use_dummy = false);
@@ -580,6 +610,14 @@ bool FinalizeAndExtractPSBT(PartiallySignedTransaction& psbtx, CMutableTransacti
  */
 NODISCARD TransactionError CombinePSBTs(PartiallySignedTransaction& out, const std::vector<PartiallySignedTransaction>& psbtxs);
 
+/**
+ * Provides helpful miscellaneous information about where a PSBT is in the signing workflow.
+ *
+ * @param[in] psbtx the PSBT to analyze
+ * @return A PSBTAnalysis with information about the provided PSBT.
+ */
+PSBTAnalysis AnalyzePSBT(PartiallySignedTransaction psbtx);
+
 //! Decode a base64ed PSBT into a PartiallySignedTransaction
 NODISCARD bool DecodeBase64PSBT(PartiallySignedTransaction& decoded_psbt, const std::string& base64_psbt, std::string& error);
 //! Decode a raw (binary blob) PSBT into a PartiallySignedTransaction