From 832ef852fbab9de2395ed0654198e90936e559ae Mon Sep 17 00:00:00 2001
From: Noah Gundotra <ngundotra@users.noreply.github.com>
Date: Mon, 26 Aug 2024 17:13:33 -0400
Subject: [PATCH] Add support for showing self-cpi (#364)

Fixes issue where events were not parsed for self-cpi's executed via
`emit_cpi!` in Anchor.

See example:
https://explorer.solana.com/tx/2iofwLXfEDjEqvGZNMuCzZF8TEGyvfogCVf4oDnAATLpGkUbSfPe7ZBuqNoNXzaV2Xb33AT7PRYd9HztdbTvF3GR?cluster=devnet
---
 .../instruction/AnchorDetailsCard.tsx         | 34 ++++++++++++++-----
 app/utils/anchor.tsx                          | 11 ++++++
 2 files changed, 37 insertions(+), 8 deletions(-)

diff --git a/app/components/instruction/AnchorDetailsCard.tsx b/app/components/instruction/AnchorDetailsCard.tsx
index af43bdd2..22186519 100644
--- a/app/components/instruction/AnchorDetailsCard.tsx
+++ b/app/components/instruction/AnchorDetailsCard.tsx
@@ -1,11 +1,12 @@
 import { Address } from '@components/common/Address';
-import { BorshInstructionCoder, Idl, Instruction, Program } from '@project-serum/anchor';
-import { IdlInstruction } from '@project-serum/anchor/dist/cjs/idl';
+import { BorshEventCoder, BorshInstructionCoder, Idl, Instruction, Program } from '@project-serum/anchor';
+import { IdlEvent, IdlInstruction } from '@project-serum/anchor/dist/cjs/idl';
 import { SignatureResult, TransactionInstruction } from '@solana/web3.js';
 import {
     getAnchorAccountsFromInstruction,
     getAnchorNameForInstruction,
     getAnchorProgramName,
+    instructionIsSelfCPI,
     mapIxArgsToRows,
 } from '@utils/anchor';
 import { camelToTitleCase } from '@utils/index';
@@ -48,12 +49,29 @@ function AnchorDetails({ ix, anchorProgram }: { ix: TransactionInstruction; anch
         let decodedIxData: Instruction | null = null;
         let ixDef: IdlInstruction | undefined;
         if (anchorProgram) {
-            const coder = new BorshInstructionCoder(anchorProgram.idl);
-            decodedIxData = coder.decode(ix.data);
-            if (decodedIxData) {
-                ixDef = anchorProgram.idl.instructions.find(ixDef => ixDef.name === decodedIxData?.name);
-                if (ixDef) {
-                    ixAccounts = getAnchorAccountsFromInstruction(decodedIxData, anchorProgram);
+            let coder: BorshInstructionCoder | BorshEventCoder;
+            if (instructionIsSelfCPI(ix.data)) {
+                coder = new BorshEventCoder(anchorProgram.idl);
+                decodedIxData = coder.decode(ix.data.slice(8).toString('base64'));
+                const ixEventDef = anchorProgram.idl.events?.find(
+                    ixDef => ixDef.name === decodedIxData?.name
+                ) as IdlEvent;
+
+                // Remap the event definition to an instruction definition
+                ixDef = { ...ixEventDef, accounts: [], args: ixEventDef.fields };
+
+                // Self-CPI instructions have 1 account called the eventAuthority
+                // https://github.com/coral-xyz/anchor/blob/04985802587c693091f836e0083e4412148c0ca6/lang/attribute/event/src/lib.rs#L165
+                ixAccounts = [{ isMut: false, isSigner: true, name: 'eventAuthority' }];
+            } else {
+                coder = new BorshInstructionCoder(anchorProgram.idl);
+                decodedIxData = coder.decode(ix.data);
+
+                if (decodedIxData) {
+                    ixDef = anchorProgram.idl.instructions.find(ixDef => ixDef.name === decodedIxData?.name);
+                    if (ixDef) {
+                        ixAccounts = getAnchorAccountsFromInstruction(decodedIxData, anchorProgram);
+                    }
                 }
             }
         }
diff --git a/app/utils/anchor.tsx b/app/utils/anchor.tsx
index adc55ab6..076924ba 100644
--- a/app/utils/anchor.tsx
+++ b/app/utils/anchor.tsx
@@ -10,6 +10,13 @@ import React, { Fragment, ReactNode, useState } from 'react';
 import { ChevronDown, ChevronUp, CornerDownRight } from 'react-feather';
 import ReactJson from 'react-json-view';
 
+const ANCHOR_SELF_CPI_TAG = Buffer.from('1d9acb512ea545e4', 'hex').reverse();
+const ANCHOR_SELF_CPI_NAME = 'Anchor Self Invocation';
+
+export function instructionIsSelfCPI(ixData: Buffer): boolean {
+    return ixData.slice(0, 8).equals(ANCHOR_SELF_CPI_TAG);
+}
+
 export function getAnchorProgramName(program: Program | null): string | undefined {
     return program && 'name' in program.idl ? snakeToTitleCase(program.idl.name) : undefined;
 }
@@ -38,6 +45,10 @@ export function ProgramName({ programId, cluster, url }: { programId: PublicKey;
 }
 
 export function getAnchorNameForInstruction(ix: TransactionInstruction, program: Program): string | null {
+    if (instructionIsSelfCPI(ix.data)) {
+        return ANCHOR_SELF_CPI_NAME;
+    }
+
     const coder = new BorshInstructionCoder(program.idl);
     const decodedIx = coder.decode(ix.data);