[Invoke Contract] Create a dropdown & retrieve function methods

src/app/(sidebar)/transaction/build/components/Operations.tsx

@@ -851,6 +851,9 @@ export const Operations = () => {
           <option value="extend_footprint_ttl">
             Extend Footprint TTL (Soroban)
           </option>
+          <option value="invoke_contract_function">
+            Invoke Contract Function (Soroban)
+          </option>
           <option value="payment">Payment</option>
           <option value="path_payment_strict_send">
             Path Payment Strict Send

src/app/(sidebar)/transaction/build/components/SorobanOperation.tsx

@@ -158,6 +158,7 @@ export const SorobanOperation = ({
                     case "extend_ttl_to":
                     case "resource_fee":
                     case "durability":
+                    case "invoke_contract":
                       return component.render({
                         ...sorobanBaseProps,
                         onChange: (e: ChangeEvent<HTMLInputElement>) => {

src/app/(sidebar)/transaction/submit/page.tsx

@@ -83,7 +83,7 @@ const isSorobanXdr = (xdrJsonString: string) => {
       return (
         "extend_footprint_ttl" in body ||
         "restore_footprint" in body ||
-        "invoke_host_function" in body
+        "invoke_contract_function" in body
       );
     });
   } catch (e) {

src/components/FormElements/ContractMethodSelectPicker.tsx

@@ -0,0 +1,36 @@
+import { useState } from "react";
+
+import { Select } from "@stellar/design-system";
+
+export const ContractMethodSelectPicker = ({
+  methods,
+  id,
+}: {
+  methods: string[];
+  id: string;
+}) => {
+  const [selectedValue, setSelectedValue] = useState<string>("");
+
+  const onChange = (e: React.ChangeEvent<HTMLSelectElement>) => {
+    setSelectedValue(e.target.value);
+  };
+
+  return (
+    <Select
+      fieldSize="md"
+      label="Select a function method"
+      id={id}
+      value={selectedValue}
+      onChange={onChange}
+    >
+      {methods.map((method) => (
+        <option key={method} value={method}>
+          {method}
+        </option>
+      ))}
+    </Select>
+
+    // @TODO
+    // Render func args
+  );
+};

src/components/FormElements/FetchContractMethodPickerWithQuery.tsx

@@ -0,0 +1,125 @@
+import React, { useState } from "react";
+import { Button } from "@stellar/design-system";
+
+import { Box } from "@/components/layout/Box";
+import { ContractMethodSelectPicker } from "@/components/FormElements/ContractMethodSelectPicker";
+import { TextPicker } from "@/components/FormElements/TextPicker";
+import { MessageField } from "@/components/MessageField";
+
+import {
+  fetchContractFunctionMethods,
+  ContractFunctionMethods,
+} from "@/helpers/sorobanUtils";
+
+import { useStore } from "@/store/useStore";
+import { validate } from "@/validate";
+
+interface FetchContractMethodPickerWithQueryProps {
+  id: string;
+  value: string;
+  error?: string | undefined;
+  label?: string;
+  disabled?: boolean;
+  onChange?: (e: React.ChangeEvent<HTMLInputElement>) => void;
+}
+
+/**
+ * FetchContractMethodPickerWithQuery
+ *
+ * This component is used to fetch the contract methods for a given contract id.
+ * It is used in the SorobanOperation component.
+ *
+ */
+export const FetchContractMethodPickerWithQuery = ({
+  id,
+  value,
+  error,
+  label,
+  disabled,
+  onChange,
+}: FetchContractMethodPickerWithQueryProps) => {
+  const { network } = useStore();
+
+  const [contractIdError, setContractIdError] = useState<string>("");
+  const [contractMethods, setContractMethods] = useState<string[]>([]);
+  const [fetchError, setFetchError] = useState<string>("");
+
+  const onContractIdChange = (e: React.ChangeEvent<HTMLInputElement>) => {
+    // reset the error and methods
+    setFetchError("");
+    setContractMethods([]);
+
+    // call the onChange callback
+    onChange?.(e);
+
+    // validate the contract id
+    if (e.target.value) {
+      const validatedContractIdError = validate.getContractIdError(
+        e.target.value,
+      );
+
+      if (validatedContractIdError) {
+        setContractIdError(validatedContractIdError);
+      } else {
+        setContractIdError("");
+      }
+    }
+  };
+
+  const handleFetchContractMethods = async () => {
+    setFetchError("");
+
+    const contractMethods: ContractFunctionMethods =
+      await fetchContractFunctionMethods({
+        contractId: value,
+        networkPassphrase: network.passphrase,
+        rpcUrl: network.rpcUrl,
+      });
+
+    if (contractMethods.methods) {
+      setContractMethods(contractMethods.methods);
+    }
+
+    if (contractMethods.error) {
+      setFetchError(contractMethods.error);
+    }
+  };
+
+  return (
+    <Box gap="md">
+      <TextPicker
+        key={id}
+        id={id}
+        label={label}
+        placeholder="Ex: CDLZFC3SYJYDZT7K67VZ75HPJVIEUVNIXF47ZG2FB2RMQQVU2HHGCYSC"
+        value={value || ""}
+        error={error || contractIdError}
+        onChange={onContractIdChange}
+        disabled={disabled}
+      />
+
+      <Box gap="md" direction="row" wrap="wrap">
+        <Button
+          disabled={!value || Boolean(contractIdError)}
+          variant="secondary"
+          size="md"
+          onClick={handleFetchContractMethods}
+          type="button"
+        >
+          Fetch contract methods
+        </Button>
+
+        <>{fetchError ? <MessageField message={fetchError} isError /> : null}</>
+      </Box>
+
+      <>
+        {contractMethods.length ? (
+          <ContractMethodSelectPicker
+            methods={contractMethods}
+            id={`${id}-method`}
+          />
+        ) : null}
+      </>
+    </Box>
+  );
+};

src/components/formComponentTemplateTxnOps.tsx

@@ -16,6 +16,7 @@ import { NumberFractionPicker } from "@/components/FormElements/NumberFractionPi
 import { RevokeSponsorshipPicker } from "@/components/FormElements/RevokeSponsorshipPicker";
 import { ClaimantsPicker } from "@/components/FormElements/ClaimantsPicker";
 import { ResourceFeePickerWithQuery } from "@/components/FormElements/ResourceFeePickerWithQuery";
+import { FetchContractMethodPickerWithQuery } from "@/components/FormElements/FetchContractMethodPickerWithQuery";
 
 import { removeLeadingZeroes } from "@/helpers/removeLeadingZeroes";
 
@@ -476,6 +477,7 @@ export const formComponentTemplateTxnOps = ({
         ),
         validate: null,
       };
+    // Soroban Only
     case "resource_fee":
       return {
         render: (templ: SorobanTemplateRenderProps) => (
@@ -502,6 +504,23 @@ export const formComponentTemplateTxnOps = ({
         ),
         validate: validate.getPositiveNumberError,
       };
+    // Soroban Only
+    case "invoke_contract":
+      return {
+        render: (templ: SorobanTemplateRenderProps) => {
+          return (
+            <FetchContractMethodPickerWithQuery
+              id={id}
+              label="Invoke Contract"
+              value={templ.value || ""}
+              error={templ.error}
+              onChange={templ.onChange}
+              disabled={templ.isDisabled}
+            />
+          );
+        },
+        validate: null,
+      };
     case "limit":
       return {
         render: (templ: TemplateRenderProps) => (

src/constants/transactionOperations.tsx

@@ -386,6 +386,15 @@ export const TRANSACTION_OPERATIONS: { [key: string]: TransactionOperation } = {
       },
     },
   },
+  invoke_contract_function: {
+    label: "Invoke Contract Function",
+    description:
+      "Invoke a function of the deployed contract using 'HOST_FUNCTION_TYPE_INVOKE_CONTRACT' from Invoke Host Function.",
+    docsUrl:
+      "https://developers.stellar.org/docs/learn/fundamentals/transactions/list-of-operations#invoke-host-function",
+    params: ["invoke_contract", "resource_fee"],
+    requiredParams: ["invoke_contract", "resource_fee"],
+  },
   revoke_sponsorship: {
     label: "Revoke Sponsorship",
     description: "Revoke sponsorship of a ledger entry.",

src/helpers/sorobanUtils.ts

@@ -1,4 +1,5 @@
 import {
+  contract,
   Address,
   Contract,
   Operation,
@@ -12,9 +13,16 @@ import {
 import { TransactionBuildParams } from "@/store/createStore";
 import { SorobanOpType, TxnOperation } from "@/types/types";
 
+export type ContractFunctionMethods = {
+  methods: string[];
+  error: string;
+};
+
 export const isSorobanOperationType = (operationType: string) => {
-  // @TODO: add restore_footprint and invoke_host_function
-  return ["extend_footprint_ttl"].includes(operationType);
+  // @TODO: add restore_footprint
+  return ["extend_footprint_ttl", "invoke_contract_function"].includes(
+    operationType,
+  );
 };
 
 // https://developers.stellar.org/docs/learn/glossary#ledgerkey
@@ -151,6 +159,39 @@ export const buildSorobanTx = ({
     .build();
 };
 
+export const fetchContractFunctionMethods = async ({
+  contractId,
+  networkPassphrase,
+  rpcUrl,
+}: {
+  contractId: string;
+  networkPassphrase: string;
+  rpcUrl: string;
+}): Promise<ContractFunctionMethods> => {
+  try {
+    const client = await contract.Client.from({
+      contractId,
+      networkPassphrase,
+      rpcUrl,
+    });
+
+    // on how to get the function methods from the contract
+    // https://github.com/stellar/js-stellar-sdk/blob/master/test/unit/spec/contract_spec.ts
+    const spec = client.spec;
+    const methods = spec.funcs();
+
+    return {
+      methods: methods.map((method) => method.name().toString()),
+      error: "",
+    };
+  } catch (e: any) {
+    return {
+      methods: [],
+      error: `error while fetching contract information: ${e?.message ? e?.message : e}`,
+    };
+  }
+};
+
 // Preparing Soroban Transaction Data
 const buildSorobanData = ({
   readOnlyXdrLedgerKey = [],

src/types/types.ts

@@ -249,7 +249,7 @@ export type SponsorshipType =
 // =============================================================================
 // Soroban Operations
 // =============================================================================
-export type SorobanOpType = "extend_footprint_ttl";
+export type SorobanOpType = "extend_footprint_ttl" | "invoke_contract_function";
 
 // =============================================================================
 // RPC